Paediatric Imaging Manual (Notes in Radiology)

Jochen Tröger Peter Seidensticker Paediatric Imaging Manual Jochen Tröger Peter Seidensticker Paediatric Imaging Man...

Author: Jochen Troger | Peter R. Seidensticker

304 downloads 1541 Views 7MB Size Report

This content was uploaded by our users and we assume good faith they have the permission to share this book. If you own the copyright to this book and it is wrongfully on our website, we offer a simple DMCA procedure to remove your content from our site. Start by pressing the button below!
Report copyright / DMCA form

DOWNLOAD PDF

Jochen Tröger Peter Seidensticker Paediatric Imaging Manual

Jochen Tröger Peter Seidensticker

Paediatric Imaging Manual With 273 Figures and 18 Tables

123

Jochen Tröger Head of Department of Paediatric Imaging Paediatric Radiology University of Heidelberg Im Neuenheimer Feld 153 69120 Heidelberg Germany

Peter Seidensticker Global Medical Affairs Diagnostic Imaging Bayer-Schering-Pharma AG Müller Straße 178 13342 Berlin Germany

Project coordination: Bayer-Schering-Pharma AG and Bayer HealthCare Pharmaceuticals, Inc., Global Medical Affairs, Diagnostic Imaging.

ISBN 978-3-540-34964-8 Springer Medizin Verlag Heidelberg Bibliografische Information der Deutschen Bibliothek The Deutsche Bibliothek lists this publication in Deutsche Nationalbibliographie; detailed bibliographic data is available in the internet at http://dnb.ddb.de.

This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable to prosecution under the German Copyright Law.

Springer Medizin Verlag springer.com © Springer Medizin Verlag Heidelberg 2008 The use of general descriptive names, registered names, trademarks, etc. in this publications does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Product liability: The publishers cannot guarantee the accuracy of any information about dosage and application contained in this book. In every individual case the user must check such information by consulting the relevant literature.

SPIN 11770107 Typesetting: TypoStudio Tobias Schaedla, Heidelberg Printing: Grosch! Druckzentrum GmbH, Heidelberg 18/5135 – 5 4 3 2 1 0

V

Preface Imaging of newborns, infants, children and adolescents Children and adolescents are not simply small adults; they suffer from different diseases and require dif ferent tr eatments. The s ame is tr ue where imagin g is co ncerned. The diagnostic strategies – usin g identical diag nostic instruments – a re dif ferent; t he care prior to, during, and following the examination differs from that of adults. For this reason, there exists in many countries a specialized line of advanced training for paediatric radiology. However, students make only a peripheral acquaintance with paediatric radiology d uring t heir s tudies. U nderstandably, paedia tricians lac k no t o nly t he a bility t o interpret the images, but also knowledge about the importance of a f inding for the next st ep toward a diagnosis and thus for treatment. And in many cases, general radiologists have insufficient contact with paediatric radiology during their course of advanced training. The a im o f t his b ook, t herefore, is t o p rovide r eadily a vailable inf ormation, limi ted t o what is essential, for physicians doing advanced training in radiology and paediatrics and for advanced students concerning the most important aspects of imaging in newborns, children, and adolescents. The diagnostic stra tegies us ed f or c hildren dif fer f rom t hose us ed f or ad ults in ma ny respects. One o f the most im portant aspects is radia tion protection, as c hildren are particularly sensitive to ionizing radiation and, with their longer life expectancy, can also expect to accumulate a hig her dose from natural and artificial – a bove all medical – ca uses. The latter increase the individual risk (malignant disease) as well as the genetic risk. The b est radia tion p rotection is t he a voidance o f a n exa mination em ploying io nizing radiation (X-ra ys, CT s can). This is acco mplished, o n t he o ne ha nd, b y est ablishing st rict indications (for example, no X-rays following trauma to the cranial vault or no imaging of the paranasal sinuses in case of acute sinusitis) and, on the other hand, if possible, by substituting ultrasonography or magnetic resonance imaging for X-rays or computer tomography. In addition to the aspect of radiation protection, however, there is als o a p hysical reason for the great value of ultrasonography in paediatric radiology. High frequencies allow for high diagnostic quality but entail less penetration depth. Given the lesser body volume of children, higher frequencies can be used in them. This is one of the reasons why ultrasonography is of greater value in paediatric radiology than in adult radiology. Therefore, diagnostic flow charts generated from adult imaging may not be applied 1:1 to paediatric radiology. Several examples will serve to substantiate the high and still incr easing value of ultrasonography in paedia tric and adolescent medicine. For the diagnosis of urinary flow disorder ultrasonography has replaced excretory urography in many areas, with the result that excretory urography has become a rare examination in paediatric radiology. Hip sonography has r eplaced the X-ray for diagnosing hip dysplasia or luxation in an infant. MRI can replace CT in most cas es of abdominal tumors. Kidney function can also be analyzed be means of functional MRI (MRI with determination of function). The list of these changes in diagnostic practice could be continued. A further aspect of radiation protection concerns the number of X-ray images made and the way in w hich an examination with ionizing radiation is p erformed. In paediatric radiology, a p.a. or an a.p. image of the thorax provides sufficient clinically necessary information in 70–80% o f cases. The r equest for X-rays should therefore not state »thorax at two levels« but rather »thorax p.a.«; the decision to take a further image can be made on the basis of the

VI

Preface

reading of the first image, if necessary. Fluoroscopic examinations must almost always be carried out using the radiation-reducing pulsed X-ray. For this it is en tirely possible to accept a reduction in image quality, as long as the diagnostic certainty is not diminished. Necessary CT exa minations must b e p erformed acco rding t o a p rotocol adapted t o t he child’s age, with a lesser dose. Active radiation protection is o f ess ential importance for c hildren and ado lescents. The protective measures should not lead to a r eduction in diagnostic r eliability, however. X-rays and CT remain an indispensable component of imaging for children. Without them, modern medicine, in pa rticular emergency medicine, would b e unthinkable. Thus it is no t a ma tter of preventing the application of ionizing radiation, but of its responsible use where necessary and of substitution with non-ionizing radiation where possible. The ALARA principle states: »As Low As Reasonably Achievable«, in other words, the lowest dose possible and the largest necessary. This book was written intentionally as a concise work of reference. We have done without technical details and without descriptions of examination procedures. An important difference in comparison to radiology for the adult lies in the diagnostic and therapeutic consequences that many findings entail. For instance, a sharply delimited zone of enhanced radiation transparency without soft-tissue swelling, lying decentralized in the metaphysis of a long bone of a 9-year-old asymptomatic child (X-ray imaging following trauma) is simply a nonosteogenic fibroma: Neither section imaging nor clinical monitoring is necessary, and by no means is a biopsy required. In a further example, a movable cystic space-occupying lesion with or without small floating particles next to o r above the urinary bladder in a g irl represents an ovarian cyst with or without internal bleeding. This f inding frequently recedes spontaneously. These are only a few of many possible examples. This book was written by several authors from various countries. The culture of examination often differs even within a co untry. We have intentionally avoided comparing examinations or expounding at length upon the differences in each case. Both methods are always logical and justifiable. The diagnosis of vesicorenal reflux in Heidelberg by means of an ultrasound examination is w ell-founded; els ewhere a n X-ra y exa mination – na turally usin g extr emely radiation s aving pulsed f luoroscopy – is fa vored. The s cientific dis cussion has no t yet b een concluded. However, it should not be allowed to become a purely economic discussion. We t hank t he a uthors f or t he hig h-quality ma nuscripts t hey p rovided. We als o t hank Springer-Verlag – a nd especially Mr. Henquinet – f or their patient, very competent work as publishers. Finally, working as a doctor requires continuous training and obtaining a specialization is an important aspect of that process. We are pleased that this publication has been rated by the state Medical Association of Baden-Württemberg with 4 CME points. Jochen Tröger Heidelberg

P B

eter Seidensticker erlin

VII

Contents 1

1.1 1.2 1.3 1.4 1.5

2

2.1 2.1.1 2.2 2.2.1 2.2.2 2.2.3 2.3 2.3.1 2.3.2 2.3.3 2.3.4 2.4 2.4.1 2.4.2 2.5

3 3.1 3.2 3.3 3.4 3.5 3.6 3.7

Radiation bio effects and dose reduction strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Donald P. Frush Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Mechanisms of radiation injury . . . . . . . . . . . . . . . . . . . . . 1 Doses of medical radiation . . . . . . . . . . . . . . . . . . . . . . . . . 1 Risks of medical radiation . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Strategies for radiation dose management. . . . . . . . . . 2 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Contrast media: posology, risks and side effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Magdalena M. WoŹniak General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Posology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Barium preparations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 MRI contrast agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Ultrasound contrast agents. . . . . . . . . . . . . . . . . . . . . . . . . 8 Contra-indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Iodine contrast agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Barium preparations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 MRI contrast agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Ultrasound contrast agents . . . . . . . . . . . . . . . . . . . . . . . . 9 Adverse reactions to contrast agents and their management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Types of adverse reactions . . . . . . . . . . . . . . . . . . . . . . . .10 Treatment of adverse reactions to contrast material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Remember! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Head and Neck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Thierry A.G.M. Huisman Developmental anomalies of the central nervous system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 Hypoxic-ischemic encephalopathy in neonates . . . .15 Intracranial haemorrhage in neonates . . . . . . . . . . . . .18 Cerebral infections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 Traumatic head injury in children . . . . . . . . . . . . . . . . . .22 Supra- and infratentorial tumours in children . . . . . .25 Non accidental traumatic brain injury in children, child abuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

3.8 3.9 3.10

Intracranial cystic lesions in children . . . . . . . . . . . . . . .30 Cystic lesions of the head and neck in childr en. . . . .33 Spinal cord neoplasm in children . . . . . . . . . . . . . . . . . .36

4

Thoracic disorders. . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.1 4.2 4.3 4.4 4.5 4.6 4.7

Donald P. Frush Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 Imaging modalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 Congenital abnormalities/neonatal anomalies . . . . .42 Infectious/inflammatory . . . . . . . . . . . . . . . . . . . . . . . . . .48 Mass or mass-like conditions . . . . . . . . . . . . . . . . . . . . . .52 Trauma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56 Toxic/metabolic and thoracic evaluation of systemic disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

5

Abdomen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

5.1 5.1.1 5.1.2 5.1.3 5.2 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.2.6 5.2.7 5.2.8 5.2.9 5.2.10 5.2.11 5.2.12 5.2.13 5.3 5.3.1 5.3.2 5.3.3

Jochen Tröger Hepatobiliary system, spleen, pancreas . . . . . . . . . . . .63 Hyun Soo Ko Hepatobiliary system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63 Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74 Pancreas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78 Urogenital tract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80 Jens-Peter Schenk Renal dysmorphology and anomalies. . . . . . . . . . . . . .80 Cystic renal diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83 Obstructive uropathy . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86 Urinary tract infections . . . . . . . . . . . . . . . . . . . . . . . . . . . .92 Renal parenchyma disease . . . . . . . . . . . . . . . . . . . . . . . .94 Nephrocalcinosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 Renal vein thrombosis . . . . . . . . . . . . . . . . . . . . . . . . . . . .97 Renal tumours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97 Diseases of the suprarenal gland . . . . . . . . . . . . . . . . . .99 Female gonads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102 Male gonads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104 Congenital genital anomalies . . . . . . . . . . . . . . . . . . . .106 Persistence of urachus . . . . . . . . . . . . . . . . . . . . . . . . . . .107 Gastro-intestinal tract . . . . . . . . . . . . . . . . . . . . . . . . . . . .108 Michael Kimpel Oesophagus (Oesophageal atresia and tracheoesophageal fistula) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108 Obstructions of the stomach and duodenum . . . . .108 High intestinal obstruction . . . . . . . . . . . . . . . . . . . . . . .110

VIII

Contents

5.3.4 5.3.5 5.3.6 5.3.7 5.3.8 5.3.9 5.3.10 5.3.11 5.3.12 5.3.13 5.3.14

6 6.1 6.1.1 6.1.2 6.1.3 6.1.4 6.1.5 6.2 6.3 6.3.1 6.3.2 6.3.3 6.4 6.4.1 6.4.2 6.5 6.5.1 6.5.2 6.5.3 6.6 6.7 6.7.1 6.8

Low intestinal obstruction. . . . . . . . . . . . . . . . . . . . . . . .111 Rotation anomalies of the midgut . . . . . . . . . . . . . . . .114 Achalasia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116 Gastro-esophageal reflux . . . . . . . . . . . . . . . . . . . . . . . .117 Foreign body ingestion . . . . . . . . . . . . . . . . . . . . . . . . . .119 Intussusception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121 Hypertrophic pyloric stenosis . . . . . . . . . . . . . . . . . . . .123 Necrotizing enterocolitis . . . . . . . . . . . . . . . . . . . . . . . . .123 Inflammatory bowel disease . . . . . . . . . . . . . . . . . . . . .124 Appendicitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126 Gastro-intestinal tumours and tumour-like lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128

Musculoskeletal system . . . . . . . . . . . . . . . . . . . . 133 Harvey Teo, David Stringer Common bone dysplasias . . . . . . . . . . . . . . . . . . . . . . . .133 Achondroplasia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133 Thanatophoric dysplasia . . . . . . . . . . . . . . . . . . . . . . . . .134 Asphyxiating thoracic dysplasia . . . . . . . . . . . . . . . . . .135 Osteogenesis imperfecta . . . . . . . . . . . . . . . . . . . . . . . . .136 Osteopetrosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137 Developmental dysplasia of the hip . . . . . . . . . . . . . .138 Infection and inflammatory . . . . . . . . . . . . . . . . . . . . . .140 Osteomyelitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .140 Septic arthritis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141 Juvenile idiopathic arthritis. . . . . . . . . . . . . . . . . . . . . . .142 Neoplasm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143 Evaluation of tumour and tumour-like bony lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143 Langerhan cell histiocytosis . . . . . . . . . . . . . . . . . . . . . .145 Trauma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146 Paediatric fractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146 Non-accidental injury . . . . . . . . . . . . . . . . . . . . . . . . . . . .148 Slipped capital femoral epiphysis . . . . . . . . . . . . . . . . .149 Rickets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150 Osteochondroses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151 Legg-Calve-Perthes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151 Muscle disorders in children . . . . . . . . . . . . . . . . . . . . . .153

Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

CME-Instructions . . . . . . . . . . . . . . inside back cover

IX

List of Contributors Donald P. Frush

Peter Seidensticker

Chief, Division of Pediatric Radiology Professor of Radiology and Pediatrics Faculty, Medical Physics Program Division of Pediatric Radiology 1905 McGovern-Davison Children’s Health Center Box 3808 Department of Radiology Duke University Medical Center Erwin Road Durham, North Carolina 27710 USA

Global Medical Affairs Diagnostic Imaging Bayer-Schering-Pharma AG Müller Straße 178 13342 Berlin Germany

Thierry A.G.M. Huisman Professor of Radiology and Pediatrics Director Pediatric Radiology Johns Hopkins Hospital 600 N Wolfe Street Baltimore, MD 21287 USA

Michael Kimpel Paediatric Radiology University of Heidelberg Im Neuenheimer Feld 153 69120 Heidelberg

Hyun Soo Ko 354/ 51 Hope Street Trilogy Residences Spring Hill QLD 4000 Australia

Jens-Peter Schenk Paediatric Radiology University of Heidelberg Im Neuenheimer Feld 153 69120 Heidelberg Germany

David Stringer Head of Department of Diagnostic Imaging Professor of Radiology KK Women’s and Children’s Hospital 100 Bukit Timah Road Singapore 229899 Singapore

Harvey Teo Department of Diagnostic Imaging KK Women’s and Children’s Hospital 100 Bukit Timah Road Singapore 229899 Singapore

Jochen Tröger Head of Department of Paediatric Imaging Paediatric Radiology University of Heidelberg Im Neuenheimer Feld 153 69120 Heidelberg Germany

Magdalena M. Woźniak Department of Paediatric Radiology Medical University of Lublin Al. Raclawickie 1 20-059 Lublin Poland

X

List of Abbreviations AAP ALARA A AP Ant AV Ar CBF CBV C CDI C CF C CNS CT C DTI Diff DWI Diff ECG Elec ECMO ED Eff ERCP Endosc

American Academy Of Pediatrics s-Low-As-Reasonably-Achievable erior-Posterior terio-Venous Cerebral Blood Flow erebral Blood Volume olour Doppler Imaging ystic Fibrosis Central Nervous System omputer Tomography usion Tensor Imaging usion-Weighted Imaging tro Cardiogramm Extracorporal Membrane Oxygenation ective Dose opic Retrograde CholangioPancreaticography FLAIR F luid-Attenuated Inversion-Recovery FNH F ocal Nodular Hyperplasia Gd-DTPA G adoliniumdiethylenetriamine-PentaAcetic Acid GI G astro-Intestinal GN Glomerulonephritis HCC Hepat ocellular Carcinoma HIV Human Immunodeficiency Virus HRCT H igh-Resolution CT IL I nterleukin IVC I nferior Vena Cava IVP I ntravenous Pyelogramm LIH Last-I mage-Hold MDCT Multidet ector CT MIBG M eta-Iodobenzylguanidine MR M agnetic Resonance MRA M agnetic Resonance Angiography MRCP M agnetic Resonance CholangioPancreaticography MRI M agnetic Resonance Imaging MRS M agnetic Resonance Spectroscopy MRU M agnetic Resonance Urography mSv M illisievert NEC Necr otizing Enterocolitis NSF Nephrogenic Systemic Fibrosis PNET P rimitive Neuroectodermal Tumours PVL P eriventricular Leucomalacia

PW Doppler Pulsed Wave Doppler PWI P erfusion-Weighted Imaging RDS Respirat ory Deficiancy Syndrom RI Resistiv e Index SPECT Single Photon Emission Computed Tomography SPGR Spoiled Gradient Echo SPIR Selective Partial Inversion Recovery STIR Shor t Inversion Recovery Tc T echnetium Technetium 99m Methylene Disphonate Tc99m MDP TNF T umour Necrosis Factor TSE Turbo Spin Echo US Ultrasonog raphy VCUG V oiding Cystourethrogram VCUS C ontrast-Enhanced Voiding Cysturosonography VIBE Volumetric Interpolated Breath-Hold Examination (Mr) VUR V esicoureteral Reflux

1 Radiation bio effects and dose reduction strategies Donald P. Frush

1.1 In

troduction

Radiation is ub iquitous. I t co mes f rom ma ny s ources, including cosmic radia tion as w ell as rado n exp osure. This natural or background exposure is t he largest single source of radiation to the world’s population. Radiation is also a necessary component of diagnostic and therapeutic imaging. Since the discovery of the X-ray in 1895, i t has been a dramatic and increasing influence on health-care. Medical radiation is als o of central importance for another reason. Because radiation has bio-effects, for example as a kno wn carcinogen (t his was r ecognized as suc h very early in t he 20 th century), medical p roviders must understand t he p otential r isks of radiation in medical imagin g. Much of what is done in medicine is a risk-benefit balance. The following material will review the risk side of the radiation equation and include mechanisms of radiation injury to tissues, dos es of medical radia tion, risks of medical radiation and outline strategies to manage radiation dose. 1.2

other ef fects. S ome o f t hese disr uptions ca n b e r epaired, others ca nnot. With hig h le vels o f radia tion, t here is cell death. With lower levels of radiation, the cell do es not die, but a va riety of mechanisms (including alteration of DNA and regulatory mechanisms) may be disrupted, resulting in unregulated a nd a bnormal tissue gr owth, o r ca ncer. This cancer de velopment is p robably a m ultistep p rocess. The implication is t hat many changes are required rather than just an effect at a single step. It is worthwhile emphasizing that rapidly de veloping tissues, suc h as in c hildren, are at greatest risk of radiation bio-effects, especially cancer. Radiation exposure in children compared with adults: ▬ Lower amounts of radiation are needed for diagnostic imaging in children ▬ Tissues a re mo re radios ensitive t han ad ults (a t le ast two times) ▬ Children have a longer lifetime to manifest radiationinduced cancer ▬ For eq ual a mounts o f radia tion, t he dep osition in children’s tissues can be higher than adults

Mechanisms of radiation injury 1.3

Radiation includes heavy particles as w ell as X-ra ys (photons). Photons are high-energy particles which, as they pass through tissue, interact at the nuclear level, causing ionizations. Ionizations can result in disr uption of DNA, among

Doses of medical radiation

Radiation dose can be measured in s everal ways [1]. F or purposes o f t his dis cussion, t he ef fective dos e (ED) allows comparison between different modalities which use

2

1

Chapter 1 · Radiation bio effects and dose reduction strategies

⊡ Table 1.1. Estimated medical radiation doses: 5 year-old (mSv) [2] CXR equivalents ▬ 3-view ankle

0.0015 1/14th

▬ 2-view chest

0.02

1

▬ Tc-99m radionuclide gastric emptying

0.06

3

▬ Tc-99m radionuclide cystogram

0.18 9

▬ Tc-99m radionuclide bone scan

6.2

310

▬ FDG PET

15.3

765

▬ F luoroscopic cystogram

1 h) reactions depending on the time of occurrence. Delayed adverse reactions are usually self-limited and minor. In t he majority o f cas es t hey a re c linicaly p resent as skin reactions. The ma in difference reported between the type of ad verse e vents f ollowing io nic a nd no n-ionic co ntrast agents is r elated t o extra vasation. Extra vasation o f io nic contrast agents can, b ecause of t heir hyperosmolality and ionicity, be associated with skin necrosis and sloughing.

Immediate adverse reactions ▬ Mild – self-limited without evidence of progression – Hives, nas al st uffiness, i tching, he adache, shakin g, dizziness, nausea, vomiting, pallor ▬ Moderate – r equiring treatment and careful observation for progression – Tachycardia, b radycardia, h ypertension, h ypotension, dyspnoea, bronchospasm, mild la ryngeal oedema, urticaria ▬ S evere – requiring hospitalisation – Severe l aryngeal o edema, c onvulsions, profou nd hypertension, profou nd h ypotension, u nresponsiveness

Some o f t he ad verse e vents (e .g. he adache, dizziness, nausea) a re v ery dif ficult to r ecord o r e ven im possible to r ecognize in c hildren, pa rticularly in ne wborns a nd infants. They may be only expressed by anxiety and weeping. Ther efore v ery y oung c hildren need t o b e ca refully monitored f ollowing a ny co ntrast-enhanced diagnostic procedure; c hanges in no rmal o r usual b ehaviour need very close monitoring.

11

2.5 · Remember!

⊡ Table 2.1. First-line equipment that should be present in the examination room

⊡ Table 2.2. Simple guidelines for first-line treatment of acute reactions to contrast media in children

Oxygen

Nausea/vomiting Transient: supportive treatment as e.g. fluid administration Protracted: appropriate anti-emetic drugs should be considered

Adrenaline 1:1000 Antihistamine H1 – suitable for injection Atropine β-2-agonist dose inhaler i.v. fluids – normal saline or Ringer’s solution Anticonvulsive drugs (diazepam) Sphygmomanometer One-way mouth »breather« apparatus

2.4.2 Treatment of adverse reactions

to contrast material

In cas e o f s evere adv erse r eactions t he a naestesiological emer gency t eam sho uld b e called immedia tely a nd perform t he f irst line tr eatment. M ost s evere a nd fa tal adverse reactions (94–100%) occur within 20 min of contrast medi um administra tion. Th us t he f irst-line dr ugs and eq uipment sho uld b e r eadily a vailable in r ooms in which contrast material is administered (⊡ Table 2.1). Resuscitation drugs for children should be stored separately in a box clearly labelled for use in children. 2.5 Remember!

▬ Adapt t he a mount o f co ntrast media t o t he b ody weight of the child ▬ Do not perform multiple studies with contrast media within a short period of time ▬ Consider a lternative imag ing te chniques, w hich do not require the administration of contrast media ▬ Use low- or iso-osmolar iodinated contrast media ▬ Consider and optimize the water balance of the child ▬ Stop administration of nephrotoxic drugs (e.g. amino glycosides) for at least 24 h prior to the administration of iodine contrast agents ▬ Even ha rmless r eactions e.g. na usea ma y r esult in a severe anaphylactoid reaction

Urticaria Transient: supportive treatment including observation Protracted: appropriate H1-antihistamine intramuscularly or intravenously should be considered Profound: in addition adrenaline Bronchospasm 1. Oxygen by mask (6–10 l/min) 2. β-2-agonist metered dose inhaler 3. A drenaline Normal blood pressure Intramuscular (1:1000): 0.01 mg/kg up to 0.3 mg maximum Decreased blood pressure Intramuscular (1:1000): 0.01 mg/kg Laryngeal oedema 1. Oxygen by mask (6–10 l/min) 2. Intramuscular adrenaline 3. Corticosteroids Hypotension Isolated hypotension 1. Elevate child’s legs 2. Oxygen by mask (6–10 l/min) 3. I ntravenous fluids 4. I f unresponsive: adrenaline 5. C orticosteroids Vagal reaction (hypotension and bradycardia) 1. Elevate child’s legs 2. Oxygen by mask (6–10 l/min) 3. A tropine intravenously 4. I ntravenous fluids 5. C orticosteroids Generalised anaphylactoid reaction 1. Call for resuscitation team 2. Suction airway as needed 3. Elevate child’s legs if hypotensive 4. Oxygen by mask (6–10 l/min) 5. I ntramuscular adrenaline 6. I ntravenous fluids 7. H1-blocker 8. β-2-agonist dose inhaler

2

12

2

Chapter 2 · Contrast media: posology, risks and side effects

The choice of imaging modality should always be strictly related to t he clinic al quest ion to b e answer ed. This is true in medicine in g eneral, but particularly in paediatric patients, w ho are generally more s ensitive to pharmacotoxicity and radiation and require sp ecial care. It should be remembered that often diagnostic imaging in children requires sedation, which increases the risk of side effects. Therefore i t sho uld b e a lways co nsidered w hether t he imaging method with the application of contrast medium is r eally necess ary, a nd if i t is t he o nly p ossibility, t he least invasive a nd r isky diagnostic mo dality o ught t o b e chosen.

References 1. ACR Practice guideline f or the per formance of pediatric c ontrast enema examinations, 1997 (res. 26), Revised 2001 (Res. 28) 2. ACR Practice guideline f or the per formance of pediatric c ontrast examinations of the upper gastr ointestinal trac t, 1997 (r es. 25), Revised 2001 (Res. 29) 3. Auger JA (2001) U se of c ontrast mat erial in pediatric mag netic resonance imaging. Applied Radiol (suppl) 23-29 4. Bhalla S, Siegel MJ, Multislice computed tomography in pediatrics. (2002) I n: Silv erman P M (Ed .), Multislic e c omputed t omography. Lippincott Williams and Wilkins, ISBN: 0-7817-3312-X, pp 231-282 5. Board of the F aculty of Clinical R adiology, The Royal College of Radiologists (1996) A dvice on the management of r eactions to intravenous c ontrast media. L ondon: Ro yal C ollege of R adiologists 6 6. Cohen MD (1993) A r eview of the t oxicity of nonionic c ontrast agents in children. Invest Radiol 28(suppl):87-93 7. Darge K , Bruchelt W, Roessling G, Troeger J (2003) I nteraction of normal saline solution with ultr asound c ontrast medium: significant implication f or sonog raphic diag nosis of v esicoureteral reflux. Eur Radiol 13:213–218 8. Darge K, Troeger J (2002) Vesicoureteral reflux grading in contrast enhanced voiding urosonography. Eur J Radiol 43:122–128 9. Donnelly LF , F rush DP (2003) P ediatric multidet ector body C T. Radiol Clin North Am 41:637-655 10. Hollingsworth C, F rush DP, Cross M, L ucaya J (2003) Helical C T of the body: a sur vey of t echniques used f or pediatric patients . AJR 180:401-406 11. Katayama H, Yamaguchi K, Kozuka T, Takashima T, Seez P. Matsuura K (1990) A dverse reactions to ionic and nonionic c ontrast media: a report from the Japanese C ommittee on the Saf ety of C ontrast Media. Radiology 175:621-628 12. Kopitzko A, C ornely D, Reither D , Wolf K J, Albrecht T (2004) L ow contrast dose v oiding ur osonography in childr en with phase inversion imaging. Eur Radiol 14:2290–2296 13. Morcos SK , Thomsen HS (2001) A dverse r eactions t o iodinat ed contrast media. Eur Radiol 11:1267-1275 14. Newman B (2001) Delayed adverse reaction to non-ionic contrast agents. Pediatr Radiol 31:597-599

15. Runge VM, Knopp MV (1999) O ff-label use and r eimbursement of contrast media in MR. J M agn Reson Imaging 10:489-495 16. Runge VM, Parker JR (1997) Worldwide clinical saf ety assessment of gadoteridol injection: an update. Eur Radiol 7(suppl 5):243-245 17. Runge VM (2000) Safety of approved MR contrast media for intravenous injection. J Magn Reson Imaging 12:205-213 18. Shehadi WH (1985) Death f ollowing intravascular administration of contrast media. Acta Radiol Diagn 26:457-461 19. Thomsen HS (2003) Guidelines f or contrast media from the European Society of Urogenital Radiology; AJR 181:1463-7120 20. Thomsen HS, M orcos SK (2004) M anagement of acut e adv erse reactions to contrast media, Eur Radiol 14:476–481 21. Weissleder R, R ieumont MJ , Wittenberg J (1997) MR c ontrast agents. In: Primer of diagnostic imaging. St. Louis, Mosby, pp 870871

3 Head and Neck Thierry A.G.M. Huisman

3.1

Developmental anomalies of the central nervous system

3.1.1 G eneral information

Developmental an omalies re sult f rom an e rroneous or ganogenesis, hist iogenesis o r c ytogenesis o f t he cen tral nervous system (CNS). E tiology is m ultifactorial including inherited or spontaneous genetic defects, intra-uterine destructive events, ischemia, infections and environmental agents. D evelopmental anomalies b elong t o t he most frequent co ngenital malf ormations (1:100 b irths). The spectrum o f malf ormations is wide , ra nging f rom tin y focal co rtical d ysplasias to co mplex cer ebral syndr omes. Cerebral a nomalies f requently ha ve a signif icant im pact on child development. An e arly and complete identification of the kind and severity of cerebral malformation will guide therapy, can give information concerning prognosis and should be used to counsel parents for future pregnancies. Diagnosis relies on detailed neuro-imaging. 3.1.2 Imaging

Conventional X-ray Conventional X-ra y is o f limi ted va lue t o iden tify, c haracterize or c lassify c erebral m alformations. In s elected

syndromes the shape and ossification patterns of the skull can be helpful. The skull may predict the brain. Typically, a f rontal and a la teral view are suf ficient. In rare cases a town view (occipital) may be helpful.

Ultrasound Imaging technique Ultrasonography (US) ca n b e us ed as a f irst-line imaging modality in neonates. The anterior fontanelle serves as acoustic window. Typically, coronal and sagittal views covering the entire brain are acquired. The p osterior or temporal fontanelles allow additional views. Th e posterior fo ssa c an b e a ssessed by u sing a s uboccipital v iew through the foramen magnum. Duplex sonography can be us ed to e valuate t he circle of Willis. A 5.0–7.5 MH z curved o r line ar a rray tra nsducer has t o b e us ed. A major ad vantage is t hat t he neo nates ca n b e exa mined at the bed side usuall y without the need f or sedation. A disadvantage is t hat US is ra rely ca pable o f iden tifying the exac t ext ent o f malf ormation, t hat co rtical malf ormations are usually outside of the field of view and that tiny migra tional a bnormalities as w ell as m yelination disorders are missed.

14

Chapter 3 · Head and Neck

Possible findings

3

▬ Hydrocephalus (symmetrical or asymmetrical) ▬ Midline defects (e.g. callosal agenesis or dysgenesis) ▬ Disorders of diverticulation or cleavage disorders (e.g. holoproscencephaly) ▬ C erebral clefts (schizencephaly) ▬ Arachno id cysts ▬ Cystic posterior fossa malformations (Dandy Walker) ▬ Small posterior fossa in Arnold Chiari malformation ▬ Vein of Galen malformation

Computer tomography Imaging technique CT is an excellent, readily available and fast imaging modality f or exa mining cer ebral malf ormations. M odern multislice CT scanners with isotropic three-dimensional data acquisition allow multiplanar reconstructions. Multiplanar r econstructions a re ess ential t o st udy co mplex malformations. Most cer ebral a nomalies ca n b e iden tified s atisfactorily b y CT . C ompared t o MRI, t he limited image contrast between white and grey matter may, however, p revent iden tification o f sub tle mig rational disturbances. I n addi tion, t he us e o f io nizing radia tion is a ma jor dis advantage in t he paediatric patient p opulation. The us e o f in travenous co ntrast media has no value in exa mining cer ebral malf ormations. The o nly exception is the evaluation of cerebral vascular malformations.

Possible findings All p reviously men tioned US f indings ca n b e iden tified b y CT. The incr eased a natomical det ail f requently allows a b etter deline ation a nd c haracterization o f t he malformation. I n pa rticular, p osterior f ossa malf ormations a re b etter iden tified b y CT. The iden tification o f subtle mig rational a nomalies o r co rtical o rganization disorders (e .g. p olymicrogyria, pac hygyria) ma y, ho wever, b e limi ted. I n cas es w here CT f indings do no t explain neurologic findings, MRI sho uld be performed. Finally, CT is limi ted in e valuating dis orders o f m yelination.

Magnetic resonance imaging Imaging technique MRI offers t he hig hest multiplanar spatial resolution in combination with a lac k of ionizing radiation. D epend-

ing on the degree of cerebral maturation or myelination, T2- o r T1-w eighted s equences sho uld b e acq uired. T2weighted s equences are esp ecially advantageous in neonates a nd y oung c hildren because th e brain is s till v ery »watery«. Typically, a slice t hickness of 2–3 mm sho uld be us ed. I f a vailable, f unctional ima ging s equences lik e diffusion t ensor imagin g (D TI) o r magnetic r esonance spectroscopy (MRS) ca n give additional microstructural and biochemical information. Magnetic resonance angiography (MRA) is helpful for cerebrovascular malformations (⊡ Fig. 3.1).

Possible findings MRI identifies all malformations that are seen by US and CT. MRI is v ery s ensitive t o identify co rtical ma lformations adjacent to the skull as well as to subtle migrational abnormalities wi thin t he w hite ma tter. A ssociated disorders o f m yelination ca n b e ass essed visuall y b y usin g T1- and T2-weighted sequences or quantified by DTI and MRS. A mino r dis advantage is t hat MRI is less s ensitive for calcif ications t hat ma y acco mpany migra tional a bnormalities. I f calcif ications a re susp ected T2*-w eighted sequences should be added. 3.1.3 Diagnosis

Diagnosis relies on high-resolution neuroimaging. In the evaluation of developmental anomalies of the CNS, e ach radiologist should b e aware that f inding one lesion/malformation me ans lo oking f or addi tional malf ormations. Frequently, t he most ob vious lesion is j ust t he tip of t he iceberg. Key information

I

I

Developmental anomalies of the CNS ▬ Ultrasonography through the fontanelles are helpful in neonates ▬ CT is diagnostic for most malformations ▬ CT uses ionizing radiation ▬ MRI is the most sensitive imaging tool ▬ High resolution imaging is essential ▬ The brain should be studied from the skull base up to the vertex ▬ The face may predict the brain ▬ If you find one developmental anomaly, look for additional anomalies

15

3.2 · Hypoxic-ischemic encephalopathy in neonates

⊡ Fig. 3.1A-F. Sagittal ( A), c oronal ( B), axial ( C, D) T2-FSE MRI, axial fractional anisotropy map (E) and axial maximum-int ensity projection MRA image (F) in a case of semilobar holoprosencephaly. High-resolution MRI shows an absent anterior corpus callosum while the splenium is present (arrow). In addition, a fusion of the frontal lobes is seen with white-matter trac ts c onnecting the ant erior hemispher es. The fractional anisotropy map clearly visualizes the hyperintense white-matter

tracts that c onnect the fr ontal lobes while the post erior hemispheres are divided (small arrows). The anterior part of the ventricular system is deformed/narrowed. MRA sho ws the associat ed anomalous dev elopment of the circle of Willis with an unpaired anterior cerebral or azygos artery ( arrowhead). The c ombined anat omical (MRI) and func tional information (DTI and MRA ) allow identification of the exac t extent of cerebral anomaly

3.2 Hypo

3.2.2 Imaging

xic-ischemic encephalopathy in neonates


Hypoxia-ischemia or perinatal asphyxia is one of the leading causes of severe neurological deficits in neonates. The exact aetiology and cascade of events in hypoxic-ischemic encephalopathy (HIE) as w ell as t he iden tification o f the p rincipal a nd su pporting o r media ting fac tors t hat determine t he s everity o f b rain in jury a re t he f ocus o f ongoing research. Clinical presentation and outcome vary significantly with gestational age and patterns of brain injury. Additional cardiopulmonary diseases may aggravate injury. Imaging should identify t he deg ree and extent of injury as e arly as p ossible in o rder to guide a nd monitor treatment (e.g. neuroprotection).

Conventional X-ray Conventional X-ray plays no role in the evaluation of HIE.

Ultrasound Imaging technique The open fontanelles in neonates serve as an acoustic window. With the use of a 5.0-7.5 MHz curved or linear array transducer the neonatal brain should be examined in t he sagittal and coronal plane. Care should be taken that the transducer is p laced at t he centre of t he fontanelle. This will allo w a symmetrical co ronal vie w o f th e b rain a nd prevents a rtefactual dif ferences in t he ec hogenity o f t he cerebral hemispheres. Duplex sonography allows examining the patency of the major arterial and venous intracra-

3

16


nial vessels as well as t he resistive index (RI). I n addition to the initial acute imaging, serial follow-up US examinations should be performed at predetermined time p oints that are related to the date of birth and gestational age.

3

Possible findings In the acute phase ▬ Focal or diffuse hyperechogenity of the periventricular white matter ▬ Hyperechogenity of the basal ganglia ▬ Reduced grey-white matter differentiation ▬ Compressed, narrow ventricles (brain oedema) ▬ N arrowed subarachnoid space ▬ Narrowed intracranial arteries ▬ Increased RI values ▬ A ccompanying subependymal hemorrhages In the chronic phase ▬ Periventricular hypochogenic cysts (cavitations) ▬ G lobal cerebral volume loss ▬ E vacuo enlargement of the ventricles, undulated borders ▬ E vacuo enlargement of the subarachnoid space ▬ Atrophic, thinned corpus callosum ▬ Normalized RI values

Computer tomography Imaging technique Contrast media a re ra rely indica ted. Dif ferent windo wlevel s etting ca n b e us eful to en hance iden tification o f subtle HIE-related density changes.

Possible findings In the acute setting, CT as co mpared to US, is less s ensitive for identifying subtle HIE-related global white matter injuries. The cortico-medullary junction may be obscured due t o a h ypodensity of t he c ortical r ibbon or b asal ganglia in HIE. S mall in traparenchymal p etechial hemorrhages o r th rombosed in tramedullary v essels a ppear hyperdense. Global oedema will efface the subarachnoid space and compress the ventricles. Patterns of injury differ between preterm and term neonates. In preterm neonates more f requently t he p eriventricular w hite ma tter is a ffected within the watershed areas, while in term neonates the basal ganglia are more frequently involved. In the chronic phase, a global volume loss of the white matter will result in a v entriculomegaly with widening of

the suba rachnoid space . The co rtical r ibbon ma y r each and im press t he v entricles, r esulting in a c haracteristic undulated margin of the ventricles. In addition, multiple periventricular h ypodense c ysts (p eriventricular leucomalacia, PVL) ma y be seen. If the basal ganglia were affected, t he bas al ga nglia a re f requently a trophic wi th disperse hyperdense calcifications.

Magnetic resonance imaging Imaging technique MRI is t he preferred imag ing mo dality in HIE. T2- a nd T1-weighted MR sequences (3 mm slice thickness) should be acq uired. The T2-w eighted s equences will sho w t he anatomy b est. T1- o r T2*-w eighted s equences a re especially s ensitive f or p etechial hemo rrhages. F unctional sequences inc luding dif fusion-weighted imag ing (D WI) with r econstruction o f a pparent dif fusion co efficient (ADC) maps are mandatory. DWI with ADC maps allows differentiating b etween p otentially r eversible vas ogenic and frequently irreversible cytotoxic oedema. In addition, quantitative 1H-MRS gives important metabolic information. MRS voxels should be positioned within the central grey matter as well as in the hemispheric white matter.

Possible findings In acute hypoxic-ischemic injury, T1-hypointense and T2hyperintense white matter oedema narrows the ventricular system as well as the subarachnoid spaces (⊡ Fig. 3.2). A T1hyperintense co rtical hig hlighting f ollowing t he co rtical ribbon is seen due to intracortical petechial hemorrhages. This T1 hyperintensity is matched by a T2 h ypointensity. Additional co rtical necr osis will r esult in a diminished corticomedullary differentiation. Moreover, signal alterations are s een within t he bas al ganglia/thalamus, hippocampus and posterior limb of the internal capsule (PLIC) (⊡ Fig. 3.2). Esp ecially t he loss o f t he no rmal T1-h yperintense signal o f the white matter tracts within the PLIC has been shown to correlate with the degree of hypoxicischemic in jury a nd o utcome. On T2-w eighted imagin g a corresponding loss of the T2 hypointensity is observed. Finally, in ma ny cases a line ar, centripetal T2 h ypo- and, T1 hyperintensity is s een within the cerebral white matter due to a stasis/thrombosis within the medullary veins. MR spectroscopy may identify lactate within the ischemic white or grey matter as well as a reduction of the normal metabolites within the brain. Diffusion-weighted imaging differentiates b etween c ytotoxic o edema a nd vas ogenic

17

3.2 · Hypoxic-ischemic encephalopathy in neonates

⊡ Fig. 3.2A-H. Preterm neonat e ( A–D) and t erm neonat e ( E–H) with severe perinatal asph yxia. I n both neonat es a series of T2-weighted FSE ( A,E), T1-w eighted SE (B,F), DWI ( C,G) and ADC-maps ( D,H) ar e presented. In the preterm neonate an asymmetric hypoxic ischemic injury to the hemispheric white-matter (arrow) (DWI-hyperintense, ADC hypointense) is seen in c ombination with injur y of the whit e matt er

tracts within the splenium of the c orpus callosum and post erior limb of the internal capsule (arrowheads). The thalami and basal ganglia are spared. In the term neonate the typical inverse hypoxic ischemic injury is seen with pr edominantly injur y t o the thalami and basal ganglia (arrowhead). The hemispheric white matter is spared. DWI is especially helpful due to its high lesion conspicuity

I

I

oedema (⊡ Fig. 3.2). The quantitative analysis of the ADC values is especially helpful in global HIE. In chronic HIE, simila rly to t he CT f indings, a f ocal or g lobal volu me l oss of t he w hite m atter i s o bserved. Periventricular c ysts are easily identified. Disp erse calcifications within t he bas al ganglia may appear T1-hyperintense.

Key information

3.2.3 Diagnosis

▬ DWI differentiates between cytotoxic and vasoge-

Diagnosis relies on t he combined analysis of the clinical history, clinical-neurological findings, laboratory tests and imaging findings. In neonatal encephalopathy without an obvious history or signs of acute perinatal hypoxia other causes of neonatal encephalopathy like e.g. metabolic diseases, co ngenital inf ections o r malf ormations sho uld b e excluded. I n addi tion, d ual in jury sho uld b e co nsidered in co mplex o r unexp lained cas es o f neo natal encep halopathy. The co mbination o f a natomical a nd f unctional MRI da ta p rogressively hel ps det ermining t herapy a nd predict outcome.

▬ Pattern of tissue injury differs between preterm

Hypoxic-ischemic encephalopathy in neonates

▬ Ultrasonography is a first-line imaging tool in HIE

▬ MRI combines anatomical information with functional data

▬ 1H MRS quantifies the amount of intrapar enchymal lactate nic oedema and term neonates

▬ In preterm neonates the periventricular white matter is frequently injured

▬ In term neonates basal ganglia are more frequently injured

▬ The MR signal of the PLIC correlates with the outcome

▬ In neonatal encephalopathy without a history of HIE other causes should be excluded

3

18


3.3

Intracranial hemorrhage in neonates


3

Intracranial hemo rrhage is o ne o f t he most co mmon causes o f ac ute f ocal neur ological sym ptoms (e .g. s eizures) in neo nates. M ultiple fac tors inc luding lo cation, extension a nd et iology o f hemo rrhage deter mine mo rbidity a nd mo rtality. I ntracranial hemo rrhages in neonates occur most f requently within the germinal matrix. The germinal matrix is a highly perfused site of neuronal proliferation. The g erminal ma trix is lo cated alo ng t he lateral v entricles a nd is hig hly vulnera ble f or str ess-related hemo rrhages (e .g. p erinatal h ypoxia). G erminal matrix hemo rrhages (GMH) a re t he most f requent intracranial hemorrhages in premature and term neonates. Less frequently, intracranial hemorrhages may occur due to neonatal tumours, intracerebral arteriovenous malformations, trauma and dural sinus thrombosis or coagulation dis orders. Extracer ebral suba rachnoidal, sub dural and ep idural haema tomas ma y r esult f rom a tra umatic birth. 3.3.2 Imaging

Conventional X-ray Conventional X-ra y p lays no r ole in t he e valuation o f GMH.

