Paediatric Imaging Manual

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

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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 different treatments. The same is true where imaging is concerned. The diagnostic strategies – using identical diagnostic instruments – are different; the 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 during their studies. Understandably, paediatricians lack not only the ability to interpret the images, but also knowledge about the importance of a finding for the next step 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 aim of this book, therefore, is to provide readily available information, limited to 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 strategies used for children differ from those used for adults in many respects. One of the most important aspects is radiation protection, as children are particularly sensitive to ionizing radiation and, with their longer life expectancy, can also expect to accumulate a higher dose from natural and artificial – above all medical – causes. The latter increase the individual risk (malignant disease) as well as the genetic risk. The best radiation protection is the avoidance of an examination employing ionizing radiation (X-rays, CT scan). This is accomplished, on the one hand, by establishing strict 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 also a physical 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 increasing value of ultrasonography in paediatric 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 replaced the X-ray for diagnosing hip dysplasia or luxation in an infant. MRI can replace CT in most cases 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 which an examination with ionizing radiation is performed. In paediatric radiology, a p.a. or an a.p. image of the thorax provides sufficient clinically necessary information in 70–80% of cases. The request 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 entirely possible to accept a reduction in image quality, as long as the diagnostic certainty is not diminished. Necessary CT examinations must be performed according to a protocol adapted to the child’s age, with a lesser dose. Active radiation protection is of essential importance for children and adolescents. The protective measures should not lead to a reduction in diagnostic reliability, however. X-rays and CT remain an indispensable component of imaging for children. Without them, modern medicine, in particular emergency medicine, would be unthinkable. Thus it is not a matter 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 or above the urinary bladder in a girl represents an ovarian cyst with or without internal bleeding. This finding 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 country. 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 well-founded; elsewhere an X-ray examination – naturally using extremely radiation saving pulsed fluoroscopy – is favored. The scientific discussion has not yet been concluded. However, it should not be allowed to become a purely economic discussion. We thank the authors for the high-quality manuscripts they provided. We also thank Springer-Verlag – and especially Mr. Henquinet – for 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

Peter Seidensticker Berlin

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 children. . . . .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 AP AV CBF CBV CDI CF CNS CT DTI DWI ECG ECMO ED ERCP FLAIR FNH Gd-DTPA GI GN HCC HIV HRCT IL IVC IVP LIH MDCT MIBG MR MRA MRCP MRI MRS MRU mSv NEC NSF PNET PVL

American Academy Of Pediatrics As-Low-As-Reasonably-Achievable Anterior-Posterior Arterio-Venous Cerebral Blood Flow Cerebral Blood Volume Colour Doppler Imaging Cystic Fibrosis Central Nervous System Computer Tomography Diffusion Tensor Imaging Diffusion-Weighted Imaging Electro Cardiogramm Extracorporal Membrane Oxygenation Effective Dose Endoscopic Retrograde CholangioPancreaticography Fluid-Attenuated Inversion-Recovery Focal Nodular Hyperplasia Gadoliniumdiethylenetriamine-PentaAcetic Acid Gastro-Intestinal Glomerulonephritis Hepatocellular Carcinoma Human Immunodeficiency Virus High-Resolution CT Interleukin Inferior Vena Cava Intravenous Pyelogramm Last-Image-Hold Multidetector CT Meta-Iodobenzylguanidine Magnetic Resonance Magnetic Resonance Angiography Magnetic Resonance CholangioPancreaticography Magnetic Resonance Imaging Magnetic Resonance Spectroscopy Magnetic Resonance Urography Millisievert Necrotizing Enterocolitis Nephrogenic Systemic Fibrosis Primitive Neuroectodermal Tumours Periventricular Leucomalacia

PW Doppler PWI RDS RI SPECT SPGR SPIR STIR Tc Tc99m MDP TNF TSE US VCUG VCUS VIBE VUR

Pulsed Wave Doppler Perfusion-Weighted Imaging Respiratory Deficiancy Syndrom Resistive Index Single Photon Emission Computed Tomography Spoiled Gradient Echo Selective Partial Inversion Recovery Short Inversion Recovery Technetium Technetium 99m Methylene Disphonate Tumour Necrosis Factor Turbo Spin Echo Ultrasonography Voiding Cystourethrogram Contrast-Enhanced Voiding Cysturosonography Volumetric Interpolated Breath-Hold Examination (Mr) Vesicoureteral Reflux

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

1.1

Introduction

Radiation is ubiquitous. It comes from many sources, including cosmic radiation as well as radon exposure. This natural or background exposure is the 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, it has been a dramatic and increasing influence on health-care. Medical radiation is also of central importance for another reason. Because radiation has bio-effects, for example as a known carcinogen (this was recognized as such very early in the 20th century), medical providers must understand the potential risks of radiation in medical imaging. 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, doses of medical radiation, risks of medical radiation and outline strategies to manage radiation dose.

1.2

other effects. Some of these disruptions can be repaired, others cannot. With high levels of radiation, there is cell death. With lower levels of radiation, the cell does not die, but a variety of mechanisms (including alteration of DNA and regulatory mechanisms) may be disrupted, resulting in unregulated and abnormal tissue growth, or cancer. This cancer development is probably a multistep process. The implication is that many changes are required rather than just an effect at a single step. It is worthwhile emphasizing that rapidly developing tissues, such as in children, 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 are more radiosensitive than adults (at least two times) ▬ Children have a longer lifetime to manifest radiationinduced cancer ▬ For equal amounts of radiation, the deposition in children’s tissues can be higher than adults

Mechanisms of radiation injury 1.3

Radiation includes heavy particles as well as X-rays (photons). Photons are high-energy particles which, as they pass through tissue, interact at the nuclear level, causing ionizations. Ionizations can result in disruption of DNA, among

Doses of medical radiation

Radiation dose can be measured in several ways [1]. For purposes of this discussion, the effective dose (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

▬ Fluoroscopic cystogram

1 h) reactions depending on the time of occurrence. Delayed adverse reactions are usually self-limited and minor. In the majority of cases they are clinicaly present as skin reactions. The main difference reported between the type of adverse events following ionic and non-ionic contrast agents is related to extravasation. Extravasation of ionic contrast agents can, because of their hyperosmolality and ionicity, be associated with skin necrosis and sloughing.

Immediate adverse reactions ▬ Mild – self-limited without evidence of progression – Hives, nasal stuffiness, itching, headache, shaking, dizziness, nausea, vomiting, pallor ▬ Moderate – requiring treatment and careful observation for progression – Tachycardia, bradycardia, hypertension, hypotension, dyspnoea, bronchospasm, mild laryngeal oedema, urticaria ▬ Severe – requiring hospitalisation – Severe laryngeal oedema, convulsions, profound hypertension, profound hypotension, unresponsiveness

Some of the adverse events (e.g. headache, dizziness, nausea) are very difficult to record or even impossible to recognize in children, particularly in newborns and infants. They may be only expressed by anxiety and weeping. Therefore very young children need to be carefully monitored following any contrast-enhanced diagnostic procedure; changes in normal or usual behaviour 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 case of severe adverse reactions the anaestesiological emergency team should be called immediately and perform the first line treatment. Most severe and fatal adverse reactions (94–100%) occur within 20 min of contrast medium administration. Thus the first-line drugs and equipment should be readily available in rooms 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 the amount of contrast media to the body weight of the child ▬ Do not perform multiple studies with contrast media within a short period of time ▬ Consider alternative imaging techniques, which 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 harmless reactions e.g. nausea may result 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. Adrenaline 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. Intravenous