Ultrasound Imaging technique US is t he p rimary mo dality t o exa mine GMH. C oronal and sagittal views of the neonatal brain are acquired with a 5.0–7.5 MHz curved or linear array transducer through the an terior fon tanelle ( ⊡ Fig. 3.3). H emorrhages wi thin the p osterior fo ssa are ve ry r are, s uboccipital v iews are consequently s eldom ne cessary. S erial exa minations a re mandatory to identify GMH co mplications like a h ydrocephalus or a venous cerebral infarction.

Possible findings In the acute and subacute phase, GMH are hyperechoic ▬ On follow-up, GMH become iso-echoic ▬ In the chronic phase, GMH are hypoechoic ▬ The ventricular lining may appear hyperechoic due to an intraventricular extension

▬ Most small GMH a re located at the level of the foramen of Monroi ▬ GMH ext ension into t he c horoid p lexus will enla rge the plexus ▬ Venous infarction shows a fan-shaped hyperechogenity of the cerebral white matter on coronal views ▬ Complicating h aemorrhagic t ransformations of ve nous infarction are initially hyperechoic ▬ In venous ischemia, progressive tissue resorption will result in an hypoechoic brain defect ▬ Duplex sonography may fail to identify patency of the subependymal veins ▬ Complicating hydrocephalus should be quantified by measuring the width of the anterior horns of the ventricles GMH a re c lassified in to t hree grades: grade I: sub ependymal hemo rrhage limi ted t o t he GM; grade II: in traventricular hemo rrhage in w hich less t han 50% o f t he ventricular volume is a ffected; grade III: in traventricular hemorrhage in w hich mo re t han 50% o f t he v entricular volume is affected (⊡ Fig. 3.3). In previous classifications a grade-IV hemorrhage was defined as a GMH wi th extension into the adjacent cerebral hemispheres. This kind o f neonatal hemorrhage is no wadays classified as »haemo rrhagic venous infarction«. These hemorrhages result from an o bliteration/compression of t he s ubependymal d eep venous system. The r esulting v enous st asis is b elieved to b e ca usative f or t he f requently haemo rrhagic v enous cerebral infarction.

Computed tomography Imaging technique In general MRI is mo re sensitive than CT. Axial CT wi th 3–4-mm slice t hickness is usua lly suf ficient to iden tify GMHs and their complications. Intravenous contrast media are rarely necessary. However, if the etiology of hemorrhage is uncle ar, a co ntrast-enhanced sequence should be considered to r ule out tumour, vascular malformation or dural venous t hrombosis. CT is less s ensitive t han US t o identify hyperacute GMH and acute venous ischemia. CT is indicated in those cases where the findings on US do not explain neurological symptoms. In addition, CT should be considered in susp ected p athology wi thin t he p osterior fossa (brainstem and cerebellum). Finally, in cas es where the acoustic windows are too small for an adequate evaluation of the cranial vault, CT should be considered.

19

3.3 · Intracranial hemorrhage in neonates

A

B

⊡ Fig. 3.3A,B. Coronal ( A) and sag ittal ( B) US examination of the brain in a 3- day-old pr emature bo y (29 w eeks of gestation). US reveals a f ocal h yperechoic germinal matrix hemorrhage (g rade II) with ex tension into the enlar ged choroid plexus of the right lat eral

ventricle (arrows). The sagittal view shows the extension of the GMH. In addition, the v entricles ar e enlar ged with a h yperechoic lining indicating intraventricular hemorrhage. The gyration patt ern is pr emature (29 weeks)

Possible findings

Possible findings

Hyperacute GMHs a re is odense t o no rmal b rain tissue . Progressive b lood c lot r etraction incr eases GMH density d uring t he ac ute a nd e arly subac ute p hases, w hile progressive red blood cell lyses during the late subacute phase will decrease the haematoma’s density. Progressive resorption in the chronic phase will result in a hypodense cyst filled with cerebrospinal fluid. Hydrocephalus is easily identified.

In t he h yperacute st age GMH is T1-is o o r h ypointense and T2 h yperintense; in t he ac ute st age T1-is o o r h ypointense and T2 hypointense, in the early subacute stage T1-hyperintense and T2 hypointense, in the late subacute stage T1 a nd T2 h yperintense and finally in t he chronic phase T1 hypointense and T2 centrally hyperintense surrounded b y a r im o f h ypointensity (hemosider in). On T2*-weighted s equences t he GMH is str ongly h ypointense, in t he cas e o f a n in traventricular ext ension t he ventricular linin gs a re f requently T2* h ypointense. On DWI an acute venous ischemia frequently shows a mixed pattern o f vas ogenic a nd c ytotoxic o edema. On PWI an increased CBV with a r educed CBF a nd a p rolonged MTT may be observed.

Magnetic resonance imaging Imaging technique MRI is widel y accep ted as t he most s ensitive imagin g modality to iden tify in tracranial hemo rrhage in g eneral and GMH in pa rticular. T1- a nd T2-weighted sequences should b e co mbined wi th T2*-w eighted s equences. Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) ma y b e completed to increase s ensitivity and sp ecificity of f indings. DWI and PWI a re esp ecially helpful in examining venous infarction.

3.3.3 Diagnosis

Clinically, GMH sho uld b e susp ected a nd r uled o ut in preterm and term neonates who present with seizures, al-

3

20

3


tered consciousness, bulging fontanelle, progressive head circumference o r a ny kind o f ac ute f ocal neur ological deficit. GMH s a re e asily iden tified o n US, CT o r MRI. Imaging should identify secondary complications like hydrocephalus or haemorrhagic venous infarction. US is the primary imaging mo dality of choice. CT o r MRI sho uld be co nsidered if US f indings do no t exp lain neur ology. CT or MRI a re indicated in neo natal hemorrhages other than GMH. Key information

I

I

Intracranial hemorrhage in neonates ▬ GMH are the most frequent intracranial hemorrhages in neonates ▬ GMH is more frequent in premature than in term neonates ▬ GMH are classified in three grades ▬ Venous ischemia results from obliteration/compression of subependymal veins ▬ Venous ischemia may be complicated by hemorrhage ▬ Hydrocephalus may complicate GMH ▬ US is the primary imaging modality for GMH in neonates ▬ Serial US examinations are necessary to exclude complications and evaluate degree of hydrocephalus on follow up ▬ CT or MRI should be considered if US findings do not explain neurologic findings

3.4 C

erebral infections


Most co ngenital cer ebral inf ections r esults f rom inf ectious ag ents t hat a re kno wn b y t he T ORCH acr onym. They inc lude Toxoplasmosis, Ot her (HIV), R ubella, C ytomegalovirus and Herpes simplex. Neonatal Herpes simplex typ e-II inf ection is typ ically acq uired d uring b irth while passing an infected birth canal. Pre- and postnatal Herpes sim plex-II inf ections a re ra re. I n t he cas e o f a complicating meningoencephalitis, prognosis is poor. Extensive perivascular infiltrates with ischemic and haemorrhagic infarction are usually fatal. Intra-uterine infections may in terfere wi th no rmal b rain de velopment. T iming of infection in r elation to the gestational age determines

the extent and kind o f injury. E arly in p regnancy, developmental brain anomalies occur with different degrees of migrational dist urbances, micr ocephaly, cer ebellar a nd brainstem h ypoplasia as w ell as in juries/malformations of the eyes and inner e ar. Later during gestation, already developed and differentiated brain structures may be injured, resulting in encephaloclastic lesions. Acquired intracranial infections may be classified according to the involved str uctures into (1) pa renchymal infections, (2) menin gitis a nd (3) v entriculitis. H erpes simplex-I encep halitis is o ne o f t he most f requent acquired cer ebral inf ections in c hildren 6 mo nths a nd older. Prognosis is f requently poor if no t diagnosed and treated e arly. U sually a s evere, necr otic haemo rrhagic meningoencephalitis de velops. The t emporal lob es a re predominantly a ffected. Meningitis ca n r esult f rom different organisms. The most f requent include Haemophilus inf luenzae a nd S treptococcus p neumoniae. Epidural empyemas, ass ociated cer ebral a ffection (menin goencephalitis) or septic dural sinus thrombosis are frightening co mplications. Ventriculitis f requently r esults f rom shunt placements. 3.4.2 Imaging

Conventional X-ray Conventional X-rays are non-specific and of no prognostic value.

Ultrasound Imaging technique Coronal a nd s agittal vie ws o f t he neo natal b rain a re acquired with a 5.0–7.5 MH z curved or linear array transducer through the anterior fontanelle. Duplex sonography may b e hel pful t o dif ferentiate b etween t halamic/basal ganglia calcif ications a nd p rominent t halamostriate v essels. In addition, complicating dural sinus thrombosis can be excluded.

Possible findings ▬ Periventricular and/or cortical calcifications ▬ Thalamic or basal ganglia calcifications ▬ P rominent thalamostriate vessels ▬ Hydrocephalus, widened subarachnoid space ▬ Gyration abnormalities (e.g. lissencephaly) ▬ White matter destruction and/or tissue loss

21

3.4 · Cerebral infections

Computer tomography Imaging technique Pre-contrast images are helpful to iden tify calcifications (⊡ Fig. 3.4) o r hemo rrhages (e .g. H erpes encep halitis). Postcontrast images may identify lesions with a disrupted blood-brain ba rrier, indica ting ac tive inf lammation as well as a v entriculitis. Diagnosis o f menin gitis ma y b e difficult on CT because an increased meningeal enhancement may be obscured by the overlying hyperdense skull. Postcontrast images are necessary to r ule out complicating d ural sin us t hrombosis a nd will incr ease s ensitivity for iden tifying sub dural o r ep idural em pyemas. B one windows a re necess ary t o st udy co mplicating inner e ar affection.

Possible findings ▬ White matter oedema with reduced grey-white matter differentiation ▬ Punctuate or diffuse intraparenchymal hemorrhages ▬ Periventricular and/or cortical calcifications ▬ Thalamic or basal ganglia calcifications ▬ Hydrocephalus and/or widened subarachnoid spaces ▬ Encep haloclastic lesions ▬ Migrational disturbances (e.g. polymicrogyria, lissencephaly) ▬ Cerebellar and brain-stem hypoplasia ▬ Mic rocephaly ▬ V entriculitis/ependymitis ▬ Epidural and/or subdural empyemas ▬ Dural sinus thrombosis ▬ Microphtalmia and chorionic calcifications ▬ Calcifications of the cochlea

Magnetic resonance imaging Imaging technique T1- and T2-weighted images should be acquired. Postcontrast T1-w eighted imag es a re v ery us eful t o st udy ac tive encephalitis, v entriculitis a nd menin geal inf lammation. T2*-weighted images will increase the sensitivity for calcifications. At least one sequence, preferably a T2-weighted sequence, should have a high spatial resolution to identify migrational disturbances, cortical malformations or areas of d ys- o r de-m yelination ( ⊡ Fig. 3.4). Al ternatively, a T1-weighted in version r ecovery s equence ca n b e us ed. Magnetic r esonance v enography ca n b e added t o s tudy patency of the dural sinuses. Diffusion-weighted imaging is v ery hel pful f or iden tifying ac tive a reas o f inf lammation (vasogenic oedema) as well as complicating ischemic (cytotoxic oedema) areas.

Possible findings ⊡ Fig. 3.4A-D. Axial non- enhanced C T ( A) sho ws disperse c ortical subcortical calcifications due to a cerebral toxoplasmosis infection. No migrational abnormalities ar e seen because inf ection oc curred af ter completed mig ration. The sec ond case ( B) of a pr oven intra-ut erine toxoplasmosis inf ection r eveals on axial T2-weighted FSE ex tensive migrational abnormalities with lissenc ephaly and a double c ortex. I n addition, the v entricles ar e enlar ged. The thir d case sho ws disperse hyperdense subcortical and whit e-matter calcifications on a non- enhanced CT (C) in a child with rubella inf ection. Axial T2-weighted MRI (D) is less sensitive for the calcifications, the dys-/de-myelination of the paratrigonal white matter is, however, better depicted

All of the findings as seen by CT White matter oedema and/or cortical oedema White matter gliosis Compared t o CT , hig her s ensitivity f or migra tional disorders (e.g. polymicrogyria) and disorders of cortical organization (e.g. focal cortical dysplasia) ▬ Compared to CT, higher sensitivity for delayed whitematter myelination, lesions within the posterior fossa and meningitis ▬ Sagittal thin slices allow to identify postinflammatory webs within the Sylvian acquaduct ▬ ▬ ▬ ▬

3

22


3.4.3 Diagnosis

3

Diagnosis relies on the combined information of serology or the identification of the infectious organism in the cerebrospinal fluid and neuro-imaging findings. MRI is t he most sensitive imaging modality and is capable of identifying small migrational or organizational cerebral abnormalities. MRI is highly sensitive in meningitis. MRV, DWI may give important functional data. In neonatal infection, US r emain t he f irst line imagin g mo dality. I f p ossible, MRI should follow US. Key information

I

I

Cerebral infection ▬ Congenital, neonatal infections frequently result from TORCH infections ▬ Congenital infections may interfere with normal brain development ▬ Kind of cerebral malformation is determined by the timing of infection in relation to the gestational age ▬ Chorioretinitis and inner-ear affection should be studied by neuroimaging ▬ US is the first-line imaging tool in neonates ▬ MRI is the most sensitive and complete second line imaging modality ▬ Tiny migrational or organizational disorders are best seen by MRI ▬ DWI is helpful because of its high lesion c onspicuity ▬ DWI allows to differentiate between vasogenic and cytotoxic oedema ▬ MR venography should be added if dur al sinus thrombosis is suspected ▬ High-resolution inner-ear CT is indicated if hearing is impaired ▬ HSV-II infection is typically acquired during birth ▬ HSV-I infection is frequently haemorrhagic and rapidly progressive

3.5

Traumatic head injury in children

not j ust small ad ults« is esp ecially tr ue f or he ad in jury. The kind o f injury is r elated to the age of the child; TBI in c hildren y ounger t han 2 y ears r esult most f requently from fa lls, w hile in c hildren o lder t han 2 y ears, mo tor vehicle accidents are more frequent. The ag e of the child is als o r elated t o t he lo cation o f f orce im pact as w ell as the mechanism of trauma. In a small c hild who is hi t by a car it is mo re likely that the direct impact involves the child’s head while in adults the legs or lower abdomen are more frequently hit. The »response« of the skull and brain to t he im pact o f f orces dif fers f rom ad ults. The sk ull is thinner, smoother and softer and the sutures may not be closed. The b rain in y oung c hildren a bsorbs t he kinetic energy of an impact differently because the brain is more »watery« and mo re ho mogeneous in densi ty. W ith p rogressive brain maturation (e.g. myelination) the brain becomes less »wa tery«. In addition, differences in den sities between cerebral structures will increase with progressing maturation. Finally, children have a la rger he ad-to-body proportion, the midface-to-skull proportion will increase and t he paranasal sinuses are de veloping. The pa ranasal may f unction as a kind o f »a ir bag« t hat a bsorbs m uch of t he kinetic ener gy if a n impact t o t he face o ccurs. In children, t he tra nsmission o f t he f orce o f im pact t o t he brain is not dampened by the paranasal sinuses. Finally, in neonates the weak neck muscles do no t yet stabilize and support the neonates head in »shaken baby« trauma. Brain in jury ca n b e di vided in p rimary in juries t hat occur at the time of impact and are directly related to the interaction of forces with the skull and brain, and secondary injuries, that occur later in time , may be multifactorial, and may lead to extensive, complicating injuries (e.g. brain oedema may result in a herniation with consecutive cerebral infarction). Goal o f diag nostic imag ing sho uld b e to ob tain a rapid diagnosis of the extent of injury to start therapy for primary injury as early as possible and to prevent secondary injury. 3.5.2 Imaging


Conventional X-ray

Traumatic brain injury (TBI) is o ne of the leading causes of de ath a nd dis ability in c hildren. H ead tra uma o ccurs in 3/1 000 children per year with a fa tal outcome in 1/10 000 p er y ear. The g eneral r ule t hat »c hildren a re

The value of conventional X-ray (skull AP a nd lateral) is an issue of ongoing discussions. In most European countries, conventional X-rays are performed because of legal concerns. H owever, t he b rain is m uch mo re im portant than t he sk ull. A nega tive co nventional X-ra y do es no t

23

3.5 · Traumatic head injury in children

exclude TBI. On the other hand, a skull fracture does not imply that a brain injury is present.

Ultrasound Imaging technique In y oung c hildren t he cra nial va ult ca n b e exa mined through the open fontanelle with a 5.0–7.5 MH z curved or linear array transducer. Osseous borders of the fontanelle p revent lo oking »a round t he co rners«. Epidural o r subdural haematomas t hat a re lo cated pa rasagittally ca n be overlooked. In addition, the visualization of the posterior fossa is limited.

Possible findings ▬ Acute, f ocal haemo rrhagic b rain co ntusions a ppear hyperechoic ▬ Chronic contusions are visualized as hypoechoic brain defects ▬ Intraventricular hemorrhage increases the echogenity of t he v entricular linin g; f luid-sedimentation le vels are frequent ▬ Subarachnoid hemorrhage may be characterized by an increased echogenity of the subarachnoid spaces ▬ Midline shif t d ue t o a n in tracerebral haema toma o r »hidden« extra-axial haematoma ▬ Brain o edema a nd a n ele vated in tracranial p ressure are characterized by a decr eased resistive index val ue (duplex sonography) ▬ Occasionally, a sk ull fracture can be identified by ultrasonography

Computer tomography Imaging technique CT is suf ficient to iden tify p rimary injuries t hat r equire emergency tr eatment (e .g. haema toma e vacuation). CT visualizes the skull and brain tissue simultaneously. Intubated children are easily accessible for anaesthesiologists while being examined. A disadvantage is the use of ionizing radiation, the limited sensitivity for subtle post-traumatic lesions a nd obs curing b eam-hardening a rtefacts wi thin the posterior fossa. CT sho uld be performed in c hildren with an altered or deteriorating level of consciousness, if seizures or focal neurological symptoms occur, if the skull is dep ressed > 1 cm, in p enetrating injuries, in c hildren with an anisocoria, in c hildren with a f ull fontanelle and in intubated children with an unclear trauma.

Soft ti ssue a nd bo ne al gorithm wi th th e a ppropriate window-level s ettings sho uld b e st udied. I mages sho uld also b e st udied wi th a windo w-level s etting t hat allo ws identifying h yperdense haema tomas next to t he h yperdense skull (e.g. Window 250 HU, level 75 HU). C oronal reconstructions a re esp ecially hel pful f or f ractures t hat extend in to t he f rontobasis o r o rbita. C ontrast media is rarely necess ary. I f e .g. a f racture cr osses a d ural sin us, contrast me dia ca n iden tify a co mplicating d ural sin us thrombosis.

Possible findings ▬ Extra-axial haematomas: subdural, epidural, subarachnoidal or intraventricular hemorrhage ▬ Intra-axial lesio ns: haemo rrhagic a nd no n-haemorrhagic b rain co ntusions, lacera tions, co rtical hemo rrhages, shearing injuries and coup/contre-coup contusions ▬ Brain o edema with a r educed grey-white matter differentiation, ef faced suba rachnoid spaces a nd co mpressed ventricles ▬ M idline shift ▬ Any kind of herniation ▬ Penetrating injuries with intracranial air inclusions ▬ S kull fractures ▬ Skull base and petrous bone fractures ▬ Complicating cer ebral is chemia d ue t o vas cular dissections ▬ On follow-up: brain defects, hydrocephalus, growing skull fractures, ischemia, secondary hemorrhages

Magnetic resonance imaging Imaging technique MRI is rarely the primary imaging modality. MRI should be us ed if a n unexp lained dis crepancy exists b etween CT f indings a nd neur ology. MRI is mo re s ensitive f or subtle f indings lik e e .g. she aring in juries. T2*-w eighted sequences are especially valuable. Compared to CT, MRI is mo re s ensitive f or iden tifying b rainstem o r cer ebellar lesions. F unctional t echniques lik e D WI/DTI ca n s erve as a b iomarker o f degr ee o f tissue in jury in in tubated children. Imaging protocols should include T1-, T2- a nd T2*- weighted sequences ( ⊡ Fig. 3.5). DWI sequences are especially h elpful b ecause of t he h igh l esion c onspicuity. In addi tion, t he dif ferentiation b etween c ytotoxic a nd vasogenic o edema gi ves inf ormation a bout p otentially salvageable b rain tissue ( ⊡ Fig. 3.5). The co mbination o f

3

24


different imaging sequences increases the sensitivity and specificity of MRI findings. Contrast media are rarely indicated. MR angiography and MR venography are helpful in identifying vascular complications.

3

Possible findings

▬ P ost-traumatic aneurysm ▬ Early signs of ischemia in e.g. herniation or vessel dissections ▬ C omplicating meningitis/encephalitis

▬ All findings as s een by CT wi th exception of detailed information a bout oss eous lesio ns, in pa rticular p etrous bone fractures ▬ Higher s ensitivity f or sub tle p ost-traumatic lesio ns (e.g. shearing injuries) ▬ Higher s ensitivity f or lesio ns wi thin t he p osterior fossa ▬ Arterial dissections and thrombosis ▬ Arterio-venous fistula (e.g. carotid-cavernous fistula)

3.5.3 Diagnosis

⊡ Fig. 3.5A-G. Two children with severe traumatic head injury. Patient one ( A–C) and patient t wo ( D–G) w ere examined b y c onventional and functional MRI. Axial T2-FSE (A) shows an ex tensive hyperintense injury to the splenium of the c orpus callosum as well as a discrete hyperintensity of the adjacent basal ganglia. On T2*-GRE (B) hypointense petechial hemorrhages are seen while on DWI the exac t extent of the injury is best seen as a hyperintensity of the corpus callosum and basal

ganglia ( arrows). I n patient 2, a subdural and epidural haemat oma is seen on axial T2-FSE ( D) and T1-SE ( E). DWI ( F) and ADC maps ( G) allow identification of irreversible tissue injury as areas with restricted diffusion ( ADC h ypointense) indicating c ytotoxic oedema within the right hemispher e ( arrows). This func tional inf ormation is essentially important to estimate prognosis

Diagnosis should be as early and as exact as possible. Detailed inf ormation a bout t he mec hanism o f tra uma a nd force impact is essential because this information tells the radiologist where to look. CT is t he most frequently used primary imaging modality, MRI is a s econd-line imaging tool f or t hose cas es w here CT f indings do no t exp lain neurology.

25

3.6 · Supra- and infratentorial tumours in children

Key information

I

I

Traumatic head injury in children ▬ Conventional X-ray has limited value in the evaluation of TBI ▬ Traumatic lesions of the brain are more important than osseous lesions ▬ Ultrasonography requires an open fontanelle ▬ Ultrasonography is limited in the identification of epi- and subdural haematomas ▬ CT is the primary imaging modality in TBI ▬ Skull base and petrous bone fractures require high-resolution CT ▬ CT is sufficient to identify all primary injuries that require emergency treatment ▬ An early diagnosis of extent of primary injury should guide treatment and prevent or limit secondary injury ▬ C omplicating meningitis/encephalitis may result from an undetected skull base fracture connecting the intracranial vault with the paranasal sinuses or epipharynx ▬ MRI should be performed if CT findings do not explain neurologic findings satisfactorily ▬ Functional MRI techniques (DWI/DTI) can serve as predictors of outcome ▬ Knowledge about the mechanism of injur y is essential

3.6

Supra- and infratentorial tumours in children


Brain t umours a re t he s econd most co mmon paedia tric neo plasm a fter leukaemia. Clinical sym ptoms dif fer from ad ults b ecause (1) dif ferent t umours a re s een in children, (2) t he lo cation o f paedia tric b rain t umours differs, (3) sk ull sutures may not yet be closed. Neonates with brain tumours may present with an increasing head circumference, failure to thrive and developmental delay. The in tracranial p ressure is ra rely ele vated b ecause t he skull su tures a re no t y et c losed. On ini tial p resentation, tumours are frequently large. Infants and children suffer more f requently f rom a n incr eased intracranial p ressure (headaches, nausea, vomiting and lethargy). In addition, depending on the location, the leading presenting symp-

tom in infa nts a nd c hildren ma y b e a decr eased visual acuity, endocrine dysfunction, seizures, focal motor deficits and ataxia. The ag e o f t he c hild is c losely r elated t o t he lo cation and typ e o f b rain t umour. I n c hildren less t han 2 y ears, most primary brain tumours are lo cated supratentorially, between 2 a nd 10 y ears most t umours are infratentorially while in children older than 10 years supra- and infratentorial tumours occur equally frequently. Age and sex of the child limi t dif ferential diagnosis. P ilocytic astr ocytomas (35%), PNET/med ulloblastomas (25%), b rainstem g liomas (25%) and ependymomas (12%) encompass 97% of all infratentorial tumours while astrocytomas (30%), cra niopharyngeomas (15%) a nd h ypothalamic/chiasmatic g liomas (15%) represent 60% of all supratentorial tumours. In children, surgery and chemotherapy are the primary treatment options. Radiotherapy is limited in neonates and y oung infa nts b ecause o f t he delet erious ef fects o f radiotherapy on the rapidly developing brain. 3.6.2 Imaging

Conventional X-ray Conventional skull X-ray is of limited value.

Ultrasound Imaging technique Ultrasonography is o f limi ted val ue in t he diagnostic work-up of brain tumours. Imaging findings are non-specific and cannot be used in t he pre-operative work up of brain tumours. The exact anatomical location and tumour extension cannot be evaluated reliably. In addition, lesions within the cerebral cortex or lesions within the posterior fossa a re dif ficult t o r ecognize. U ltrasonography ca n b e helpful in e valuating complicating hydrocephalus on follow-up examinations.

Possible findings Focal lesion, either hypo- or hyperechoic Mass effect, displacement of midline structures Compression of the ventricles Displacement of intracranial vessels Intratumoural, hyperechoic hemo rrhage o r calcif ications ▬ Perifocal, vasogenic oedema ▬ Focal or generalized enlargement of the ventricles ▬ ▬ ▬ ▬ ▬

3

26


▬ Postoperative, intracranial air inclusions ▬ Postoperative, subarachnoid hemorrhage

3

Computer tomography Imaging technique Non-enhanced CT is ess ential t o sho w in tratumoural hemorrhage or calcification. Contrast-enhanced CT identifies a reas wi th a disr upted b lood-brain ba rrier a nd increases sensitivity and specificity of CT. Spatial resolution sho uld b e o ptimized to iden tify sma ll lesio ns. The reconstructed slices sho uld be between 3 a nd 5 mm slice thickness. B one windo ws a re necess ary if t he lesio n is adjacent to t he skull to r ule out oss eous inf iltration, destruction or erosion.

Possible findings ▬ All t he p reviously men tioned ul trasound imagin g findings ▬ The solid tumour components may be hypo-, iso- or hyperdense ▬ The solid tumour component may be hyperdense due to acute hemorrhages or calcifications ▬ Cystic components are usually hypodense ▬ Cystic co mponents ma y b e is odense o r h yperdense depending on the protein content or possible intracystic hemorrhage ▬ Perifocal, vasogenic oedema is hypodense ▬ Vasogenic oedema is frequently restricted to the white matter ▬ The neo plasm ma y b e no n-enhancing, pa rtially enhancing or strongly enhancing ▬ Enhancement pattern may change over time. Progressive enhancement usually indicates transformation to a higher malignancy grade

Magnetic resonance imaging Imaging technique In the pre-operative work-up, triplanar imaging should be performed usin g p re- a nd p ostcontrast T1-w eighted s equences as well as T2-weighted high-resolution sequences for an atomical d etail ( ⊡ Fig. 3.6). FL AIR s equences will differentiate b etween p erifocal g liosis a nd vas ogenic o edema. F unctional t echniques a re h elpful f or es timating tumour grade . MRA a nd MR V sho w dila ted su pplying or draining vessels and displacement and patency of t he intracranial vasculature. Intraventricular or subarachnoid

tumour seeding should be excluded. In these cases, a spinal MRI is mandatory (⊡ Fig. 3.6). Postoperative MRI sho uld b e p erformed wi thin 24 h. I n most cas es, b lood-brain-barrier disr uption d ue t o reparative p rocesses alo ng t he r esection si te do es no t occur wi thin 24 h p ostoperative. C onsequently, a n e arly postoperative imaging will allow identification of residual tumour tissue.

Possible findings All imaging findings as seen by ultrasound and CT, however in higher anatomical detail and soft-tissue resolution. MRI is somewhat less sensitive for calcifications. 3.6.3 Diagnosis

Diagnosis relies on a high-resolution imaging, evaluation of contrast enhancement pattern, location and functional information as e .g. su pplied b y MRI. I maging f indings should al ways b e co rrelated wi th t he ag e a nd s ex o f t he patient. The lo cation gi ves a nother c lue t o diagnosis. Imaging ca nnot gi ve def inite hist ology. B iopsies r emain necessary in s elected c ases. Follow-up imagin g is necessary to rule out transformation of tumour grade. Key information

I

I

Supra- and infratentorial tumours in children ▬ By taking the age, sex and location into account, differential diagnosis can be narrowed ▬ Pre-operative work-up requires high-resolution imaging ▬ Contrast-enhanced imaging increases sensitivity and specificity ▬ Functional MRI techniques may give important additional information ▬ Ultrasonography is of limited value ▬ CT (pre- and postcontrast) is an important primary screening modality ▬ MRI is the primary, pre-operative imaging modality ▬ MRI should be performed in multiple planes using different sequences ▬ Postoperative imaging should be performed within 24 h ▬ Cerebrospinal fluid tumour seeding should be excluded in brain tumours that are likely to seed

3.7 · Non accidental traumatic brain injury in children, child abuse

⊡ Fig. 3.6A-E. Axial and c oronal c ontrast-enhanced T1-weighted MRI (A,B) in a child with an anaplastic astr ocytoma of the lef t c erebellar hemisphere. L ocal tumour with inhomogeneous enhanc ement is r evealed as well as intraventricular CSF-metastases within the lef t lateral ventricle. The second child with tumour recurrence after subtotal resec-

3.7

Non accidental traumatic brain injury in children, child abuse


Traumatic brain injury (TBI) is a leading cause of life-long morbidity and mortality in children. Child abuse is a f requently unrecognized, misrecognized or underrecognized cause of TBI in children. Physical child abuse or non-accidental trauma can occur on a single occasion or the child may b e exp osed to repetitive episodes of physical abuse. Early recognition of non-accidental injury is ess ential to limit in jury, t o p revent r epetitive in juries a nd t o »s ave« possible siblings for physical or psychological abuse. Unfortunately, child a buse is dif ficult to p rove e arly. In addition, raising t he suspicion of child abuse may have far reaching consequences.

27

tion of a IV -ventricle ependymoma sho ws a T2-hyperintense, strongly contrast-enhancing tumour recurrence at the foramen magnum as well as CSF drop metastases (arrow) within the spinal canal (C,D). Sagittal T2weighted images of the lumbar spine (E) show a metastatic mass within the lowest portion of the spinal canal in a child with an ependymoma

Child abuse is f requently a radio logical diagnosis. I maging findings like e.g. multiple long bone, rib or skull fractures, sim ultaneous o ccurrence o f o ld a nd ne w f ractures and c hronic sub dural hema tomas a re hig hly sug gestive of c hild a buse. The radio logist p lays a n im portant r ole in t he r ecognition a nd do cumentation o f p hysical c hild abuse. He should be familiar with the different patterns of injury because the type and distribution of lesions are age related. B abies are more li kely to ha ve b een sha ken w hile older infants are more frequently beaten or strangulated. In shaken babies, the shear forces that interact on the interface of brain tissue of different densities, e.g. gray-white matter junction, will result in diffuse axonal injury in combination with direct cortical contusions. In addition, t he compression of the thorax while shaking the baby may result in a hypoxic-ischemic in jury o f t he b rain. I n o lder c hildren, that are beaten, the direct impact of the forces may result in

3

28

3


haemorrhagic b rain co ntusions. I n stra ngulated c hildren, an additional hypoxic-ischemic injury may be seen. The radio logist sho uld co rrelate t he distr ibution a nd severity of injury with the »story of trauma«. If the »story of trauma« does not match or explain imaging findings, if the imaging findings look »unusual« or if traumatic lesions of dif ferent ages are s een, physical child abuse should b e suspected and the referring physician should be alerted.

most frequent fractures encountered in child abuse. If child abuse is susp ected, skull X-ray should be part of the skeletal survey (⊡ Fig. 3.7). The radiologist should however be aware that depending on the kind and mechanism of child abuse (e.g. shaken baby), conventional X-ray may be unremarkable. Significant brain injury may be present without skull fractures. CT a nd/or MRI, a re necessary if t he child presents with unexplained neurological symptoms.

3.7.2 Imaging

Ultrasound Imaging technique

Conventional X-ray Conventional X-ray is o ften the first line imag ing modality. Physically abused children often present as trauma patients in emer gency rooms. Skull fractures are the second

Ultrasonography can be used in young children in whom the fontanelle is not yet closed. A 5.0–7.5 MHz curved or linear a rray tra nsducer sho uld b e us ed. US is limi ted in the detailed evaluation of traumatic brain injury. Diffuse

⊡ Fig. 3.7A-F. Lateral Skull X-ray (A) shows a fronto-parietal fracture line (arrows). Axial C T, precontrast (B) and post contrast injection (C) in a child with a chronic, mixed isodense subdural hematoma on the right. After contrast injec tion the pial v essels facilitate demarcation of the hemat oma from the isodense brain. Axial C T ( D) and f ollowup MRI ( E) in a shaken bab y syndrome. I nitial C T shows an unusual collection of subacut e, hyperdense blood within the S ylvian fissure

as w ell as bifr ontal h ygromas. F ollow-up MRI sho ws the T2-hyperintense right subdural h ygroma. Axial C T ( F) and f ollow-up MRI ( G) in a shaken bab y with suff ocation. I nitial C T sho ws a h yodense hypoxic-ischemic injury of both occipital lobes. Follow-up MRI showed extensive cortical-subcortical occipital injury with progressive global atrophy. Haemorrhagic cortical contusions were also identified (not shown)

29

3.7 · Non accidental traumatic brain injury in children, child abuse

shearing in juries in shak en ba by in jury a re dif ficult t o recognize. Localized in traparenchymal h ematomas m ay be dir ectly s een o r susp ected if midline str uctures a re displaced. Epidural and subdural hematomas are usually difficult to recognize b ecause the osseous b orders of the fontanelle may prevent identification of hematomas along the la teral cer ebral hemisp heres. Dif fuse b rain o edema due to hypoxia may be recognized by US.

Possible findings ▬ Multiple small hyperechoic lesions (acute diffuse axonal injury) ▬ Focal hyperechoic lesion (acute haemorrhagic contusion) ▬ Hyperechoic brain oedema ▬ Displaced midline str uctures due to subdural or epidural hematoma ▬ Hyperechoic, acute subdural or epidural hematoma ▬ Fluid-fluid levels within a chronic subdural or epidural hematoma ▬ Hyperechoic suba rachnoid r eflections d ue t o subarachnoid hemorrhage ▬ Focal, hypoechoic, fluid filled brain defects (old contusion) ▬ Hyperechoic linin g o f v entricles (in traventricular hemorrhage)

Computer tomography Imaging technique Non-enhanced axial co mputer t omography (CT) sho uld cover t he en tire b rain f rom t he sk ull bas e t o t he v ertex. Multiple window-level settings should be studied including a b one alg orithm r econstruction. A hig h-window level s etting ca n b e hel pful to iden tify sma ll sub dural hematomas. Intravenous contrast injection is ra rely necessary ma y ho wever facili tate deline ation o f is odense chronic sub dural hema tomas ( ⊡ Fig. 3.7), ma y sho w f ibrinoid »webs« within chronic subdural hematomas and may identify trauma related dural venous thrombosis.

Possible findings ▬ Hyperdense, petechial hemorrhages at the interface of gray and white matter and within the dorsal brainstem in diffuse axonal injury ▬ Acute is o- o r sub acute h yperdense haemo rrhagic brain contusion ▬ Chronic, hypodense brain contusion or brain defect

▬ Acute, is odense o r sub acute h yperdense sub dural o r epidural hematoma ▬ Chronic, hypodense subdural or epidural hematomas ▬ Subdural or epidural hematomas with multiple densities due to recurrent hemorrhages in r epetitive trauma ▬ Subarachnoid hyperdense hemorrhage ( ⊡ Fig. 3.7) ▬ Intraventricular hemo rrhage wi th f luid-sedimentation level ▬ Hypodense cer ebrum wi th p reserved h yperdense brainstem and cerebellum in hypoxic-ischemic injury (⊡ Fig. 3.7) ▬ Chronic cortical and subcortical atrophy with cortical calcifications (⊡ Fig. 3.7) ▬ Subdural, hypodense hygroma ▬ Skull f ractures, p etrous b one f ractures, in tracranial air-inclusions O ccasionally r etinal a nd sub retinal hemorrhages can be seen

Magnetic resonance imaging Imaging technique Multiplanar T1-, T2- a nd T2*-w eighted MR -sequences which co ver t he en tire b rain sho uld b e acq uired. I mage resolution, esp ecially slice t hickness sho uld b e ada pted to t he c hild’s ag e. Ro utinely, 2-4 mm slices wi th a f ieldof-view b etween 160 a nd 200 mm a re suf ficient. T2*weighted images are especially helpful to iden tify hemosiderin. Dif fusion w eighted imagin g ma y enha nce t he sensitivity for small, non-haemorrhagic shearing injuries. Intravenous contrast injection is rarely necessary. MR-angiography and MR-venography sequences can be added if vascular injuries are suspected.

Possible findings ▬ T1-hyperintense, T2-h ypointense p etechial hemo rrhages at t he interface o f gray a nd w hite matter a nd within the dorsal brainstem in diffuse axonal injury ▬ Acute T1/T2-iso- or subacute T1-hyperintense haemorrhagic brain contusion ▬ Chronic, T1-hypointense, T2-hyperintense brain contusion or brain defect ▬ Acute, T1/T2-isointense or subacute T1-hyperintense subdural or epidural hematoma ▬ Chronic, T1-hypo, T2-hyperintense sub dural o r ep idural hematomas ▬ Chronic hematomas may b e T1-hyperintense d ue t o an elevated protein content.

3

30

3


▬ Subdural o r ep idural hema tomas wi th m ultiple intensities d ue t o r ecurrent hemo rrhages in r epetitive trauma ▬ Subarachnoid hyperdense hemorrhage ( ⊡ Fig. 3.7) ▬ Intraventricular hemo rrhage wi th f luid-sedimentation level ▬ T2-hyperintense, T1-hypointense cerebrum with preserved in tensity o f b rainstem a nd cer ebellum in h ypoxic-ischemic injury (⊡ Fig. 3.7) ▬ Chronic co rtical a nd s ubcortical a trophy wi th co rtical T1-hypo or hyperintense, T2-hypointense calcifications ▬ Skull f ractures, p etrous b one f ractures, in tracranial hypointense air-inclusions with susceptibility artifacts ▬ Occasionally retinal and subretinal hemorrhages can be seen ▬ Diffusion w eighted imagin g ma y sho w lesio ns wi th cytotoxic oedema and hemorrhages with a peripheral rim of vasogenic oedema 3.7.3 Diagnosis

Non-accidental brain injury in child abuse should always be co nsidered if t he »sto ry o f t rauma« do es no t ma tch the neur ological st atus o f t he c hild a nd/or t he imagin g findings. I maging sho uld inc lude a sk eletal sur vey wi th skull X-rays. CT ca n be applied in t he emergency workup, MRI is ho wever the most s ensitive imaging modality. Radiological diagnosis of non-accidental injury should be combined wi th p hysical f indings (b ruises, s cars, b urns) and opthalmological findings (retinal hemorrhages). The radiologist sho uld aler t t he c linician as e arly as p ossible to prevent additional assaults. In addition, siblings within the same household should not be forgotten. Key information

I

I

Non accidental traumatic brain injury in children, child abuse ▬ Non-ac cidental injury ▬ Shaken baby ▬ Child abuse ▬ Chronic subdural hematoma ▬ Suff ocation ▬ Strangulation ▬ Unusual traumatic brain injury ▬ Retinal hemorrhage ▬ Skeletal survey

3.8

Intracranial cystic lesions in children


Most p rimary in tracranial c ysts a re b enign dis orders o f development. Cysts can also develop as co mplications of surgery, trauma or infection. Intracranial cysts may be incidental findings on imaging or the leading cause of focal neurological def icits. Hemorrhages within t he c ysts may result in a rapid increase in the size of the cysts. Arachnoid c ysts a re b enign, f luid-filled lesio ns t hat are lined b y a t hin layer of arachnoidea. Arachnoid cysts are located between the dura and pia mater and are filled with a fluid that resembles cerebrospinal fluid; the protein content may be elevated. Cysts are isolated from the subarachnoid space or ventricular system. They may remodel the ad jacent sk ull b y c hronic co mpression. The y sho uld be differentiated from epidermoid cysts. Leptomeningeal c ysts o ccur as co mplications o f sk ull fractures due to an entrapment of lacerated meninges within the fracture. Meninges and underlying brain tissue may protrude t hrough a gr owing skull defect. The sk ull defect may gr ow o ver time b ecause t he c hronic p ropagation o f CSF pulsations prevents consolidation of the skull fracture. Neuroepithelial cysts are benign, fluid-filled cysts lined by a single layer of ependymal-like cells. These cysts occur at m ultiple lo cations a nd a re na med acco rdingly: in traventricular ep endymal c ysts, c horoids p lexus c ysts a nd choroids fissure cysts. Cysts a re als o enco untered in co njunction wi th t umours (e .g. p ilocytic astr ocytoma, haema ngioblastoma) and af ter p arenchymal hemo rrhage o r is chemia (p orencephalic cysts). 3.8.2 Imaging

Conventional X-ray Conventional X-ra y ma y r eveal a t hinning, s calloping o r remodelling of the skull. Growing skull fractures and their exact extent are easy to identify on lateral or AP views of the skull. The smooth borders of the defect are characteristic.

Ultrasound Imaging technique The transfontanellar approach with a 5.0–7.5 MHz curved or linear array transducer may be used to iden tify c ystic

31

3.8 · Intracranial cystic lesions in children

intracranial lesions in neonates. Duplex sonography confirms the hypovascularity of primary intracranial cysts.

Possible findings

▬ The ventricles may be compressed or displaced ▬ Depending on the location, parts of the ventricles may be entrapped ▬ In leptomeningeal c ysts, US ma y show t he dural defect ▬ In growing f ractures, t he skull defect can b e us ed as acoustic window

▬ Uncomplicated cysts are anechoic or hypoechoic ▬ Uncomplicated cysts are well marginated with smooth borders ▬ Intracystic hemo rrhage incr eases t he ec hogenity o f the cyst ▬ Fluid-sedimentation levels indicate intracystic hemorrhage ▬ Complicated c ysts (a fter hemo rrhage o r inf ection) frequently display multiple septa and are consequently multicompartimentalized ▬ The cyst wall is usually thin and hypovascular on Duplex sonography ▬ Adjacent brain tissue may be compressed ▬ Intracranial a rteries a nd v eins ma y b e disp laced o r compressed

Contrast-enhanced s eries a re ra rely necess ary. I n co mplicated, multiseptated c ysts, injection of contrast media in t he v entricular syst em a nd cist erns ca n b e hel pful t o identify the different compartments of the cyst and their communications ( ⊡ Fig. 3.8). Measurement of the Hounsfield uni ts ca n b e hel pful in dif ferentiating a rachnoid cysts from epidermoids. If CT is not conclusive, MRI with diffusion weighted imaging will be diagnostic.

⊡ Fig. 3.8A-F. Axial prenatal ultrasonography (A) shows a multiloculated retrocerebellar h ypoechoic ar achnoidal c yst. F oetal T2-weighted MRI (B) and postnatal T1-SE MRI (C) confirm the arachnoidal c yst. Compres-

sion of the sylvian ac quaduct results in a ventriculomegaly. Axial CT (D) and CT after intrathecal injec tion of c ontrast media ( E,F) show that the shunted arachnoidal cyst does not communicate with the ventricles.

Computer tomography Imaging technique

3

32


Possible findings

3

▬ Hypodense, well-marginated lesions with smooth borders ▬ Intracystic hemo rrhage incr eases t he den sity o f t he cyst ▬ Fluid-sedimentation levels indicate intracystic hemorrhage ▬ Complicated c ysts (a fter hemo rrhage o r inf ection) frequently display multiple septa and are consequently multicompartimentalized. The s epta ca n b e dif ficult to distinguish ▬ The c yst wall is us ually t hin and non-enhancing, reflecting the hypovascularity ▬ Adjacent brain tissue may be compressed ▬ Vasogenic oedema is recognized as an area of hypodensity within the white matter ▬ The ventricles may be compressed or displaced ▬ Depending on the location, parts of the ventricles may be entrapped ▬ In growing fractures, the skull defect can be examined in detail ▬ Skull thinning, scalloping or remodelling

Magnetic resonance imaging Imaging technique Triplanar T1- and T2-weighted high-resolution sequences are suf ficient to image intracranial c ystic lesions. FL AIR imaging is hel pful to iden tify p erifocal g liosis. Dif fusion-weighted MR wi ll co nfirm t he f luid co ntent a nd is especially hel pful t o dif ferentiate a rachnoid c ysts f rom epidermoids. C ontrast me dia a re ra rely ne cessary a nd should b e us ed o nly if co mplications o ccur o r inf ection is suspected.

Possible findings ▬ Uncomplicated c ysts are T1-hypointense and T2-hyperintense, similar to CSF ▬ The c yst wall is t hin, w ell-marginated a nd no n-enhancing ▬ FLAIR sequences may reveal a hyperintense perifocal gliosis within the adjacent white matter ▬ On dif fusion-weighted imagin g t he c yst is h ypointense on DWI and hyperintense on ADC maps. ▬ Epidermoids are T1- a nd T2-isointense to uncomplicated cysts ▬ Epidermoids a re D WI-hyperintense a nd AD C-hypointense

▬ Intracystic hemorrhage will increase T1- signal intensity and decrease T2- signal intensity. Fluid-sedimentation levels occur ▬ After intralesional hemorrhage, the cyst wall may enhance ▬ Compression, displacement or obstruction of parts of the ventricular system are well identified ▬ In leptomeningeal c ysts, pulsation artefacts with signal loss can be seen crossing the dural tear ▬ The high soft-tissue resolution and triplanar imaging are hel pful in iden tifying sma ll cho roid-fissure neuron-epithelial cysts 3.8.3 Diagnosis

Arachnoid, leptomeningeal and neuro-epithelial cysts are symptomatic due to compression or displacement of t he functional cen tre o f t he cen tral ner vous syst em (CNS). Depending o n t he lo cation, f ocal neur ological def icits, seizures or CSF circulation disturbances (hydrocephalus) are observed. In many instances, however, these cysts are clinically silent and are found only incidentally. Key information

I

I

Intracranial cystic lesions in children ▬ Arachnoid, leptomeningeal and neuro-epithelial cysts are benign lesions ▬ Arachnoid cysts may remodel the skull ▬ Meningo-encephaloceles should be excluded ▬ CSF-filled cysts should be differentiated from epidermoids ▬ CSF-filled cysts and epidermoids may have similar densities and signal intensities on conventional CT and MRI ▬ Diffusion-weighted MR allows differentiation between CSF-filled cysts and epidermoids ▬ Contrast-enhanced sequences are indicated if complicating cyst infection is suspected ▬ Cyst density/signal intensity changes if hemorrhage occurs ▬ Cysts may be septated, preventing complete drainage if shunted or punctured ▬ Injection of contrast media into the cyst may reveal compartmentalization or communication with adjacent cysts ▬ Leptomeningeal cysts may prevent fracture consolidation or result in a growing fracture

33

3.9 · Cystic lesions of the head and neck in childr en

3.9

Cystic lesions of the head and neck in children


Most cysts within the head and neck are benign disorders of d evelopment. Cy sts c an a lso re sult f rom i nfection, trauma a nd as a co mplication o f sur gery. C ysts o f t he head and neck region can b e symptomatic due to compression o f important f unctional str uctures. L arge c ysts can al so i nterfere wi th th e n ormal a natomical d evelopment o f t he vis cerocranium. A esthetic p roblems ma y also be a major concern. Hemorrhages within the cyst or complicating infection may result in a ra pid increase in the size o f the cysts. Rapid cyst enlargement can lead to life-threatening si tuations. I maging sho uld lo calize a nd characterize t he c ystic lesio ns. H igh-resolution imag ing allows exact allocation of the lesion to the different anatomical spaces of the neck. Congenital cystic neck masses include b ranchial c left c ysts, t hyroglossal d uct c yst a nd lymphangiomas. Thes e lesio ns sho uld b e dif ferentiated from inf lammatory o r ne oplastic c ystic he ad a nd ne ck masses. Lymphangioma o r c ystic h ygroma is a co ngenital malformation of the lymphatic channels within the neck. It ca n o ccur in co mbination wi th hema ngiomas (l ymphhaemangioma). L ymphangiomas ca n sho w m ultiple small cystic components (capillary lymphangioma), multiple medium-sized c ysts (cavernous l ymphangioma) or large f luid-filled co mpartments (c ystic l ymphangioma or hygroma). Branchial c left a nomalies inc lude c ysts, sin us trac ts and f istula t hat r esult f rom a n a nomalous de velopment of t he b ranchial a pparatus. D epending o n t he in volved branchial component, different locations of the branchial cleft a nomalies a re enco untered. Ano malies o f t he f irst and especially of the second branchial apparatus are most frequent. Ano malies o f t he t hird a nd f ourth b ranchial apparatus are rare. Thyroglossal duct cysts are developmental anomalies that result f rom a fa ilure of a s egment of t he t hyroglossal duct to obliterate. The thyroglossal duct is the »path« that the thyroid gland follows during its descent from the foramen cec um a t t he t ongue bas e t o i ts f inal p osition in the inf rahyoid neck. Cysts may o ccur at any lo cation along the thyroglossal duct.

3.9.2 Imaging

Conventional X-ray Conventional X-ray is indicated for the initial evaluation of deformations and displacements of the osseous structures of the head and neck region (⊡ Fig. 3.9). In addition, displacement o r co mpression o f t he a ir-filled la rynx o r trachea ca n b e s een. R arely, f lebolites o r co mplicating soft-tissue calcif ications a fter hemo rrhage o r inf ection can b e s een. Gas inc lusions indica te s evere inf lammation. C alcified l ymph no des r esult f rom inf ections b ut should als o ra ise t he p ossibility o f t uberculous l ymph node infection.

Ultrasound Imaging technique Ultrasonography is t he p rimary imag ing mo dality f or examining he ad a nd neck mass es ( ⊡ Fig. 3.9). I maging should b e p erformed wi th 5.0–7.5 MH z c urved a rray and line ar tra nsducer. The nec k sho uld b e exa mined in a syst ematic fashio n co vering all a natomical spaces. Comparison with the contra lateral side is helpful. Duplex sonography a nd p ower D oppler s onography a re necessary to study the neck vessels for their location and their patency. I n addi tion, p ower D oppler s onography a llows evaluating the vascularity of the lesion.

Possible findings ▬ Uncomplicated cystic masses present hypoechoic, well circumscribed ▬ Cysts are lined by a thin wall; intracystic septa may be seen ▬ Haemorrhagic c ysts ha ve a n incr eased ec hogenity, fluid-sedimentation levels may be seen, cyst walls may be thickened ▬ Infected cysts will show a thickened cyst wall and are usually hypervascularized on power Doppler sonography ▬ In ly mphhaemangiomas, t he ly mphangioma is h ypoechoic, the haemangioma hyperechoic with an increased vascularity ▬ In inf ected c ysts, enla rged l ymph no des wi thin t he neck are seen ▬ Neck vessels may be displaced or obliterated ▬ Branchial cleft or thyroglossal duct cysts have an appearance similar to lymphangiomas, the location and extension indicate etiology and nature of the lesion

3

34


3

⊡ Fig. 3.9A-F. Axial T2-FSE MRI (A) of the neck shows a large T2-hyperintense multic ompartimentalized lymphang ioma of the right neck . Ultrasonography ( B) is especially sensitiv e t o identify the multiple hyperechogenic septae within the h ypoechogenic lymphang ioma.

On C T ( C,D) the lesion is h ypodense and displac es/deforms the adjacent osseous struc tures. The c ontrast-enhanced neck v essels ar e patent but displac ed. C onventional X -ray ( E) c onfirms the osseous remodelling

▬ In thyroglossal duct cysts, the thyroid gland should be examined in det ail. An ec topic t hyroid g land should be excluded (thyreoid scan!) ▬ Inflammatory cystic masses (e.g. abscesses) should be suspected in t he a ppropriate c linical sym ptomatology and identification of a generalized lymphadenitis colli ▬ Differentiation f rom c ystic ne oplasm ca n b e dif ficult

Possible findings

Computer tomography Imaging technique Contrast-enhanced CT wi th co ronal a nd s agittal r econstructions co vering th e n eck fr om th e s kull ba se t o th e jugulum are diagnostic for most cystic neck lesions. Images should be studied in soft-tissue and bone window-level settings ( ⊡ Fig. 3.9). In selected cases, injection of diluted contrast media in to c utaneous f istulae p rior t o imagin g can enhance identification of fistula tracts.

▬ Cystic nec k mass es a re h ypodense o n CT a nd w ell marginated ▬ Cyst walls are thin and non-enhancing ▬ Intracystic s eptae ma y b e dif ficult to iden tify. US is more sensitive! ▬ Haemorrhagic cysts show an increased density and/or fluid-sedimentation levels ▬ Haemorrhagic or infected cysts may have a thickened cyst wall with or without cyst wall enhancement ▬ In l ymphhaemangiomas, t he haema ngiomatous co mponent will show a st rong enhancement. Occasionally, dilated contrast enhancing intralesional vessels are seen ▬ Enlarged l ymph n odes; d isplacement o f a natomical structures are easily identified ▬ Complicating vessel thromboses are recognized as hypodense filling defects within the strongly enhancing vessel lumen in partial thrombosis (infectious thrombosis), or the vessel is not contrast-enhancing at all in complete thrombosis

35

3.9 · Cystic lesions of the head and neck in childr en

▬ Differentiation b etween l ymphangioma, b ranchial cleft cyst and thyroglossal cyst relies on the exact anatomical lesion localization ▬ Calcified l ymph no des a nd c yst wall calcif ications present hyperdense ▬ Abscesses in l ymphadenitis co lli a re cen trally h ypodense with a strong peripheral enhancement ▬ Displacement of neck structures is easily identified by CT ▬ Bony erosion, remodelling and possible infectious affection (complicating osteomyelitis) ▬ Two- a nd t hree-dimensional b one r econstructions facilitate interpretation of complex osseous remodelling ▬ Enhancement patterns may differentiate between congenital a nd inf lammatory c ystic neck mass es a nd cystic neck neoplasms

Magnetic resonance imaging Imaging technique The dif ferent imagin g co ntrasts t hat ca n b e g enerated, the f unctional imag ing information (dif fusion-weighted imaging) and the lack of ionizing radiation are advantageous ( ⊡ Fig. 3.9). Imaging should include pre- and postcontrast T1-w eighted s equences as w ell as T2-w eighted sequences. Fat s aturation pulses will incr ease s ensitivity of co ntrast-enhanced T1-w eighted s equences. I n s elected cas es, sub traction imag es (p re- a nd p ostcontrast s equences) are helpful. MR-angiography and MR-venography sequences should be added if vascular complications are suspected.

Possible findings ▬ Uncomplicated c ysts a re T1-h ypo- a nd T2-h yperintense ▬ Cyst walls are T1- and T2-hypointense ▬ Cyst walls may show contrast enhancement after cyst hemorrhage or inflammation ▬ Intracystic septa are difficult to identify by MRI, US is most sensitive! ▬ Haemorrhagic c ysts a re T1-is o- o r hyperintense a nd T2-iso- or hypointense ▬ Haemorrhagic c ysts f requently r eveal a f luid-sedimentation level on all MRI sequences ▬ Complicated cysts and especially abscesses are DWIhyperintense a nd AD C-hypointense d ue t o t he r estricted diffusion

▬ In lymphhaemangiomas, the haemangiomatous component is T1-iso or hypointense and strongly enhancing ▬ Complicating osteomyelitis increases the STIR-signal intensity of the affected bone marrow ▬ MR angiography and MR venography are highly sensitive to thrombosis ▬ The hig h a natomical det ail a nd s oft-tissue r esolution facilitate differentiation between lymphangiomas, branchial cleft and thyroglossal duct cysts 3.9.3 Diagnosis

Diagnosis r elies o n t he co mbination o f a g ood c linical examination a nd hig h-resolution imagin g. The dif ferentiation between the different c ystic neck masses is bas ed on the proper identification of the anatomical landmarks. Ultrasonography can be especially valuable to differentiate between a uniloculated and multiloculated cystic neck lesion. Thin s epta can be missed on CT o r MRI. Finall y, necrotic neoplastic lesions may mimic c ystic lesions and should be considered and consequently ruled out. Key information

I

I

Cystic lesions of the head and neck in childr en ▬ Congenital cystic neck masses should be differentiated from inflammatory and neoplastic cystic neck masses ▬ Complicating infection, hemorrhage or compression of vital structures should be diagnosed as early as possible ▬ Ultrasonography is the primary imaging modality ▬ CT is especially helpful for the pre-operative planning of associated osseous deformities or malformations ▬ MRI is highly sensitive due to the high spatial and contrast resolution ▬ Diffusion-weighted imaging allows differentiation of abscesses ▬ Contrast-enhanced sequences increase sensitivity and specificity ▬ Vascular complications should be excluded ▬ In branchial cleft and thyroglossal duct cysts the exact extent and anatomical location should be studied to achieve complete surgical resection

3

36


3.10

Spinal cord neoplasm in children


3

Spinal co rd neo plasm a re ra re, 0.5–1% o f all cen tral nervous syst em (CNS) t umours a re lo cated wi thin t he spinal co rd. 2–4% o f all g lial CNS g lial t umours a re located in t he sp inal co rd; 35% o f all in traspinal t umours are intrinsic spinal cord neoplasm; 90% are glial tumours and most a re malignant. All ag e groups are affected, but spinal cord neoplasm is more frequent toward the end of the first decade. There is no s ex predilection. Spinal cord neoplasm is less common in children compared to adults. Children usuall y p resent (v ery) la te b ecause sp inal co rd tumours usuall y p resent wi th slo wly p rogressive un specific clinical findings. Retrospectively, there is f requently a long history of symptom exacerbations and remissions which i s be lieved t o r esult fr om pe ritumoural oed ema fluctuation. Every child with persisting back pain should be taken seriously. 25-30% of all children with spinal cord neoplasm p resent wi th bac k pa in. Additional sym ptoms include progressive motor weakness, progressive scoliosis, gait disturbance, rigidity and paraspinous muscle spasm. Sensory def icits a re less co mmon. 15% o f c hildren wi th spinal cord neoplasm present with symptoms of increased intracranial pressure. This ma y b e related to an ele vated cerebrospinal f luid (CS F) p rotein co ncentration, d ue t o a b lockage o f t he f oramen magnum, a suba rachnoid t umour hemorrhage or a subarachnoid tumour seeding. The s ame neo plasms a re s een in ad ults a nd c hildren. The incidence and presentation differ however. 90–95% are glial tumours, 60% are Pilocytic or anaplastic astrocytomas, 30% are (myxopapillary) ependymoma. Non-glial tumours include hema ngioblastoma, sub ependymoma, ga nglioglioma, met astasis, l ymphoma, neur ocytoma, etc. A s r ule o f thumb: In children, astrocytomas are much more frequent than ependymomas, while in ad ults the ependymomas are much more frequent than astrocytomas. Ependymomas are more f requent in neur ofibromatosis 2, w hile astrocytomas are more frequent in neurofibromatosis 1. Finally, the higher the tumour location, the more likely a syrinx will develop. 3.10.2 Imaging

Conventional X-ray Conventional sp inal X-ra y has a v ery limi ted diagnostic value. If a s coliosis is s een without segmentation anoma-

lies, a spinal cord process should be excluded. If the spinal canal o r t he neur oforamina a re widened a sp inal co rd process is likely. Spinal X-ray is still o f value for the neurosurgeon in the planning of his operation. In addition, it may confirm the exact anatomical level of the spinal cord lesion. Myelography is rarely performed in the diagnostic work-up of tumours in children.

Ultrasound Imaging technique In neonates and very young children the spinal canal and cord can be examined from the back with a 5.0-7.5 MH z linear a rray tra nsducer. W ith p rogressing ossif ication o f the do rsal sp inal elemen ts t he diagnostic va lue de clines. In our experience, US is o f limited value in the diagnostic work-up of spinal cord tumours. US can however be helpful intraoperatively. If the US-transducer can be positioned directly on top of the spinal cord, US can guide surgery.

Possible findings ▬ Focal enlargement/widening of the spinal cord ▬ Narrowing of the subarachnoid, perimedullary space at the level of the tumour ▬ Focal hyper- or hypoechoic intramedullary tumour ▬ Intratumoural calcifications or hemorrhage ▬ Peritumoural, hypoechoic cysts ▬ Hyper- or hypovascularity of the tumour ▬ Adjacent, enlarged tumour vessels ▬ S yringo-hydromyelia

Computer tomography Imaging technique Axial co ntrast-enhanced CT wi th s econdary s agittal a nd coronal reconstructions. Bone algorithm to identify intratumoural calcifications and bony erosions, e.g. widening of the neuroforamina or spinal canal. Myelo-CT is nowadays rarely performed because of the high resolution of MRI.

Possible findings ▬ Focal enlargement/widening of the spinal cord ▬ Narrowing of the subarachnoid, perimedullary space at the level of the tumour ▬ The tumour may be hypo-, iso- or hyperdense ▬ Intratumoural calcifications or hemorrhage ▬ P eritumoural h ypodense c ysts w hich ma y enha nce peripherally

37

3.10 · Spinal cord neoplasm in children

▬ Perifocal h ypodense sp inal co rd o edema a nd/or v enous stasis ▬ Variable contrast-enhancement of the tumour ▬ Enlarged adjacent t umour v essels (e .g. in hema ngioblastoma) ▬ S yringo-hydromyelia ▬ Cerebro spinal fluid (CSF) tumour seeding ▬ Tumour extension through the neuroforamina ▬ Erosion a nd/or widenin g a nd/or s calloping o f t he spinal canal or neuroforamina

Magnetic resonance imaging Imaging technique Sagittal and axial pre- and postcontrast T1-weighted images sho uld b e co mbined wi th T2-w eighted s equences. Coronal imag es ma y b e added . Thin-sliced t hree dimensional he avily T2-w eighted (lo ng ec ho tra in) images may be helpful to identify intramedullary c ysts, to study t he cen tral ca nal a nd t o e valuate t he na rrowing of t he p erimedullary suba rachnoid space . Thr ee dimensional time-of-flight or contrast enhanced dynamic magnetic resonance angiography (MRA) should be considered in highly vascularized lesions like e.g. hemangioblastoma.

Possible findings Spinal astrocytoma (⊡ Fig. 3.10a) ▬ 50% are cervico-thoracic in location and affect only a small number of segments ▬ Diffuse inf iltrating t umour wi thout a c lear c leavage plane between tumour and normal spinal cord ▬ Tumour is T2-h yperintense, T1-h ypo o r is o-intense, rarely haemorrhagic ▬ Variable, mild to moderate contrast enhancement ▬ 20-40% have peri- or intratumoural cysts as w ell as a syrinx (caudal or rostral) ▬ Tumour is usuall y ex centric in lo cation wi th asymmetric cord expansion ▬ Spinal canal may be enlarged/widened ▬ CSF-seeding presents as no dular intradural enhancement, most f requently in t he dep endent spinal canal (⊡ Fig. 3.10b) Spinal ependymoma ▬ Most frequently in cervical cord ▬ Central lo cation (a rises f requently f rom ep endym o f central canal). Symmetric spinal cord enlargement.

▬ Less inf iltrating, p redominantly co mpression o f adjacent no n-affected sp inal co rd. Of ten c lear c leavage plane ▬ Peritumoural cysts common, Intratumoural cysts less common ▬ Tumour frequently T2 hyperintense, T1 hypo- or isointense ▬ Strong co ntrast en hancement, sma ll t umour v essels may be seen ▬ High vascularity may result in intratumoural and subarachnoid hemorrhage ▬ Often »cap sign«: rim of T2-hypointense hemosiderin at tumour poles Myxopapillary ependymoma ▬ Predilection for conus medullaris and cauda equina ▬ Mucin p roducing, p olylobulated t umour t hat ma y scallop osseous spinal canal ▬ T2-hyperintense, T1 h ypo- o r is o-intense, str ongly enhancing tumour 3.10.3 Diagnosis

Children wi th bac k-pain, p rogressive s coliosis, p rogressive motor weakness, gait disturbance and muscular rigidity/hypertonia should be taken seriously. A spinal canal or spinal cord tumour should be ruled out according to the slogan: Diagnos e ag gressively, t reat co nservatively. F requently, unnecess ary, no n-diagnostic tests a nd imagin g is p erformed delaying diagnosis. MRI is t he most s ensitive imaging modality for spinal cord lesions and should be us ed e arly in diagnos e ma king. Diagnostic CS F-taps should b e do ne a fter MRI is p erformed. A CS F-tap f requently results in a dural enhancement which may mimic subarachnoid tumour seeding. Key information

I

Spinal cord neoplasm in children ▬ Spinal cord neoplasm ▬ A strocytoma ▬ Ependymoma ▬ M yxopapillary ependymoma ▬ Hemang ioblastoma ▬ Back pain ▬ T umour cysts ▬ S yringo-hydromyelia

I

3

38


3

A

References 1. 2. 3. 4. 5. 6. 7.

B ⊡ Fig. 3.10A,B. (A) Sagittal T2, T1, contrast-enhanced T1 and thin-slice heavily T2-weighted MRI sho ws an expanding T2-hyperintense, slightly T1-hypointense, strongly enhancing intramedullary astrocytoma. The thin sliced heavily T2-weighted image sho ws peritumoural c ysts along the cr anial border of the tumour (other patient) ( B) Sagittal pre- and post-contrast T1weighted MRI reveals a linear enhancement along the surface of the lumbar spinal cord as well as multiple c ontrast enhancing metastatic nodules due to CSF-seeding in a child with an anaplastic spinal cord astrocytoma

Barkovich A J (2000) P ediatric neur oimaging, 3 rd edn. Lippinc ott Williams & Wilkens, Philadelphia Osborn A G (2004) Diag nostic imag ing: brain. Amirsy s, Salt Lake City Tortori-Donati P (2005) P ediatric neur oradiology: Brain. Springer Verlag, Berlin, Heidelberg, New York Harnsberger HR Diagnostic imaging: head and neck. Amirsys, Salt Lake City, Utah Triulzi F, Baldoli C, Parazzini C (2001) Neonatal MR imag ing. Magn Reson Clin North America Paneth N, Rudelli R, Kazam E, Monte W (1994) Brain damage in the preterm infant. Clinics in Developmental Medicine Ball WS (ed) (1997) P ediatric neur oradiology. Philadelphia-New York, Lippincott-Raven

4 T

horacic disorders Donald P. Frush

4.1 In

troduction

The thorax is the most common region to undergo imaging e valuation in c hildren. While a c hest radiograph (or chest X-ray) is the most frequently performed procedure, computed tomography (CT), ul tra sonography (US) a nd magnetic r esonance (MR) imagin g als o p rovide im portant diagnostic inf ormation f or paedia tric t horacic a nd intrathoracic a bnormalities. K nowledge o f t he r elative advantages and disadvantages of the modalities provides an opportunity for optimal diagnostic imaging strategies for the range of disorders in infants and children. The systematic review of these disorders can be based on t he t raditional cl assification s cheme, c onsisting of congenital (inc luding neo natal) a bnormalities, inf ectious/inflammatory conditions, tumour and tumour-like conditions, tra umatic a bnormalities o r t oxic/metabolic disorders, which includes thoracic manifestations of systemic dis orders. Al ternatively, dis orders co uld b e c lassified bas ed o n t he p resentation, suc h as f ever, mass o r wheezing. H owever, the sign s o r sym ptoms o f tho racic disorders in c hildren a re r elatively no n-specific a nd o ften o verlap t he indi vidual dis order c lassifications no ted above. For example, wheezing can be caused by infection (viral o r bac terial), t oxic exp osure (inhala tion), tra uma (aspirated foreign body) or congenital anomalies (such as tracheal compression by a vas cular ring such as a do uble

aortic a rch). Ther efore, t he f ollowing ma terial wi ll b e divided bas ed o n t he tradi tional c lassification s cheme, and sub classified by r egion (c hest wall , a irway, l ung parenchyma, mediastinum, heart and great vessels). Within each category, the role of the various imaging modalities will be addressed (and general technique provided, when pertinent) wi th mo re in-dep th dis cussion a nd ill ustration of the more common of the disorders. The r eader is referred t o s everal o ther ex cellent r eferences f or a mo re in-depth discussion [2,3]. 4.2 Imaging

modalities

The st andard imagin g mo dalities f or e valuation o f t horacic and intrathoracic dis orders in infa nts and children as well as the benefits and relative disadvantages are found in ⊡ Table 4.1 [1]. With few exceptions, chest radiography is t he f irst (a nd o ften o nly, e .g. f or p neumonia) imaging mo dality us ed to ass ess t horacic signs or symptoms. Because the radiograph is a relatively low -radiation dose, inexpensive, w idely a vailable and r elatively c onsistently performed, it provides an excellent survey of lung parenchyma, cardiovascular structures, mediastinum and chest wall structures. Fluoroscopy has a limi ted r ole b ut is us ed t o ass ess dynamics of the intrathoracic airway, lung expansion (e.g.

40

Chapter 4 · Thoracic disorders

⊡ Table 4.1. Choosing the appropriate thoracic imaging modality in children

4

Imaging type

What it reveals

Advantages

Disadvantages

Chief uses

Radiography

Soft tissue including lung and anatomy

    

 Provides basic anatomical information for only a few tissue densities

 Screening for infection (viral and bacterial pneumonia), chest pain, respiratory distress, trauma (including foreign body), dysplasias

Fluoroscopy

Anatomical and functional information

 Provides images in real time  Widely available

 Radiation dose may be substantial  More expensive than radiography

 Diaphragm movement, air trapping (e.g. aspiration), thoracic airway dynamics luminal (e.g. oesophagal) evaluation

Sonography

Real-time evaluation of soft tissues, upper torso vessels

   

No radiation exposure Painless Portable Widely available

 Operator-dependent: images obtained are highly dependent on sonographer expertise  More expensive than radiography

 Screening of soft tissue masses, pleural fluid, peripheral lung abnormalities, anterior mediastinum in young children

Computed tomography (CT)

 Information from virtually any organ system  Best for lung parenchyma

 Excellent depiction of anatomical detail  Very fast exam time  With IV contrast can examine organ enhancement as well as blood vessels  MDCT provides multiplanar and 3-dimensional information

 Much higher radiation dose than radiography  Often requires IV contrast media  Relatively expensive

 Complicated pneumonia, trauma, mediastinal masses, interstitial lung disease, pulmonary masses, metastatic surveillance, cardiovascular evaluation (CT angiography), including pulmonary emboli

Magnetic resonance imaging (MRI)

 Detailed highcontrast information of organs and other soft tissue  Dynamic cardiac evaluation

 Allows for multiplanar and 3-dimensional evaluation  Does not require routine use of IV contrast material for imaging of the chest (unlike CT)  Superior depiction of soft tissue and organ contrast differences  No radiation exposure  Painless

 Often requires sedation in children younger than 7 years  Expensive  Scanner is noisy  Monitoring is limited  Requires wait for scheduling  Picture quality highly susceptible to child movement  Exams can take up to 45-60 min

 Chest wall masses, mediastinal masses, CV evaluation

Nuclear medicine

Structure, and function of organs, soft tissues, and bones

 Generally delivers lower radiation dose than fluoroscopy or CT  Adverse reactions rare

 May take a long time and require sedation  Offers limited anatomic information compared with other techniques

 Limited  PET for CV evaluation  PET-CT for tumour surveillance  Bone scan for infection  Some cardiac function (sestamibi, myoview) stress tests

Low radiation dose Inexpensive Readily available Quick No preparation necessary

4.2 · Imaging modalities

in t he s etting o f asp iration o f a f oreign b ody), co ntrast evaluation o f t he o esophagus, a nd t o ass ess dia phragm motion in the setting of possible hemidiaphragm paralysis or paresis. Disorders of the oesophagus are assessed using either ba rium o r wa ter-soluble co ntrast d uring f luoroscopic evaluation. The wa ter-soluble media a re generally used under conditions where there is potential leakage of contrast, since barium can result in granuloma formation. Dynamic information, (i.e. aspiration, oesophageal emptying a nd gastr oesophageal r eflux), as w ell as str uctural evaluation is provided by contrast-enhanced fluoroscopic evaluation of the oesophagus. Ultrasonography sho uld al ways b e co nsidered as a second-line mo dality f or e valuation o f t hose p rocesses which are considered intrathoracic but peripheral in nature (recall, there is no co herent sound transmission and ability t o f orm a s onographic imag e t hrough a ir-filled structures such as t he lung) [2]. This includes assessment of the presence or characteristics of pleural effusions [e.g. septations or loculations), chest wall masses or evaluation of p otential me diastinal mass es in t he neonate or infa nt (⊡ Fig. 4.1). One typ e of sonography is echocardiography. This is in general reserved for evaluation of the heart and great v essels. I f t here is a susp icion o f co ngenital he art disease, ec hocardiography sho uld b e us ed in co njunction wi th c hest radiography. In t hese cir cumstances, CT angiographic a nd MR a ngiographic t echniques w ould be used to answer questions not able to be addressed by echocardiography. CT is divided into conventional (slice-by-slice or stepand-shoot) or helical techniques. Helical technology uses a sin gle det ector (sin gle-slice CT), o r, c urrently, f rom 4–64 arrays of detectors [all called m ultidetector array or MDCT). Much o f CT t oday is p erformed usin g MD CT technology [3,8]. Overall, CT gives the best global assessment of all t horacic and intrathoracic structures. In particular, the highest level of anatomical information regarding l ung pa renchyma is p rovided b y a CT exa mination, especially if hig h-resolution CT (HR CT) (t hin-slice a nd high-detail) techniques are used. In addition, CT provides excellent mo rphological a nd a natomical inf ormation f or mediastinal or cardiovascular structures (especially if angiographic technique, or CT a ngiography—CTA—is utilized) and osseous abnormalities. Because of its relatively wide a vailability, fast exa mination times (wi th ne w 64slice technology chest CT examinations can be performed in under 0.5 s in neo nates and in under a f ew seconds in adult-sized teenagers) and consistent examination detail,

41

⊡ Fig. 4.1. Transverse view of normal infant th ymus ( thymus). Bor rowed with permission Academy of Medicine, Singapore

CT is often the second-line evaluation when radiography does no t p rovide suf ficient inf ormation f or diagnosis o r management (such as surg ical planning) and ultrasonography is also unlikely to be diagnostic. However, consideration should be given to the relatively high radiation dose provided by a chest CT examination. This dose may be in excess o f t he eq uivalent o f 100 c hest X-ra ys f or a sin gle CT examination. MR imagin g is usuall y r eserved f or a p roblem-solving t ool w hen radiography is in sufficient, s onography is unlikely t o r esult in suf ficient diagnostic inf ormation, and e valuation o f l ung pa renchyma is no t cr itical. I n particular, MR p rovides excellent evaluation of the chest wall, sp inal a nd pa raspinal r egion, t he r emainder o f t he mediastinum and cardiovascular structures. With non-IV contrast-enhanced ca rdiac-gated inf ormation (o r b lackblood techniques) or with IV co ntrast media (MR a ngiography), excellent cardiovascular assessment is achieved including functional information that is unavailable from a CT examination.

4

42


4.3 C

ongenital abnormalities/ neonatal anomalies

4.3.1 In troduction

4

There is a variety of disorders which are of congenital nature or associated with birth. This is a particularly unique category since t hese a bnormalities ei ther do no t exist in ad ults o r a re extr emely ra re (f or exa mple p ulmonary sequestration or bronchogenic cysts) compared with their frequency in the paediatric population. 4.3.2 Chest wall

General information Imaging can provide important information on generalized a bnormalities of t he shape, size o r configuration of the t horax, pa rticularly in t he neo nate wi th r espiratory distress o r p otential sk eletal d ysplasia, o r in t he s etting of p ectus ex cavatum. I n addi tion, t he p resence o f f ocal abnormalities such as co ngenital mass es incl uding haemangiomas o r vas cular ma lformations is wel l addr essed by diagnostic imaging [4].

⊡ Fig. 4.2. Radiograph of chest wall mass in a y oung child which was a congenital rib anomaly fully demonstrat ed on radiography (arrows). No further imaging was necessary

Imaging Radiography is the first modality to be used when evaluating congenital thoracic abnormalities, including deformity or mass or mass-like conditions. Radiography can provide important information in terms of rib, sternum or thoracic spine a bnormalities, incl uding t he sho ulder r egion (including the clavicle) which may account for abnormalities in size o r co nfiguration o f t he t horax. This inf ormation may be diagnostic. Of no te, suspected masses in c hildren often r eflect in significant co ngenital a nomalies o r asymmetry in chondro-osseous structures (⊡ Fig. 4.2) [4]. Ultrasonography, o r so nography, ca n be u sed th ere is a susp icion of an anomaly of the ribs or costovertebral region. Sonography is also useful in assessing the presence or a bsence o f a co ngenital c hest wall mass. S onography can als o b e us eful in det ecting t he nature of other chest wall mass es suc h as t he g eneral ca tegory o f vas cular masses co mposed o f ei ther haema ngiomas o r vas cular malformations (such as ly mphatic o r veno us ma lformations), inf lammatory mass es (such as adeni tis, a bscess or cell ulitis) o r c yst o r c yst-like co nditions. H owever, if assessing the total extent of a lesion, cross-sectional imag-

ing (such as CT o r MR e valuation) is o ften indicated for evaluation of masses.

Sonography technique ▬ High-resolution linear transducer (10–17 MHz) ▬ Or thogonal planes ▬ Doppler for assessment of flow (soft tissue vs. complex fluid) and in the setting of possible inflammatory conditions ▬ Careful assessment of contralateral area for comparison purposes CT can also show whether a co ngenital mass is o r is no t present. CT ma y b e diagnostic f or co ngenital va riations of the vertebrae, ribs or sternum, of which the latter two frequently are the cause of concern in adolescent patients. CT will als o indica te t he p resence o f a mass al though often the features are non-specific. CT is especially useful in assessing the degree of pectus abnormality, particularly when a surgical intervention is anticipated ( ⊡ Fig. 4.3). In

43

4.3 · Congenital abnormalities/neonatal anomalies

this case, a very low-dose examination may be performed because o nly a sk eletal a nd l ung pa renchyma det ail is necessary. As is t he case in o ther regions of the body including the b rain, sp inal co rd a nd m usculoskeletal syst em, MR imaging p rovides t he b est s oft-tissue co ntrast inf ormation, a nd is v ery us eful in ass essing mass es no t o therwise addressed adequately by radiography or sonography. When s edation is r equired for MR imagin g, CT ma y b e considered as t he next mo dality in chi ldren f or w hom sedation for CT would not be required. In this case, a IV contrast CT examination is indicated. For s onography o f t he c hest wall , a hig h-resolution transducer (10–17 MH z) is g enerally indica ted. F or CT examination, dep ending o n t he typ e o f a bnormality, either a no n-contrast-enhanced o r IV co ntrast-enhanced examination ma y b e p erformed. I f t here is susp icion o f a tumour or tumour-like condition as a ca use for a mass, then IV co ntrast is indica ted. For skeletal abnormalities, in general, a non-contrast examination is sufficient.

symptoms are often non-specific. For example, tachypnea may be due to infectious causes, masses or congenital lesions such as congenital lobar emphysema. These entities can t hen b e distinguished f rom congenital airway dis orders such as an aberrant bronchus or tracheo-oesophageal fistula. Fluoroscopic evaluation of congenital anomalies is generally limi ted t o ass essment o f trac hea a bnormalities and diaphragm motion (sonography is an alternative). Airway dis orders ca n b e di vided into la rge a nd small airway dis orders. M ost co ngenital a bnormalities o f t he airway are large airway disorders. Congenital primary abnormalities of the airway are rare and consist most often of tracheomalacia and bronchomalacia, accessory (i.e. cardiac bronchi) airways or other abnormal branching patterns, or tracheo-oesophageal f istula. M alacia is b est addr essed b y bronchoscopy, b ut MD CT p erformed d uring r espiration and subsequently segmented to depict cycles of respiration can show the dynamic nature of airway collapse. Branching anomalies are b est depicted by CT. For example, CT b est demonstrates the anomalous airway branching patterns of a tracheal (or pig) bronchus where an upper lobe bronchus arises dir ectly f rom t he trac hea. The a irway ca n als o b e secondarily involved due t o other congenital lesions suc h as the mediastinal or bronchogenic cysts or cardiovascular abnormality such as a double aortic arch. These will be addressed in subsequent sections. In addition, fast or cine MR techniques can be applied although the greatest use of this technique is for evaluation of upper airway obstruction. For the tracheo-oesophageal fistula, careful fluoroscopic evaluation using contrast media is indicated. In g eneral, IV co ntrast-enhanced CT exa mination is best in addr essing a irway a bnormalities b ecause i t b etter o utlines ad jacent vas cular str uctures f rom p otential masses a nd b etter def ines a irway a bnormalities. N ewer multidetector (MD CT) t echnology a ffords m ultiplanar and v olume t hree-dimensional r econstructions wi th excellent depiction of airway morphology with some functional information [5].

4.3.3 Ai rway

4.3.4

The role of radiography is b oth in primary assessment of the airway, such as deviation, narrowing or other primary abnormality, and in secondary involvement of the airway with other congenital lesions, as mentioned above. Radiography als o has a cr itical r ole in ass essing o ther co nditions which may mimic airway abnormalities, as signs and

Introduction

⊡ Fig. 4.3. Pectus excavatum evaluation b y CT. The degree of ant eroposterior narrowing (in addition t o sternal tilt) is w ell assessed using this modality. Borrowed with permission Elsevier

Lung parenchyma

The spectrum of congenital lung lesions includes a va riety of disorders ( ⊡ Table 4.2) [6]. Thes e may present with non-specific signs or symptoms or be incidentally discovered during imaging for reasons unrelated to the disorder (e.g. discovered during evaluation for trauma).

4

44


⊡ Table 4.2. Congenital lung and airway disorders

4

1. Airway a. Trachea i. Tracheomalacia ii. Congenital stenosis b. More distal large airway i. Bronchogenic cyst ii. Bronchial atresia 2. Lung parenchyma a. Pulmonary maldevelopment i. Underdevelopment 1. Agenesis/atresia 2. Aplasia 3. Hypoplasia (includes scimitar syndrome) 4. Secondary to other process (e.g. diaphragm hernia) ii. Other 1. Horseshoe lung b. Pulmonary sequestration i. Intralobar ii. Extralobar c. Congenital cystic adenomatoid malformation (CCAM) also known as congenital pulmonary airway malformation (CPAM) d. Congenital lobar emphysema (CLE) e. Pulmonary cyst f. Hybrid lesions (usually associated with sequestration or CCAM) 3. Other a. Vascular i. Pulmonary arteriovenous malformations

Imaging Evaluation The ini tial mo dality f or susp ected co ngenital l ung a bnormalities is radiogra phy. Thes e dis orders ca n a lso b e detected in u tero either by s onography or MR imagin g. Radiography should be performed when a mass or abnormal aeration persists over approximately three examinations. For example, pulmonary sequestration can mimic recurrent p neumonia. Af ter t he s econd p neumonia in an identical location, it is worthwhile to obtain a followup r adiograph on ce an a ppropriate p eriod of an tibiotic treatment has ensued (e.g. after 3–4 weeks) to make sure that this resolves. If the opacity persists, IV co ntrast CT is warranted. This p rinciple of follow-up is als o the case with persistent anomalies and aeration, such as hyperinflation. When a mass is detected by foetal evaluation, CT examination in the postnatal period is indicated. CT is the principle modality for evaluation of congenital lung abnormalities. A IV contrast examination should be performed. For most examinations, the angiographic tech-

nique to optimally opacify t he arterial supply and venous drainage is p referred ( ⊡ Fig. 4.4). CT als o gi ves important information in other mass lesions such as the bronchogenic cysts, w here t he a ttenuation will b e t hat o f f luid a nd t he wall is typically thin or imperceptible (⊡ Fig. 4.5). Congenital lobar emphysema presents as h yperinflation of a lob e, particularly an upper lobe ( ⊡ Fig. 4.6). Care must be taken to r ule o ut ca uses o f acq uired em physema, suc h as co mpression from an intrinsic abnormality or an endobronchial lesion. For these reasons, IV contrast material is helpful in evaluation of any potential congenital lung anomaly. In general, the role of ultrasonography for definition of t hese c ongenital lu ng abn ormalities i s l imited du e to the in traparenchymal na ture o f t he co ngenital lesio ns. While peripheral abnormalities might be d etected by sonography, information obtained is usually insufficient for management, usually surgical resection. MR imagin g is us eful in ass essment o f mass lesio ns such as bronchogenic cysts. In addition, MR angiography can identify arterial and venous components of a sequestration. However, since better lung anatomy is afforded by CT examination, this is usually the preferred modality. 4.3.5 Mediastinum

The spectrum of mediastinal dis orders is g enerally covered by mass and mass-like conditions (see below). 4.3.6 C ardiovascular system

With the advent of echocardiography and, more recently, improved spa tial inf ormation ob tained wi th co ntrastenhanced CT a nd MR , t he r ole o f radiogra phy in t he diagnosis of sp ecific lesions in co ngenital cardiovascular disease in c hildren has c hanged dramatically. Practically speaking, infants with suspected congenital heart disease will have an echocardiogram, often diagnostic, with radiography reserved for use to indicate potential non-cardiac mimics of congenital he art dis ease, or as a bas eline modality (for example to determine if pulmonary oedema or pleural effusion develop) or for detecting other anomalies associated with congenital he art dis ease such as a r ib or vertebral a nomalies. W hen ec hocardiography is in sufficient, t hen co ntrast-enhanced MR o r CT is indica ted (⊡ Figs. 4.7, 4.8) [7,8]. The r elative b enefits o f t hese modalities are listed below.


45

⊡ Fig. 4.4. Pulmonary sequestration. Ar terial supply ( arrow, upper left) and v enous drainage (arrow, lower right) eventually into the pulmonar y vein are demonstrated. Borrowed with permission Elsevier

⊡ Fig. 4.5. Bronchogenic cyst in a y oung child. C T examination demonstrates the fluid density cyst (arrow) in the middle mediastinum

⊡ Fig. 4.6. CT of c ongenital lobar emphysema. Note hyperinflation of the left lung compared with the right

4

46

4


CT ▬ Fast: cardiovascular assessment can now be performed in < 1 s ▬ Less need for sedation compared with MR ▬ Superior spatial resolution compared with MR ▬ Better patient monitoring ▬ Superior assessment of lung parenchyma ▬ Metallic devices or pacers are not contra-indications MR ▬ Better soft-tissue contrast evaluation ▬ N o radiation ▬ Functional inf ormation (e .g. ca rdiac o utput, ejec tion fraction; det ermination o f p ressure gradien ts acr oss stenoses; r esurgent f ractions p ulmonary-to-systemic flow ratio) One gr oup o f co ngenital lesio ns in w hich radiogra phy does play an important role is in vascular rings (⊡ Fig. 4.9) [9]. In this setting, symptoms are often those of reactive airways disease and close inspection of the mediastinum, especially t he a irway, wi th radiogra phy p rovides important c lues t o t he presence and typ e of vas cular r ing. These include deviation of the trachea to the left from a right-sided ao rtic a rch, o ften wi th a n a berrant lef t subclavian artery, or double aortic arch, or anterior bowing of t he trac hea o n t he la teral exa mination sug gesting a left aortic arch with aberrant right subclavian artery (in addition t o a berrant lef t sub clavian a rtery wi th a r ightsided arch). Occasionally, other lesions are not clinically evident in t he ne onatal p eriod a nd t hese ma y p resent

⊡ Fig. 4.7. Pulmonary embolism. C ontrast enhanced C T with c oronal reformation demonstrat es the emboli ( arrows) bilat erally. Borr owed with permission Springer

⊡ Fig. 4.8. Axial contrast enhanced CT examination. Right-sided aortic arch with aberrant lef t subcla vian ar tery ( arrow) Not e mild tracheal narrowing (short arrow). Borrowed with permission Springer

later in c hildhood inc luding p ulmonary a rtery st enosis, (increased ma in pulmonary a rtery s egment), aortic st enosis (left ventricular hypertrophy and dilated ascending aorta), coarctation (left ventricular hypertrophy, reverse three-sign at the aortic arch) and systemic-to-pulmonary shunts such as a v entricular septal defect or atrial septal defect. These will have enlargement of specific chambers or o verall ca rdiomegaly w hich sho uld p rompt e chocardiographic evaluation. R adiography is als o useful in t he postoperative period for congenital heart disease. 4.3.7 Thoracic imaging unique to neonates

While all t he imagin g mo dalities ha ve s ome a pplication to t horacic dis orders in t he neo nate, radiogra phy is b y far the most often performed in this age group. The neonate wi th r espiratory distr ess ca n ha ve ei ther a p rimary intrathoracic a bnormality, o r a n extra thoracic co ndition which manifests with pulmonary symptoms. In this latter case, the normal radiograph is hel pful in f ocusing attention on extrathoracic conditions (e.g. birth-related central nervous system injury such as hypoxic ischemic insult, or urosepsis), o r in p roviding r eassurance f or co nservative treatment such as o xygen f or cen tral dep ression f rom administration o f medica tion t o t he mo ther. F or t hose conditions which are thoracic and the cause of respiratory distress, t he ma jor co nditions, a nd dif ferentiating f eatures, are found below. These four conditions will account


47

A ⊡ Fig. 4.10. Hyaline membr ane disease in a pr eterm infant. R adiograph demonstrates diffuse ground glass opacities

B

C ⊡ Fig. 4.9A-C. Double aortic arch presenting with wheezing. A Frontal chest radiograph shows leftward deviation of the trachea ( arrow) due to right-sided ar ch. B Axial image fr om c ontrast enhanc ed chest C T shows posterior junction of the arches (arrow), and C the narrowing of the left bronchus (A descending (midline) thoracic aorte)

for t he vast ma jority o f t horacic aetio logies o f neo natal respiratory distress (⊡ Figs. 4.10, 4.11 ) 1. Surfactant def iciency dis ease (o r r espiratory distr ess syndrome, RDS, or hyaline membrane disease, HMD) a. P reterm b. Diffuse ground glass opacities c. Effusion is very rare d. Traditionally lo w v olume, b ut t his is ra rer c urrently with administration of surface acting agent prior to the first radiograph 2. N eonatal pneumonia a. Any pa ttern p ossible (f ocal o pacity, m ultifocal opacity, focal or diffuse ground glass opacities) b. Term or preterm appearing child c. Small to moderate pleural effusion is m uch more common 3. Aspiration: ca n b e a mniotic f luid alo ne, b lood, o r fluid with meconium—the latter results in most severe changes) a. Generally, term neonate b. Areas o f h yperinflation a nd a telectasis (o r o ther heterogeneous opacities), c. Pneumothorax or pneumomediastinum d. Effusion is not typical 4. Transient t achypnea o f t he ne wborn (T TN) o r r etained foetal lung fluid a. T erm neonate b. Streaky, predominantly central opacities c. S mall pleural effusion

4

48


impossible especially in a preverbal child with respiratory distress and fever [10]. The imagin g e valuation o f t he imm unocompromised child with infectious disease will have a slightly different algorithm than that of the immunocompetent child given the potential for opportunistic infections (such as unusual viral agents, a nd f ungal p rocesses) as w ell as de velopment o f other disorders such as primary malignancy or post-transplant lymphoproliferative disorder in certain populations.

4

4.4.2 Chest wall

⊡ Fig. 4.11. Gr oup B str eptococcal pneumonia in an infant. R adiograph shows diffuse g round glass g ranularity but, what is not t ypical for hyaline membrane disease , the main diff erential consideration, is the presence of small bilateral pleural fluid collections (arrows)

Causes of diffuse granularity in the neonate ▬ Hyaline membrane disease ▬ P neumonia ▬ O edema ▬ Micr oatelectasis ▬ Chronic lung disease (bronchopulmonary dysplasia) ▬ B ilateral hypoplasia Cardiovascular anomalies also can result in n eonatal respiratory distress although as a gr oup they are much less common than those listed immediately above. In general, when there is a susp icion of a ca rdiac anomaly, echocardiography is indica ted a nd is o ften p erformed p rior t o radiography for diagnostic p urposes. The r ole of CT a nd MR angiography is thus very limited. 4.4 Inf

ectious/inflammatory

4.4.1 In troduction

Infection is t he most co mmon dis order in volving t he chest in infants and children. It is also the most common reason for imaging evaluation. Infections in the immunocompetent child generally consist of bacterial, particularly pneumonia, a nd viral p rocesses. The c linical distinc tion between t hese tw o aetio logies ca n b e q uite dif ficult o r

Chest wall inf ections such as adenitis, cellulitis or phlegmon or abscess formation are best addressed by sonography if limi ted in ext ent, o r b y co ntrast-enhanced CT o r MR if the extent is adjacent to structures such as the bone or in trathoracic r egions. R adiography has a limi ted r ole in susp ected c hest wall inf ection. F or cas es o f cell ulitis, with possible abscess formation, sonography is suf ficient to ex clude f luid co llections w hich ma y b e access ed f or drainage. If this is a c linical question, then sonography is the sufficient examination. A b one scan can be obtained for susp icion o f chest b ony in volvement in cas es w here infection is kno wn o r susp ected els ewhere in t he b ody, but usually s onography or cross-sectional imaging is indicated for assessment of regional or focal infection of the chest wall. Radionuclide imaging has a limi ted role but could be used in assessment of perhaps a multifocal infectious process such as chr onic r ecurrent m ultifocal oste omyelitis. In addition, in the setting of a potentially haematogenous origin o f ost eomyelitis wi th s everal r egions w hich ma y be affected within or outside the chest a b one scan is a n excellent sur vey. MR imag ing ca n a lso p rovide ex cellent evaluation of bones and soft tissues if t he infectious process is limited to the thorax (⊡ Fig. 4.12) 4.4.3 Ai rway

Infectious co mplications in t he a irway in t he paedia tric population co nsist mos tly o f viral etio logies (trac heobronchitis) due to a va riety of pathogens. Primary bacterial p rocesses a re ra re. I nvolvement o f t he in trathoracic trachea from bacterial tracheitis (or pseudomembranous tracheitis) is usua lly due to extension from the subglottic airway and manifests usually with upper airway signs and

4.4 · Infectious/inflammatory

⊡ Fig. 4.12. Coronal T2-weighted MR imaging of bilateral osteomyelitis and septic arthritis in the shoulders (arrows)

49

⊡ Fig. 4.13. Right upper lobe air space disease. Note branching lucencies which are air bronchograms

symptoms (for example str idor, drooling). Subtle abnormalities of the trachea will be difficult to see radiographically. B ronchoscopy i s u sually a pplied wh en addi tional diagnostic assessment is indicated. Of imaging modalities, CT gives the best airway evaluation, especially with multiplanar and 3-D capabilities. Imaging in general has a limited role with the rare primary infection of the trachea. 4.4.4 L ung parenchyma

Radiography is the first modality in cases of suspected lung infection [10]. In an appropriate clinical scenario, a normal chest X-ra y ca n hel p in ex cluding p neumonia as a ca use for t he sym ptoms; t his ma y ob viate a ntibiotics. Ex cluding p neumonia is p robably t he most im portant r ole f or radiography. Technique is cr itical, since p oor p ositioning may obs cure pa thology a nd p oor in spiration ma y mimic pathology. R adiography ca n hel p dif ferentiate viral f rom bacterial p rocesses (s ee b elow), b ut is no t r eliable f or determining specific types of organisms. Typical radiograph findings in p neumonia a re w ell r ecognized, co nsisting o f consolidation (airspace disease with hallmark air bronchograms; ⊡ Fig. 4.13), ill-def ined ma rgins a nd p leural ef fusions. Adenopathy can occasionally be present but is r elatively rare. An unfortunately often overlooked presentation of pneumonia in the young child is abdominal pain. In the setting of abdominal pain, an abdomen radiograph may be performed and careful investigation of the lung bases must ensue (⊡ Fig. 4.14). The final role of radiography is to assess

⊡ Fig. 4.14. L eft lo wer lobe pneumonia with effusion pr esenting in a child with abdominal pain which is wh y the abdominal radiog raph was obtained

4

50


4

A

A

B ⊡ Fig. 4.15A,B. C omplicated pneumonia. A F rontal chest radiog raph shows right upper lung airspac e disease and small fluid c ollection. The child did not r espond t o antibiotics . B S everal view s of the IV contrast-enhanced C T examination sho w loculat ed pleural fluid c ollection with some enhanc ement. Pleural stripping was nec essary t o treat this empyema

for complications, such as parapneumonic effusions (these consist of either reactive transudate or empyema), necrosis cavitation or pneumatocele formation (⊡ Fig. 4.15). In contrast to the process of bacterial infection, viral infection ca n o ccur. I n t his, t he a irways a re a ffected, manifesting wi th dif ferent radiogra phic f eatures co nsisting o f a bnormalities in aera tion pa rticularly in a ir trapping, peribronchial thickening seen on the face as a »doughnut« appearance or in p rofile, with streaky hilar opacities ( ⊡ Fig. 4.16).

B ⊡ Fig. 4.16A,B. Viral pneumonitis in a young child. A Chest radiography shows parahilar opacities. B Note on lateral examination full appearing hilar region (arrows)

Radiographic features of common pulmonary infections in children Bacterial Pneumonia ▬ Focal (more common than multifocal) opacity ▬ Ill-def ined margin – Exception is r ound p neumonia w hich is usuall y seen only in the first decade ▬ Air space in volvement: a ir b ronchogram (t his is a hallmark of airspace disease) ▬ Normal lung volumes

51

4.4 · Infectious/inflammatory

Viral pneumonitis ▬ Generally symmetric: centralized or diffuse ▬ I nterstitial Involvement – P eribronchial thickening – S treaky hilar opacities – On lateral, these superimpose to create full looking hila – Pitfall: may look like adenopathy ▬ Hy perinflated lungs ▬ At electasis

Mimics of pneumonia ▬ N ormal thymus (⊡ Fig. 4.17) ▬ At electasis ▬ C ongenital lesions – Bronchogenic c yst, sequestration, congenital c ystic adenomatoid malformation ▬ Ar tefact ▬ Co ntusion ▬ In halation ▬ He morrhage ▬ F ocal oedema ▬ Pulmo nary embolism ▬ Langerhans cell histiocytosis, alveolar proteinosis, collagen vascular disease, vasculitis CT is used in evaluation of parenchymal infections that are not responsive to t herapy ( ⊡ Fig. 4.15). Findings t hat CT provides inc lude necrosis, cavitation, p leural a bnormalities (b ronchopleural f istulae, f luid co llections) o r c hest wall involvement. In general, a IV co ntrast-enhanced CT examination is indica ted in t he setting of pulmonary infection. This will help to define adjacent vessels, potential enhancement of viable lung which may be atelectatic, or absence of enhancement of consolidated lung, suggesting necrosis. CT exa mination als o gi ves t he b est ass essment of the nature and extent of infection, including the presence o f p neumatocele f ormation. F or t hese r easons, in the s etting of complicated pneumonia (i .e. unresponsive to a ntibiotics, o r p rogressive co nsolidation o r de velopment for large pleural fluid collection), CT examination is usually the s econd-line mo dality in e valuation following serial radiographs. Septic em boli ca n o ccur as a s equela o f r emote infection. R adiography ca n demo nstrate t he m ultiple illdefined no dules a nd disp lay ca vitation. This ma y b e sufficient wi th a str ong c linical hist ory. H owever, CT

A

B ⊡ Fig. 4.17A,B. Normal prominent thymus mimicking pneumonia in a child. A Frontal chest radiograph demonstrates an opacity in the right upper lung which was tr eated with antibiotics , being mistaken f or pneumonia. A CT was performed after follow-up X-ray was unchanged and af ter discussion that this was most likely th ymus. B C ontrastenhanced examination of the C T examination demonstrat es normal thymic tissue T

evaluation p rovides s uperior m orphological eval uation, particularly f or ass ociated co mplications inc luding necrosis or empyema. CT is no t able to define the nature of pleural fluid as well as sonography. The r ole o f s onography f or ass essment o f inf ectious processes i s pr imarily l imited t o e valuation of t he pre sence and of characteristics of pleural fluid, or in confirming t hat a n o pacity is pa renchymal a nd no t p leural [2]. Sonography is hel pful in det ermining w hether a p leural effusion is p resent o r no t a nd may b e all t hat is needed prior t o asp iration o r ca theter dra inage o f f luid. S ometimes consolidation with or without atelectasis can make

4

52

4


the chest X-ray appearance one t hat mimics ef fusion. In this cas e, s onography ca n demo nstrate t he p resence o f consolidated lu ng i n t he ab sence of e ffusion. I t is wel l recognized th at so nography will p rovide m ore deta iled information about the nature of pleural fluid such as t he number, thickness and extent of septations or loculations, and t he p resence o f deb ris. W hile t hese f eatures do no t always indica te a n em pyema, t heir a bsence is hel pful in that t he f luid is most lik ely no t a n em pyema. D ecubital radiographs ca n hel p det ermine t he p resence o f p leural fluid, and w hether or not this f luid is f ree-flowing (supporting a tra nsudate more than an exudative empyema); however, s onography p rovides mo re inf ormation a nd is less cumbersome to perform. If a t horacostomy t ube is a nticipated, o ne sho uld obtain a s onographic evaluation after the CT t o help define the character of the fluid; highly septated and thickwalled co llections a re mo re dif ficult t o dra in a nd ma y require operative intervention. MR imaging has a limi ted role in assessment of community acquired pneumonia. For evaluation of the spine or paraspinal region, or for secondary involvement of the adjacent chest wall, MR should be the principle modality. 4.4.5 Mediastinum

Mediastinitis in c hildren is ra re, esp ecially co mpared with ad ults. M ediastinitis in c hildren is us ually s een in the p ostoperative s etting. Either CT o r MR will iden tify the extent and nature of t he process and can b e us ed to monitor therapy. 4.4.6 C ardiovascular system

For cardiac and pericardial infections, echocardiography is indicated. For the great vessels, such as m ycotic aneurysms, CT a ngiography o r MR a ngiography b est dep ict the size and location of the vascular infection 4.4.7 Other inflammatory conditions:

non-infectious vasculitis

Vasculitis can present either with large-vessel involvement (such as T akayasu’s a rteritis), in w hich cas e CT o r MR imaging b est disp lays t he in volvement, o r small v essel

disease with a variety of patterns in the lung from ground glass o pacities t o no dular, ill-def ined a reas o f pa renchymal involvement, including cavitation, to airspace opacities. R adiography ca n sug gest t he no dular in volvement, but the above patterns are best depicted by CT. 4.5

Mass or mass-like conditions

4.5.1 In troduction

Mass or mass-like conditions can occur in the chest wall, airway, l ung o r mediastin um. W hile mass es ma y als o occur within the heart or vessels, in general echocardiography is t he f irst-line mo dality f or t hese. B oth b enign and maligna nt mass es co mprise t he sp ectrum o f mass and mass-like conditions. Specific imaging features (discussed in greater detail below) can help in distinguishing between these two general categories. One exa mple is lesion location. When a mass is within the lung in children, this is ra rely ca ncer, unlik e in ad ults. I n addi tion, most endotracheal mass es in c hildren are going t o b e b enign, primarily consisting of papillomas. The primary objective of imaging mass a nd mass-like condition is first to identify whether or not the mass is present. When present, the next step is to def ine the nature or the lesion (i.e. specific imaging features), the extent of the abnormality and the mass effect on adjacent structures. Radiography is o ften t he f irst mo dality us ed in t he setting o f t horacic mass es. Thes e a re usuall y dis covered incidentally as a r esult of imaging for non-specific respiratory symptoms (⊡ Fig. 4.18). Once detected, the location is im portant f or f urther f ollow-up. F or exa mple, in tra parenchyma lung masses may be treated with antibiotics, if there is a hist ory of fever or other signs of pulmonary infection. R adiographic f ollow-up is no t wa rranted b ut may b e ob tained to assur e r esolution. F or t hose mass es detected wi thin t he mediastin um, cr oss-sectional imaging is usuall y wa rranted. I n a neo nate o r infa nt, w here a p otential a bnormality o f t he a nterior mediastin um is present, s onography ma y hel p to deter mine w hether a mass is present or not and some features of this mass, such as calcification or areas of necrosis or cyst. As in most t horacic e valuation, co ntrast-enhanced chest CT gives optimal evaluation. Evaluation of anterior of middle mediastin um mass es or pulmonary parenchyma mass es is b est a fforded b y CT (s ee co ngenital l ung abnormalities below).

53

4.5 · Mass or mass-like conditions

For p osterior mass es, MR imagin g is t he p rimary modality gi ven t he fac t t hat 80-90% o f t hese mass es a re neurogenic in o rigin. Because of this, optimal evaluation of t he intraspinal contents and v ertebral co lumn is wa rranted. This is b est afforded by MR imagin g. For middle and a nterior mediastinal mass es, CT ca n gi ve suf ficient information for diagnosis, o r limited dif ferential considerations. In addition, CT p rovides adequate information for surgical planning.

A

4.5.2 Chest wall

Most chest wall masses are usually identified or suspected by c linical exa mination. W ithin t he c hest wall , mass es may arise from any of the tissues, including bone, muscle, skin o r vas cular str uctures, inc luding l ymphatic a bnormalities (⊡ Fig. 4.19) [4, 11]. In cer tain si tuations, a c hest radiogra ph ma y hel p to def ine a n oss eous a bnormality w hich is co ngenital in na ture a nd sim ply no t ma nifest un til la te infa ncy o r childhood. U ltrasonography ca n b e us ed t o confirm t he presence of a mass. I n a s etting where the mass is p otentially due to inflammation, an ultrasound may be a sufficient examination to determine hypervascularity, with or without central fluid collection which could represent an abscess. Sonography can be u sed for evaluation of breast abnormalities in infa nts and children, both male a nd female. Since radiography is v ery low-yield, sonography is the first imaging evaluation when assessing breast region masses. In general, however, for mass or mass-like conditions of the chest wall, MR imaging gives superior contrast information and is usually the next imaging modality. For evaluation of masses of the bones of the thorax, including the shoulder girdle, sternum, ribs and spine, CT provides information r egarding t he ext ent a nd c haracter o f oss eous mass es (e .g. c hondroid o r ost eoid matrix, p eriosteal reaction, calcif ication), b ut MR gi ves mo re inf ormation

B ⊡ Fig. 4.18A,B. Posterior mediastinal mass (ganglioneur oma). A Frontal chest radiog raph in this t eenage girl shows large mass with slight effect on subjac ent ribs ( arrows). B C ontrast-enhanced chest C T ex amination sho ws fairly homogenous sof t tissue att enuation mass in the posterior mediastinum with scattered punctate calcifications. Borrowed with permission American College of Radiology

⊡ Fig. 4.19. C oronal T2-weighted MR imag ing of neur ofibromas ( arrows) in the distribution of the br achial plexus

4

54


on t he p resence a nd ext ent o f ma rrow in volvement a nd associated soft-tissue abnormalities. 4.5.3 A irway abnormalities

4

Tracheal mass es are relatively rare and consist predominantly o f pa pillomas. Oth er m asses in clude gra nulomas such as after endotracheal intubation, or foreign bodies. 4.5.4 L ung parenchyma

Within the lungs, the majority of mass or mass-like conditions a re d ue t o ei ther co ngenital a bnormalities (f or example bronchogenic c yst, sequestration, congenital c ystic adenomatoid m alformation pre viously d iscussed u nder congenital lung abnormalities ( ⊡ Fig. 4.20) or round pneumonia. Ot her co nditions inc lude ps eudotumours (lo culated pleural fluid projected over the lung), or contusion. Primary lung malignancies in children are extremely rare.

Congenital lung malformations Solid mass-like ▬ B ronchogenic cyst ▬ Pulmo nary sequestration ▬ Rarely, co ngenital c ystic adeno matoid malf ormation (CCAM): more often air-filled ▬ Hybrid of above lesions

A

Air-filled mass-like ▬ Congenital cystic adenomatoid malformation ▬ C ongenital diaphragmatic hernia ▬ D iaphragm elevation ▬ P neumatocele 4.5.5 Mediastinum

Within the mediastinum, the location and specific features (e.g. cysts, fat, calcification) of the abnormality are helpful in distinguishing between the anomalies (⊡ Tables 4.3–4.6) [12]. Again, a variety of potentially benign and malignant processes can be present. In general, MR is indica ted for posterior mediastinal p rocesses w hile ei ther CT o r MR is us eful f or e valuation o f mass es wi thin t he a nterior o r middle mediastin um ( ⊡ Fig. 4.21). CT is hel pful in de-

B ⊡ Fig. 4.20A,B. Congenital c ystic adenomatoid formation in a y oung child presenting with r espiratory distress. A Frontal chest radiog raph demonstrates multiple air fluid levels. B CT shows these changes

55

4.5 · Mass or mass-like conditions

⊡ Table 4.3. Anterior mediastinal masses in children

⊡ Table 4.5. Posterior mediastinal masses in children

1. THYMUS

1. NEURAL (>85%)

Normal thymusa

Cyst

Hypertrophya

Thymic carcinoma

Lymphomaa

Thymoma

Hyperplasia

Cystic dysplasia

Thymolipoma / fibrolipoma 2. LYMPHOMAa

Nerve cell (ganglion) Neur oblastoma (including ganglioneuroblastoma)

Ganglioneuroma

Nerve sheath Neur ofibroma Benig n schwannoma (neurilemmoma)

Malignant schwannoma

Teratomaa / teratocarcinoma

Choriocarcinoma

Other (rare) P araganglioma (alt ernate terms chemodectoma, pheochr omocytoma)

Seminoma

Embryonal carcinoma

2. NON NEURAL (< 15%)

Endodermal sinus tumour

Mixed types

Foregut Bronchogenic cyst Oesophageal duplication

Abnormally (e.g. aneurysm)

Thyroid ectopia

Vascular malformations

Langerhans cell histiocytosis

Metastases

Extension of paracardiac tumours / pericardial cysts

Vascular Aortic aneurysm Azygos/haemiazygos enlargement

3. GERM CELL TUMOURS

4. OTHER

amore

common

⊡ Table 4.4. Middle mediastinal masses in children 1. Adenopathy Lymphomaa Metastasesa Infectiona Sarcoid Langerhans cell histiocytosis 2. Gastrointestinal / Foregut Oesophageal duplication cysta Bronchogenic cysta Neurenteric cyst Hernia Oesophagus (dilation) 3. Other Vascular malformations (e.g. lymphatic or venous) Paracardiac tumours Aortic and other vascular aneurysms amore

common

tecting calcification which can be useful feature in limi ting the differential considerations of mediastinal mass es. Likewise, the presence of fat is also a helpful feature. This can be seen well using either CT or MR. Fluid-containing masses are also identified as such b y CT or MR although the signal characteristics of small fluid-filled regions may be more difficult to see with MR and warrant IV contrast administration.

Neurenteric cyst Oesophageal dilation Haemangioma

Lymphatic Lymphoma

Lymphangioma

Paravertebral Hematoma Extramedullary haematopoiesis

Abscess Metastases

Diaphragmatic Bochdalek hernia Paraesophageal or hiatal hernia Other Mesenchymal tumours (sar coma, lipoma, fibroma) Nodal infiltration (e .g. Castleman, sarcoid, histoplasmosis)

Eventration

Teratoma Leukaemia

⊡ Table 4.6. Specific imaging features of anterior mediastinal masses Cysts and Cystic Conditions True thymic cysts (unilocular, multilocular) Germ cell tumours Langerhans cell histiocytosis Lymphatic malformation (e.g. cystic hygroma) Lymphoma Treated lymphoma Thymic dysplasia of HIV infection Thymoma Thymic carcinoma Calcification Germ cell tumour Langerhans cell histiocytosis Lymphoma Thymic cysts Fat-containing masses Thymolipoma Germ cell tumour (usually mature teratoma) Vascular malformations

4

56


this te chnique ma y b e us ed f or mo rphological ass essment in these cases. 4.6 T

rauma

4.6.1 In troduction

4

⊡ Fig. 4.21. Lymphoma encircling the trachea, which contains an endotracheal tube, and encases the brachiocephalic veins (arrows)

Virtually all tho racic trauma consist of ingested foreign bodies, such as swallowed coins, aspirated material, or a blunt o r p enetrating in jury. The s election o f t he imaging mo dality and algorithm will dep end on t he typ e of trauma. R adiography is o ften us ed b oth f or asp irated and swallo wed ma terial, as w ell as in p enetrating a nd blunt tra uma. Chest radiogra phy is o ften suf ficient f or minor b lunt tra uma a nd is als o t he ini tial mo dality in the setting of severe penetrating or blunt trauma before additional e valuation a nd imagin g is p erformed. This additional imaging is almost always CT in the acute setting [13]. 4.6.2 Chest wall

⊡ Fig. 4.22. Coronal T1-weighted cardiac (ECG) gated heart MR showing fibroma in the wall of the lef t ventricle (arrow)

4.5.6 C ardiovascular system

Echocardiography is t he ini tial mo dality f or e valuation of cardiac mass es. C ontrast-enhanced MRI ca n b e helpful in ass essing intracardiac mass es not suf ficiently evaluated b y ec hocardiography, a nd f or ass essment o f paracardiac mass es a nd ca rdiac in volvement b y extracardiac mas ses ( ⊡ Fig. 4.22). The d ynamic inf ormation afforded by MR is an advantage compared with CT, and

Radiography helps in ass essment of minor blunt trauma. While detecting a p otential rib fracture is often the clinical q uestion, t he mo re im portant t ask is t o det ect t he sequelae of these fractures consisting of a f luid collection (haemothorax) or pneumothorax. The radiograph is als o usually sufficient for detection of clavicular fractures. For complex tra uma t o t he c hest wal l, imagin g p lays o nly a minor role, aside f rom evaluation of the spine. For more complete evaluation of structures other than those mentioned above, osseous anatomy is best assessed by CT (e.g. sternal fractures or fractures of the shoulder girdle), and associated s oft-tissue injury is b est addressed using MR . One important exception to the above is t he presence of posterior rib fractures, particularly in infa ncy and young childhood. These have a hig h association with non-accidental injury (infant or child abuse; ⊡ Fig. 4.23). Diaphragm in jury ca n b e inc luded in t he c hest wall category. Injury t o t he diaphragm ca n o ccur with either penetrating o r b lunt trauma, inc luding b lunt a bdominal trauma. Diaphragm injury can easily be overlooked given other co nfounding f indings inc luding co ntusion o r aspiration. MD CT wi th co ronal a nd sa gittal r eformations can disp lay her niation o f in tra-abdominal co ntents in to the thorax.

57

4.6 · Trauma

help in det ecting a radio-o paque foreign b ody, or asymmetric aeration (either atelectasis or air trapping), which is a s econdary finding. CT is mo re sensitive in det ecting an aspirated foreign body although bronchoscopy is often the next st ep with strong clinical suspicion or supportive findings on radiography (atelectasis or air trapping). Fluoroscopy can be used if t here is a q uestion of obstruction, demonstrating decr eased c hange in l ung v olume o n t he affected side ( ⊡ Fig. 4.24). With a history of blunt or penetrating in jury, pa rticularly in t he s etting o f a p ersistent pneumothorax with a thoracostomy tube present, CT may demonstrate the injury to the trachea or bronchus. 4.6.4 L ung parenchyma

⊡ Fig. 4.23. Acute posterior rib fractures (arrows) in an abused infant

Risk stratification of fractures on chest radiography for non-accidental injury High risk ▬ P osterior rib fractures ▬ S ternal fractures ▬ Sc apular fractures ▬ Fractures of posterior elements ▬ Proximal humeral metaphyseal corner fractures Moderate risk ▬ M ultiple fractures ▬ Fractures of varying ages ▬ Vertebral body fractures Low risk ▬ C lavicle fractures ▬ Humeral diaphyseal fractures 4.6.3 A irway abnormalities

Trauma to the airway consists of aspirated material, such as a f oreign b ody o r dir ect in jury wi th p enetrating o r severe b lunt in jury (she aring f orces). R adiography ca n

There is little role for any other modality in assessing lung parenchymal tra uma t han CT . R adiography is in sensitive t o t he p resence a nd ext ent o f in jury, a nd t he o ther modalities, lik ewise, do no t gi ve suf ficient pa renchymal detail. CT can depict lung injury including pleural disease (pneumothorax and haemothorax), contusion, laceration, haematoma, p neumatocele, fa t em boli (f rom la rge, lo ng bone fractures) and aspiration (⊡ Fig. 4.25). 4.6.5 Mediastinum

Mediastinal tra uma is als o b est addr essed b y CT ini tially. For in jury, pa rticularly p enetrating, ne ar t he o esophagus, a water-soluble contrast swallow is indicated to exclude oesophageal injury. Radiography in the setting of acute trauma is indicated to ass ess s econdary signs of aortic injury (addressed below), including mediastinal haematoma, and can also show mediastinal haematoma from spine fractures. 4.6.6 C ardiovascular system

CT a ngiography is indica ted t o ass ess vas cular in jury, including the aorta and branch vessels in the acute setting (⊡ Fig. 4.26). I njury inc ludes diss ection, tra nsaction a nd thrombosis. MR a ngiography ca n als o b e us ed t o ass ess vascular injury, but because CT is us ed for assessment of head, spine and intra-abdominal and pelvic injury, in addition to injury to the lung or airway, CT is t he preferred modality for ass essment of arterial injury as w ell. In t he subacute o r c hronic s etting, f or ass essment o f vas cular

4

58


*

4

** ⊡ Fig. 4.24. Value of chest fluor oscopy in demonstrating air trapping. Sequence of films taken during fluor oscopy shows changes in siz e of the right hemithorax but no change on the left, where there was an obstructing foreign body. *Expiration, **Inspriration

⊡ Fig. 4.25. Teenage f emale f ollowing mot or v ehicle c ollision. C T shows anterior pneumothorax (arrowheads), dense right lung c onsolidation, likely combination of atelectasis and contusion, and post-traumatic distal airway disruption evident as pneumatoceles (arrow)

⊡ Fig. 4.26. Aortic transection in a 17-year-old following motor vehicle collision. Note irregularity at the transverse aortic arch (arrow) with CT.

4.7 · Toxic/metabolic and thoracic evaluation of sy stemic disorders

trauma inc luding a neurysm, st enosis o r tra uma-related thrombosis, MR a ngiography o r v enography sho uld b e the initial consideration (if ultrasonography is not useful) because there is no radiation involved as with CT. Radiography is hel pful in ass essing f or s econdary signs o f vas cular (usuall y ao rtic) in jury. Traditional f eatures include widening of the superior mediastinum, left apical ca p, b lurring o f t he ao rtic a rch, widenin g o f t he left pa ravertebral str ipe a nd r ightward de viation o f t he distal trachea or oesophagus at the same level. Some of these f indings (visualiza tion o f t he ao rtic a rch a nd mediastinal widenin g) a re less r eliable in y oung chi ldren given t he p resence o f a radiogra phically visib le t hymus. The decision about further imaging must be made bas ed on clinical concern, including mechanism of injury, other evidence of at least mo derately s evere chest t rauma, and some or all of the above radiographic features. 4.7

Toxic/metabolic and thoracic evaluation of systemic disorders

4.7.1 In troduction

There are a variety of patterns that can affect the lung in what is a wide range of systemic disorders of entities in childhood [14]. These include secondary phenomena such as infection in t he s etting o f b oth p rimary o r acq uired imm unodeficiency (i.e. due to antibiotics or cancer chemotherapy) or acquired imm unodeficiencies, s epsis, b leeding dis orders, embolic p henomena, met astatic dis ease (w hich incl udes both cancer and other multiorgan disorders such as L angerhans cell histiocytosis—or eosinophilic granuloma—and consists o f chest wall in volvement, me diastinal mass es, hilar adeno pathy, a nd p ulmonary met astases; ⊡ Fig. 4.27), vasculitides, connective tissue dis orders, congenital dis orders such as c ystic f ibrosis and pulmonary manifestations of met abolic dis orders such as g lycogen sto rage dis ease (cardiomegaly) o r Niemann P ick dis ease (interstitial l ung disease). Radiography is usually the initial imaging modality. If further information is necess ary, CT is g enerally the modality of choice since both lung parenchymal as well as mediastinal evaluation are possible, as opposed to MR imaging, where the lung is insufficiently evaluated. The p ulmonary ma nifestations o f systemic dis orders include o edema, w ell or p oorly def ined pulmonary no dules, airspace opacities or interstitial disease (such as bronchiectasis), Interstitial lung disease (ILD) has a va riety of

59

⊡ Fig. 4.27. M etastatic ost eosarcoma with lar ge pulmonar y masses and nodules, including ar eas of ossification ( arrows) which is characteristic of some metastatic osteosarcomas

causes in infants and children [15]. It is beyond the scope of this chapter to detail ILD in c hildren. In fact, it is presently a p oorly c lassified a nd ra pidly e volving gr oup o f disorders. For evaluation of interstitial lung disease, highresolution CT (HRCT) is a technique where relatively thin slices provide greater spatial resolution than that resulting from standard chest CT exa mination. HRCT is indica ted for t he def inition o f susp ected in terstitial l ung dis ease (nodular or reticular opacities on radiography), if there is a clinical suspicion of ILD in the presence of a normal chest X-ray (e .g. b ronchiectasis in a c hild susp ected o f b eing immunodeficient), assessment of pulmonary function abnormalities in the setting of normal chest X-ray, or if there is known systemic dis ease of which ILD ma y be manifestation (e .g. s arcoid o r syst emic l upus er ythematosis) in which the HRCT is used to assess the severity of disease or as a baseline as a measure of therapeutic response. It is extr emely im portant to ob tain HR CT imag es without respiratory motion as this may obscure important findings. Children should be able to breath hold (they can rest b etween slices) o r b e in tubated o r ha ve s ome o ther technique (suc h as co ntrolled assist ed ventilation). With the newest very fast CT, HRCT images may be relatively motion-free at the end o f inspiration or expiration; however, t he imag es in b etween a re usuall y no n-diagnostic due to motion. Interstitial lung disease is seen with hemosiderosis (a irspace o pacities, f ibrosis), al veolar p roteinosis (a irspace o pacities, in terstitial t hickening), l ymphangioleiomyomatosis (in terstitial t hickening), in terstitial

4

60


4

A

B ⊡ Fig. 4.28A,B. H igh-resolution C T at t wo levels near the carina ( A,B) of a y oung child with Langerhans c ell histioc ytosis demonstrating multiple c ystic r egions. Detail is sufficient ev en when scanning while breathing

pneumonias [2] a nd L angerhans cell his tiocytosis (small nodules, cavitation, cysts) (⊡ Fig. 4.28).

Common causes of bronchiectasis in children ▬ Cystic fibrosis (most common) (⊡ Fig. 4.29) ▬ Recurrent infection (includes immunodeficiencies) ▬ F oreign body ▬ Oth er – Congenital/syndromic: Kartegaener’s syndrome (ciliary dyskinesia)

⊡ Fig. 4.29. Chest C T examination in child with c ystic fibr osis. Not e scattered bronchiectasis

Pulmonary manifestations are the most common for cystic f ibrosis (CF). Tho racic ma nifestations incl ude b ronchiectasis, a irspace dis ease, adeno pathy, p neumothorax and pneumomediastinum. R adiography is us ed to assess acute signs or symptoms. CT is a b etter modality for assessing (e .g. CF s coring syst em) dis ease p rogression o r when radiography is inconclusive. With congenital immunodeficiency, most findings are related to infection, particularly opportunistic organisms such as viruses or fungi [16,17]. Malignancy is also associated with t he congenital or primary immune def iciency, especially those with T-cell abnormalities. Radiography is still the primary modality for an initial survey. However, with the increased morbidity associated with infections in the patient population with immune disorders, aggressive evaluation is usuall y warranted, usually CT exa mination (⊡ Fig. 4.30). I mage-guided b iopsy als o p lays a r ole, depending on the location of the lesion.

General aeration disorders A. Unilateral air trapping or lucent hemithorax: – Congenital lobar emphysema – Congenital cystic adenomatoid malformation – Endobronchial p rocess (e .g. m ucous, t umour, f oreign body) – Exobronchial p rocess (extr insic co mpression suc h as mediastinal mass or vascular ring), – B ronchiolitis obliterans

61

References

3. 4.

5.

6.

7. 8.

9. 10.

11. 12. ⊡ Fig. 4.30. Young child with sev ere c ombined immune deficienc y (SCID) with candida pneumonia and sec ondary chest wall in volvement. Borrowed with permission American Journal of Roent genology

13.

14.

– P atient rotation – P neumothorax – L ung cyst – Chest wall deformities – Contralateral volume loss or hypoplasia B. Volume loss/small/opaque hemithorax – Atelectasis (including endobronchial and exobronchial processes – L ayering effusion – Hypoplasia (e.g. primary hypoplasia, space occupying mass such as congenital diaphragmatic hernia) – Contralateral h yperinflation o r asymmetricall y increased lucency – Chest radiation – Large soft-tissue mass

References 1. 2.

Paterson A, Frush DP (2001) The pros and cons of imaging options. Contemp Ped 18(4):73-94 Coley BD (2005) Pediatric chest ultrasound. In: Frush DP (ed) Pediatric chest imaging, W.B. Saunders, Philadelphia, PA, pp 405-418

15.

16.

17.

Donnelly LF , F rush DP (2003) P ediatric multidet ector body C T. Radiol Clin North Am. 41:637-655 Fefferman NR, Pinkney LP (2005) Imaging evaluation of chest wall disorders in childr en. I n: F rush DP (ed) P ediatric chest imag ing, W.B. Saunders, Philadelphia, PA, pp 355-370 Long FR (2005) Imaging evolution of airway disorders in children. In: Frush DP (ed) Pediatric chest imaging, W.B. Saunders, Philadelphia, PA, pp 371-389 Paterson A (2005) I maging evaluation of c ongenital lung abnor malities in infants and childr en. I n: Frush DP (ed) P ediatric chest imaging, W.B. Saunders, Philadelphia, PA, pp 303-323 Frush DP, Herlong RJ (2005) P ediatric thoracic C T ang iography. Pediatr Radiol 35:11-25 Chung T (2005) M agnetic resonance angiography of the body in pediatric patients: experienc e with a c ontrast-enhanced time -resolved technique. Pediatr Radiol 35:3-10 Hernanz-Schulman M. (2005) Vascular rings: a prac tical approach to imaging diagnosis. Pediatr Radiol. 35(10):961-79 Donnelly LF (2005) I maging in immunoc ompetent children who have pneumonia. I n: Frush DP (ed) P ediatric chest imag ing, W.B. Saunders, Philadelphia, PA, pp 253-265 Laor T (2004) MR imaging of soft tissue tumors and tumor -like lesions. Pediatr Radiol 34:24-37 Franco A, Mody NS, Meza MP (2005) Imaging evaluation of pediatric mediastinal masses . In: Frush DP (ed) P ediatric chest imag ing, W.B. Saunders, Philadelphia, PA, pp 325-353 Westra SJ, Wallace EC (2005) Imaging evaluation of pediatric chest trauma. In: Frush DP (ed) P ediatric chest imag ing, W.B. Saunders, Philadelphia, PA, pp 267-281 Brody AS (2002) Thoracic manif estations of sy stemic diseases . In: Lucaya J and Strif e JL (eds) P ediatric chest imag ing, Springer, Berlin Heidelberg New York, pp 245-264 Brody AS (2005) I maging considerations: interstitial lung disease in children. I n: Frush DP (ed) P ediatric chest imag ing, W.B. Saunders, Philadelphia, PA, pp 391-403 Hollingsworth CL (2005) Thoracic disor ders in the immunoc ompromised child . I n: F rush DP (ed) P ediatric chest imag ing, W.B. Saunders, Philadelphia, PA, pp 435-477 Yin EZ, F rush DP, Donnelly LF , Buck ley RH (2001) P rimary immunodeficiency disorders in pediatric patients: clinical f eatures and imaging findings. AJR 176:1541-1552

4

5 A

bdomen Jochen Tröger

5.1

Hepatobiliary system, spleen, pancreas

Hyun Soo Ko 5.1.1 Hepa tobiliary system

Congenital and neonatal abnormalities Biliary atresia and neonatal hepatitis Neonatal jaundice that persists beyond 4 w eeks of age is in 90% of cases due to biliary atresia or neonatal hepatitis. All other forms of non-neonatal hepatitis usually are due to viral inf ection wi th most ly no rmal a ppearance o f t he liver on US, MRI a nd CT (s ometimes gall bladder thickening is seen in patients with hepatitis). Biliary a tresia a nd neo natal hepa titis ha ve simila r clinical, biochemical and histological f indings, hence diagnostic imaging plays an important role in dif ferentiating pa tients wi th b iliary a tresia w ho under go p rompt laparatomy and patients with neonatal hepatitis who will be treated medically. The distinc tion b etween b iliary a tresia a nd neo natal hepatitis depends on a demonstration of the morphology and function of the biliary duct system. In biliary atresia some or all major hepatic ducts are absent and, despite the mechanical obstr uction, t he proximal intrahepatic ducts are usually small. In neonatal hepatitis the intra- and extrahepatic bile duct system is patent but small. The ini tial ima ging p rocedure is US t o ex clude c holedochal c yst and dilatation of the extrahepatic bile duct system. Onl y a bout 20% o f pa tients wi th b iliary a tresia

have a n iden tifiable ga llbladder, t hus t he f inding o f a normal ga llbladder only is a ble to su pport t he diag nosis of neonatal hepatitis. Hepatobiliary s cintigraphy wi th 99T c-labelled iminodiacetic acid (ID A) der ivates p rovides acc urate diagnosis wi th e vidence o f gast ro-intestinal ex cretion o f tracer in pa tients wi th n eonatal h epatitis a nd lac k o f gastro-intestinal ex cretion o f tracer (o ften ass ociated with a n incr eased ur inary ex cretion) in neo nates wi th biliary atresia.

Choledochal cyst and Caroli disease A c holedochal c yst is a n unco mmon diagnosis, wi th higher incidence in f emales and orientals and half o f the patients b eing 1-10 y ears o ld. It is a lo calized dila tation of the bile duct system with five types (modified Todani classification, see ⊡ Table 5.1). Choledochal cysts can be subdivided into two groups: one gr oup wi th neo natal ja undice ca used b y st enosis o r atresia o f t he b iliary tr ee a nd t he o ther, diagnos ed la ter in lif e, b eing ass ociated wi th co mmon d uct s tones a nd pancreatitis. Complications: cholangitis, pancreatitis, stone formation and liver cirrhosis. US, hepatobiliary scintigraphy with 99Tc-labelled iminodiacetic acid (ID A), MRI a nd ER CP allo w a sp ecific diagnosis. Differential diagnosis inc ludes t he w hole sp ectrum of o ther f luid-filled mass es (e .g. hepa tic c yst, pa ncreatic pseudocyst).

64

Chapter 5 · Abdomen

⊡ Table 5.1. Choledochal cyst Type 1: dilatation of extrahepatic common bile duct (⊡ Fig. 5.1) Type 2: localized, cystic diverticulum of the common duct Type 3: dilatation if the distal intramural portion of the common bile duct (choledochocele) Type 4: multiple cystic dilatations involving intra- and extrahepatic biliary ductuli (⊡ Fig. 5.2) Type 5: (Caroli disease): multiple intrahepatic cysts

5

Inflammatory diseases Hepatic abscess

A

Hepatic a bscesses a re v ery ra re in c hildren (usuall y immunocompromised patients). In 50% hepatic abscesses are multiple and may be associated with hepatomegaly, elevation of the right hemidiaphragm, right pleural effusion, right lower atelectasis/ infiltration and gas within the abscess. Imaging modalities include US, MRI, CT demonstrating a hypoechoic round lesion with mildly echogenic rim on US and a typical contrast-enhancing wall on MRI and CT (⊡ Fig. 5.3).

Cholelithiasis, acute cholecystitis and hydrops of gallbladder The prevalence of cholelithiasis is 2% in often asymptomatic children (⊡ Fig. 5.4). In newborn and infants it may be idiopathic, but is o ften diagnosed in as sociation with obstructive co ngenital b iliary a nomaly, t otal pa renteral n utrition, furosemide, small bowel disease, cystic fibrosis and haemolytic anaemia. In adolescents, pregnancy and oral contraception may be added to the list of causes of gallstones. The di agnostic gold st andard f or b iliary sto nes is US. The typ ical a ppearance o n US ec hogenic o pacities within the gallbladder that shift with gravity and show an acoustic shadowing. The dist inction between small no nshadowing gallstones and biliary sludge may be difficult. Neonatal cholelithiasis may resolve spontaneously. Persisting (> 6 h) right upper quadrant pain with typical s onographic f indings sug gests ac ute calc ulous (85%) or acalculous (15%) cholecystitis. Acalculous cholecystitis is often associated with recent surgery. US has up to 100% s ensitivity and specificity in diagnosing ac ute cho lecystitis, demo nstrating a ga llbladder wall t hickening (> 3 m), a p ositive s onographic Murphy sign (abdominal pain during US scanning of the gallbladder) a nd h ydrops o f t he ga llbladder (disten sion > 5 cm in AP dia meter or enlargement greater than 4 x 10 cm).

B ⊡ Fig. 5.1A,B. Choledochal cyst type 1 of a 3-year-old girl A US (longitudinal view) B MRI RARE sequence (coronal plane)

⊡ Fig. 5.2. US (longitudinal view) of a 9-year-old boy with choledochal cyst type 4

65

5.1 · Hepatobiliary system, spleen, pancreas

Scintigraphy, co ntrast enha nced CT a nd MRI ma y gi ve additional information, e.g. gallbladder function, pericholic morphology. Complications of acute cholecystitis are gallbladder gangrene, peric holecystic a bscess, im pacted g allstone lea ding to cystic duct obstruction (Mirizzi syndrome), emphysematous c holecystitis, empyema, d uodenal obstr uction d ue t o eroded gallstone (Bouveret syndrome) or gallstone ileus.

Hepatobiliary tumours A

B

The liver is, a fter the kidney and adrenal glands, the third most co mmon si te o f o rigin o f a bdominal maligna ncies. Approximately 5-10% of all abdominal tumours are situated in the liver and about one third of all primary liver tumours in c hildren a re b enign (s ee ⊡ Table 5.2 ). The ma in role of imaging is t he dif ferentiation b etween b enign and malign tumours, their extension and thus resectability and response to tr eatment. P recise dia gnosis u sually ca n be m ade wi th clinical presentation, age, laboratory results and imaging. US with colour Doppler examination is us eful for assessing t he s olid a nd f luid na ture a nd vas cularity o f t he lesion; however, MRI a nd CT a re best for evaluating the preoperative lo calization a nd r esectability. MRI sho ws a slight advantage over CT and CT is superior in postoperative follow-up in detecting recurrences.

⊡ Fig. 5.3A,B. MRI (Hast e, transv ersal plane) of a 20-y ear-old f emale with inflammatory cholangitis (A) and secondary splenic abscess (B)

Haemangioendothelioma/ cavernous haemangioma

⊡ Fig. 5.4. US of a 12-year-old boy with incidentally diagnosed cholelithiasis (thick arrow) with acoustic shadow (arrows) (transversal view)

Haemangioendothelioma is t he most co mmon benign hepatic tumour during the first 6 months of life (⊡ Fig. 5.5). The no menclature o f ca vernous haema ngioma a nd haemangioendothelioma is not consistent, and it is probable that they belong to the same entity in different phases of evolution. US demo nstrates het erogeneous, p redominantly h ypoechoic, hepatic lesions with vas cular components and calcifications in 50%. MRI sho ws a het erogeneous, p redominantly h ypointense, lesio n o n T1-w eighted imag es and va rying degr ees o f h yperintensity o n T2-w eighted images with early peripheral rim enhancement, while CT shows a hypo-attenuating mass with early peripheral rim enhancement and variable delayed central enhancement. Main co mplications a re co ngestive he art fa ilure d ue to AV sh unting haemo rrhagic dia thesis (K asabach-Merritt syndr ome), obstr uctive ja undice, r upture o f t umour (haemoperitoneum) a nd, ra rely, maligna nt tra nsformation into angiosarcoma.

5

66


⊡ Table 5.2. Paediatric hepatic tumours Tumour

Prevalence

Focal nodular hyperplasia

3%

Adenoma

1%

Mesenchymal

Haemangioendothelioma/ cavernous haemangioma

18%

Other

e.g. Mesenchymal hamartoma

4%

Benign Epithelial

5

Malignant Epithelial

A Hepatoblastoma

36%

Hepatocellular carcinoma

20%

Mesenchymal

Mesenchymal sarcoma

7%

Other

e.g. Hepatic metastases, rhabdomyosarcoma of biliary ductuli

11%

Differential diagnoses: ▬ hepatoblastoma (ele vated alpha foetoprotein, het erogeneous mass, low vascularity) ▬ mesenchymal hamartoma (usually multilocular cystic mass) ▬ metastatic neur oblastoma (ele vated ca techolamines, adrenal mass)

B

Hepatic adenoma It is t he most co mmon hepatic tumour in y oung women after use of oral contraceptives and is very rarely seen during childhood (⊡ Fig. 5.6). US usually demonstrates a well-demarcated solid, heterogeneous mass wi th va riable ec hogenicity w hile MRI shows a r ound mass o f decr eased in tensity (ex cept in those cas es wi th f resh in tratumoural haemo rrhage p resenting as a h yperintense mass o n T1w imag es). C ontrast-enhanced studies show a transient hyperintense and on delayed images an iso- to hypointense mass. CT demonstrates features similar to MRI (decreased density with characteristically contrast enhancement).

Focal nodular hyperplasia (FNH) FNH ( ⊡ Fig. 5.7) is a ra re benign congenital hamartomatous ma lformation a nd co ngenital a rteriovenous ma lformation; trigg ering f ocal hepa tocellular h yperplasia is postulated as i ts cause. Oral co ntraceptives do no t cause but stimulate its growth. FNH is usuall y discovered incidentally, since it rarely presents itself with abdominal pain

C ⊡ Fig. 5.5A–C. US of a 1-year-old girl with abdominal pain due to haemangioendothelioma A US with par tly solid , par tly c ystic abdominal mass (transversal plane). B T2w MRI (transversal plane). C T1w contrastenhanced MRI (c oronal plane) demonstrating c ontrast enhancement of the solid part of the tumor

67


A

B

C

D

⊡ Fig. 5.6A–D. MRI and C T of a 21-y ear-old male with h ypopharynx carcinoma and incidentally diag nosed hepatic adenomas (seg ment 3 of the left lobe and segment 6/7 of the right lobe). MRI: T1 axial plane A Unenhanc ed phase with iso - t o slightly h yperintense adenomas . B Equilibrium contrast-enhanced phase with hypointense masses and

a peripheral rim enhanc ement of the adenoma of the right lobe). C T axial plane demonstrating the hepatic adenomas with c ontrast enhancement during the ar terial phase (C) and iso- to hypodense signal during the equilibrium phase (D)

while li ver f unction is no rmal. M ost FNH s a re w ell cir cumscribed, no n-encapsulated wi th a no dular cir rhoticlike mass, a nd a re hig hly vas cularised. A cen tral s car is common whereas calcifications are extremely rare. US demonstrates a ho mogeneous mass wi th a va rying echogenicity but hyperechoic central scar and displacement of hepatic vessels. Non-enhanced CT shows an iso-, slightly hypoattenuating homogeneous mass that after contrast material injection is transiently hyperintense after 30-60 s and isodense during the equilibrium phase. During the arterial phase the central scar is hypodense and may be hyperdense on delayed images. On MRI FNH is usuall y homogeneous

with is o- or hypointense appearance on T1-weighted images and slig htly hyper- to is o-intense appearance on T2weighted ima ges co mpared t o n ormal li ver pa renchyma. Contrast-enhanced MRI studies show analogous enhancement during arterial, portal venous and delayed phases. Differential diagnoses include hepatic adenoma, haemangioma, hepa toblastoma a nd hepa tocellular ca rcinoma, and may still b e hard to be distinguished by US, CT or MRI. N uclear sul phur co lloid s cintigraphy s can ca n lead to final diagnosis with a pathognomonic normal (5070%) to »hot« (elevated up to 10%) uptake, whereas other differential diagnoses show no significant uptake.

5

68

5


A

B

C

D

⊡ Fig. 5.7A–D. US of a 4-year-old girl with incidentally diagnosed FNH. Transversal US without (A) and with (B) power-Doppler. C Transversal T2w MRI. D Transversal contrast-enhanced T1w MRI (ar terial phase) demonstrating a high flo w supplying ar tery. Arrows supplying ar tery (B) powerDopper, (D) MRI

Hepatoblastoma Hepatoblastoma ( ⊡ Fig. 5.8) is t he t hird most co mmon abdominal t umour a nd t he most co mmon p rimary hepatic t umour in c hildren. H emihypertrophy a nd t he Beckwith-Wiedemann Syndrome, trisomy 18 and familial adenomatous p olyposis a re o ften ass ociated wi th hepatoblastoma. Most patients a re < 3 y ears o ld a nd t here is a hig her incidence a mong ma les. The t umour is usua lly large, solitary, and well-delineated with a ps eudocapsule. Serum AFP is elevated in 90% of cases. US demo nstrates a la rge het erogeneous, ec hogenic, hypervascular mass, o ften with calcifications, occasionally with cystic areas (hemorrhage, necrosis). CT sho ws an inhomogeneous mass with a peripheral rim enhancement. On MRI, hepa toblastoma p resents as h ypointense o n T1-w eighted a nd h yperintense wi th h ypointense f ibrous s epta o n T2-w eighted imag es. I nhomogeneous ar eas o f hemo rrhage w ith t ypical a ppearance

(hyperintense o n T1w a nd h ypointense o n T2w) ma y be seen. Differential diagnosis: ▬ haemang ioendothelioma ▬ met astatic neuroblastoma ▬ mes enchymal hamartoma ▬ h epatocellular carcinoma

Hepatocellular carcinoma (HCC) HCC is t he s econd most co mmon maligna nt hepa tic tumour in children. Children are usually > 5 years of age with a peak at 1214 years. The majority have an elevated AFP serum level. HCC usually presents as a focal mass or as a dif fusely infiltrating mass t hat is inho mogeneous, wi th va riable echogenicity a nd ra rely wi th calcif ications o n US. On MRI and CT HCC presents as a heterogeneous mass with contrast enhancement. Except for age, clinical symptoms

69


Mesenchymal sarcoma (undifferentiated sarcoma, embryonal sarcoma) This is a rare primary malignant tumour in children. The majority are 5-10 years of age and approximately 90% are < 15 y ears. The t umour presents as a la rge, hypovascular mass wi th w ell-delineated b orders wi th a f ibrous ps eudocapsule and cystic areas. Necrosis and hemorrhage are common, whereas usually no calcif ications are seen. The tumour ma y inf iltrate in to t he dia phragm, t he l ung a nd other locoregional structures. US, MRI and CT show a heterogeneous, partially cystic mass with contrast enhancement of fibrous septa.

Hepatic metastases

A

The most co mmon hep atic met astases ar e f rom neur oblastoma ( ⊡ Fig. 5.9), Wilms tumour, leukaemia and lymphoma. They usually present as s olitary or multiple solid nodules within the liver parenchyma. Their echogenicity, density a nd in tensity ma y va ry, b ut t hey o ften sho w a n increased peripheral enhancement.

Rhabdomyosarcoma of the biliary tree This is the most common malignant biliary tract tumour in children, with variable age at diagnosis. Usually, biliary obstruction a nd s eldom lob ulated in traluminal mass es may be seen with all imaging modalities.

Trauma of the liver

B ⊡ Fig. 5.8A,B. 3-year-old bo y with abdominal pain due t o hepat oblastoma with intratumoral hemorrhage and highly inhomogeneous parenchymal pattern (coronal TIRM MRI (A) and transversal US (B))

are simila r t o hepa toblastoma, a nd wi th imagin g alo ne a dif ferentiation b etween hepa tocellular ca rcinoma a nd hepatoblastoma is not possible. Fibrolamellar carcinoma of the liver is a rare variant of HCC (approx. 3%), is usually a tumour of the young adult (mean age 20 y ears) and has no ass ociation with chronic liver dis ease. The hallma rk o f t his va riant is a cen tral hyperechoic scar.

Blunt tra uma o f t he li ver is t he s econd most co mmon abdominal in jury a fter tra uma o f t he sp leen. C ontrastenhanced CT is the major tool to evaluate a blunt abdominal tra uma ( ⊡ Fig. 5.10). CT sho ws a h ypoattenuating haematoma with variable shape (depending on type of liver injury), hypodense wedge-shaped areas as focal hepatic devascularization and focal contrast enhancement as si te of ac tive b leeding. A haemo peritoneum, in trahepatic/ subcapsular gas and rupture of spleen are often associated with t hese f indings. US demo nstrates a het erogeneous liver wi th lac k o f no rmal vas cular pa ttern a nd lo calized echogenic areas of hemorrhage.

Vascular abnormalities Portal hypertension Portal hypertension is in most cas es caused by increased resistance to portal venous blood flow. It is seldomly congenital, traumatic or caused by arterioportal fistulas.

5

70

5


A

A

B

B ⊡ Fig. 5.9 A,B. US and MRI of a 4-month-old boy with hepatic metastasis due to neuroblastoma. The liver is inhomogeneous with multiple nodules (A) US of the liver (transversal plane). B MRI T2 TSE (axial plane)

A decr eased p ortal v enous b lood f low ma y b e d ue to prehepatic (e.g. p ortal vein t hrombosis or p ortal vein compression), intrahepatic (e.g. liver fibrosis, liver cirrhosis, hepatitis) or posthepatic obstruction (e.g. Budd-Chiari syndrome, he art fa ilure). P rehepatic p ortal obstr uction, especially due to portal vein occlusion, is mo re common in children (approx. 70%) than in adults. Portoportal a nd p ortosystemic co llaterals de velop with an increased portal resistance. During childhood the most common complication of portal vein thrombosis is splenomegaly a nd ac ute gastr ointestinal, o ften o esophageal, hemorrhage. Other complications include renal enlargement and portal venous collaterals. Portal v ein t hrombosis ma inly o ccurs b etween t he ages of 3 a nd 10. A small gr oup can be related directly to

⊡ Fig. 5.10A,B. US and CT of a 6-year-old boy with hepatic rupture after blunt abdominal trauma, demonstrating the ruptur ed area in the long itudinal. (A) US and transversal (B) contrast enhanced CT view of the liver

previous umbilical catheterization or ascending omphalitis but in most cas es portal vein thrombosis is idiopathic. In children with liver cirrhosis, portal hypertension is often detected through abnormal laboratory results of liver function, hence gastr o-intestinal hemo rrhage is a ra ther rare complication. Doppler US sho uld det ermine t he dia meter o f t he portal vein, portal venous blood flow and flow direction and evaluation of present collaterals. One of the first signs of portal hypertension is t he loss o f blood flow variation during respiration. Portal vein branch occlusions are difficult to def ine by US. Af ter portosystemic shunts, portal venous blood flow is inversed with a continuous hepatofugal blood flow. MRI and CT are useful techniques to determine portal vein t hrombosis, cavernous transformation of t he p ortal vein and portal collaterals (⊡ Fig. 5.11).

71


Budd-Chiari syndrome The Budd-Chiari syndrome (hepatic venous obstruction) is uncommon during childhood and in a bout two-thirds of cases idiopathic. In one third it is caused by thrombosis (e.g. sic kle cell dis ease, leukaemia) o r no n-thrombotic obstruction (e .g. t umour, co nstrictive p ericarditis, r ight heart failure). Doppler sonography is a useful, non-invasive method for e valuating t he B udd-Chiari syndr ome. Typical f indings a re t he small dia meter a nd a bsence o f b lood f low in hepa tic v eins a nd in u p t o 90% a h ypertrophy o f t he caudate lob e, with prominent hepatic veins draining t he caudate lobe into the inferior vena cava. MRI a nd CT als o demo nstrate t he a bsence o f b lood flow in hepatic veins and may provide additional information about collaterals and anatomical structures.

A

Hepatic veno-occlusive disease (HVOD) HVOD is def ined b y obstr uction o f t he hepa tic v enous system at the level of the central and sublobular veins. The majority of c ases are du e t o pre vious c hemotherapy or certain medication (e.g. alkaloids), hepatic radiation and bone marrow transplantation. Imaging is ca pable t o ex clude t he B udd-Chiari syndrome (pa tent ma jor hepa tic v eins), b ut def initive diagnosis requires biopsy and histological evaluation. HVOD is o ften ass ociated wi th a ga llbladder wa ll t hickening, ascites, hepa tosplenomegaly, decr eased dia meter o f t he major hepatic veins, increased diameter of the portal vein and portal venous collaterals.

Diffuse hepatic parenchymal disease Hepatitis Except f or neo natal hepa titis, viral inf ections a re th e most common cause of hepatitis. Radiology is very rarely requested because US, MRI a nd CT usuall y show a no rmal appearance. Gallbladder wall thickening is sometimes seen.

Congenital hepatic cyst Congenital hepatic cysts (⊡ Fig. 5.12) are the second most common b enign hepa tic lesio n a fter haema ngioma. A defective development of aberrant intrahepatic bile ducts leads to this very high incidence with 50% being detected at autopsy, and 20-30% detected during life. They mostly appear solitary and may be associated with tuberous sclerosis and polycystic kidney disease.

B ⊡ Fig. 5.11A,B. CT of a 9-y ear-old girl with por tal vein thrombosis consecutive splenomegaly and v enous c ollaterals due t o idiopathic liv er fibrosis. A C T por tal v enous phase with c ontrast-enhanced aor ta and hepatic ar teries but non- enhanced por tal vein ( white arrows). B Reformatted CT demonstrates splenomegaly and multiple venous collaterals

Polycystic liver disease is an autosomal dominant disease with a f emale predominance t hat is co mbined with polycystic kidney disease in up to 50% of cases. The cysts are usually located throughout both lobes of the liver. US shows a typ ical c ystic str ucture t hat ma y co ntain f luidfluid le vels a nd typ ical a ttenuation is s een wi th CT a nd MRI without contrast enhancement.

Fatty replacement Fatty replacement of normal liver parenchyma may have several causes (e.g. cystic fibrosis, high-dose steroid ther-

5

72


apy, glycogen storage disease, malnutrition and long-term hypernutrition). US ( ⊡ Fig. 5.13A) sho ws f ocal o r dif fused incr eased echogenicity, w hereas CT imagin g sho ws ma rkedly decreased attenuation. MRI ( ⊡ Fig. 5.13B) f indings are high signal intensity in T1w images and low signal intensity in fat-saturated weighted images.

Increased iron storage

5

Increased storage of iron in t he liver is d ue to metabolic diseases such as haemachromatosis or after multiple blood transfusion or major thalasemia with haemosiderosis. The li ver usuall y a ppears no rmal t o h ypoechoic o n US, w hereas CT demo nstrates a ma rkedly dif fuse a nd increased attenuation of liver parenchyma. On MRI T2w sequences, the liver parenchyma is hypointense.

Cirrhosis Cirrhosis ( ⊡ Fig. 5.14) is a c hronic liver disease with irreversible widespread hepatic fibrosis, diffuse parenchymal necrosis and no dular p arenchymal r egeneration. Ther e are m ultiple aetio logies, a nd in c hildren t he most co mmon causes are chronic cholestasis (e.g. in c ystic fibrosis, biliary a tresia, inf lammatory b owel dis ease, hepa titis), hereditary diseases (e.g. tyrosinemia, galactosemia, alpha1-antitrypsin def iciency, W ilson dis ease) a nd ia trogenic causes (total parenteral nutrition). Typical morphological findings such as enlargement of the left hepatic and caudate lobe, nodules of regeneration and surface nodularity, dilatation of the hepatic artery are readily det ected o n US, CT a nd MRI. Reg enerative li ver nodules usually have signal intensity similar to normal liver parenchyma o n MRI a nd t herefore ma y b e dif ferentiated from HCC nodules in t he cirrhotic usually have a simila r signal intensity compared to normal liver parenchyma and therefore ma y b e dif ferentiated f rom H CC no dules. The latter are typically hyperintense on T2w images and show a marked contrast enhancement during the arterial phase.

Liver transplantation Pre-operative evaluation

A

There a re s everal indications f or li ver tra nsplantation in children. Assessment o f p ortal v ein size , hepa tic b lood f low, detection o f p ortosystemic sh unts, un suspected t umours and anatomical abnormalities are important pre-operative information that may be provided by US. In children with complex a natomical str uctures o r in w hom US do es no t lead to satisfying results (e.g. non-compliance, obesity) CT and MRI may also play a role in pre-operative evaluation.

Postoperative evaluation

B ⊡ Fig. 5.12A,B. US A Oblique view and MRI. B. Transversal plane, T1 contrast-enhanced) of a 9-year-old girl status post liver transplantation and incidentally diagnosed hepatic cyst in segment 2 (white arrow)

Depending o n t he typ e o f tra nsplantation (w hole-organ versus split-organ), hepatic localization and vascular anatomy may vary. Portal vein and hepatic artery anastomosis are usuall y p erformed end t o end w hereas t he r ecipient hepatic portion of the IVC is usually resected and replaced by the donor segment of the IVC. Regarding biliary anastomosis many different surgical techniques are applied. Common p ostoperative co mplications a re hepa tic artery t hrombosis resulting in infa rction, biliary a nastomosis leaks and strictures. Periportal oedema is a n early finding, caused by a l ymphedema due to lack of normal lymphatic drainage which presents as hyperechoic on US

73


and as a »p eriportal collar« of high intensity on T2w images on MRI and low attenuation on CT. Doppler US is ess ential in p ostoperative e valuation because o f i ts no n-invasive ass essment o f hepa tic haemodynamics. MRI T2w fa t-saturated s equences o r co ntrast enhanced T1w sequences with hepatobiliary contrast agents may b e helpful in diagnosin g biliary anastomosis leaks (⊡ Fig. 5.15). Key information

I

▬ US is diagnostic for most biliary stones, cholestasis, cysts and fatty replacement

▬ MRI and CT are valuable tools for preoperative ▬

I

▬

Hepatobillary system ▬ Persistent neonatal jaundice is in 90% due t o biliary atresia or neonatal hepatitis ▬ Hepatobiliary scintigraphy allows to diagnose biliary atresia

▬ ▬

A

A

B

B

⊡ Fig. 5.13A,B. 1-month-old bo y with c oagulopathy, hepat osplenomagly and fatt y r eplacement of the liv er. A US: long itudinal view of the liv er demonstrating diffused incr eased echogenicit y of the par enchyma. B MRI: c oronal STIR sequenc e sho wing a homogenous decrease of liver intensity

assessment of hepatic tumours but MRI is slightly superior to CT in postoperative follow-up. CT and US are most useful in detecting trauma of the liver Vascular liver abnormalities such as por tal hypertension usually can be easily diagnosed with US Doppler US is essential in pre- and postoperative assessment of liver transplants Radiological exams rarely show any abnormality in hepatitis

⊡ Fig. 5.14A,B. 14-year-old boy with c ystic fibrosis and cirrhosis with multiple inhomogeneous intrahepatic nodules and surface nodularity. A Longitudinal view of liver on US. B CT: portal venous phase of liver

5

74


5.1.2 Spleen

Splenic congenital abnormalities Asplenia There are multiple syndromes with associated asplenia or polysplenia. In asplenia usually complex heart anomalies are present a nd US, MRI a nd radio nuclide s cintigraphy wi th 99TC-labelled sul phur co lloid le ad t o co nfirmation o f asplenia.

5

Polysplenia A

Poysplenia ( ⊡ Fig. 5.16) ma y als o b e ass ociated wi th less severe ca rdiac p roblems, hemih ypertrophy a nd b iliary atresia. Polysplenia sho uld no t b e co nfused w ith access ory splenic tissue or post-traumatic fragmentation of spleen.

Accessory spleen An accessory spleen ( ⊡ Fig. 5.17) is a v ery common variant with an incidence of 10-30%. It is a small, round, softtissue mass t hat is lo calized at the lower border or hilum of an otherwise normal spleen.

Wandering spleen

B

Wandering spleen is due to lax or lack of splenic ligaments with a mal positioned sp leen t hat is usuall y diagnos ed incidentally. However, torsion and thus vascular thrombosis/infarction may occur, leading to inhomogenous echogenicity on US a nd inhomogenous enhancement during the portalvenous or delayed images on MRI or CT.

Splenomegaly There are many causes (see ⊡ Table 5.3 ) of splenomegaly (⊡ Fig. 5.18). The most common aetiology is portal hypertension in chronic liver disease

Focal lesions C ⊡ Fig. 5.15A–C. 21-year-old girl with liver transplantation due to BuddChiari syndrome showing a periportal oedema and splenomegaly with collaterals. A Transversal MRI hast e sequenc e (peripor tal »c ollar«). B CT r eformatted c oronal view (peripor tal »c ollar« and splenomegaly , collaterals). C Transversal MRI c ontrast-enhanced T1 sequenc e (c ollaterals)

Focal lesions of the spleen, except for affection in association with leukaemia and lymphoma are very rare.

Cystic splenic lesions Simple cysts can be congenital (mostly epidermoid cyst = true c yst) o r s econdary (usuall y ps eudocysts, ex cept f or parasitic lesions) to vascular (laceration/haematoma, cystic degeneration of infarct), infectious (abscess, tubercu-

75


A ⊡ Fig. 5.17. US of a 5-y ear-old boy with incidentally diag nosed accessory spleen (longitudinal view)

⊡ Table 5.3. Causes that may lead to splenomegaly Congestive splenomegaly

Portal hypertension, cirrhosis, congestive heart failure, cystic fibrosis, sickle cell anaemia

Neoplasm

Leukaemia, lymphoma, lymphoproliferative disease, Langerhans cell histiocystosis, metastases

Storage disease

Gaucher disease, Niemann-Pick disease, mucopolysaccharidoses

Infection

Tuberculosis, hepatitis, infectious mononucleosis, echinococcosis, malaria

Haemolytic anaemia

Haemoglobinopathy, hereditary spherocytosis, primary neutropenia, thrombotic thrombocytopenic purpura, ECMO (extracorporal membrane oxygenation)

Extramedullary haematopoiesis

Myelofibrosis

Collagen vascular disease

Systemic lupus erythematosus, rheumatoid arthritis, Felty syndrome

B ⊡ Fig. 5.16A,B. US of an 8-y ear-old g irl with incidentally diag nosed polysplenia. A Longitudinal view B Transversal view and situs inversus

losis, parasitic) or b enign/ malignant tumorous (cavernous haema ngioma, l ymphangioma, l ymphoma, necr otic metastases) reasons. Splenic cysts are usually surrounded by normal splenic parenchyma. The y ma y b e ec hogenic o n US ( ⊡ Fig. 5.19) or h yperdense o n CT if t hey co ntain fa t, c holesterol o r debris d ue to p revious hemo rrhage o r inf ection. A p yogenic a bscess is a s onolucent mass a nd ma y b e s eptated or co ntain gas t hat is hig hly ec hogenic o n US. MRI a nd CT demo nstrate a typ ical c ystic a ppearance (hig h signal on T2w a nd varying intensity on T1w imag es, depending on protein and solid content on MRI and low attenuating mass on CT).

Solid splenic lesions Leukaemia and lymphoma are the most co mmon causes for s olid lesio ns o f t he sp leen ( ⊡ Fig. 5.20). L ymphatic nodules may vary in ec hogenicity and size, ranging from

Trauma

Splenic rupture, splenic haemorrhage

Others

Haemodialysis, autoimmune lymphoproliferative syndrome, sarcoidosis

a miliary pattern to asymmetr ic, s olitary affection up to 10 cm in diameter. Arteriovenous a nd l ymphatic malf ormations o ften show some cystic-like components. Lymphatic malformations o f t he sp leen a re o ften ass ociated wi th l ymphatic malformations at other sites of the body. A healed splenic infarction is h yperechoic on US a nd may lead to shrinkage und calcification of the spleen.

5

76


5

A

A

B ⊡ Fig. 5.19A,B. US of the spleen (long itudinal view) of a 10-y ear-old girl with incidentally diagnosed cyst. A B-mode. (B) Colour-Doppler

B ⊡ Fig. 5.18A,B. MRI (TIRM coronal plane) and US (longitudinal view) of an 8-year-old boy with splenomegaly due to DiGeorge disease

Trauma of the spleen Blunt trauma of the spleen is t he most co mmon abdominal in jury ( ⊡ Fig. 5.21). C ontrast-enhanced CT is t he major t ool t o e valuate a b lunt a bdominal tra uma. CT

shows a hypoattenuating haematoma with variable shape associated wi th h ypodense w edge-shaped a reas o f f ocal splenic devascularization and focal contrast enhancement as site of active bleeding. Free splenic fluid is often noted. US demo nstrates a het erogeneous sp leen wi th lo calized echogenic areas of hemorrhage. Key information

I

I

Spleen ▬ Asplenia or polysplenia often are associated with syndromes whereas an accessory spleen is a common normal variant ▬ Focal lesions of the spleen are very rare ▬ CT and US are most useful in detecting trauma of the spleen

77


A

B

C

⊡ Fig. 5.20A–C. US (longitudinal view. A) Contrast-enhanced CT. B and MRI (TIRM coronal plane, C) of a 15-year-old boy with diagnosed Hodgkin disease and affection of spleen

A

B

⊡ Fig. 5.21A,B. Reformated contrast-enhanced CT (A) and longitudinal view of US (B) of a 14-year-old boy after blunt abdominal trauma. Splenic rupture (arrows) perisplenic and perihepatic fluid in C T

5

78


5.1.3 P ancreas

Pancreatic developmental abnormalities Pancreas divisum

5

Pancreas divisum is the most common variant of the pancreas. It leads to the main drainage of pancreatic secretion through the accessory duct of Santorini, and is thus implicated as a cause of acute pancreatitis. US is usually unable to depict pancreas divisum. MRI, esp ecially MRCP, may show the separate ventral and dorsal portions with their ducts in so me ca ses, wh ereas co nventional ER CP i s s till the gold standard leading to a definite diagnosis.

⊡ Table 5.4. Causes of acute pancreatitis Infection

Viral (mostly), bacterial, fungal, parasitic

Drug toxicity

Acetaminophen, Valproic acid, Steroids

Cholestasis

Biliary stones

Peptic ulcer

Duodenal ulcer

Hereditary diseases

Cystic fibrosis, congenital (hereditary) pancreatitis

Anatomical abnormalities

Pancreas divisum

Trauma

Accidental trauma, non-accidental trauma (child abuse)

Annular pancreas Annular pancreas is an encircling of the duodenum which is usuall y ass ociated wi th in trinsic d uodenal st enosis o r atresia a nd o ften diagnos ed d uring infa ncy b ecause o f intermittent vomiting. US is neither sensitive nor specific in diagnosin g a nnular pa ncreas, t hus MRI wi th MR CP or t hin-sectional CT is necess ary in o rder t o ac hieve a n accurate diagnosis.

Pancreatic parenchymal disease Pancreatitis There a re m ultiple dis eases a nd a bnormalities t hat ca n cause ac ute pancreatitis (s ee ⊡ Table 5.4 ), yet s ome cas es of pancreatites are idiopathic. Diagnosis is ma inly bas ed on clinical findings and laboratory results. US is generally the first radiological modality to evaluate ac ute pa ncreatitis ( ⊡ Fig. 5.22) a nd is a ble to sho w pancreatic enlargement, dilatation of the pa ncreatic duct, abnormal echogenicity and peripancreatic fluid collection. However, t he pa ncreas ma y als o a ppear no rmal o n US. MRI and CT may help to confirm the diagnosis in difficult cases, but are mostly employed in searching for causes and complications (e.g. pseudocysts, necrosis, abscess). Chronic pancreatitis is a continued inflammatory disease of t he pancreas t hat le ads to ir reversible damage to its a natomy a nd f unction. A etiology ma y b e c lassified in c hronic calcif ying pa ncreatitis (Kwashiokor, met abolic dis orders, h yperlipidemia a nd h ypercalcemia) a nd in chronic obstructive pancreatitis (e.g. cystic fibrosis, developmental abnormalities, trauma). Plain f ilm may reveal multiple ir regular calcif ications. Typical radio logical f indings o n US, MRI a nd CT a re ir regular pa ncreatic ma rgins wi th irr egular d uct dila tation, pancreatic calcif ications, small a nd s ometimes a trophic

pancreatic p arenchyma, p ancreatic ps eudocysts a nd mi ld biliary duct dilatation. The parenchyma usually appear hyperechogenic on US and hypointense on fat-saturated T1w images with diminished contrast enhancement on MRI.

Cystic fibrosis Cystic f ibrosis ( ⊡ Fig. 5.23) ma y le ad t o pa ncreatic d ysfunction ra nging f rom mild m ucus acc umulation in t he ducts t o s evere mu cus p lugging a nd p ancreatic at rophy, fibrosis a nd c yst f ormation. Due t o f ibrous a nd fa tty infiltration, the pancreas appears echogenic and small on US, and also has a fa t-equivalent signal o n MRI a nd CT. Calcifications a nd small c ysts ma y b e s een in addi tion; however, large, macroscopic cystic replacement should not be mistaken for a cystic tumour.

Other Differential diagnos es o f a n ec hogenic a nd/or inho mogeneous pa ncreas o n US, o n MRI a nd CT inc lude t he Schwachmann syndr ome (ex ocrine pa ncreatic in sufficiency a nd b one ma rrow d ysfunction), haemosider osis and chronic pancreatitis. Cystic pancreatic lesions may also be associated with autosomal dominant Von Hippel-Lindau disease (VHLD) and autosomal dominant polycystic kidney disease (ADPKD).

Pseudocysts and congenital cysts A ps eudocyst has o nly a f ibrous wall a nd is most co mmonly a complication after trauma or inflammation. It is a well-defined fluid collection with a thick wall and typically hypoechoic on US and has all the criteria of a cyst on MRI and CT. It can be present as a complicated cyst after haemorrhage or inflammation.

79


A

B

C

D

⊡ Fig. 5.22A–D. 12-year-old girl with acut e oedematous pancreatitis A Transversal US and B transversal T2 Haste sequence demonstrates the oedematous, hypoechogenic pancreatic head (C) and corpus (D)

Pancreatic tumours Pancreatic t umours a re extr emely ra re in c hildren a nd include rha bdomyosarcoma, ca rcinoma, m ucinous c ystadenoma, pancreatoblastoma, islet cell tumours [functioning (85%): e .g. insulinoma, gastrinoma, non-functioning (15%): e.g. somatostatinoma] and secondary lesions (e.g. neuroblastoma, Burkitt lymphoma). Key information

I

I

▬ Pancreatic abnormalities such as pancreatitis or ⊡ Fig. 5.23. Longitudinal view of US of a 3-year-old girl with echogenic and small pancreas caused by cystic fibrosis (arrow)

True congenital cysts are extremely rare, and radiological findings may help to distinguish a true cyst from a pseudocyst (with the true cyst having a thinner wall, loculations, septations, otherwise normal pancreatic parenchyma).

pancreatic tumours in children are rare

▬ Pancreatic changes in cystic fibrosis includes fibrosis and fatty infiltration that can be seen on US, MRI and CT

5

80


5.2 Ur

ogenital tract

Jens-Peter Schenk 5.2.1 Renal dysmorphology and anomalies

Renal agenesis and hypoplasia Renal agenesis

5

Renal agenesis is a rare anomaly and is usually unilateral. If a compensatory hypertrophy of the contralateral kidney is s een, a t le ast a f unctional unila teral kidne y is hig hly possible. Associated anomalies of genito-urinary, skeletal, cardiovascular, gastro-intestinal, central nervous or respiratory system should be excluded. The syndrome of bilateral renal agenesis leads to oligohydramnios, hypoplastic lungs and characteristic potter facies. Severe hypoplastic lungs limit extra-uterine life.

Renal hypoplasia Renal hypoplasia is defined as a reduction in the number of nephrons. The kidne ys are small (< 3 p ercentile) with a normal parenchyma structure. Renal hypoplasia may be bilateral or unilateral. Segmental hypoplasia in unila teral kidney is p ossible (Ask-Upmark kidney). Bilateral hypoplasia presents in chronic renal failure.

Imaging Ultrasound

If a kidne y is nei ther orthotopic nor in a typical dystopic location, i t is indica tive o f unila teral r enal ag enesis. B ecause of p ossible a ccompanying an omalies of t he ute rus and ovaries, ultrasound should include the inspection of the female genito-urinary tract. Measurement of the renal volume is obligatory. The evaluation of the renal size, either by ellipsoid formula or by volumetry in 3-D-US, is decisi ve. A renal volume between the 3rd and 97th percentile should be termed normal. In hypoplasia a normal renal structure is found.

Possible findings in renal agenesis ▬ Unilateral lack of the kidney parenchyma ▬ Contralateral compensatory hypertrophy ▬ Complete lack of the kidneys in bilateral agenesis

Pitfalls ▬ Pe lvic kidney ▬ Lumbal dystopic kidney covered by intestinal air ▬ Cl umb kidney

Possible findings in renal hypoplasia ▬ N ormal structure ▬ Volume < 3rd percentile ▬ Unilateral or bilateral hypoplasia ▬ Se gmental hypoplasia

Pitfalls ▬ Anomalies in renal structure (dysplasia) ▬ Failures in volume measurement MRU

MRU can distinguish between agenesis and aplasia. Ureters and ureter buds with aplasia or renal hypoplasia can be dif ferentiated. MR ur ography is indica ted in all cas es with co mbined g enito-urinary trac t malf ormations o r suspicious vaginal urinary output (ureteral ectopia). Scintigraphy

Functional k idney p arenchyma c an b e do cumented with r enal s cintigraphy. S cintigraphy p roves f unctional sin gle kidne y b ut no t kidne y ag enesis. S cintigraphy can b e necess ary in co mplicated dis ease wi th c linical symptoms. Key information

I

I

Renal agenesis ▬ US first and sufficient in most patients ▬ Contralateral compensatory hypertrophy ▬ Genital malformations should be excluded with ultrasound in females ▬ MR Urography and scintigraphy are indicated in patients with clinical symptoms or further genitourinary tract malformations. Renal hypoplasia

▬ US first, in routine diagnostics no further imaging methods

▬ Volume measurement decisive ▬ Differentiation to dysplasia by renal structure analysis

Duplex kidney Duplication of t he collecting system is a co nsequence of the de velopment of two ureteric buds in t he mes onephric d uct. Two as cending b uds le ad t o a ur eter d uplex, a premature di vision o f t he ur eteric b ud le ads t o a ur eter fissus. The ur eter dra ining t he lo wer s egment migra tes

81

5.2 · Urogenital tract

more cep halad a nd la teral t han t he ur eter dra ining t he upper segment. There is often reflux to the ureter of the lower collecting system. Upper pole ureter is p rone to ureteral ectopia and obstruction. Ectopic ureterocele is due to cystic ballooning of t he dist al ur eter b etween m ucosa a nd b ladder m uscle. In girls, ur inary dr ibbling, in b oys, orchiepididymitis, are clinical presentations of ureteral ectopia in duplex kidneys.

Imaging

Possible findings in duplex kidney ▬ Two distinct renal poles separated by a bridge of normal parenchyma ▬ Ureterohydronephrosis in one or both poles ▬ Ec topic ureter ▬ U reterocele ▬ Me gaureter ▬ Dysplasia of the upper pole ▬ Signs of urinary tract infection or VUR

Ultrasound

Pitfalls

Routine ul trasound usuall y det ects a d uplication o f t he collecting system by dilatation of the upper or lower pole due to reflux or obstruction. Ultrasound examination can suggest duplication of t he ur inary trac t and ec topic ureteral insertion, but cannot prove it.

▬ Single dilatation of a calix ▬ Missing the ureterocele due to bladder ▬ A co ne o f no rmal pa renchyma cen tral in t he r enal hilum can imitate a bridge of parenchyma ▬ Crossed ectopia with or without fusion

⊡ Fig. 5.24. MRU (ceT1-FFE), dynamic contrast study (40 min) in bilateral duplex kidney. Late contrast-enhancement in the upper renal pelvis of the left kidney due to decreased function and obstruction

5

82


so t hat a nd a n obstr uction ca n b e mis sed. U pper p ole obstruction le ads to a disp lacement o f t he lo wer p ole, which can indicate a duplex system. IVP can be replaced by MRU.

VCUG or VCUS VCUG is performed to detect VUR and associated infravesical obstruction. Even ectopic ureters, refluxive or obstructive, or both, can sometimes be detected in V CUG. To detect reflux in t he upper or more often in t he lower renal pelvis of the duplex kidney, VCUG can be replaced by VCUS. The s ensitivity of reflux detection is hig her in VCUS tha n in V CUG. Esp ecially in r epetitive exa minations f or f ollow-up st udies, V CUS ca n a void radia tion exposure to the gonads.

5

Key information

I

I

Duplex kidney ▬ Urinary tract infection, hydronephrosis and urinary dribbling ▬ US suggests duplication ▬ VCUG/VCUS to detect VUR in duplex kidneys ▬ Combined information of anatomy, renal function and urodynamics in MRU

Other renal anomalies ⊡ Fig. 5.25. 3D-MR-morphology in bilat eral duplex k idney, megaureters in both upper poles and ec topic ur eter ostium of the lef t side . Normal size of both lower poles (arrows)

MRUrography MRU demonstrates anatomical details, even in non-functioning p oles (3-D T2/HASTE s equence) ( ⊡ Fig. 5.25). Ectopic ur eteral o rifices a re b est visualized in MR U. Contrast-enhanced MRU with 2-D or 3-D T1 sequences combine t he inf ormation o f co ntrast ex cretion in t he kidney with do cumentation of the ureters. Information of partial renal f unction (%) a nd urodynamic information can be achieved ( ⊡ Fig. 5.24).

Intravenous pyelogramm (IVP) Experience wi th t his met hod sho wed a lac k o f inf ormation in no n-functioning p oles o f a d uplex syst em,

Horseshoe kidneys are the most common type of renal fusion. Usually, both lower poles connect across the midline by a n ist hmus l ying next t o t he ao rta a nd inf erior v ena cava. H orseshoe kidne ys a re usuall y in l umbal d ystopic position a nd a re f requently f ound in T urner’s syndr ome and Trisomie 18. Hydronephrosis can be associated when ureteropelvic junction obstruction is caused by high ureteral insertion or anomalous vessels. In cr ossed ec topic kidne ys, o ne kidne y lies o n t he opposite side f rom ureteral insertion of the bladder. The most co mmon typ e in cr ossed ec topy is t he unila teral fused typ e wi th inf erior ec topia. Cr ossed r enal ec topia may be associated with VUR.

Imaging Imaging modalities are similar to those of duplex kidneys. US can detect anomalies of the renal position in cr ossed ectopia; it often cannot distinguish b etween ec topy with or without fusion. The ist hmus in ho rseshoe kidne ys is usuall y det ectable by US.

83


Key information

I

Fusions anomalies ▬ Cr ossed ectopy ▬ I ncomplete rotation ▬ Urinary tract obstruction ▬ VUR associated with renal anomalies ▬ Missing kidney on one side ▬ Two kidneys adjacent to each other Horseshoe kidney ▬ Isthmus in horseshoe kidney ▬ Association with Turner syndrome

I

5.2.2 Cystic renal diseases

Multicystic dysplastic kidney (MCDK) MCDK is the most common cystic disease. It is most commonly unilateral, with a contralateral normal kidney. A s egmental ma nifestation is v ery ra re. The i psilateral ureter is a bnormal or absent. Association with ipsilateral genital anomalies is p ossible. As primary volume differs, MCDK often appears as a n abdominal mass in neo nates. Spontaneous regression and disappearance of the MCDK is a common finding. Complications can be caused due to continuing growth with compression of adjacent organs, hemorrhage and inflammation (⊡ Fig. 5.26).

Imaging Ultrasound

Diagnosis is usuall y ac hieved s olely by s onography. Follow-up mo nitoring is necess ary t o ex clude co mplications. Doppler sonography can evaluate the perfusion of residual renal parenchyma. Residual parenchyma can be responsible for complications.

Possible findings ▬ ▬ ▬ ▬

Little residual renal parenchyma Multiple cysts of different size Differentiation of a renal pelvis is often not possible Compensatory hypertrophy of the contralateral kidney

Pitfalls ▬ H ydronephrosis ▬ Cystic renal tumours ▬ Ovarian cysts in newborn ▬ Polycystic kidney disease

⊡ Fig. 5.26. MCDK of right kidney with multiple cysts

Scintigram, VCUG and MRUrography Other imaging modalities become necessary in complications o r ass ociation wi th o ther r enal a nomalies, suc h as duplex kidne ys wi th M CDK o r in pa tients wi th ur inary tract dilatation of the contralateral kidney. MRUrography is the preferred modality in differential diagnosis of complex anomalies with MCDK. Key information

I

I

Multicystic dysplastic kidney ▬ Diagnosis made by Ultrasound ▬ Complications are rare, but possible ▬ Further imaging in complex anomalies and before surgical therapy

Renal dysplasia A dist urbed r enal o ntogenesis r esults in r enal d ysplasia, which can be focal (e.g. in d uplex kidneys) or present as a diffuse renal disease. Clinical symptoms depend on the underlying disease or syndrome. In patients with bilateral dysplasia, r enal fa ilure det ermines t he c linical co urse o f the disease.

Imaging Ultrasound

In general, dysplastic kidne ys are small. US sho ws a h yperechogenic kidne y wi th a r educed co rticomedullary differentiation. I n r enal c ystic d yplasia c ysts o f va rying size infiltrate the renal parenchyma. Associated VUR can be diagnosed with VCUS.

5

84


Renal scintigram Evaluation o f kidn ey fun ction i s n ecessary in pa tients with complications (obstruction, VUR) and before surgical interventions.

Polycystic kidney disease

5

Polycystic kidne y dis ease inc ludes m ultiple her editary diseases: a utosomal r ecessive p olycystic kidne y dis ease (ARPKD), a utosomal do minant p olycystic kidne y disease (ADPKD), juvenile nephronophthisis and medullary cystic dis ease co mplex (M CDC), co ngenital nep hrotic syndrome and syndromal cysts. The sp ectrum o f t hese dis eases r eaches f rom is olated cysts to diffuse and progressive disease of the kidney parenchyma. I n t he f ollowing, o nly ARPKD , AD PKD, MCDC and juvenile nephronophthisis will be described.

⊡ Fig. 5.27. »Pepper and salt structure« in ARPKD, longitudinal scan

ARPKD Manifestation a nd course of ARPKD va ries, a nd usuall y the dis ease is diagnos ed in e arly infa ncy. Dila tations o f the co llecting d ucts le ad t o m ultiple c ysts in co rtex a nd medulla. B ilateral mass es are typical after birth. Hepatic cysts are f requently ass ociated, liver cir rhosis and p ortal hypertension a re s een in s evere cas es. This dis order is diagnosed prenatally with oligohydramnion and is o ften associated with lung hypoplasia. Severe renal involvement in the neonatal period leads to early death.

⊡ Fig. 5.28. ARPKD, transverse scan

Imaging Ultrasound

Markedly enla rged a nd unif ormly h yperechogenic kidneys are typical at birth. US ma y fail t o def ine t he c ysts if t hey a re t oo small . A typ ical f inding is a b ilaterally speckled increased echogenicity of renal tissue with inhomogeneously reduced tissue dif ferentiation (»pepper and salt structure«). In the course of the disease, cysts increase in size and number (⊡ Fig. 5.27–5.30).

IVP IVP is a ra rely us ed imagin g t echnique. B ecause t he collecting d ucts r un f rom co rtex t o med ulla, radial streaks a nd t ubular s triation a re t he typical f indings in ARPKD.

MRU Muliple c ysts o f t he r enal pa renchyma a re b est visib le in hig hly T2-w eighted s equences. I n demo nstration o f

⊡ Fig. 5.29. C oronal MRI (3-D -T2-SPIR) in poly cystic k idney disease with multiple cysts in both kidneys

kidney dis ease together with liver involvement and lung hypoplasia, MRI is als o a us eful tool in planning surgical therapy.

85


⊡ Fig. 5.30. Transverse MRI (c eT1SPIR) with c ontrast enhancement in residual parenchyma in both kidneys (polycystic kidney disease)

⊡ Fig. 5.31. ADPKD, sonography with long itudinal scan. P arenchymal cyst (arrow)

ADPKD

from dila tated dist al t ubules a nd co llecting d ucts, b ut some o f t he c ysts ca n als o b e f ound in t he renal co rtex. Interstitial fibrosis, glomerular sclerosis and cortical atrophy lead to renal insufficiency. Clinically, patients show all symptoms of renal failure.

ADPKD is a ca use o f end-st age r enal fa ilure in ad ults, but manifestation of the disease often takes place during childhood. I nitially, o nly a f ew c ysts exis t; in t he co urse of t he dis ease b oth kidne ys are enlarged and more c ysts develop in cortex and medulla. Children may present with hematuria or unilateral or bilateral flank masses. Hypertension is p ossible. F urther s econdary co mplications o f the cysts are hemorrhage, sedimentation and infection. Ultrasound examinations of the children’s family (parents) hel p t o dif ferentiate b etween AD PKD a nd o ther cystic renal diseases (⊡ Fig. 5.31).

Imaging Ultrasound

US demo nstrates c ysts in va rious size . I n small infa nts usually t he r enal pa renchyma lo oks no rmal, o nly sin gle cysts may be detectable. Positive family screening is considered diagnostic. In later childhood the number of cysts with varying size incr eases. Hyperechoic parenchyma in bilaterally enlarged kidneys is possible.

MRI In very rare cases with complications and differentiation of complicated c ysts, MRI ca n b e helpful, but it is no t a routine diagnostic tool.

MCDC MCDC is an autosomal dominant inherited disease. Typical ag e of ma nifestation is in o lder c hildren a nd ado lescents. C ysts a re lo cated in t he med ulla. C ysts de velop

Imaging Ultrasound

Typical findings in US are small kidneys. In early MCDC no sp ecific signs exist. I n the later course of the dis ease, multiple cysts lying in t he renal parechmya, loss of corticomedullary differentiation and hyperechoic parenchyma can b e f ound. I n r outine diagnosis no f urther imagin g is needed , b ecause t he diagnosis is made b y mo lecular genetic examination and family history.

MRI MRI is not specific, cysts may be visualized better.

Juvenile nephronophthisis Familial juvenile nephronophthisis is in herited recessively. This disease is a sclerosing tubulo-interstitial nephropathy wi th small t ubular a nd g lomerular c ysts. Chr onic renal failure determines the course of the disease.

Imaging Ultrasound

In US co rticomedullary dif ferentiation is r educed a nd a slight h yperechogenicity is obs erved. K idneys a re small or size decr eases in t he co urse o f t he dis ease. C ysts a re located in t he corticomedullary junction zone. Cysts are

5

86


small, up to 10 mm. In routine diagnosis no further imaging is needed, because the diagnosis is made by molecular genetic examination and family history.

MRI MRI is not specific, cysts may be visualized better Key information

5

I

I

Cystic renal diseases ▬ Ultrasound first ▬ Further imaging only in complications ▬ Classic appearance: – MCDC – Cysts of different sizes, very little parenchyma and decreasing size. – ARPKD – Pepper and salt kidney. Enlarged kidney. – ADPKD – Single cysts in small infants, increasing number and size of cysts in the course of disease. Enlarged kidney. – MCDC – Older children with medullary cysts, hyperechoic kidneys with loss of corticomedullary differentiation. Small kidney. – Juvenile nephronophthisis – Cysts in corticomedullary junction zone, hyperechogenicity. Small kidney. – Diagnosis sometimes not specific with imaging. Family history, molecular genetics and even biopsy may be necessary.

Possible findings ▬ Diameter of renal pelvis > 10 with caliceal dilatation ▬ Diameter > 12 mm without caliceal dilatation ▬ Standstill of renal growth by moderate dilatation can indicate obstruction ▬ Aberrant v essel in D oppler s onography next to t he ureteropelvic junction

Pitfalls ▬ Cystic kidne y dis ease may mimic s evere renal p elvic dilatation ▬ VUR with intermittent renal pelvic dilatation ▬ U reteral stenosis ▬ I nfravesical stenosis

5.2.3 Obstruc tive uropathy

Ureteropelvic junction obstruction Renal pelvic dilatation can occur as a dila ted renal pelvis with or without calyceal dilatation. Special focus is on calyceal dilatation, b ecause p elvic dilatation wi thout cal yceal dilatation can be a normal variant. Renal pelvic dilatation can occur in obstructive disease or without obstruction.

⊡ Fig. 5.32. Ur eteropelvic junc tion obstruc tion with enlar gement of renal pelvis, longitudinal scan

Imaging Ultrasound

In p renatal dia gnosed pe lvic dila tation, ul trasound m ust confirm t he diagnosis a fter b irth. B ecause o f decr eased postnatal diuresis, US sho uld be repeated after the first 2 days of life. In antenatal diagnosed renal pelvic dilatation, a normal US has to be repeated after 4-6 weeks for definitive exclusion of ur inary trac t obstr uction. When pain is the leading symptom, diurese-US gives a correlation to the pelvic dilatation (⊡ Fig. 5.32–5.33).

⊡ Fig. 5.33. Dilatation of renal pelvis in transverse scan

87


MAG3 Tc99m diuretic renogram

Magnetic resonance urography (MRU)

Urodynamic studies are classified according to the O’Reilly classification a nd a id in det ermining b etween sur gical and medical tr eatment. Di uretic r enograms demo nstrate function a nd dra inage ( ⊡ Fig. 5.34). A s cintigram sho uld not be performed before the 6th week of life as the kidney’s function is still immature.

MRU is necess ary in pa tients wi th co mplex a natomical findings o r uncer tain ul trasound in terpretations. Esp ecially w hen t he lo cation o f t he obstr uction is no t c lear, further MRI is necess ary. S tatic-dynamic MR U ca n r eplace scintigram and IVP.

⊡ Fig. 5.34. Diuretic renogram in ureteropelvic junction obstruction. Urodynamic decompensation of the left kidney

5

88


Key information

I

I

Upper ureteropelvic junction obstruction ▬ Diagnosis by Ultrasound ▬ Diuretic scintigram for graduation of the obstruction ▬ US and Scintigram together in follow-up studies ▬ MRU combines anatomical and functional information in complex anatomy.

5 Distal ureter stenosis/primary megaureter Primary obstructive megaureter is the second most common reason for hydronephrosis in ne wborn. About 20% are b ilateral. The obstr uctive co mponent ca n r eturn t o normal. Due to the high incidence of spontaneous remission, conservative treatment is indicated.

⊡ Fig. 5.35. Distal ureter stenosis with enlargement of the renal pelvis and renal calices, longitudinal scan

Imaging Ultrasound

Postpartal US can detect primary megaureter very early. A sufficient hydration is im portant, for this reason it is important to perform the study after the first 2 da ys of life ( ⊡ Fig. 5.35–5.36).

Possible findings ▬ ▬ ▬ ▬

Retrovesical dilatation of the ureter Renal pelvis dilatation Pathological structure of the kidneys Ureterocele with obstructive megaureter

Pitfalls ▬ L ow hydratation ▬ Confound with ovaries in females ▬ Peristaltic wave of the ureters ▬ Intermittent vesico-ureteral reflux ▬ Obstructive uropathy in duplex kidneys ▬ Infravesical obstruction with megaureters ▬ M egaureter-megacystic syndrome

VCUG Is indicated to dif ferentiate obstr uctive megaureter f rom VUR (See Vesico-ureteral reflux, below)

MAG3 Tc99m diuretic renogram The s cintigraphy is p erformed simila rly t o ureteropelvic junction obstruction (⊡ Fig. 5.37).

⊡ Fig. 5.36. Retrovesical dilatation of the ureter (arrow), transverse scan

MRUrography Megaureters are best detectable after hydration and furosemid application. MRU has r eplaced IVP in imagin g of the urinary tract in obstructive megaureter (⊡ Fig. 5.38). Key information

I

I

Distal ureter stenosis ▬ Ultrasound as a basic imaging method ▬ Prenatal diagnosed megaureters ▬ Urinary tract infection ▬ Diff erential diagnosis: VUR ▬ Conservative treatment depending on isotope renogram ▬ MRU in complex anatomy

89


⊡ Fig. 5.37. Diuretic renogram in distal ureter stenosis, compensated situation with decrease of activity after application of furosemid

Vesico-ureteral reflux

Imaging

Reflux o f ur ine f rom t he b ladder to t he ur eter a nd r enal p elvis d ue t o in sufficient val vular mec hanism a t t he ureterovesical j unction le ads t o in termittent o r c hronic dilatation of the urinary tract. The bac terial inflow from the bladder in t he kidne ys can result in a n urinary tract infection wi th p yelonephritis. Rec urrent inf ections a re responsible for renal scarring and loss of function.

Ultrasound

US det ects indir ect sign s o f VUR , t o p rove t hat VUR contrast st udies a re necess ary. W hen in termittent dilatation o f t he r enal p elvis o r dif ferent dia meters o f t he renal p elvis b efore a nd a fter mic turition a re obs erved, think of VUR!

5

90


5

⊡ Fig. 5.38. MRI (3D T2 SPIR) in distal ureter stenoses in both sides

⊡ Fig. 5.39. VCUG, normal urethra

Possible findings

Possible findings

▬ ▬ ▬ ▬

Dilatation of the renal pelvis and ureters Thickening of the urothel Reduction of the renal parenchyma Structure anomalies and hyperechogenicity in refluxnephropathy

VCUG (voiding cysturethrogram) VCUG r emains t he g old-standard exa mination f or imaging t he b ladder a nd ur ethra in susp ected VUR . Anatomical det ails a re b est visualized in V CUG. V CUG is necessary to exclude an urethral obstr uction through an urethral valve (⊡ Fig. 5.39–5.41).

▬ Contrast media b efore o r d uring mic turition in t he ureter or renal pelvis ▬ Associated bladder diverticulum ▬ Subvesical obstruction, e.g. urethral valve ▬ Uni- or bilateral VUR ▬ Ref luxing megaureter

Pitfalls ▬ Retrograde filling of the vagina ▬ Underestimation of the degree of VUR

91


Contrast-enhanced voiding cysturosonography (VCUS) VCUS has alr eady proven to b e a val uable alternative in the diagnosis o f V CUG. C oncordance b etween V CUS and V CUG is a bout 90%. C ontrast enha ncement is achieved with the use of microbubbles. Harmonic imaging is r ecommended, to increase sensitivity and specifity (⊡ Fig. 5.42–5.45).

Possible findings ▬ Microbubble regurgitation into the terminal ureters or renal pelvis ▬ I ntrarenal reflux ▬ Intermittent dilatation of the urinary tract, especially during micturition

⊡ Fig. 5.40. VCUG, urethral valve (thin arrow) with dilatation of the prostatic part of the urethra, pseudodiverticula of the bladder (thick arrow)

⊡ Fig. 5.42. Transverse scan with harmonic imag ing bef ore c ontrast application. Ureter (arrow)

⊡ Fig. 5.41. VCUG with v esico-ureteral r eflux in the lef (arrow)

t ur eter

⊡ Fig. 5.43. Transverse scan with micr obubbles in the bladder and in both ureters after micturition (arrows)

5

92


5.2.4 Urinary tract infections

Acute pyelonephritis

5 ⊡ Fig. 5.44. L ongitudinal scan of the k idney bef ore r eflux (anechoic renal pelvis)

In sym ptomatic inf ections u pper ur inary trac t inf ection (acute p yelonephritis) m ust b e distin guished f rom lo wer tract infection (ac ute c ystitis). If t he renal p elvis and parenchyma are involved, inflammatory oedema and microabscesses de velop. C olliquation o f inf ectious f oci r esults in a renal abscess. Complications of abscess formation are perinephritis and perirenal abscesses. In pyonephrosis, the renal pyelon is dilated with sedimentation of necrosis and pus. C omplicated ur inary trac t inf ections a re bas ed o n abnormalities of the kidney, VUR or bladder dysfunction. Upper urinary tract infections present with high fever and generalized sym ptoms, dep ending o n ag e. H ematogenic infections of the kidneys are possible, but less common.

Imaging Ultrasound

The primary examination should be obtained to r ule out hydronephrosis o r o ther r enal a nomalies. F urthermore, in p yelonephritis a ca reful exa mination o f t he kidne y parenchyma is necessary. The correct measurement of the kidney v olume sho uld b e p erformed, a n incr ease o f t he renal p arenchyma of up t o d ouble it s volu me i s p ossible in young children.

Possible findings ⊡ Fig. 5.45. Longitudinal scan of the k idney with harmonic imag ing and r eflux in the r enal pelvis (arrows) af ter mic turition (h yperechoic renal pelvis)

Pitfalls ▬ Intravaginal reflux mimicking reflux in the ureters ▬ Echo-enhancement from air in the bowel loops ▬ Strong aco ustic shado w d ue to a hig h micr obubble concentration in t he b ladder obs cures r eflux in t he terminal ureters Key information

I

I

Vesicoureteral reflux ▬ VCUS in females or follow-up studies possible ▬ VCUG in males to exclude infravesical obstruction is necessary ▬ Indication is urinary tract infection

▬ Renal anomalies ▬ Increase of kidney volume ▬ Loss of the corticomedullary differentiation ▬ High ec hogenicity o f t he pa renchyma, es pecially t he renal cortex ▬ Hypo- o r no n-echogenic f oci r epresenting micr oabscesses ▬ Larger defect in necrosis ▬ Demarcation of abscess formation ▬ Pelvic wall thickening (> 0.8 mm) ▬ Renal sinus hyperechogenicity ▬ Ureteritis with ureter wall thickening ▬ Sedimentation in the bladder or renal pelvis ▬ Perirenal fluid collection in perinephritis ▬ I ncreased perirenal echogenicity

Pitfalls ▬ Pelvic wall thickening in VUR, postoperative ureteropelvic o bstruction o r r enal tra nsplant r ejection po ssible

93


▬ Loss o f co rticomedullary dif ferentiation in d ysplasia or other chronic renal disorders ▬ Hypoechogenic f oci in l ymphoma o r nep hroblastomatosis ▬ Diffuse enla rgement o f t he kidne y in leukaemia o r lymphoma.

Colour Doppler imaging (CDI) and power Doppler sonography In CDI the perfusion of the kidneys can be evaluated. Further evaluation of the peripheral renal vessel architecture can b e ac hieved t hrough t he us e o f a mplitude mo dified Doppler (power Doppler).

Possible findings ▬ S egmental perfusion defects ▬ Areas of devascularization ▬ Non-perfusion in abscess formations ▬ Ad jacent hyperperfusion ▬ Displacement o f no rmal vess els b y ad jacent inf lammation

Pitfalls ▬ Perfusion defects by renal scarring ▬ Good cooperation of the patient is necessary to avoid Doppler artefacts

MRI MRI can detect renal scarring and acute edema. A gr eat advantage is t he p ossibility o f visualizin g t he co mplete renal co llecting syst em in r elation t o t he inf lammation. A s afe det ection o f r enal a bscess f ormations is a nother advantage a nd in p re-operative p lanning MRI is a v ery useful tool. In addition, t he technique of magnetic r esonance urography (MRU), with visualization of the urinary tract o r r enal f unction a nalysis, hel ps t o p lan t he next therapeutic decisions.

Possible findings ▬ Enlargement of the kidney ▬ P erirenal edema ▬ Loss of corticomedullary differentiation ▬ Fl uid collection ▬ Renal and perirenal abscess formation ▬ Renal p elvic dila tation in r elation t o inf lammatory foci

Pitfalls ▬ Difficult interpretation after surgical intervention ▬ Motion artefacts in case of insufficient sedation

CT An indication for uro-CT in c hildhood is gi ven in co mbined severe trauma and infection, complex disease with urolithiasis or in special situations with uncertain abscess formation or tumour diagnosis. B est demonstration is in the late postinjection phase with contrast medication. CT is a hel pful method in c linical progression under t he appropriate therapy.

Possible findings ▬ Hypodense str iated tr iangular-shaped a reas wi thin the renal parenchyma ▬ Hyperdensitiy of urolithiasis or calcifications ▬ A bscess formation ▬ Contrast-enhancement of the abscess membrane ▬ Air-fluid level in abscess formations ▬ Sedimentation in the pyelon ▬ Loss o f co rticomedullary dif ferentiation in co ntrast phase ▬ Perirenal retroperitoneal edema (hyperdense in comparison to the perirenal fat)

Pitfalls ▬ Underestimation of the disease in e arly postinjection phase ▬ Missed inf lammatory foci in a rterial or e arly venous phase ▬ Without early injection phase or native scans, differentiation o f ur olithiasis v ersus co ntrast ex cretion in the calices is difficult

Renal scintigram For diagnosis of function and obstruction the MAG3 scintigram is preferred. As for the detection of renal involvement in pyelonephritis, DMSA scanning is considered to be the gold standard. The r outine use of DMSA scans in acute p yelonephritis is unnecess ary, b ut is indica ted in complex situations before therapeutic decisions.

Possible finding ▬ Decreased focal uptake

Pitfall ▬ No differentiation between new lesion and old lesion

5

94


Voiding cysturethrography and voiding cysturosonography Because of a significant association between pyelonephritis and VUR , children should be studied to assess reflux up to several weeks after the acute infection.

Chronic pyelonephritis

5

Permanent inf lammation o f t he r enal pa renchyma in recurrent upper urinary tract infections and delayed treatment in p yelonephritis r esults in chr onic p yelonephritis (called r eflux nep hropathy). C omplications a re m ultiple scarring o f t he kidne y, r esulting in r enal h ypertension, renal failure or end-stage renal disease.

Imaging Ultrasound

Kidneys ca n a ppear wi th dif fuse o r lo cal s carring. Through t he dif fuse s carring t he ec hogenicity increases and a lost o f co rtical-medullary dif ferentiation is observed. Volume measurements are of high importance in a gr owing c hild t o det ect a s tagnation o f gr owth in t he renal parenchyma.

DMSA scan und MAG3 renogram Both met hods ca n b e necess ary, dep ending o n c linical conditions and therapy planning. 5.2.5 Renal parenchyma disease

Glomerular, tubular, interstitial and vascular diseases are summarized in the term renal parenchyma disease. Affection of the kidneys is p ossible in inher ited diseases or in systemic dis eases, e.g. inf ections, auto-immune dis eases, malignant diseases, metabolic changes or storage diseases. Symptoms ma y b e p roteinuria, hema turia, nep hritic o r nephrotic syndrome, hypertension and renal failure. Some s pecial en tities o f r enal pa renchyma di sease are Schönlein-Henoch nephritis, rapidly progressive glomerulonephritis (GN), ac ute postinfectious GN, vas culitis syndromes, IgA nephropathy, haemolytic-uremic syndromes or systemic lupus erythematosis.

out renal anomalies, obstruction, reflux nephropathy, cystic renal disease or dysplasia and renal tumours. Typical in systemic disease is the bilateral involvement (⊡ Fig. 5.46).

Possible findings ▬ Loss of corticomedullary differentiation ▬ Cortical hyperechogenicity (in comparison to the liver and spleen) ▬ Reduction of size in more chronic disease ▬ Enlargement of the kidney in acute disease ▬ No rmal size possible ▬ Additional CD I ca n sho w t he p erfusion o f t he r enal parenchyma (important f or microthrombotic dis eases, e.g. haemolytic uremic syndrome or for peripheral reduced flow, e.g. in glomerulonephritis) ▬ Because o f syst emic in volvement, s onography o f t he whole abdominal situs is im portant to detect as cites, pleural a nd ca rdial ef fusions, li ver, b owel a nd pa ncreas involvement

Pitfalls ▬ Enlargement of the renal pelvis in poly-uric renal failure ▬ Different size in the course of disease ▬ Similar findings in different diseases ▬ Hyperechogenicity of the cortex can be normal in the first 3 months of life.

Other imaging modalities IVU, CT, MRT are not specific in r enal parenchyma disease. IVU a nd CT wi th in travenous io dinated co ntrast enhancement should be avoided in renal insufficiency.

Imaging Ultrasound

US is t he p rimary imagin g mo dality in a ll pa renchyma diseases of the kidneys. S onography is im portant to rule

⊡ Fig. 5.46. S choenlein’s purpura with h yperechoic renal cortex, longitudinal scan

95


Possible findings ▬ D elayed parenchymal enhancement ▬ Reduced corticomedullary differentiation ▬ Renal enlargement Key information

I

I

Renal parenchyma disease ▬ Inherited and systemic disease with renal involvement ▬ Clinical symptoms are not specific ▬ US to rule out other renal disorders ▬ Combined information in US on renal size, bilateral or unilateral involvement, renal parenchymal echogenicity and corticomedullary differentiation and visibility of the collecting system may suggest the etiology of disease. ▬ Extrarenal associated changes may help in differential diagnosis ▬ Sonographically guided renal biopsy for histological differentiation

▬ Twinkle sign in CDI (⊡ Fig. 5.48) ▬ H ydronephrosis

Pitfalls ▬ M edullary nephrocalcinosis ▬ Acoustic shadow missing (diameter < 3 mm) ▬ Fungus, necrotizing renal papillis, aberrant renal papilla, Tamm-Horse-Fall proteinuria.

Radiography Plain f ilm radiogra phy is t he s econdary met hod w hen symptoms caused by kidney stones are not explicable.

5.2.6 Nephr ocalcinosis

Urolithiasis Renal calculus is a co mplication of nephrocalcinosis and a p ossible f inding in r ecurrent p yelonephritis. K idney stones can present in ac ute f lank pain. Urolithiasis must be excluded in patients with uncertain hematuria, unilateral hydronephrosis and abdominal pain.

⊡ Fig. 5.47. Urolithiasis with calculus in the distal ur eter behind the bladder. Typical acoustic shadow of the calculus (arrow). Longitudinal scan

Imaging Ultrasound

US must localize the calculus in t he kidney parenchyma (e.g. co rtical o r med ullary calcif ications), th e co llecting system (e .g. renal calices o r renal p elvis), t he ureter (e .g pelvi-ureteric j unction, dist al ur eter) o r in t he b ladder. US of nephrolithiasis in t he renal pelvis is v ery sensitive. Detection of ureterovesical urolithiasis demands patience and is im portant in t he follow-up after lithotripsy. With US and other imaging methods, coral calculus, single or multiple uroliths and sedimentation in the collecting system must be differentiated (⊡ Fig. 5.46–5.48).

Possible findings ▬ Echoic acoustic reflexion ▬ Ac oustic shadow

⊡ Fig. 5.48. Twinkle sign in CDI of the calculus in long itudinal scan

5

96


5

⊡ Fig. 5.50. Same patient af ter c ontrast application in lat e phase radiogram. Contrast collection in the dilatat ed renal pelvis and ur eter down to the concrement in level S1

⊡ Fig. 5.49. Radiography before i.v. contrast application. Oval calculus (arrows) in projection of the right ureter next to vertebra S1

granulomatous nephritis. CT gi ves t he b est visualization and is t he best method in lo calizing a kidne y and ureter calculus. CT should be performed as a low-dose CT. MRI is not an imaging mo dality for visualization of calcif ications or calculus, but is necess ary in imagin g of complex diseases with inflammatory pseudotumour. Key information

IVP Routine IVP is no t indica ted in all cas es o f ur olithiasis. IVP is necess ary f or p lanning o f p yelotomy, endos copic therapy o r li thotripsy in r enal calc ulus o f t he size mo re than 5 mm ( ⊡ Fig. 5.49–5.50).

Possible findings ▬ R adiopaque calculus ▬ Areas without contrast medication in the pelvicaliceal collecting system ▬ Dilatation of the collecting system ▬ Single calyceal ectasia

CT and MRI CT or MRI is needed in co mplicated calculus in complex diseases, e.g. a bscess-forming p yelonephritis o r xa ntho-

I

I

Urolithiasis ▬ Indication: Hematuria, flank pain and hydronephrosis ▬ US method of choice ▬ for therapy planning: IVP ▬ CT or MRI only in nephrolithiasis and in complex inflammatory disease

Parenchymal nephrocalcinosis Cortical, co rticomedullary a nd m edullary calcif ication must b e distin guished in pa renchymal calcif ications o f the kidne y. M edullary calicif ications a re f ound in, e .g. renal t ubular acidosis, B artter syndr oma o r f urosemid therapy. C ortical ma nifestation is f ound a fter r enal v ein thrombosis or primary hyperoxaluria. Vitamin D therapy can result in corticomedullary calcification.

97


⊡ Fig. 5.51. Medullary nephrocalcinosis, longitudinal scan of the right kidney

⊡ Fig. 5.52. Longitudinal scan of the right kidney, 2 months after renal vein thr ombosis in a newborn. Shrink age of the k idney with small hyperechoic peripheral calcifications in the renal cortex

Imaging

Imaging

Ultrasound

Ultrasound demonstrates renal enlargement and replacement of the normal corticomedullary relationship in th e acute phase. Increased echogenicity can be generalized or in focal areas. In f ollow-up st udies t he kidne y b ecomes shr unken and calcified (⊡ Fig. 5.52). CDI demo nstrates loss o f v enous D oppler signal in renal v eins. D ecrease in syst olic f low v elocity a nd increase in resistance index result in arterial perfusion.

Ultrasound is superior in detection of parenchymal calcifications to other imaging methods (⊡ Fig. 5.51).

Possible findings in medullary nephrocalcinosis ▬ Narrow, a nnular h yperechoic r egion b etween co rtex and medulla ▬ Complete hyperechogenicity of the renal medulla

Pitfalls ▬ U rolithiasis ▬ N ecrotizing renal papillitis ▬ Renal vessels

Possible findings in cortical nephrocalcinosis ▬ Diffuse hyperechogenicity of the renal cortex.

Pitfalls ▬ Ne phritis ▬ Diffuse renal parenchyma disease 5.2.7 Renal vein thrombosis

Patchy thrombosis of the intrarenal veins of both kidneys causes s evere co ngestion a nd hema turia. One o r b oth kidneys b ecome enla rged. Renal v ein t hrombosis ca n follow a fter r espiratory distr ess, s evere deh ydration o r shock.

Possible findings ▬ Enlargement and hyperechogenicity in acute phase ▬ Loss of venous flow signal in CDI ▬ Shrinking and calcification in late phase

Pitfalls ▬ A cute infectious nephritis ▬ N ephrocalcinosis ▬ H ypoplastic-dysplastic kidney 5.2.8 Renal tumours

The nephroblastoma (Wilms’ tumour) is the most common r enal t umour in c hildhood. The t umour t end t o occur mainly in children of less t han 5 years. Preferred locations f or met astases a re t he lo coregional l ymph nodes and the lung. Liver metastases are possible. Other dist ant met astases, e.g. in t he sk eletal system, a re

5

98

5


rare. Association with clinical syndromes (WiedemannBeckwith, D enys-Drash, WAGR syndr ome) sho uld b e considered. Renal cell ca rcinoma, c lear cell s arcoma, rha bdoid tumour occur in less t han about 10% o f malign renal tumours in childhood. Mesonephric adenoma is a very rare benign renal tumour. In t he f irst 6 mo nths o f lif e, mes oblastic nep hroma occurs more often than Wilms’ tumour. Complicated renal cysts, cystic dysplasia and multilocular cystic nephroma can make diagnostic problems and m ust b e dif ferentiated f rom c ystic nep hroblastoma.

MRI MRI is the standard procedure before therapy. MRI gives a global view of the abdomen (⊡ Fig. 5.53–5.54). Contrast s equences a re necess ary to distin guish b etween tumour and renal parenchyma.

Imaging Ultrasound

Ultrasound is the fundamental imaging method. Nephroblastomas p resent as a r enal mass w ith displ acement o f the renal pelvis and neighbouring organs, including retroperitoneal vessels. Detection of renal vessels is im proved by CD I. Renal v ein disp lacement m ust b e distin guished from tumour invasion with tumour thrombus. Panorama imaging is a us eful to ol f or v olume me asurement of t he tumor. Because bilateral tumours are possible, it is important to exclude a second mass in t he contralateral kidney. Next to t he main tumour nephrogenic rests are p ossible in renal parenchyma.

Findings ▬ Homogeneous or inhomogeneous renal mass ▬ Displacement of neighbouring anatomical structures ▬ Echogenic tumour thrombus in renal vein or inferior vena cava ▬ Lymph node enlargement ▬ Calcifications in about 14% of nephroblastomas ▬ Tumour b leeding wi th cen tral f luid/sedimentation levels ▬ Cystic tumours with tumour parenchyma are found in the case of cystic nephroblastoma ▬ Complete c ystic t umours a re f ound in m ultilocular cystic nephroma

⊡ Fig. 5.53. MRI (cor T2 fs) of nephroblastoma in the left kidney

Pitfalls ▬ Differentiation from neuroblastoma and other suprarenal tumours can be difficult. ▬ Cystic nep hroma ca nnot b e dist inguished f rom c ystic pa rtial dif ferentiated nep hroblastoma b y imagin g methods

⊡ Fig. 5.54. MRI (trans ce T1 VIBE) of the nephroblastoma (arrows) with tumour necrosis and perfusion in the peripheral tumour parenchyma

99


Lymph node metastases are best visible in MRI, which is superior to CT in dete ction of tumour thrombus.

Possible findings ▬ Hypointense pseudocapsule in T2w sequences ▬ In T2 hyperintensive and T1 hypointensive renal mass with displacement of other organs ▬ Hyperintense tumour thrombus in hypointense vessel signal in T2w sequences ▬ Contrast enhancement of residual renal parenchyma ▬ Contrast enhancement of vital tumour areas, hypointense tumour necrosis ▬ Hyperintensive b leeding in t he t umour in T1w s equences ▬ Lymph node metastasis

Pitfalls ▬ Benign and other malign renal tumours ▬ Pyelonephritis can imitate a renal mass

CT If MRI is not available, CT is the method of choice before therapy. Contrast medication is necessary

Possible findings ▬ Hyperdense areas in case of bleeding in native scans ▬ Imhomogeneous mass after contrast enhancement

Pitfalls ▬ Low-contrast enha ncement o f t he inf erior v ena cava in early phase studies can make detection of tumour thrombus impossible Key information

I

I

Renal tumours ▬ Tumor detection in ultrasound ▬ MRI preferred for local tumour extension and abdominal metastases ▬ Invasion in renal vein and inferior vena cava is typical

5.2.9 Diseases of the suprarenal gland

Hemorrhage of the suprarenal gland Hemorrhage into the adrenal gland occurs in the neonatal period. Hemorrhage can result in death from exsanguina-

tion and hypo-adrenalism. Most f requently, hemorrhage is asymptomatic. Because o f dif ferentiation t o neur oblastoma in ne wborns, ca techolamine met abolites in ur ine ca n hel p. I n the cas e of unclear diagnosis, f urther diagnostics ca n b e interrupted for the next weeks and sonographic follow-up examinations a re ne cessary to demo nstrate t he v olume regression of the lesion. Another ca use o f b leeding in to adr enal g lands is the shock from meningococcemia, the Waterhouse-Friderichsen syndrome.

Imaging Ultrasound

Ultrasound is the method of choice to detect adrenal hemorrhage in ne wborn. Mostly hemorrhage is dete cted because of imaging of the kidneys after birth. Hypoechoic mass above the upper pole of the kidney is the typical finding. Mixed echogenicity with hyperechoic areas are possible. Fl uid-fluid le vels ca n o ccur. I n la ter exa minations the volume of t he adrenal g land decreases, calcif ications occur after resorption of the bleeding (⊡ Fig. 5.55–5.56).

MRI or CT MRI or CT is not necessary in early detection after birth. Only in suspicious neuroblastoma for any other reason, is further imaging necessary. If volume regression is absent, MRI b ecomes necess ary. Hyperintense T1w signal is indicative of hemorrhage. Key information

I

I

Suprarenal hemorrhage ▬ Detection by ultrasound ▬ Follow up examination to demonstrate volume regression ▬ Calcifications in follow-up studies ▬ Difficult to distinguish from neuroblastoma (laboratory findings)

Neuroblastoma and other suprarenal tumours Neuroblastoma is most frequently diagnosed in infants below the age of 5 years. Neuroblastomas originate in neural crest cells of the sympathetic nervous system. Nearly 70% of neur oblastomas a rise in t he a bdomen. A typ ical lo cation (about 50%) is the adrenal gland. The tumour extends to sur rounding tissue b y lo cal in vasion a nd t o r egional lymph nodes. Metastatic spread in b one marrow, skeleton

5

100


Imaging Ultrasound

In an y c ase o f susp icious neur oblastoma, s onography o f the neck, abdomen and retroperitoneal space, is indicated as well as chest X-ray (⊡ Fig. 5.57–5.58).

Possible findings: ▬ ▬ ▬ ▬ ▬

5 ⊡ Fig. 5.55. Longitudinal scan of the right adrenal gland in a newborn. Normal appearance

Encasement of retroperitoneal vessels Ventral displacement of aorta and vena cava Stippled tumour calcifications Single tumour of the adrenal gland Extended tumour mass in the retroperitoneum

Pitfalls: ▬ A drenal bleeding ▬ N ephroblastoma

MRI

⊡ Fig. 5.56. H ypoechoic o val mass ( arrow) abo ve the k idney in the case of a adrenal hemorrhage in a newborn, longitudinal scan

and li ver is f requent. T umours lo calized t o o ne side o f the a bdomen o ften cr oss t he midline . N euroblastomas frequently s ecrete neurogenically der ived subst ances, e.g. catecholamine metabolites or neuron-specific enolase. More than 50% of patients have metastatic disease. Primary diagnosis is p erformed with ultrasound. Imaging studies include local staging with MRI or CT of the tumour region and chest radiograph. Bone scan and meta-iodobenzylguanidine (MIBG) scintigram define sites of metastases and demo nstrate t umour r esponse to chemo therapy. R adiological diagnosis must be confirmed by tissue biopsy. Other t umour en tities in t he adr enal g lands suc h as pheochromocytoma or adrenal carcinoma in childhood are very rare diseases. The ma in differential diagnosis t o neuroblastoma is the Wilms’ tumour in the upper renal pole.

MRI is t he b est met hod t o diagnos e t he r elation o f t he tumour to surrounding organs. MRI has to be preferred to CT because of better soft-tissue differentiation. Three-DMR-angiography with high spatial resolution can demonstrate the affected retroperitoneal vessel structures. Timeresolved contrast MRI ca n demonstrate tumour necrosis and vital tumour areas. In the case of tumour invasion into the neuroforamina, s agittal s equences o f t he sp ine a re r equired. S pinal cord compression has to b e excluded. Volume-rendering techniques in post processing allow exact tumour volume measurement.

Possible findings ▬ Encasement of retroperitoneal vessel structures ▬ Ventral displacement of aorta and vena cava ▬ Infiltration of adjacent organs ▬ In filtration into neuroforamen

Pitfalls ▬ Differentiation to nephroblastoma ▬ Adrenal bleeding in newborn

Jod-meta-iodobenzylguanidine (MIBG)scintigram

123

MIBG as a n a nalogon o f ca techolamine p recursors is taken u p in neur oblastoma a nd o ther neur o-endocrine tissue ( ⊡ Fig. 5.59). P rimary t umour a nd met astases ca n be demo nstrated. Ph ysiological u ptake ca n b e f ound in the adr enal g land, li ver, sp leen, in testine, m yocardium,

101


bladder and thyroid. In SPECT, physiological uptake can be differentiated from neuroblastoma. An MIBG scan can be negative in neuroblastoma.

Bone scan Bone scan is helpful in defining sites of metastases in the skeleton and to differentiate between bone metastases and infiltration of the bone marrow. Bone scan demonstrates the incr ease o f met abolic ac tivity in lo cations o f b one metastases.

A V

Radiography ⊡ Fig. 5.57. Sonography, transverse view of a neuroblastoma. Encasement of inferior vena cava (V) and aorta (A)

Size o f oste olytic met astases in b one s can-positive lesions ca n b e det ermined b y radiogra phy. I n f ollow-up examinations, t herapy r esults ca n b e do cumented. S tability of the bone can be estimated in conventionel X-ray images. Key information

⊡ Fig. 5.58. Neur oblastoma in MRI. Encasement of the mesent artery, aorta and vena cava with hyperintense tumour mass

eric

⊡ Fig. 5.59. MIBG scintigram in neuroblastoma. Uptake in tumour mass

I

I

Suprarenal tumours ▬ Cervical and abdominal sonography for basic imaging ▬ stippled calcifications typical for neuroblastoma ▬ Tumour extension demonstrated in MRI ▬ MRI in suspicious intraspinal extension ▬ Chest radiograph for metastatic disease and primary chest tumours ▬ Bone scan, MIBG scan and whole -body MRI for metastatic disease ▬ Radiography in osteolytic lesions

5

102


5.2.10 F emale gonads

Developmental anomalies of the uterus and vagina

5

Vagina a nd u terus a re f ormed b y t he M üllerian d uct. Common Müllerian duct anomalies are hydrocolpos, hydrosalpinx, hema tometra, didel phic, b icornuate o r unicornuate uterus. Müllerian anomalies are associated with heritable disorders, e.g. Mayer-Rokitansky-Kuster-Hauser syndrome o r K aufman-McCusick syndr ome. Ano malies of the gonads are often associated with renal anomalies. In h ydrocolpos t he vagina b ecomes dist ended wi th fluid. The u terus is p ushed a bove t he f luid-filled vagina or ca n b e dist ended in t he cas e o f h ydrometrocolpos. Retention of the urine can occur secondarily. Because of the maternal hormone stimulus in newborn, endocervical glands produce mucus, and a clinical sign sometimes is a bulging hymen. In puberty haematocolpos develops with the onset of menstruation.

Imaging Ultrasound

Ultrasound with transabdominal approach is the method of choice to detect genital anomalies. A full bladder serves as a n aco ustic windo w a nd allo ws, t ogether wi th tissue harmonic imagin g, a hig h-resolution imagin g o f u pper vagina, u terus a nd o varies ( ⊡ Fig. 5.60). CD I mak es i t possible to distinguish between non-perfused fluid collections and perfused masses.

Typical findings in hydrocolpos ▬ Sharply defined hypoechoic or slight echogenic mass behind the bladder ▬ Oval shape of a mass behind or above the bladder ▬ In the case of hemorrhage echoic fluid-fluid levels ▬ In CDI no colour Doppler signals in the mass

Pitfalls ▬ Anatomical localization can be difficult, e.g. in o varian cysts or hydrosalpinx ▬ Cystic pelvic tumours, e.g. ventral meningocele ▬ Massive dilatation of megaureters

Ovarian mass Ovarian follicular cysts occur in newborn and children in puberty, and usually dis appear sp ontaneously. Esp ecially in newborn, large ovarian cysts are observed. In general,

⊡ Fig. 5.60. Enlarged vagina and uterus (hydrometrocolpos) with fluid/ fluid level in a girl with urogenital sinus. Longitudinal scan

cysts in babies can be controlled in ultrasound studies and volume regression can be documented in follow-up studies. Large ovarian cysts in adolescents can lead to ovarian torsion of the adnexa. In ovarian torsion prompt surgical intervention i s n ecessary. In termittent s harp ab dominal pain is characteristic. Single c ysts m ust b e dif ferentiated f rom t eratoma, which is usually benign; but malignant teratomas can occur. M alignant o varian t umours, e .g. g erm cell t umours can be a solid mass or occur as a more cystic mass.

Imaging Ultrasound

In ul trasound o varian c ysts p resent as no n-echogenic masses in t he lo wer a bdomen, f requently la rger t han 2 cm. I n t he cas e o f hemo rrhage in t he c yst, t he s onographic a ppearance ca n c hange in f ollow-up st udies. Hyperechoic inho mogeneous str ucture ca n ca use diagnostic problems. Fluid-fluid levels indicate hemorrhage. CDI demo nstrates no cen tral p erfusion. Of ten o varian rest tissue wi th small f ollicles is no rmal. B ecause of t he varying lo cation o f t he o varies in t he a bdomen, esp ecially in ba bies, t he co ntralateral o vary is s ometimes difficult to find. A secure differentiation of ovarian cysts and pa roophoron c ysts is no t p ossible in ul trasound. A typical sign f or t eratoma is calcif ication wi th aco ustic shadow in a t hickened wall o r tissue no dule. In the case of ovarian torsion with acute pain, loss of perfusion in an inhomogenous enlarged ovary should be documented in ultrasound (⊡ Fig. 5.61–5.63).

103


Possible findings Unechoic mass in single ovarian cysts Mixed echogenicity in hemorrhage Loss of total perfusion in torsion of the adnexa. Free fluid in t he abdomen in t he case of ovarian torsion or malignancy ▬ Thickening of the wall or tissue no dule in t he wall of the cyst with calcification indicates teratoma ▬ Inhomogeneous p erfused tissue in s olid a nd pa rtial cystic masses in malignant masses ▬ ▬ ▬ ▬

Pitfalls ⊡ Fig. 5.61. Hemorrhage in the o vary during normal menstrual c ycle as an accidental finding. CDI in longitudinal view.

▬ All o ther c ystic mass es o f t he a bdomen ca n mimic ovarian cyts, e.g. bowel duplication cysts

Radiography Only teratomas can be presumed on radiographs, mostly as an incidental finding. In patients with acute abdominal pain, an abdominal radiograph is indica ted to exclude ileus o r perforation of hollow viscus with free air in the abdomen. Calcifications in different ovarian neoplasms or tooth buds in t he case of teratomas can be identified in radiographs of the abdomen.

MRI

⊡ Fig. 5.62. Patient with acute abdominal pain. CDI in transverse view. Lack of perfusion signals in torsion of the adnexa

⊡ Fig. 5.63. Oval mass in the lower abdomen with liquid anechoic and hyperechoic areas. Little h yperechoic spots demonstrat e calcification in a germ cell tumour. Transverse view

MRI can be helpful in the case of complication of unclear classification of the cyst. In T1w imag es or sequences with fat saturation fatty tissue ca n b e s eparated a nd indica te t eratoma. MRI ca n identify hemorrhage and vital tissue can be differentiated through contrast enhancement (⊡ Fig. 5.64–5.66).

⊡ Fig. 5.64. MRI (transv erse T1 TSE) bef ore c ontrast application. H ypointense mass in the lower abdomen in germ cell tumour

5

104


5.2.11 Male

gonads

Testicular torsion

5

⊡ Fig. 5.65. MRI (transv erse T1 SPIR) af ter c ontrast application. C ontrast enhancement of the solid ar eas in the tumour , lack of enhanc ement in liquid areas

Acute testicular torsion has to be diagnosed urgently and is a n emer gency. Testicular t orsion p resents wi th s crotal swelling, r eddening a nd p ain (ac ute s crotum). 1:4000 boys is affected. Testicular torsion is defined as a rotation of the longitudinal axis o f the spermatic cord. Strangulation o f t he v essels r esults in ir reversible da mage o f t he testicular parenchym after 6 h of ischaemia. About 30% of patients with acute scrotum have a testicular torsion.

Imaging Imaging methods concentrate on morphological and perfusion parameters. Detection of testicular torsion is p ossible in d ynamic contrast studies in MRI o r scintigraphy. In routine clinical work, sonography with CDI has b ecome an adequate method to replace surgical exploration in t he case of hydated torsion or epididymitis

Ultrasound Sonography with CDI and pulsed Doppler, have become the on ly m ethod of h igh cl inical v alue. D escription of tissue str ucture a nd ec hogenicity in co mparison of b oth testes, v olumetry a nd ass essment o f cen tral a nd p eripheral blood flow and documentation of arterial and venous blood flow in triplex mode is necessary. If available within a sho rt time a fter c linical exa mination, CD I is o f hig h clinical value in ac ute scrotum. Maximal systolic velocity in intratesticular arteries is 4-12 cm/s. After puberty, lowflow resistance with RI b etween 0.48 und 0.75 is no rmal. Before p uberty, diast olic f low is uncer tainly visib le. I n the ca se o f do ubt, s urgical exp loration i s s till in dicated (⊡ Fig. 5.67). ⊡ Fig. 5.66. C oronal MRI ( c eT1 SPIR) in acut e t orsion of the adnex e. Contrast enhancement in the ut erus, but lack of enhanc ement in the left ovary after haemorrhagic infarction (arrow)

Key information

I

I

Ovarian mass ▬ Detection of ovarian cysts in ultrasound ▬ Follow-up examinations in ovarian cysts in newborn ▬ MRI in complicated cysts ▬ MRI in presumption for teratoma or other malignant neoplasms

Possible findings Inhomogenous structure of the testes Increase of volume in acute phase Decrease of volume in late phase Calcifications in long term follow-up examinations Concomitant hydrocele in acute phase Torsion of spermatic cord Absence of central venous perfusion Low arterial perfusion to absence of arterial perfusion Fewer p erfusion signals in co mparison t o t he o ther side ▬ Hyperperfusion after retorsion ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬

105


▬ Absence of diastolic arterial flow especially in or after puberty ▬ H igh-resistance index

Pitfalls ▬ Non-compliance can make a correct diagnosis impossible ▬ Low f low is det ectable only with correct handling of Doppler system ▬ Gain, PDF and Wall filter must be correctly adjusted ▬ Diagnoses of testicular torsion in ma ldescending testes are not secure with sonography ▬ Partial or intermittent torsion possible ▬ Total avulsion injury of the testis with disconnection of testical vessels Key information

I

I

⊡ Fig. 5.67. Acute torsion of the lef t swollen testicle. Power Doppler so nography with hypoechoic parenchyma without central Doppler signals

Testicular torsion ▬ B-mode sonography is helpful, but exclusion of testicular torsion only in morhological sonography is not possible ▬ Absence of central venous flow and low arterial perfusion in CDI indicates testicular torsion ▬ In any doubt surgical exploration

Inflammation of testes, epididymis and scrotum Inflammatory dis eases of t he s crotum are responsible in approximately 60% o f ac ute s crotum in infa nts. M ostly acute hydatid torsion causes a painful inflammatory reaction of the epididymis and scrotum. In clinical examination the s o-called blue dot sign ca n indicate hydatid torsion. Appendage of epididymis and testicular appendage (hydatid of Morgagni) are distinct anatomically. In viral infections, e.g. mumps, painful swelling of the scrotum is observed with epididymo-orchitis. In newborn meconiumperitonitis and orchitis, in infants a nd ado lescents ac ute s crotum wi th vas culitis in Schoenlein’s purpura are rare dis eases with ac ute s crotal swelling. Painless swelling of t he s crotum is obs erved in scrotal oedema, e.g in nephritic syndrome. Inflammation due to injury of the scrotum can be observed after a st ab wound with bacterial infection.

Imaging Ultrasound has to dif ferentiate between testicular torsion and inflammatory diseases of the scrotum. In epididymitis and hydatid torsion a swelling and hyperperfusion in CDI

⊡ Fig. 5.68. H ydatide t orsion with h yperechoic nodule ( arrows) nex t to the testicle

are found with or without reactive hyperperfusion of the testes. In the case of hydatid torsion a small h yperechoic nodule ca n b e demo nstrated in s ome cas es ( ⊡ Fig. 5.68). This diagnostic sign is in secure and not always found in hydatid t orsion. C oncomitant h ydrocele is f requent. I f bacterial infection is considered voiding cysturethrogram is indicated to exclude urethral obstruction.

Possible findings in sonography ▬ Swelling of epididymis or testes ▬ C oncomitant hydrocele

5

106


▬ Hyperperfusion in CDI (‘balls on fire’) ▬ RI < 0.5 ▬ Vsyst>15 cm/s ▬ Hyperechoic nodule in hydatide torsion ▬ Hyperechoic air reflex in stab wounds ▬ Swelling and hyperperfusion of scrotal wall

Pitfalls

5

▬ Reactive hyperperfusion af ter test icular torsion or in intermittent torsion ▬ S crotal tumours ▬ S crotal hernia ▬ Varicocele with hyperperfusion dependent on Valsalva’s manoeuver 5.2.12 Congenital genital anomalies

Anomalies o f s ex dif ferentiation ha ve va rious etio logies. Genital disturbances are determined by endocrinic or chromosomal dis orders a nd im paired b iochemical p rocesses in em bryological de velopment. P atients ca n ha ve co nsistency or inconsistency between their gonadal and genetical sex. A c hild with ambiguous external genitals needs exac t morphological e valuation o f t he g enitalia t o c lassify t he anomaly a nd t o def ine s urgical tr eatment. A nomalies a re found in hermaphroditism, congenital adrenal hyperplasia, testicular feminization and gonadal dysgenesis.

It must be defined whether the patient has a vagina a nd a urogenital sinus. Location of connection of these structures in relation to the perineum must be demonstrated. Often a voiding c ysturethrogram with suprapubic puncture is sufficient because of a retrograde contrast filling of the vagina (⊡ Fig. 5.69). Urogenital sinus ranges with degree of masculinization, beginning with almost normal female pattern.

Possible findings ▬ Tract of sinus urogenitalis ▬ Impression of uterine cervix on the vaginal vault ▬ Hy pospadia ▬ Perineal urethral ostium ▬ Ut ricle ▬ B lind-ending vagina ▬ P seudovagina ▬ Contrast material opacifying the uterine canal Key information

I

I

Congenital genital anomalies ▬ S onography ▬ Genit ography ▬ C atheter technique ▬ Retrograde filling of Müllerian structures in voiding cysturethrogram ▬ MRI in complex anomalies

Imaging Imaging st udies a re p erformed t o def ine t he r elation between ur inary trac t and internal genital anatomy. The aim of radiological methods is the identification of uterus, vagina, bladder and urethra. Urogenital sinus is t he most common appearance in adrenogenital syndrome. Urethra and vagina f low into a co mmon sinus trac t, w hich ends perineal most ly ne ar a p rominent p hallus o r enla rged clitoris. I n addi tion t o s onography, t he most im portant diagnostic technique is g enitography. Complex urorectogenital malformations need further imaging with MRI.

Genitography Different methods of genitography are described; the flushing technique and the catheter technique. The flushing technique means a retrograde injection of contrast medium under moderate pressure. In the catheter technique, the bladder is filled with the help of a second catheter or suprapubic puncture, a nd a v oiding c ysto-urethrogram is co nducted.

⊡ Fig. 5.69. P atient with adr enogenital syndr ome. Genit ogram performed as voiding cysturethrogram in urogenital sinus

107


5.2.13 Persistence of urachus

Inflammation in t he um bilical r egion a re obs erved in umbilical gra nuloma, p ersistent str uctures o f t he umbilical co rd o r inf lammation o f t he p ersistent urac hus. If t here is a ur ine-like dis charge f rom t he um bilicus, persistent urach us sho uld b e susp ected. P ersistent urachus or urachus cyst is associated with dysfunction of the bladder outlet.

Imaging Ultrasound

In sonography the urachus fistula is found directly below the a bdominal wa ll in t he mid line b etween b ladder a nd umbilicus. Mostly thickening of the urachus wall indicates the inf lammatory r eaction o f t he f istula. M idline di verticula of the bladder can remains of the urachus and differ in size, dependent on the bladder volume. Fluoroscopy o f a s uspected f istula wi th io dine co ntrast medication is no t a r outine method. In the case of seropurulent s ecretion o f t he um bilicus o r fa iled tr eatment with cauterization with silver nitrate of t he umbilicus in granulomas, a surgical exploration is in a ny case indicated. Next to remains of the urachus, a p ersitent remain of the omphalo-enteric duct must b e excluded additionally (⊡ Fig. 5.70–5.72).

⊡ Fig. 5.70. Longitudinal scan bet ween umbilicus and bladder in the midline. Hypoechoic fistula in persistent urachus (arrow)

Possible findings ▬ Enlarged urachus rest between bladder and umbilicus ▬ Urachus with hypoechoic sinus ▬ Increase of f low signals in CD I in inf lammatory disease

⊡ Fig. 5.71. Transverse view. Hypoechoic center of the o val structure in the midline behind the abdominal wall

Pitfalls ▬ Physiological urac hus r est in p reterm infa nts a nd newborn ▬ U mbilical granuloma ▬ B owel structures ▬ Om phalo-enteric cysts Key information

I

Persistence of urachus ▬ S onography ▬ Urachus cysts ▬ Urachus diverticulum ▬ Urachus fistula

I ⊡ Fig. 5.72. L ongitudinal view of the bladder . Ur achus div erticulum (arrow) above the bladder

5

108


5.3 G

astro-intestinal tract

Michael Kimpel

5.3.1 Oesophagus (Oesophageal atresia

and tracheo-esophageal fistula)

Fluoroscopy

To p rovide f urther inf ormation t o t he sur geon a nd t o prove the diagnosis, a fluoroscopy with contrast injection into the oesophagus is often performed. It is mandatory to use a small quantity of low-osmolar, non-ionic, water-soluble contrast agent ( ⊡ Fig. 5.74) via a tube placed in the proximal oesophagus. Postoperative radiology

5

General Information Oesophageal a tresia usuall y o ccurs a t t he u pper/middle t hird o f t he o esophagus, wi th o r wi thout p resence of trac heo-esophageal f istula (TEF). The len gth o f t he gap va ries a nd is g enerally lo ngest in t he a bsence o f a fistula. Oesophageal atresia and TEF a re classified as f ollows (Vogt c lassification), showing the approximate frequency of appearance: Vogt I: Complete absence of oesophagus Vogt II (7%): Atresia without fistula Vogt IIIa (1%): Atresia with proximal fistula Vogt III b (87%): Atresia with distal fistula Vo gt III c (2%): Atresia with proximal and distal fi stula Vogt IV (3%): H-type fistula, no atresia In approximately 50% of the cases with oesophageal atresia other anomalies can be found. This association is often described as VACTERL complex, an acronym for vertebral defects, anal atresia, cardial anomalies, tracheo-esophageal fistula, renal dysplasia and limb anomalies. While many babies with oesophageal atresia may have one or more of the named anomalies, only very few will have all of them.

Imaging Radiography

The ini tial imag es o ften sho w t he inef ficient a ttempt t o place a nas ogastral tube, s o one will s ee t he tube in t he proximal o esophageal p ouch. I t is hel pful t o inf late a ir into the probe to visualize the dilated upper oesophageal pouch. If the stomach is filled with air there has to be a distal fistula (⊡ Fig. 5.73).

The risk of anastomotic leakage or recurrent TEF is up to 10%. In some cases, if s urgery is p erformed without preoperative f luoroscopy, a p roximal f istula (in V ogt III c atresia) may be not detected intra-operatively and so still persists (⊡ Fig. 5.74). For t hese r easons a p ostoperative co ntrol o f t he o esophagus with low-osmolar contrast agent is recommended before the first admittance of oral alimentation. Key information

I

Oesophageal atresia

I

▬ Initial plain radiography shows the diagnosis in most of the cases

▬ Air in the stomach indicates the presence of a distal tracheoesophageal fistula

▬ Fluoroscopy with oesophageal instillation of low-osmolar contrast agents verifies the diagnosis and allows to differentiate the kind of atresia ▬ Postoperative control assures the consistence of the anastomosis before first oral alimentation ▬ Do not forget screening for additional malformations

5.3.2 Obstructions of the stomach

and duodenum

General information Obstruction of the stomach

Congenital obstruction of the stomach is v ery rare. Agastria is described in single cases. Microgastria is uncommon and may exist isolated or with complex malformation. Although atresia o f t he st omach ne ar t he a ntrum o r pylorus exists, in most cas es t he r eason f or gastr ic obstruction is a mucosal web or diaphragm.

109

5.3 · Gastro-intestinal tract

⊡ Fig. 5.73. Oesophageal atr esia with distal TEF, sho wing the tube in the upper oesophageal pouch, which is filled with inflat ed air. Air in the st omach indicat es the pr esence of distal tracheo -esophageal fistula

A

Obstruction of the duodenum

The most common reason for high intestinal obstruction is t he duodenal stenosis o r atresia (w hile atresia is mo re frequent than stenosis). Reasons can be the failed recanalization of the duodenum as well as mucosal webs (complete or incomplete) or a pancreas annulare.

Imaging Radiography

In complete obstruction, plain radiography usually shows an (air-)dilated s egment b efore and t he loss o f intestinal air behind the obstruction. In duodenal atresia the classic finding is the »doublebubble sign«, sho wing air in t he stomach and the dilated proximal duodenum (⊡ Fig. 5.76). If plain radiography detects duodenal atresia, no f urther examination is necessary, as air is a sufficient contrast media and positive contrast provides no further information. I f t he st omach a nd/or d uodenum is deco mpressed

B ⊡ Fig. 5.74A,B. Oesophageal atresia (VOGT III A), AP (A) and lateral view (B). Postoperative control; proximal fistula (arrow) was not seen during surgery. Aspiration of contrast media

5

110


5

⊡ Fig. 5.76. Distended stomach and proximal duodenum. No distal air: duodenal stenosis

Key information

I

I

Obstructions of stomach and duodenum ⊡ Fig. 5.75. Postoperative anast omotic leak and mild st enosis af ter oesophageal r epair (same patient as F ig. 5.74, no w af ter sec ond surgery)

▬ Initial plain radiography shows the diagnosis in most of the cases

▬ Distended stomach / duodenum (»double bubble sign«) with no (or reduced) distal air

▬ Fluoroscopy with positive contrast agents is only necessary in special cases

(e.g. by vomiting), a small amount of air can be insufflated via nasogastral tube. In inco mplete obstr uction (st enosis) p lain radiography may show a normal air distribution.

5.3.3 High intestinal obstruction

Fluoroscopy

General Information

In s ome cas es, usuall y in st enosis, no t a tresia, f luoroscopy a nd admi ttance o f lo w osmo lar wa ter-soluble contrast ag ent ca n b e us eful to lo cate t he stenosis p reoperatively.

Jejunal atresia and stenosis

Obstruction proximal to the distal ileum appears as hig h intestinal obstruction. The r eason for atresia ( ⊡ Fig. 5.77) is usually an ischemic injury.

111


⊡ Fig. 5.78. Microcolon (unused colon; antegrade filling via ileal stoma)

distinctive in incomplete obstruction. Air-fluid levels may be seen, but are not mandatory. The a bsence of air-fluid levels does not exclude an ileus! Fluoroscopy

⊡ Fig. 5.77. Distended stomach, duodenum and first loops of jejunal in patient with jejunal atresia

Classification of Intestinal atresia (Kir ks): Type I membranous atresia Type II blind ends separated by fibrous cord Type IIIa blind ends s eparated wi th a n ass ociated V shaped mesenteric gap Type IIIb apple-peel small-bowel atresia Type IV multiple atresias

Imaging Radiography

In co mplete obstr uction, p lain radiogra phy will sho w dilated, a ir-filled b owel lo ops, o ften wi th a b ulbous end just b efore t he obstr uction. The si tuation ma y b e less

In most cases, fluoroscopy is not necessary, as plain radiography clearly demonstrates the diagnosis. In some cases a contrast enema (using a low osmolar, water-soluble contrast agent) will be requested to exclude additional stenoses or atresia. An unused colon (microcolon (⊡ Fig. 5.78) is possible. 5.3.4 Low intestinal obstruction

General information Low in testinal obstr uction me ans a n obstr uction in t he distal ileum or in the colon. The most common reasons are: ▬ Meconium plug syndrome ▬ M econium ileus ▬ Ile al atresia ▬ H irschsprung disease ▬ Anorectal malformations / anal atresia

5

112


Imaging Radiography

Plain radiography will sho w dilated loops, and often it is not possible to distinguish whether there are small bowel loops involved or small b owel and colon. For this reason in most of the cases a contrast enema will be necessary. Fluoroscopy

5

Contrast enema sho uld be performed using low-osmolar water-soluble contrast agents, to avoid fluid shiftings into the b owel. B arium should only b e us ed in H irschsprung disease. In t he cas e o f a dist al small b owel obstr uction, t he contrast enema will sho w the typical aspect of an unused colon, t he micr ocolon, w hich usuall y has a dia meter o f less than 1 cm ( ⊡ Fig. 5.78). Meconium plug syndrome – functional immaturity of the colon

The so-called Meconium plug syndrome was so named, as in early descriptions of the syndrome a possible aetiologic role for the retained meconium was estimated. The better term is: functional immaturity of the colon (⊡ Fig. 5.79). The syndr ome is c haracterized b y dela yed pass age (> 24-48 h) o f meco nium a nd in testinal dila tation. A contrast enema (water-soluble contrast media) shows meconium r etention, o ften visualized as a »p lug«. I n ma ny cases t he meco nium p lug is dislo dged a fter t he enema study. I n s ome cas es t he lef t co lon a ppears small (small

⊡ Fig. 5.79A,B. Functional immaturity of the colon: dilated proximal bowel loops and rectal meconium plug (evacuated after enema)

A

left colon syndrome). The pathophysiological mechanism is assume d to b e an immaturity of t he myenteric plexus nerve cells, s o t he c linical a nd radio logical f eatures may be similar to Hirschsprung’s disease. Meconium ileus

The meconium ileus has to be strictly differentiated from the above d escribed fu nctional i mmaturity of the colon. In meconium ileus a low intestinal obstruction is present, resulting b y t he in spissation o f a bnormal meco nium in the distal ileum and colon. Usually it occurs in newborn with cystic fibrosis (CF), and is present in 5-10% of the cases. Volvulus, atresia, perforation and peritonitis are common complications. Contrast enema (wa ter-soluble co ntrast ag ent) will show an (empty) microcolon. Meconium pellets are found in t he dist al ileum, sho wing m ultiple r ound, f illing defects. Ileum loops are distended. Hirschsprung’s disease

In H irschsprung’s dis ease ( ⊡ Fig. 5.80) in tramural ga nglion cells o f the distal colon are absent. As the neuronal cells migrate in p roximal dir ection, t he na rrow s egment (caused by permanent contraction of the circular muscle layer) ext ends dis tally f rom t he migra tion a rrest t o t he anus, so it is o nly necessary to exa mine the distal, colon up to the splenic flexura. Proximal to this point, the colon is dilated. It is important to kno w t hat in ne wborn contrast enema ma y lo ok

B

113


normal. As the narrow segment could be distended while filling t he co lon, la te X-ra y co ntrols sho uld b e ob tained 24 h a fter co ntrast enema t o e valuate a n un usual r etention of barium. If there is o nly an ultrashort aganglionar segment, the radiological findings usually are the same as in obstipation! Anal atresia

Anal atresia exists wi th or without fistula. In most o f the cases t he a tretic r ectum co mmunicates wi th t he g enitourinary trac t o r sho ws a r ectocutaneous f istula. Anal atresia is usuall y classified as hig h or low atresia (rectum ending b elow o r a bove t he p uborectalis slin g), w hich has t herapeutic a nd p rognostic sig nificance. A s p atients with low atresia have hig her incidence o f genito-urinary anomalies, pre-operative renal ultrasound is mandatory. International c lassification of an orectal m alformations (Wingspread 1984): High atresia: ▬ Female: anorectal agenesia with or without rectovaginal fistula, rectal atresia ▬ Male: a norectal ag enesia wi th o r wi thout r ectoprostatic fistula, rectal atresia

▬ Male: r ectobulbar f istula o der a nal ag enesia wi thout fistula Low atresia: ▬ Female: a novestibular fi stula, a nocutaneous fi stula, anal stenosis ▬ Male: anocutaneous fistula, anal stenosis In a nal a tresia wi th f istula a co ntrast enema usin g lo wosmolar water-soluble contrast agent can be performed to demonstrate t he length of t he f istula and probable communications with the urinary tract (⊡ Fig. 5.81). Transperineal sonography

In addi tion, o r in cas es wi th im perforate a nus, a tra nsperineal sonography can be performed in o rder to measure t he dist ance b etween p erineum a nd r ectal endin g (⊡ Fig. 5.82).

Intermediate atresia: ▬ Female: r ectovestibular-rectovaginal fi stula o r a nal agenesia without fistula

⊡ Fig. 5.80. Hirschsprung’s disease

⊡ Fig. 5.81. Anal atr esia with fistula t o the v estibule (marked with a lead button)

5

114


MRI of the pelvis

As a norectal malf ormations a re o ften ass ociated wi th other a nomalies, esp ecially wi th t hose o f t he l umbar spine o r t he g enito-urinary trac t, a n MRI o f t he p elvis should b e p erformed. The s ectional imag es als o allo w a detailed pre-operative planning, as one can see the pelvic and sp hincter m uscles. Transversal, co ronar a nd s agittal images should be acquired (⊡ Fig. 5.83). Key information

5

I

Low intestinal obstruction

I

▬ Contrast enema will be necessary in most of the cases

▬ Water-soluble, low-osmolar contrast agent should be used to avoid fluid shifts

A

▬ Meglumine diatrizoate (Gastrografin) should not be used

▬ In Meconium plug syndrome (functional immaturity of the colon) the contrast enema is often therapeutic ▬ In Hirschsprung’s disease barium should be used, including late X-ray controls ▬ Pre-operative renal ultrasound should not be forgotten in patients with anorectal malformation ▬ Screening for additional malformations (remember the VACTERL association)

5.3.5 Rotation anomalies of the midgut

B ⊡ Fig. 5.82A,B. Anal atr esia: distance between the markers fr om rectum to perineal skin is 1 cm

A

B

⊡ Fig. 5.83A,B. Anal atresia, coronar and sagittal view show the blindending rectum (arrow)

General information Malrotation

During normal development the b owel will r otate counterclockwise three times 90° a round the superior mesenteric artery (SMA) to its final position. If the bowel does not r otate co mpletely d uring em bryonic de velopment, problems can occur. This condition is called non-rotation (incomplete rotation, 1 x 90°) or malrotation (malrotation I: 2 x 90°, malrotation II: change in rotation direction after initial 90° rotation in the right direction). The typical history o f a pa tient wi th intestinal malr otation dep ends o n age a t p resentation a nd degr ee o f in testinal obstr uction. Signs a nd sym ptoms a re o ften p resented as in termittent and incomplete. Symptoms may be bilious vomiting and feeding intolerance, some may also have upper abdominal distension.

115


Volvulus

Radiography

If volvulus occurs in patients with intestinal malrotation, the obstr uction is typ ically co mplete, a nd b lood su pply of the midgut is reduced. The symptoms depend on the degree o f is chaemia. I t ca n ra nge f rom l ymphatic a nd venous congestion with simple oedema to full intestinal necrosis.

Plain f ilm radiogra phy ca n sho w t he c lassical sign s o f a high intestinal obstruction, but also absence of abdominal air can be found. Free peritoneal air shows perforation as complication.

Imaging Ultrasound

Malrotation ( ⊡ Fig. 5.84) is most lik ely w hen in version of t he S MA a nd t he su perior mes enteric v ein (S MV) is shown. Volvulus is hig hly probable if t he SMV is sho wn to b e coiling around the SMA (»whirlpool sign«). Ot her findings may be fixed midline bowel loops and duodenal dilation with distal tapering.

Fluoroscopy

Upper gastro-intestinal series using barium is t he study of cho ice to ob tain t he diagnosis. I f imminen t sur gery is necess ary, wa ter-soluble co ntrast ag ents sho uld b e used. If the anatomy is normal, the duodenal C-loop crosses the midline a nd t he d uodenojejunal j unction is lo cated left of t he spine. If contrast ends a bruptly or t apers in a corkscrew pa ttern, midgu t v olvulus o r s ome o ther f orm of proximal obstruction may be present.

A

B

C

⊡ Fig. 5.84A–C. Doppler images of malrotation situs: note the inversion of the superior mesenteric vessels, the SMV (V) is located vetrolateral left to the artery (A)

5

116


Lower gastro-intestinal series (barium enema) ma y be used to identify the location of the cecum, but a normally located cecum does not rule out a malrotation (⊡ Fig. 5.85).

Bowel duplications General information Intestinal d uplications ma y o ccur a nywhere f rom o esophagus to rectum, but are mostly located in t he small bowel (35% dist al ileum). U sually, t he wall co ntains gastric mucose, covered by a cir cular muscle layer. Duplication c ysts ma y b e asym ptomatic o r ca use a bdominal ble eding, co mpression o f t he b owel, obst ruction o r invagination.

Imaging

5

Radiography

Abdominal radiogra ph ca n sho w dislo cation o f b owel loops b y a n o paque mass o r, in t he cas e o f obstr uction, dilated loops. Ultrasound

The c lassical a ppearance is a c ystic mass ( ⊡ Fig. 5.86), tubular str uctures a re less co mmon. S ometimes a h ypoechogenic r ing (smo oth m uscle) wi th a n inner , h yperechogenic la yer (m ucosa) ca n b e iden tified. I n t he cas e of bleeding or infection, debris can be seen at the bottom of the cyst. Often the cyst can already be identified with in utero ultrasound. 5.3.6 A chalasia

General information ⊡ Fig. 5.85. Contrast enema in malr otation: the c olon is positioned abnormally, with c ecum (arrow) and t erminal ileum in the upper left quadrant

A

The failure of relaxation of the lower oesophagus sphincter (ac halasia) ca uses a f unctional obstr uction o f t he lower oesophagus and leads to a dilated oesophagus with

B

⊡ Fig. 5.86A,B. Duplication cyst in the upper right quadrant with little debis inferiorly. Longitudinal panorama view (A). Transversal view (B)

117


A

⊡ Fig. 5.87. Achalasia: classic beak appearance of distal oesophagus

characteristic morphology (⊡ Fig. 5.87). Fewer than 5% of cases of achalasia occur in children.

Imaging Radiography

On chest radiography the dilated oesophagus with an airfluid level may be visible. B

Fluoroscopy

In elder chi ldren t he o esophagogram sho ws t he classic »beak a ppearance« o f t he dist al es ophagus. I n y ounger children the findings may be subtle. Key information

I

I

▬ Air-fluid level in plain film radiography ▬ Beak appearance of the distal oesophagus ▬ Seldom in children (less than 5%) 5.3.7 G astro-esophageal reflux

General information Gastro-esophageal reflux (GER) is a v ery common disorder. One ca n distin guish b etween t he f unctional, p hysiological reflux and pathological reflux by the number and severity of reflux episodes.

⊡ Fig. 5.88A,B. A Ultrasound of the lower oesophagus sphincter: sphincter closed, no reflux. B Sphincter open, gastro-esophageal reflux! (arrow)

Imaging Ultrasound

In most o f t he cas es, t he diagnosis ca n b e ob tained from t he hist ory a nd p hysical exa mination. I n ne wborn abdominal ul trasound is t he imagin g st udy o f c hoice t o detect GER ( ⊡ Fig. 5.88). I n a lo ngitudinal s ection t he oesophagogastral j unction i s vi ewed (a fter f eeding th e infant in order to assure adequate filling of the stomach). Usually a hia tal her nia can b e diagnos ed if p resent. The examination has to be performed for at least 15 min while the number of refluxes are counted. Three or less refluxes are considered to be physiological, more than three reflux episodes in 15 min are pathological.

5

118


5

⊡ Fig. 5.89A,B. A 10° head down without provocation. Sphincter closed, no reflux. B Syphon test: sphincter open, gastroesophageal reflux!

A

Fluoroscopy

Upper GI s eries hel p t o e valuate t he a natomy o f t he oesophagus a nd ma y sho w GER in o lder infa nts a nd children (where ultrasound is no longer useful any more or if r equired f or p resurgical p lanning), e ven w hen sensitivity a nd sp ecificity a re lo w f or t he diagnosis o f GER. GER ma y o ccur sp ontaneously in o esophagography, b ut as i t is a n ep isodic e vent i t ma y no t sho w during t he exa mination. I n o lder chi ldren b arium ca n be us ed, in infa nts a nd if t here is a r isk o f asp iration, water-soluble co ntrast ag ents sho uld b e us ed. An axial hernia ( ⊡ Fig. 5.90) will be r ecognised in f luoroscopy and is associated with GER (in contrast to the rare paraoesophageal hernia). Sensitivity can be raised by provocation tests such as the syphon-test (10° head down position, water drinking) (⊡ Fig. 5.89). Em ptying o f t he st omach sho uld b e do cumented at the end of the examination. If t he pa tient ca nnot swallo w (e .g. d ue t o men tal deficiency) t he exa mination ca n b e p erformed usin g a nasogastral tube, placed in the oesophagus.

B

Key information

I

I

Gastro-esophageal reflux

▬ Not every reflux episode is a pathological

▬

▬

▬ ▬

event: functional reflux is physiological and does not need any treatment Ultrasound of oesophagogastral junction (in newborn) or oesophagogram in older infants show anatomy (axial hernia?) and reflux episodes Low sensitivity and specifity of imaging methods: history and physical examination are very important Provocation tests such as the syphon test may increase sensitivity Negative radiological tests never exclude gastro-esophageal reflux. Additional oesophageal pH measurement (via naso-esophageal probe, monitoring over 24 h) should usually be performed

119


A

B

C

⊡ Fig. 5.90A–C. Oesophagography showing axial hiatal hernia

5.3.8 Foreign body ingestion

General Information Infants and younger children swallow all kinds of foreign objects, like coins, pins, toys, small batteries and so on. Usually t he ob jects pass t he gastr o-intestinal trac t without complications and leave the body in t he normal way. I n s ome cas es, t hese ob jects ma y lo dge in t he o esophagus, usually at the thoracic inlet/upper oesophageal sphincter, a t t he le vel o f t he ao rtic a rch o r a t t he lo wer oesophageal sphincter. Patients with oesophageal foreign bodies usually present as acutely symptomatic. Objects in the oesophagus need to be removed (endoscopically) to prevent ulcera a nd consecutive perforation with mediastini tis. I f a f oreign b ody pass es t he lo wer oesophageal sphincter, it will usuall y pass t he rest of the gastro-intestinal tract as w ell and in most cas es no in vasive treatment is necessary.

Imaging Radiography

Most o f t he swallo wed ob jects a re o paque und will b e identified on plain radiographs ( ⊡ Fig. 5.91). If possible, it is helpful to have a sample of the ingested foreign body.

After f oreign b ody in gestion t he radiography should show the entire GI tract, including the nasopharynx. The standard t horax X-ra y is in sufficient, b ecause a fter t he stomach t he u pper o esophageal sp hincter is o ne o f t he most common sites where foreign bodies lodge. Fluoroscopy

A quickly performed pulsed, low-dose fluoroscopy using the last-imag e-hold te chnique f or do cumentation usually leads to lower radiation doses than plain film radiographs o f t he s ame r egions. F or t his r eason i t sho uld be preferred, b eing p erfomed by an exp erienced examiner. If t here is e vidence f or a no n-opaque f oreign ob ject in t he o esophagus, a co ntrast exa mination usin g wa tersoluble, low osmolar contrast media can to be performed (⊡ Fig. 5.92). Due to the risk of occult perforation Barium must not be used. As described above, most o f the ingested foreign objects do not get stuck, and pass the whole gastro-intestinal tract t o le ave t he human b ody in t he natural way. S o in absence of complications and clinical symptoms it is usually not necess ary to prove radiologically t hat t he object has left the intestine.

5

120


5

A

B

C

⊡ Fig. 5.91A–C. Foreign body. A,B Coin lodged at upper oesophageal sphinc ter. C Allen key lodged in the st omach

Of course t he parents often want to know if t he foreign body has b een evacuated after a p eriod of time, but without c linical sym ptoms t his sho uld b e no indica tion for t he application of additional radiation. It is b etter t o examine the faeces.

Appendix: magnets, magnetic toys If mo re t han o ne magnet is swallo wed, t hey ha ve t o b e evacuated immedia tely. I f t he magnets pass t he p ylorus, they usually have to be extracted surgically. Magnets stic k t ogether a nd s o ma y p rovide necr osis and perforation of the bowel, resulting in severe peritonitis. Cases with fatal outcome have been reported! Key information

I

Foreign body ingestion

I

▬ Usually foreign bodies pass the intestine with

⊡ Fig. 5.92. Non-opaque oesophageal foreign body located in the up per oesophagus

no problems. So usually no specific treatment is necessary ▬ Objects that pass the gastro-esophageal junction usually will pass the rest ▬ Objects lodged in the oesophagus are critical and need to be removed

121


▬ Documentation of the ingested object using low-dose fluoroscopy and last image hold technique may save radiation compared to plain film radiography ▬ Negative imaging and persistent clinical evidence for foreign objects in the oesophagus should lead to an oesophagography with water-soluble contrast agents (or endoscopy) ▬ Ingested objects in the small intestine of patients with no clinical symptoms usually need not be controlled radiologically ▬ Cave: magnets have to be extracted immediately if more than one is ingested!

A

5.3.9 In tussusception

General nformation Intussusception is t he in vagination o f a n in testinal s egment into the contiguous distal segment, leading to consecutive mec hanical obstr uction a nd is chaemia o f t he bowel segment involved. While ileo ileal in tussusceptions u sually de vaginate spontaneously, most o f the intussusceptions are ileocolic (90% of the cases) and need to be treated. The c lassical pa tient wi th sp ontaneous ileo colic invagination is a b oy (twice as f requently as girls) under 2 years of age (most common age is 3 months to 1 year). As in a bout 10% o f all cas es t he in tussusception is secondary t o s ome o ther pa thology (e .g. M eckel di verticulum, l ymphoma o f t he b owel, d uplication c ysts a nd other), especially patients not of the »classical« age (under 1 month or older than 4 years) should be checked for additional pathology, because in these cases the frequency of pathological lead points rises to 50%.

Imaging Ultrasound

An intussusception is a n emergency in paedia tric radiology and needs immediate treatment (⊡ Fig. 5.93). The procedure of choice is a n abdominal ultrasound of t he a bdomen a nd es pecially o f t he b owel. F or t his procedure a line ar probe (7.5 MH z or higher) should be used. E very s ector o f t he a bdomen sho uld b e exa mined carefully.

B ⊡ Fig. 5.93A,B. Intussusception, classical appear ance in abdominal ultrasound: target sign (A transverse) and sandwich sign (B longitudinal)

The a ppearance o f t he in tussusception is c lassical (target sign in transverse, sandwich or pseudokidney sign in longitudinal section) and is usually (but not always) located near the flexura hepatica in the right upper abdominal quadrant. Accompanying mesenteric lymphnodes are common. Radiography

Additional plain film radiography may show abnormalities in most cases [such as dilatation of the ileum, air-fluid levels (ileus), a lack of air in colon], but is neither specific nor always necessary for the diagnosis. Fluoroscopy

A contrast enema (preferrably with water-soluble contrast agents due to the risk of perforation) of course leads to the diagnosis (⊡ Fig. 5.94).

5

122


ways be documentated ( ⊡ Fig. 5.95C). The oedamatous ileocecal valve is usually visible and has to be distinguished from residual intussusception. Results usin g a ir in stead o f wa ter f or r eduction o f intussusception a re eq ual t o h ydrostatic de vagination, but as t he examination is p erformed under f luoroscopy control, ul trasound sho uld b e p referred (no radia tion dose). If t he p rocedure fa ils t o r educe t he in vagination, a second attempt after a break is suitable. If the hydrostatic devagination do es no t w ork o ut p roperly, t he r eduction has to be done surgically. Signs of successful hydrostatic devagination are: ▬ Visible valve of Bauhin ▬ Absence of Intussusception signs ▬ Flow of fluid from coecum to ileum ▬ Flow of stool through valve of Bauhin from ileum t o coecum

5

⊡ Fig. 5.94. Contrast enema with intussusc eption. Head of the intussuscepted ileum clearly visible

Therapy When t he p atient is haemo dynamically st able a nd no t decompensated, hydrostatic reduction should b e given a try before admitting the patient to surgery. C ontra-indications a re ele ctrolyte dera ilment o r clinica l e vidence o f perforation and/or peritonitis. Hydrostatic de vagination ca n b e p erformed in ultrasound as w ell as in f luoroscopy, acco rding t o t he less radia tion, t he s onographyically co ntrolled h ydrostatic r eduction sho uld b e t he tr eatment o f f irst c hoice (⊡ Fig. 5.95). The pa tient sho uld b e p repared adeq uately, g etting intravenous access, a nasogastral tube and a mild sedation (e.g. chloralhydrate). A ca theter is p laced t hrough t he a nus a nd held b y assisting p ersonnel, balo on catheters should not b e used due to the risk of perforation. Warm saline solution is now admitted f rom a n enema bag under ul trasound co ntrol. No devices to raise the pressure are allowed. Successful reduction is indicated by free flow of water and faeces through the valve of Bauhin, which should al-

In 5-10% r e-invagination after successf ul hydrostatic reduction will o ccur, usually within 72 h o f the tr eatment. The tr eatment o f t he r ecurrent in tussusception is t he same as de cribed ab ove, b ut o ne sho uld r emember t hat intussusceptions can be a secondary phenomenon due to pathological lead points. Perforation as a complication to hydrostatic reduction is seldom (< 0.5%). Key information Intussusception

I

I

▬ An intussusception is an emergency and needs immediate treatment

▬ Imaging method of the first choice is the abdominal ultrasound

▬ Ultrasound finding will be a target sign (trans-

▬ ▬

▬ ▬

verse) or sandwich sign (longitudinal), mostly located in right abdominal quadrant Usually the treatment is radiological so that no surgical intervention is necessary Hydrostatic reduction (or reduction using gas) under ultrasound control should be the method of first choice Recurrent intussusception (5-10%) is treated in the same way If hydrostatic devagination fails, the reposition has to be done surgically

123


5.3.10 Hypertrophic pyloric stenosis

General information Infantile h ypertrophic p yloric stenosis is t he most co mmon cause of intestinal obstruction in infancy. Hypertrophy a nd h yperplasia o f t he p yloric m uscular la yers le ad to s econdary st enosis. Clinical sym ptoms sho w a c lassic appearance: progressive non-bilious vomiting or regurgitation occurs after feeding, the infant feels hungry most of the time, weight loss occurs.

Imaging Ultrasound A

Ultrasound of the pyloric region (using a linear probe, frequency 7.5 MHz or higher) is the imaging study of choice for detecting pyloric stenosis (⊡ Fig. 5.96). The pylorus has to be scanned and measured longitudinal and transverse, a diameter of the muscular layer over 3 mm and a pyloric length over 15 mm are pathological. Fluoroscopy

Ultrasound usuall y le ads t o t he diagnosis. I f t he s onography is inconclusive (which should be very seldom) and alternative diagnoses are considered, a contrast examination of the upper GI trac t can be performed. The typ ical appearance is a n elo ngated pyloric c hannel (str ing sign) and a bulge of the pyloric muscle into the antrum (shoulder sign) and lack of pyloric passage. B

Key information

I

Infantile hypertrophic pyloric stenosis

I

▬ Classical clinical appearance and ultrasound ▬ Sonographic evaluation of the pyloric region: muscular layer thickness > 3 mm and pyloric length > 15 mm are pathological

5.3.11 Necr otizing enterocolitis

General information

C ⊡ Fig. 5.95A–C. Devagination pr ocedure under ultrasound guidanc e (A,B). Oedematous valve of Bauhin af ter successful hydrostatic reduction (C)

Necrotizing enterocolitis (NEC) is a m ural or transmural necrosis of segments of the intestine, mostly affecting the terminal ileum or proximal colon, with an onset 2 w eeks up t o s everal mo nths p ostpartum. The ma jor r isk f or development of NEC is premature of birth.

5

124


5 A

B

⊡ Fig. 5.96A,B. Hypertrophic pyloric stenosis (A transverse x–x diameter, +–+ thickness, B longitudinal scan) (1-1 lenght and 2-2 thick ness of the pyloric muscle)

Ultrasound

The characteristic ultrasound appearance is thick-walled loops of b owel w ith h ypomotility. Fre e i ntraperitoneal fluid is a common finding. In the presence of pneumatosis intestinalis, gas reflexes can be identified in the thickened intestinal walls a nd gas ma y b e p resent in t he p ortal venous circulation within the liver. Key information

⊡ Fig. 5.97. Pneumatosis intestinalis: submucosal air (arrows)

Imaging Radiography

Abdominal radiographs will show dilated loops in sequential st udies. An enla rged dist ance b etween t he gas-f illed loops indicates wall thickening. In early stages the findings are un specific, b ut later o ften c haracteristic sub mucosal / subserosal air occurs: pneumatosis intestinalis (⊡ Fig. 5.97). Pneumatosis is found in 50–75% of the cases. Portal v enous gas a nd ga llbladder gas a re p athognomonical sign s a nd indica te s evere dis ease. A p neumoperitoneum is a n indica tor f or p erforation a nd le ads t o surgical intervention.

I

I

Necrotizing enterocolitis ▬ Disease of the premature newborn with an onset 2 weeks to several months postpartum, preferred site is the terminal ileum and the proximal colon ▬ Abdominal radiography is the most impor tant imaging modality ▬ Uncharacteristic findings in early stage: dist ended, separated bowel loops ▬ Pneumatosis intestinalis and gas in the por tal venous system are characteristic and indicate serious disease ▬ Pneumoperitoneum as an indicator of perforation usually requires surgery

5.3.12 Inflammatory bowel disease

General information Inflammatory bowel diseases mainly include Crohn’s disease (CD) and ulcerative colitis (UC). As in paediatrics it

125


⊡ Fig. 5.98. Panorama image of the colon descendens showing thickening of the intestinal wall in ulcerative collitis

is often difficult to distinguish between CD a nd UC, t he less specific term inflammatory bowel disease is in co mmon use. Crohn’s disease (CD)

CD is a tra nsmural gra nulomatous inf lammation o f unknown aetiology which may occur in every part of the gastro-intestinal tract. The prevalently affected segment is the terminal ileum; most c hildren show affections of the distal ileum and the right hemicolon. Ulcerative colitis (UC)

The inflammation of UC is usuall y limited to the mucosal la yer. I t co mmonly begin s a t th e r ectal m ucosa a nd spreads p roximally wi thout ski p lesio ns. UC sho ws a variety of extra-intestinal manifestations like arthritis and sclerosing cholangitis.

Imaging Ultrasound

Patients wi th inf lammatory b owel dis ease o ften p resent with a va riety o f a bdominal sym ptoms inc luding, pa in, (bloody) dia rrhoea, GI pass age p roblems u p to ileus, maldigestion etc. The imagin g met hod dep ends o n t he pa tient’s co mplaints, b ut a n ini tial ul trasound will b e o ne o f t he f irst imaging techniques. Of course, a co mplete abdominal scan has t o be performed, but the main region of interest will b e the bowel structures, which should be examined with a linear probe of at least 7.5 MHz. The inf lamed bowel commonly shows a wall t hickening; diameters above 3 mm are pathological (⊡ Fig. 5.98 and

5.99). P ower D oppler s onography ca n o ften demo nstrate hyperperfusion ( ⊡ Fig. 5.99B). F ree p eritoneal f luid ma y

be another sign o f inf lammation. Stenoses le ad to dilated proximal bowel segments (more often in CD than in UC).

Radiography

The indication to plain film radiographs depends on the clinical sym ptoms. I f t he pa tient p resents wi th tra nsit problems or ileus, plain film radiographs of the abdomen are helpful to detect air-fluid levels and dilated bowel segments. I f a p erforation is co nsidered, p lain radiog raphy shows free peritoneal air. Fluoroscopy

Nowadays, wi th incr easing p ossibilities o f MRI t echniques, f luoroscopy p lays a mino r r ole in t he diagnosis of inflammatory bowel disease, especially as the extent of inflammation is det ected in a n endos copy. Nevertheless, a variety of contrast studies may be performed according to clinical symptoms and complications. Enterocutaneous fistulae ca n b e visualized b y in jection o f wa ter-soluble contrast ag ent. U pper GE s eries a nd small-b owel f ollow-through (prefered by Sellink-procedure) can localize stenosis and entero-enteral fistulae. In patients with colitis involvement of the small b owel, detection of skip lesions help to lead to the diagnosis CD.

MRI An elega nt imagin g met hod t o do cument t he ext ent o f inflammatory b owel dis ease is t he s o-called h ydro-MRI (⊡ Fig. 5.100). The b owel str uctures will b e dist ended b y water filling transanal and peroral and so become evaluable. A b owel pa ralysis is ac hieved wi th B uscopane i .v. N ative

5

126


and co ntrast-enhanced tra nsverse a nd co ronar s cans a re performed. Best distension of the small bowels is achieved by not drinking the water, but applying it via a nas ojejunal

probe (which has to be MRI-compatible). Possible findings are e.g. pathological contrast enhancement of the wall, wall thickening, interenteric abscesses or fistulae.

CT If sectional imaging is required, MRI is usually preferred. In t he cas e o f MRI co ntra-indications o r in emer gency situations an abdominal CT can be indicated. Key information

5

I

Inflammatory bowel disease

I

▬ Abdominal ultrasound detects wall thickening of the bowel (a linear probe of at least 7.5 MH z should be used ▬ Upper GI series and/or enteroclysis (Sellink) show intestinal transit problems and may detect stenosis and fistula, but are seldom performed nowadays ▬ Hydro-MRT shows extent of the inflammation, stenosis and complications such as fistula and abscesses and should be preferred to CT ▬ Local extension of inflammation is detected in endoscopy

A

5.3.13 A ppendicitis

General information B ⊡ Fig. 5.99A,B. Wall thickening and h yperperfusion of the t erminal ileum in Crohn’s disease

A

B

Appendicitis is t he most co mmon r eason f or sur gery in childhood. As the major complications are abscess formation and perforation, which may lead to general peritonitis, early diagnosis is necessary.

C

⊡ Fig. 5.100A–C. Classical appearance of Crohn’s disease in hydro-MRI (T1 (A), T2 (B), T13d+Gd (C), T1+Gd: thickening of ileal wall ( arrow)

127


While in o lder children the pain is most ly located to the lower right quadrant, especially younger children do often not localize the pain to the right lower abdomen.

Imaging

While c linical diagnosis a nd US b ecome mo re dif ficult after perforation, radiographic findings often become more distinc tive, s o i t co uld b e hel pful o n susp icion o f perforation.

Ultrasound

Possible findings

US should be the first preferred modality. The s ensitivity and specifity for the diagnosis are both 85-95%. A 5.0-7.5 MHz linear array transducer has to be used to examine the patient at the point of maximal tenderness in the lower right abdomen. Gradually a pplied co mpression ma y disp lace o ther loops o f t he b owel. L ongitudinal a nd tra nsverse s cans are p erformed ( ⊡ Fig. 5.101). I f t he a ppendix ca nnot b e identified, a complete scan of the whole abdomen should be performed because of the variability of the appendiceal position a nd in o rder t o ex clude o ther r easons f or t he abdominal pain.

▬ Ap pendicoliths ▬ Small bowel obstruction ▬ P aralytic ileus ▬ Free peritoneal (subphrenic) air is uncommon ▬ Extral uminal a ir, lo cated b etween caec um a nd th e peritoneal fat line are seen in some cases

Possible Findings ▬ Transversal: target sign ▬ Diameter > 6 mm, not compressible ▬ Longitudinal: tubular structure, blind end ▬ H yperperfusion ▬ Ap pendicoliths ▬ Periappendiceal / intraperitoneal fluid ▬ A bscess formation

Pitfalls

A

▬ Retrocecal appendix is difficult or even not visible ▬ After p erforation the appendix is no lo nger distended and is difficult to visualize; the patient feels sometimes better after perforation ▬ Many other diseases may mimic appendicitis, such as yersiniosis, Cr ohn’s dis ease, dist al in testinal obstr uction in c ystic f ibrosis a nd e ven gast ro-enteritis wi th mesenteric adenitis ▬ Most s erious dif ferential diagnosis in f emale is t he torsion o f t he r ight o vary, s o t he o varies ha ve t o b e visualized in the examination ▬ The f irst men struation in y oung girls o ften ca uses pain similar to an appendicitis Radiography

Plain f ilm radiogra phy is no t st andard p rocedure in uncomplicated a ppendicitis, as i t ma y lo ok co mpletely normal in ac ute a ppendicitis. An a ppendicolith ma y b e seen in 5-10% of the cases.

B ⊡ Fig. 5.101A,B. Appendicitis US target sign (A transverse) and hyperperfusion (B longitudinal)

5

128


Computed tomography

CT gives the best visualization of an appendicitis and its possible co mplications, as i t no t o nly sho ws t he a ppendicitis a nd p eri-appendiceal r egion, b ut als o t he ef fect of inf lammation on other str uctures and any abdominal extensions (⊡ Fig. 5.102). As one of the major targets of paediatric radiology is the reduction of radiation in c hildhood, CT s cans in a ppendicitis are reserved for the unclear cases.

5

Note

In o ur o pinion, t he dos e r eduction asp ect sho uld b e valued b efore eco nomical as pects a nd CT s cans sho uld remain an exception. Key information

I

▬ Ultrasound first ▬ On special indications:

A

I

– R adiography – Computed tomography (CT)

▬ »Classic appearance«: – Pain in the right lower abdomen with – T arget sign

▬ Evidence for complications: – Absc ess formation – Paracecal or free peritoneal fluid – P aralysis

▬ After perforation the patient often feels better

B ⊡ Fig. 5.102A,B. Appendicitis CT. A Appendicolith (native) and B postcontrast inflammated appendix (post contrast)

for a short period of time

▬ »Appendicitis is primarily a clinical diag nosis«; physical examination by surgeon is mandatory!

5.3.14 Gastro-intestinal tumours and

tumour-like lesions

Not e very en tity o f gastr o-intestinal t umours will b e discussed in this manual. Serving as an example the nonHodgkin lymphoma (exemplary for malignant tumours) and the lymphangioma / haema ngioma (exemplary for a benign tumour) are shown.

Non-Hodgkin-lymphoma General information As neo plasms o f t he l ymphoid system, l ymphomas ca n occur in almost e very o rgan syst em. The no n-Hodgkin-lymphoma (p resenting as l ymphoblastic, small no ncleaved cell: B urkitt; ⊡ Fig. 5.103 or Burkitt-like, or largecell l ymphomas, L CLs) ma y o ccur in t he sma ll b owel, mostly in the ileocecal region. It should be noted that the first symptom may be an intussusception!

Imaging Ultrasound

Ultrasound of the ileocecal region may show an inhomogeneous structure of low echogenity. The intestinal lumen is o ften ha rdly visib le. The in testinal wal l usuall y s eems

129


A

B

⊡ Fig. 5.103A,B. Burkitt-Lymphoma of the ileum (A), panorama view (SieScape B)

A

B

⊡ Fig. 5.104A,B. MRI (T2) A Burkitt lymphoma of the ileum. B Illustration of the displaced blood vessels

to be thickened. Often, accompanying mesenteric lymph nodes are visible. Of course, a complete abdominal ultrasound should be performed. If it is only a minor spatial extent in early disease and it is o ften no t p ossible t o distin guish b etween ile al l ymphoma a nd inf lammatory b owel dis ease b y s onographic appearance, but additional clinical symptoms and laboratory findings usually lead the way.

Additional staging imaging

If a l ymphoma is most lik ely, a co mplete st aging has t o be performed. Imaging includes sectional imaging of the abdomen (MRI is preferred (⊡ Fig. 5.104), but CT will also do), cranial MRI and chest radiographs / thoracic CT. An additional testicular ultrasound is preferable. If available, a whole-body MRI can cover large parts of the staging imaging.

5

130


Key information

I

Non-Hodgkin-lymphoma

I

▬ Intestinal NHL prefers ileocecal region ▬ Wall thickening and accompanying lymph nodes are common

▬ In the early stages ultrasound may not be able to distinguish between NHL and inflammation ▬ A complete tumour-staging is required

5 Intra-abdominal lymphangioma and haemangioma General information

⊡ Fig. 5.105. Haemangioma in the liver

Haemangiomas and ly mphangiomas are v ascular m alformations as a r esult o f a bnormal (l ymph)angiogenesis and can be located on almost every site of the body. Both mostly occur sporadically, but in s ome cases haemangiomas are inherited in a n autosomal dominant way, or are part of syndromes. A ma jor co mplication o f la rge haema ngiomas is congestive he art fa ilure d ue t o signif icant a rteriovenous shunting.

Imaging

A

Ultrasound

Abdominal ultrasound is a cost effective screening modality t o det ect t hese malf ormations in t he mes enterium or t he p arenchymatous o rgans ( ⊡ Fig. 5.105), b ut ca nnot exclude t he p resence o f haema ngioma/lymphangioma. The relation to other relevant structures often cannot be depicted accurately. Colour-flow a nd PW D oppler demo nstrate t he p erfusion a nd ma y iden tify f eeding v essels in cas e o f haemangioma, l ymphangiomas ma y lo ok ne arly t he s ame in B-mo de ul trasound, b ut will sho w no p erfusion in colour-flow imaging. MRI

Especially if surgery is planned, sectional imaging is necessary to demonstrate the size and relation of the lesion to the sur rounding tissue, o rgans a nd v essels ( ⊡ Fig. 5.106). Three p lane s ections in T1 a nd T2 w eightings a nd co ntrast-enhanced st udies sho uld b e p erformed. An MR angiography is very helpful to show the vascular anatomy in haemangiomas.

B ⊡ Fig. 5.106A,B. Left retroperitoneal lymphangioma (MRI T2w)

131


Key information

I

I

Intra-abdominal lymphangioma and haemangioma

▬ Congestive heart failure is a common complication of large haemangiomas with arteriovenous shunting in newborn ▬ Pay attention to syndromic complexes! ▬ Colour-flow ultrasound helps to distinguish between haemangioma and lymphangioma and may show feeding vessels ▬ Abdominal MRI should be per formed pre-operatively if surgery is required, and should include MR angiography

5

6 Musculosk

eletal system

Harvey Teo, David Stringer

6.1 C

ommon bone dysplasias

6.1.1 A chondroplasia

General information Achondroplasia is t he co mmonest f orm o f sho rt-limb dwarfism. It is a no n-lethal a utosomal do minant co ndition c haracterized b y sho rt st ature wi th disp roportionately short arms and legs, a large head and facial features. De nouvo mutations cause 75-80% of cases. The condition is caused by mutations in t he gene for f ibroblast growth factor re ceptor-3 ( FGFR3) r esulting in t he c haracteristic clinical and radiological features.

Clinical features ▬ Sho rt stature ▬ Rhizomelic shortening of the arms and legs ▬ Limitation of elbow extension ▬ T rident hands ▬ Genu varum (bow legs) ▬ Thoracolumbar gibbus in infancy ▬ Exaggerated lumbar lordosis ▬ Large head with frontal bossing ▬ M idface hypoplasia

Imaging Prenatal ultrasound Prenatal detection of homozygous achondroplasia is possible but is still challenging even in expert hands. Prenatal diagnosis o f heter ozygous acho ndroplasia is e ven mo re difficult b ecause f emoral sho rtening g enerally ma nifests only in t he third trimester. However, with increasing use of 3-D US imagin g and foetal MRI, mo re accurate diagnosis may be possible in the future.

Plain radiographs Skeletal sur veys sho w t he f ollowing c haracteristic f eatures: ▬ Midface h ypoplasia, enla rged cal varia wi th f rontal bone prom inence an d s hortening of t he b ase of t he skull. The foramen magnum is diminished in size. ▬ Narrowing of the interpedicular distances from proximal t o dist al in L1-L5 is s een o n a a nteroposterior radiograph of the lumbosacral spine. ▬ The lateral view reveals shortening of the pedicles and vertebral b odies wi th p osterior s calloping. Tho racolumbar kyphosis associated with wedging of T12 or L1 may be present. ▬ The pelvis is broad and short, and the ilium is squareshaped ( ⊡ Fig. 6.1). The s acrosciatic no tch is small ,

134

Chapter 6 · Musculoskeletal system

6.1.2 T hanatophoric dysplasia

General information Thanatophoric d ysplasia (TD) is t he co mmonest f orm of let hal sho rt-limb d warfism o ccurring in t he neo natal period. The condition is caused by de nuovo mutations in the gene for fibroblast growth factor receptor-3 (FGFR3) located o n c hromosome 4p16. H istopathologically t here is a disorganization of endochondral bone formation with lack of ordered rows of cartilage cells.

Clinical features

6 ⊡ Fig. 6.1. Frontal pelvic radiograph illustrating narrowing of the interpedicular distance from proximal to distal lumbar vertebra, square iliac wing (i), small sacr o-sciatic notch (small arrow), flat ac etabulum (large arrow), short femoral neck (n) and coxa vara (cv)

and t he acet abular r oof is ho rizontal. The f emoral neck is short and an apparent coxa vara may be seen. ▬ Metaphyseal flaring of the long bones is p resent. The long bones are also short and thick. In the first year of life, the proximal metaphyses of the femur and the humerus have oval-shaped radiolucent areas. The dist al femoral physes have an inverted-V shaped configuration.

Neuroimaging Cervical cord compression at the cervicomedullary junction due to narrowing of the formanen magnum is a co mmon cause of death in infancy. MRI of the brain is the modality of c hoice t o a ssess c ervicomedullary c ompression a t t he foramen magnum, fusion of C1 or isolated subaxial cervical stenosis, myelomalacia, intramedullary c yst, or angulation at the craniocervical junction. Hydrocephalus may also be detected. MRI ca n ass ess t he degr ee o f sp inal st enosis o f the lower lumbar segements. Ultrasound can be used in the neonate to detect ventricle size and other abnormalities.

Affected neonates are characterized by: ▬ Growth deficiency with an average length of 40 cm at term ▬ Macrocephaly wi th f rontal b ossing, a f lattened nas al bridge, and proptotic eyes ▬ Hydrocephalus also contributes to the macrocephaly ▬ Narrow thorax with small r ibs and a p rotuberant abdomen ▬ Small, short limbs There a re tw o c linically def ined sub types d ue t o dif ferences in the mutation pattern on the abnormal gene. Type 1 i s c haracterized b y a n ormal s kull wi th cur ved s hort long b ones, w hilst typ e 2 is c haracterized b y a c lovershaped skull due to premature closure of the sutures and straight femurs.

Imaging Prenatal Imaging Prenatal ul trasound ca n b e made in t he 2 nd or 3 rd trimester and reveals polyhydramnios, generalized micromelia, a narrow thorax, flattened, hypoplastic vertebrae, shortened lim bs wi th sho rt c urved o r stra ight f emora, large o r c loverleaf he ad, small ha nds, f eet a nd f rontal bossing. H owever, dif ferentiation f rom o ther sk eletal dysplasias li ke f ibrochondrogenesis o r a telosteogenesis is difficult.

References

Plain radiographs

Gordon N (2000): The neur ological c omplications of achondr oplasia. Brain Dev 22(1): 3-7 Krakow D , Williams J 3r d, P oehl M, R imoin DL, Platt LD (2003) U se of thr ee-dimensional ultr asound imag ing in the diag nosis of prenatal-onset skeletal dy splasias. Ultrasound Obst et Gynec ol. 21(5):467-72

Skeletal surveys show the following characteristic features (⊡ Fig. 6.2): ▬ Disproportionate large skull ▬ Narrow thorax with short cupped ribs ▬ Severe platyspondyly and a generalized dwarfism.

135

6.1 · Common bone dysplasias

▬ Characteristic »F rench t elephone r eceiver« asp ect o f the f emora a nd h umeri is typ ical f or t he typ e 1 TD . The long bones are straight in type 2 TD. ▬ H-shaped vertebra on the AP view with sparing of the height of the pedicles.

References

Prognosis

6.1.3 Asph yxiating thoracic dysplasia

The condition is lethal and death results from respiratory failure in all cases.

General information

Sahinoglu Z, Uludogan M, Gurbuz A, K arateke A (2003) P renatal diagnosis of thanatophoric dysplasia in the sec ond trimester: ultrasonography and other diag nostic modalities. Arch Gynecol Obstet. 269(1):57-61

Jeune’s asphyxiating thoracic dystrophy (ATD) is a sho rtlimbed short-rib p olydactyly dwarfism t hat is cha racterized b y t horacic cag e def ormity a nd s evere r espiratory distress at birth. The syndrome is inherited in an autosomal recessive manner and the locus has b een mapped to chromosome 15q13.

Clinical features ▬ The chest is na rrow, elo ngated a nd b ell-shaped. The heart size is normal with little room for the lungs ▬ Respiratory movements are restricted by the deformed chest wall and there is pulmonary dysplasia/hypoplasia ▬ Surviving pa tients ma y suf fer f rom r enal fa ilure d ue to juvenile nephronophthisis, liver dysfunction due to cholangiopathy or retinal dystrophy

Imaging Prenatal imaging Prenatal ultrasound diagnosis sho uld be suspected if t he ratio of the thoracic circumference to the abdominal circumference is less t han normal or if t here is dis cordance between the gestational age and thoracic circumference.

Plain radiographs

⊡ Fig. 6.2. Babygram of a thanat ophoric dwar f sho wing a narr ow thorax with cup shaped ribs (thin arrow), H-shaped vertebrae (medium arrow) and curved long bones (large arrow)

The following are characteristic features (⊡ Fig. 6.3): ▬ The c lavicles a re ho rizontal in o rientation. The r ibs are short and horizontal with expansion of the costochondral junctions. The thorax is bell-shaped ▬ The long b ones are short but not to t he s ame degree as in acho ndroplasia or thanatophoric dwarfism. Metaphyseal widening is present. Pre- and postaxial hexadactyly may be present. The epiphyses of the phalanges are cone-shaped and the phalanges are hypoplastic ▬ Squaring of the iliac win gs and underdeveloped pelvic bones are present. The proximal femoral epiphyses are prematurely visible, which is highly suggestive of ATD

6

136


Prognosis This condition is usually lethal, but sporadic cases surviving to childhood have been reported.

References den Hollander NS, Robben SG, Hoogeboom A J, Niermeijer MF, Wladimiroff JW (2001) Early prenatal sonographic diagnosis and followup of Jeune syndrome. Ultrasound Obstet Gynecol. 18(4):378-83 Kajantie E, Andersson S, K aitila I (2001) F amilial asphyxiating thoracic dysplasia: clinical variabilit y and impac t of impr oved neonatal intensive care. J Pediatr 139(1):130-3

6

6.1.4 Osteogenesis imperfecta

General information Osteogenesis imperfecta (OI) is a g enetic disorder of increased bone fragility, low bone mass, and other connective-tissue ma nifestations. The underl ying pathophysiology is the production of abnormal collagen I molecules as well as a decr ease in t he production of normal collagen I molecules. This results from mutations in the loci coding for p ro-α 1 a nd p ro-α 2 c hains w hich f orm t he helical structure of collagen 1.

⊡ Fig. 6.3. Chest radiograph illustrating horiz ontal clavicles (c), shor t, horizontal ribs with expansion of the c ostochondral junctions (r) and a bell-shaped thorax

Clinical features The widely accepted classification of Sillence classifies OI into four subtypes (⊡ Table 6.1)

⊡ Table 6.1. Summary of the clinical features of the four different subtypes of OI Type 1

aAD

Type 2

Type 3

Type 4

Sclera

Blue

+/-

Variable

Normal

Dentinogenesis imperfecta

A: Present B: Absent

Yes

Yes

A: Absent B: Present

Fractures (in utero)

10%

100%

50%

Rarely, usually in infancy

Hearing loss

Yes

No

No

No

Others

 Premature arcus senilis  Easy bruisability  Mild short stature

 Short trunk  Lethal perinatal  Connective tissue fragility  Short, angulated limbs

 Limb shortening  Frontal bossing  Pulmonary hypertension  Triangular facies

 Mild angulation  Shortening  No bleeding diathesis

Inheritance

ADa

AD with new mutation

AD with new mutation (rarely AR)b

AD

Epidemiology

1 in 28500

1 in 62500

1 in 68800

No data but very rare

autosomal dominant; bAR autosomal recessive

137

6.1 · Common bone dysplasias

The typ e-1 f orm has t he b est p rognosis a nd b one fragility is mild . L igamentous laxi ty is co mmon. The type-2 form has t he worst prognosis with many dying in utero or in t he neonatal p eriod. Type 3 has s evere b one fragility and osteopenia. The b ones are usually markedly deformed at birth. Individuals survive to childhood. Type 4 is t he rarest form of OI. Its features are very similar to child abuse.

Imaging Plain radiographs ▬ Generalized osteoporosis is present ▬ In the milder cases such as types 1 and 4, the bones are thin a nd gracile wi th t hin co rtices ( ⊡ Fig. 6.4a). The skull vault may be normal ▬ In t he mo re s evere f orms o f O I suc h as typ es 2 a nd 3, t he b ones a re t hick a nd sho rt wi th m ultiple f ractures a nd h yperplastic call us f ormation. The sk ull is osteopenic a nd multiple w ormian b ones a re present. Multiple rib fractures may cause the bones to become broad and deformed. Platyspondyly and scoliosis are often present (⊡ Fig. 6.4b)

A

Cross-sectional imaging Plain radiographs are diagnostic a nd cross-sectional imaging is reserved for specific indications only.

Prenatal Ultrasound OI, esp ecially typ e 2, ca n b e diagnos ed o n p renatal ultrasonography b y t he s econd tr imester. Findin gs include b owing, sho rtening a nd a ngulation o f t he lo ng bones due to fractures and easy visualization of intracranial structures due to decreased ossification of the skull vault.

Treatment Physiotherapy, rehabilitation, and orthopaedic surgery are the ma instay of treatment f or patients with ost eogenesis imperfecta. I n r ecent y ears, b iphosphonate t herapy has been used with success.

References Rauch F, Glorieux FH (2004) Ost eogenesis imperfecta 24;363(9418):137785 Ablin DS (1998) Ost eogenesis imper fecta: a r eview. Can Assoc R adiol J 49(2): 110-23

B ⊡ Fig. 6.4A,B. A Type-1 ost eogenesis imper fecta. Plain X -ray of the right tibia and fibula sho wing thin gracile bones and cortices. Healing fractures of the mid-tibial shaf t and upper fibula ar e seen. B Type-2 osteogenesis imper fecta. Newborn with c ongenital fr actures, callous formation and bowing of the femurs, tibias and fibulas (arrows)

6.1.5 Osteopetr osis

General information Osteopetrosis is a het erogeneous gr oup o f her editary conditions in w hich t here is a fa ilure of b one resorption by osteoclasts. This decr ease in ost eoclast activity results in g eneralized ost eosclerosis a nd ob literation o f ma rrow spaces and cranial foramina. This r esults in b one brittleness and decreased bone marrow function.

6

138


Clinical features The classical clinical features are: ▬ P athological fractures ▬ V isual impairment ▬ Bone marrow failure There are three major forms of the disease: ▬ M alignant infantile ▬ I ntermediate ▬ Ad ult form

6

The malignant infantile form is a utosomal recessive and clinically most severe with patients suffering from growth retardation and failure to thrive due to bone marrow failure. The ad ult form is mild , occurring in ad ults between 20 a nd 40 y ears o ld. It is a utosomal do minant a nd ma y be dete cted inciden tally. P atients suf fer f rom f requent fractures, which heal with difficulty, and no bone marrow suppression is present.

Imaging Plain radiographs Radiological f indings va ry dep ending o n t he f orm o f disease. The b ones are generally uniformly s clerotic, but alternating sclerotic and lucent bands may be noted in the iliac win gs a nd ne ar t he ends o f lo ng b ones ( ⊡ Fig. 6.5). A b one-within-bone a ppearance ma y b e s een. The entire s kull i s th ickened a nd den se, e specially a t th e ba se. Sinuses a re small a nd under pneumatized. Vertebrae a re extremely radio den se o r ma y sho w al ternating ba nds, known as t he »rugger-jersey« sign. Evidence of fractures or osteomyelitis may be present.

Cross-sectional imaging The diagnosis is made o n plain radiographs but CT a nd MR imaging can aid in the evaluation of facial, skull base, intracranial a nd cra nial ner ve in volvement. I n addi tion, MR imaging can be useful in ass essing the degree of the marrow in volvement in t he maligna nt infa ntile f orm o f the disease.

⊡ Fig. 6.5. Plain radiog raph of the lo wer limbs sho wing generaliz ed increased density of the bones due to osteopetrosis

6.2

Developmental dysplasia of the hip

General information Developmental d ysplasia o f t he hi p (D DH) co mprises a spectrum of abnormality ranging from acetabular dysplasia t o f rank dislo cation o f t he hi p. B reech p resentation, skull mo ulding def ormities a t b irth, neur omuscular disorders, congenital torticollis, congenital f oot def ormities and a fa mily history are risk factors. DDH is b ilateral in up to one-third of patients.

References Tolar, J, Teitelbaum, SL, Orchard, PJ (2004) Osteopetrosis. N Engl J M ed 351: 2839-2849 Stoker DJ (2002) Ost eopetrosis. Semin Musculoskelet R adiol 6(4):299305

Clinical features DDH ca n b e dete cted o n p hysical exa mination b y p erforming the Barlow’s and the Ortolani’s manoeuvre.

6

139

6.2 · Developmental dysplasia of the hip

⊡ Fig. 6.6. Frontal pelvic radiog raph showing a superiorly dislocat ed right hip. Hilgenreiner’s (H) line is a horiz ontal line drawn through the triradiate cartilages and Perkin’s (P) line is perpendicular to Hilgenreiner’s line from the outer edge of the ac etabulum. The normally located femoral head ( F) on the lef t is situat ed inferior and medial t o Hilgenreiner’s and P erkin’s lines r espectively. The ac etabular angle or index (i) is formed by the H ilgenreiner’s line and a line along the ac etabular roof. The right acetabular index is greater than the left

A

Imaging Plain radiographs ▬ Radiographs are not used in the diagnosis of DDH in infants less t han 3 mo nths of age because the unossified epiphyseal cartilaginous portions of the hip joint cannot be visualized ▬ Radiographs ca n b e us ed o nce t he f emoral he ad has ossified which is 3 t o 6 mo nths in f emales and 4 t o 7 months in males. The acet abular index, P erkin’s a nd Hilgenreiner’s lines are used in the evaluation of DDH (⊡ Fig. 6.6)

Ultrasound US is o ptimally p erformed w hen t he pa tient is 4 t o 6 weeks of age, allowing for resolution of physiological hip instabilities t hat ma y o ccur in t he f irst mo nth o f lif e. I n the »dynamic standard minimum examination«, the hip is evaluated in the coronal plane at rest, and in the transverse/ flexion plane both at rest and with the application of stress (⊡ Fig. 6.7). Some use Graf angles to detect dysplasia.

CT A limi ted tw o o r t hree-slice lo w-dose CT ma y b e p erformed within 24 h a fter surgical reduction to check on the reduction.

B ⊡ Fig. 6.7A,B. A Coronal view of the hip showing the femoral head (H) situated within the acetabulum (A). The standard mid-acetabular plane is achieved when there is visualization of a straight iliac line (I) and the point where the iliac bone and triradiat e car tilage join in the medial part of the ac etabulum ( small arr ow). The labrum is also seen ( thick arrow). B Transverse dynamic views of the left (Lt) hip performed prior and after the application of str ess in an att empt to piston the femoral head (H) out of the ac etabulum (A). The hip is stable in this patient. M femoral metaphysis

References Ng SM, Tang APY, Kan PS, Lai YM (1999) Ultrasound of the infant hip . J Hong Kong Coll Radiologists 2: 54-60 Harcke HT, Kumar SJ (1991) The role of ultrasound in the diagnosis and management of congenital dislocation and dysplasia of the hip. J Bone Joint Surg 73A: 622-8

140


6.3

Infection and inflammatory

6.3.1 Osteom yelitis

Anatomy and pathology

6

Osteomyelitis is def ined as inf ection o f t he b one a nd bone ma rrow. Or ganisms sp read via t he blo odstream to lo dge in t he slow-flowing sinusoids in t he met aphyseal r egions o f t he lo ng b ones. I n infa nts, tra nsphyseal v essels ena ble sp read o f t he o rganisms in to t he epiphysis. After 1 year of age, the transepiphyseal vessels close a nd t he inf ection ca nnot cr oss t he gr owth p late. In o lder ado lescent a nd ad ults, f usion o f t he g rowth plate r e-establishes t he vas cular co ntinuity b etween the ep iphysis a nd met aphysis a nd inf ection ma y aga in spread f rom t he met aphysis to t he ep iphysis. S pread of t he inf ective p rocess in to t he j oint ca uses s eptic arthritis. Complications in ost eomyelitis ma y le ad t o gr owth plate da mage wi th subs equent g rowth a rrest a nd deformity. Ot her co mplications inc lude s epticaemia, p ersistent met aphyseal ca rtilage, leg len gthening d ue to chronic h yperaemia, a vascular necr osis, ost eolysis a nd, in rare cas es, systemic a myloidosis. Staphylococcus aureus ca uses gr eater t han 90% o f all cas es acr oss all a ge groups.

Scintigraphy The s ensitivity of T c99m MD P has a n acc uracy o f 90% in det ecting t he presence of ost eomyelitis. O steomyelitis shows incr eased u ptake in all t hree p hases o f t he t echnetium 99m met hylene disp honate (Tc99m MD P) t hreephase b one s can w hich co mprises t he b lood f low (a ngiographic phase), early tracer uptake within bone (blood pool p hase) a nd dela yed u ptake 2 t o 4 h la ter (dela yed phase). C ellulitis o r s oft-tissue inf lammation sho w increased uptake in t he first two phases with normal bone activity in the delayed phase.

Clinical findings ▬ Fever, pain with passive movement, tenderness, swelling, decreased range of movement and erythema over the involved limb are noted ▬ Chronic osteomyelitis may be defined as the presence of bone infection lasting more than 6 weeks. It is clinically e vident with dis charging sinuses at t he affected site and low-grade fever

Plain radiography ▬ Deep soft tissue swelling is the initial finding ▬ Bony cha nges such as oste openia, b ony dest ruction and cortical erosion a re only s een a fter loss o f 30 t o 50% o f b one minera lization a nd diagnosis ma y b e delayed (⊡ Fig. 6.8) ▬ In c hronic ost eomyelitis a mix ed pa ttern o f b ony erosion a nd s clerosis is s een. Thick co rtical la mellar periostitis d ue t o in volucrum f ormation a nd med ullary sclerosis are noted

⊡ Fig. 6.8. Plain X -ray of the right lo wer leg of a newborn sho wing a lucency (arrow) in the distal tibia due t o osteomyelitis

141

6.3 · Infection and inflammatory

Ultrasonography US is able to dete ct soft tissue swelling, thickening of the periosteum and the presence of subperiosteal fluid before plain radiog raphic cha nges a re e vident. I n la ter dis ease, cloaca can also be seen on US.

Computed tomography CT is useful in evaluating the subacute and chronic stages of infection. The sequestra, involucrum, cloaca, abscesses and s oft tissue ext ension o f t he dis ease is w ell ass essed (⊡ Fig. 6.9).

Magnetic resonance imaging The s ensitivity o f MRI f or det ecting a nd e valuating t he extent of osteomyelitis ranges from 88 t o 100%. I nfected marrow is lo w in signal in tensity on T1-w eighted imaging and high on T2-weighted and STIR imaging. Infected marrow enhances after the administration of gadoliniumdiethylenetriamine-penta-acetic acid (G d-DTPA) on T1weighted s equences. Subperiosteal collections, abscesses, cortical t hickening and f ibrotic de vascularized s equestra may be seen. MRI a nd b one s cintigraphy a re eq ually s ensitive in diagnosing early osteomyelitis but MRI is a ble to provide

excellent imag es alb eit wi th incr eased cost. The c hoice between MRI a nd b one s cintigraphy t hus dep ends o n local factors.

References Saigal G, A zouz EM, Abdenour G (2004) I maging of ost eomyelitis with special r eference t o childr en. S emin Musculoskelet R adiol. 8(3):255-65 Blickman JG, van Die CE, de Rooy JW (2004) Current imaging concepts in pediatric osteomyelitis. Eur Radiol. 14 Suppl 4:L55-64

6.3.2 S eptic arthritis

General information Septic a rthritis is a n inf ectious inf lammation o f a jo int. Modes of inf ection inc lude haematogenous spread, contiguous spread from osteomyelitis, direct implantation or post-surgical. The commonest organism is Staphylococcal aureus.

Clinical features ▬ Fever, er ythema a nd jo int sw elling ma y b e s een in infants and older children ▬ Neonatal septic arthritis may be insidious, leading to a delay in diagnosis ▬ The erythrocyte sedimentation rate (ESR), total white blood co unt a nd t he C-r eactive p rotein a re o ften elevated. Blood cultures are positive in less than 40% of cases whereas joint aspirates are positive in up to 60% of cases

Imaging Plain radiographs Plain radiographs may show: ▬ O steomyelitis ▬ Soft-tissue swelling and widening of the joint space ▬ Periarticular osteopenia in later stages

Ultrasound

⊡ Fig. 6.9. Axial C T image of a newborn with ost eomyelitis of the up per metaphyseal r egion of the right humerus with bon y destruc tion (small arrow) and septic arthritis (large arrow)

▬ US is sensitive in the detection of joint effusion but is unable to distinguish between a septic or aseptic effusion (⊡ Fig. 6.10) ▬ US is als o us eful in guidin g needle p lacement jo int aspiration procedures

6

142


References Lee SK , Suh K J, K im YW, R yeom HK , K im YS, Lee JM, Chang Y, K im YJ, Kang DS (1999) S eptic ar thritis v ersus transient syno vitis at MR imaging: preliminary assessment with sig nal intensity alterations in bone marrow. Radiology 211(2):459-65 Malleson PN (1997) M anagement of childhood ar thritis. Part 1: A cute arthritis. Arch Dis Child. 76(5):460-2. Review

6.3.3 Juv enile idiopathic arthritis

General information Juvenile idiopathic arthritis (JIA) is a heterogeneous group of childhood conditions characterized by persistent joint inflammation in one or more joints.

6

Clinical features JIA is def ined by the presence of joint swelling or two of the f ollowing: j oint t enderness, decr eased ra nge o f motion (R OM), pa in on R OM, or joint wa rmth f or at le ast 6 weeks without another cause, in c hildren younger than 16 years of age. ⊡ Fig. 6.10. US of the right hip sho wing an echogenic effusion due t o septic arthritis (arrow)

CT and MRI ▬ Cross-sectional imaging with CT a nd MRI sho uld be used only in more complex cases where evaluation of the surrounding structures is important ▬ Joint ef fusions, syno vial en hancement, sw elling a nd hypertrophy of the joint may also be seen on MRI ▬ Septic a rthritis m ay al so s how s ignal a bnormalities in t he ad jacent b one ma rrow o n fa t-suppressed G dDTPA enha nced T1 a nd o n T2 w eighted imag es. These features are not seen on transient synovitis ▬ CT may show b ony destr uction in cas es due to contiguous spread from adjacent osteomyelitis

Treatment and complications Treatment o f s eptic a rthritis is a n emer gency. C omplications suc h as a vascular necr osis, b ony a nkylosis a nd growth def ormity ma y r esult. Op en sur gical dra inage of the joint or repeated joint aspirations may need t o be carried out.

Classification The classification t ask force in c hildhood rheumatologic disease o f t he I nternational L eague f or R heumatology standardized classification of childhood inflammatory arthritis t o p rovide a s olid basis f or co llaborative r esearch and clinical guidance. JIA has six sub-types: ▬ Systemic a rthritis (extra-a rticular ma nifestations including rash, f ever, l ymphadenopathy, hepatosplenomegaly and serositis predominate at onset) ▬ Oligoarthritis (< f ive jo ints in volved in t he f irst 6 months) – P ersistent – Ext ended ▬ Polyarthritis (five or more joints involved in the first 6 months) – RF -positive – RF -negative ▬ Enthesitis-related a rthritis (inc luding j uvenile a nkylosing sp ondylitis a nd a rthritis ass ociated wi th inflammatory bowel disease) ▬ P soriatic arthritis ▬ Others – t his ca tegory acco mmodates dis ease f itting the definition of JIA but not fulfilling any of the

143

6.4 · Neoplasm

defined sub types o r f itting in to tw o o r mo re o f t he defined subtypes

Imaging Plain radiographs Plain radiographs frequently show the following findings: ▬ Soft-tissue swelling and widening of the joint space ▬ Late st age j oint space na rrowing a nd a nkylosis (⊡ Fig. 6.11) ▬ Articular surface erosions ▬ Peri-articular osteopenia in later stages However, t hese f eatures lac k s ensitivity a nd sp ecificity. Several radio logical gradin g syst ems ha ve b een f ormalized t o s core t he degr ee o f s everity o f radiogra phical findings, but these are limited in c hildren because of the cartilaginous structure of the epiphyses, which may mask the real timing of development of bone erosions

MRI MRI is r ecommended t o mo nitor JI A p rogression a nd response to therapy because of its ability to assess synovial

hypertrophy, soft tissue swelling, articular cartilage, joint integrity and bone marrow changes. Fast sp in-echo T2 o r in termediate-weighted imagin g and 3D-sp oiled gradien t ec ho (S PGR) T1-w eighted s equence with fat supression maximize the contrast between bone and cartilage, allowing for early assessment of cartilage damage. Post-gadolinium T1-weighted images provide information regarding inflamed and proliferated synovium.

Ultrasound US is s ensitive in t he det ection o f jo int ef fusion a nd synovial hypertrophy and is also useful in guiding needle placement in joint aspiration procedures.

Monitoring disease progression Although many centres use plain radiographs to follow up patients with JIA, t here is a n increasing us e of MRI a nd US in t his regard. Patients should be managed on a cas eby-case basis due to the higher cost of these modalities.

References Petty RE, S outhwood TR, M anners P, Baum J , Glass DN, G oldenberg J, He X, M aldonado-Cocco J , Or ozco-Alcala J , P rieur AM, Suar ezAlmazor ME, Woo P (2004) I nternational L eague of A ssociations for Rheumatology. International League of Associations for Rheumatology classification of juv enile idiopathic ar thritis: sec ond revision, Edmonton, 2001. J Rheumatol.31(2):390-2. Gylys-Morin VM, Graham TB, Blebea JS, Dar dzinski BJ, Laor T, Johnson ND, Oestreich AE, Passo MH (2001) Knee in early juvenile rheumatoid arthritis: MR imaging findings. Radiology.220(3):696-706

6.4 Neoplasm 6.4.1 Evaluation of tumour and tumour-like

bony lesions

General Information Evaluation o f b one lesio ns co nsists o f lesio n det ection, characterization, staging, biopsy guidance and identification of residual or recurrent disease post-treatment.

Imaging Plain radiographs ⊡ Fig. 6.11. Plain wrist radiog raph sho wing ank ylosis of the carpal bones (arrow) due to long-standing JIA

Radiographic e valuation o f t he f ollowing c haracteristics provide inf ormation r egarding t he ag gressiveness a nd diagnosis of bone lesions (⊡ Fig. 6.12; ⊡ Table 6.2).

6

144


Evaluation of the lesion matrix may provide evidence of t he tissue o f o rigin. E.g. Cho ndroid t umours usuall y show e vidence of ir regular, punctate ca lcification, w hich may take the shape of rings or arcs. Fibrous dysplasia may give rise to a »ground-glass« density.

CT CT provides t he following information regarding t he lesion a nd is esp ecially us eful in co mplex-shaped b ones such as the spine and pelvis. CT is als o useful in e valuat-

ing t he extent of cortical involvement and breakthrough and matrix calcification.

Scintigraphy Technetium (Tc)-99m-labelled diphosphonate bone scintigraphy is us ed in t he staging of bone tumours to evaluate f or t he p resence o f met astases a nd ski p lesio ns. PET imaging is playing an increasing role in t he evaluation of recurrent or residual disease post-treatment.

6

⊡ Fig. 6.12A,B. A Plain X-ray of the right distal femur showing an aggressive lytic lesion with a wide zone of transition (small arrow) and marked periosteal new bone formation (large arrow) consistent with an osteosarcoma B T1weighted MR image post-administration of Gd-DTPA of the same patient shows marked tumour enhancement within the marrow (small arrow) and extracompartmental spread (large arrow)

A

B

⊡ Table 6.2. Radiographic features of slow, intermediate and aggressive bone lesions Radiographical features

Slow-growing

Intermediate

Fast-growing, aggressive

Pattern of destruction

Geographic well-defined margins

Moth-eaten multiple small 2-5 mm latencies

Pre-emptive - numerous small, diffuse lytic lesions

Margins of the lesion

Well-defined sclerotic edge

Well-defined non-sclerotic edge

Ill-defined

Cortical response

Intact

Trabeculation, endosteal scalloping or expansion

Cortex destroyed

Periosteal reaction

None or solid

Single lamella

Multi-lamellated, speculated, Codman’s triangle

Extra osseous extension

Only occasionally present

May or may not be present

Present

Examples

Simple bone cyst

Langerhans cell histiocytosis

Ewing’s sarcoma, osteosarcoma

145

6.4 · Neoplasm

6.4.2 Langerhan cell histiocytosis

MRI MR imaging is used in the local staging of bone tumours. This is ac hieved by e valuating the extra- o r intramedullary extent of tumour disease (⊡ Fig. 6.12) and the involvement of the adjacent muscle compartments, neurovascular structures, growth plate, skip lesions and joints. Tumours can then be surgically staged using the Enneking system. The Ennekin g sys tem o f surg ical st aging of bone and soft tissue tumors is based on grade (G), si te (T), and met astasis (M) a nd us es histological, radiological, and clinical cr iteria. It is t he most widel y us ed st aging system and has b een adopted by the Musculoskeletal Tumour Society (⊡ Table 6.3). ▬ Gr ade – G0 – benign lesion – G1 – low-grade malignant lesion – G2 – high-grade malignant lesion ▬ Si te – T0 – benign intracapsular and intracompartmental lesion – T1 – intracompartmental lesion – T2 – extracompartmental lesion ▬ M etastasis – M0 – no regional or distant metastasis – M1 – regional or distant metastasis The surgical stage of the tumour determines management.

References O’Donnell, P (2003) E valuation of f ocal bone lesions: basic principles and clinical scenarios. Imaging 15: 298-323 Teo HE, P eh WC (2004) The role of imag ing in the stag ing and tr eatment planning of primary malignant bone tumors in children. Eur Radiol.14(3):465-75

⊡ Table 6.3. Enneking system for surgical staging of malignant bone and soft tissue tumours Stage

Grade

Site

Metastasis

IA

G1

T1

M0

IB

G2

T2

M0

IIA

G2

T1

M0

IIB

G2

T2

M0

III

G1 or G2

T1 or T2

M1

General information Langerhans cell histiocytosis (LCH) is a group of idiopathic disorders c haracterized by t he proliferation of sp ecialized bone marrow-derived L angerhans cells (L Cs) and mature eosinophils. The peak incidence is between 1 and 4 years.

Clinical features There are three clinical variants of LCH known as eosinophilic gra nuloma (EG), L etterer-Siwe dis ease (LS) a nd Hand-Schüller-Christian (HSC) disease: ▬ EG is a b enign, indo lent f orm a ffecting c hildren b etween t he ag es o f 5 a nd 15 y ears. A sin gle o r a f ew skeletal lesions are seen. The most commonly affected sites a re t he sk ull, ma ndible, sp ine, r ibs a nd lo ng bones. Patients may present with local pain, swelling and tenderness or pathological fractures. ▬ LS is a n ac ute, f ulminant f orm a ffecting c hildren less t han 2 ye ars of age. It is char acterized b y he patosplenomegaly, l ymphadenopathy, skin lesio n, o titis media, l ung in volvement, a naemia, leuk openia a nd thrombocytopenia. ▬ HSC is a n in termediate c linical f orm a ffecting c hildren between the ages of 2 and 10 years. This form is characterized by multifocal, chronic involvement and classically presents as t he tr iad of dia betes in sipidus, proptosis and lytic bone lesions.

Imaging Plain radiographs ▬ Early st age sk eletal lesio ns ha ve a n ag gressive, p ermeative a ppearance. I n la ter st ages t hey a ppear as well-defined, p unched o ut, l ytic lesio ns wi th li ttle periosteal reaction. Surrounding sclerosis is seen only in the healing stage of the disease. ▬ Widespread oste opaenia, co rtical t hinning a nd t rabeculae p rominence ma y b e s een in dif fuse b ony involvement ▬ A lesion with a beveled edge may be seen in the skull vault due to dif ferential destr uction of the inner a nd outer tables of the skull vault. A b utton sequestion is a des cription gi ven t o a r ounded l ytic lesio n wi th a central area of intact bone ▬ A solitary collapsed vertebral body known as vertebra plana is characteristic of LCH (⊡ Fig. 6.13)

6

146


Once t he diagnosis is ac hieved, sk eletal sur veys a nd/or bone scintigraphy should be performed to determine the extent of skeletal involvement.

Scintigraphy Although most authors believe that the method of choice is the skeletal survey, the improvements in t he quality of gamma ca meras a nd imagin g t echniques have produced better r esults in r ecent r eports. B oth met hods a re co mplimentary.

Cross-sectional imaging

6

CT and MRI are used to better evaluate the extent of bony destruction, extra-compartmental soft-tissue involvement and to stage the lesions. The skeletal destruction is better demonstrated on CT w hilst bone marrow and soft-tissue involvment is b etter demo nstrated o n MRI. L esions a re

typically low in signal in tensity on T1-weighted imaging, high in S TIR and T2-weighted imaging and demonstrate enhancement a fter t he administra tion o f gado linium. Healing lesions show a decrease in signal intensity on T2weighted images, with resolution of the soft-tissue swelling and decreased enhancement after the administration of gadolinium.

Prognosis Patients with EG ha ve an excellent prognosis. The p rognosis in pa tients wi th HSC is r elated t o t he ext ent a nd areas of involvement. The prognosis in patients with LS is poor with most dying within 1 to 2 years.

References Azouz EM, Saigal G, Rodriguez MM, P odda A (2005). Langerhans ’ cell histiocytosis: pathology , imag ing and tr eatment of skeletal involvement. Pediatr Radiol 35(2):103-15 Kilborn TN, Teh J , G oodman TR (2003) P aediatric manif estations of Langerhans c ell histioc ytosis: a r eview of the clinical and r adiological findings. Clin Radiol 58(4):269-78

6.5 T

rauma

6.5.1 P aediatric fractures

General information Musculoskeletal in juries acco unt f or 12% o f paedia tric visits to the emergency department, with fractures making up a large proportion of these numbers. Paediatric b one is mo re elast ic t han ad ult b one a nd can bend without breaking. This r esults in uniq ue childhood fractures such as the plastic deformation, torus and greenstick fractures. Fractures extending into the physeal plate may cause growth arrest, and angular deformity may result. Fractures involving the physis have been classified and described by Salter and Harris.

Types of paediatric fractures Plastic deformation of bone/torus/greenstick/ complete diaphyseal fractures

⊡ Fig. 6.13. Lateral neck radiograph showing vertebra plana of the C3 vertebral body (arrow)

▬ Plastic deformation occurs as a result of longitudinal compression o f a lo ng b one. W ith incr easing f orce, microfractures o ccur a nd t he b one t hen los es its capacity to regain its original shape and remains bowed.

147

6.5 · Trauma

This f racture o ccurs most co mmonly in t he radi us and ulna ▬ Torus fractures are also known as buckle fractures and are inco mplete f ractures o ccurring o n t he co ncave side of the bone with outward buckling of the cortical margin. These fractures occur most commonly in the metaphyseal regions of long bones (⊡ Fig. 6.14) ▬ A greenstick fracture is an incomplete fracture occurring only on the convex side of the long bone

A

▬ A co mplete f racture o ccurs w hen t he f racture line propogates co mpletely t hrough t he b one a nd most commonly involve the diaphyseal region

Physeal fractures The Salter-Harris classification of physeal fractures is t he most widel y accep ted c lassification a nd it relates t he radiological appearance of physeal fractures with treatment and morbidity (⊡ Table 6.4).

⊡ Fig. 6.14A,B. AP and lateral views of the left wrist showing a torus fracture of the anterior radial aspect of the distal radius (arrow)

B

⊡ Table 6.4. Salter-Harris classification of growth plate fractures associated with age of occurrence, fracture line, site of involvement and prognosis Type

Age (years)

Mechanism

Fracture line

Site

Prognosis

I

Paediatric Imaging Manual (Notes in Radiology)

Paediatric Imaging Manual

Percutaneous Tumor Ablation in Medical Radiology (Medical Radiology Diagnostic Imaging)

Urogenital Imaging (Direct Diagnosis in Radiology)

Radiology Review Manual

Cardiac Imaging (Direct Diagnosis in Radiology)

Emergency Radiology: Imaging and Intervention

Radiology Review Manual

Musculoskeletal Imaging Cases (McGraw-Hill Radiology)

Diagnostic Nuclear Medicine (Medical Radiology Diagnostic Imaging)

Learning Vascular and Interventional Radiology (Learning Imaging)

Textbook of Radiology and Imaging (Vol. 1)

Textbook of Radiology and Imaging (Vol. 2)

Clinical PET-CT in Radiology: Integrated Imaging in Oncology

Pediatric Radiology Review (Contemporary Medical Imaging)

Radiologia-Radiology-Advanced Imaging Of The Abdomen

Radiology Fundamentals: Introduction to Imaging and Technology

Essential Radiology: Clinical Presentation Pathophysiology Imaging

The Manual of Paediatric Feeding Practice

Gastrointestinal Imaging: The Requisites (Requisites in Radiology) 3rd ed

Case Studies in Medical Imaging: Radiology for Students and Trainees

Radiology

Radiology

Paediatric Anaesthesia (Problems in Anaesthesia)

Paediatric Neurosurgery

Paediatric Radiography

Paediatric Handbook

Paediatric Dentistry

Restorative Techniques in Paediatric Dentistry

Paediatric Imaging Manual (Notes in Radiology)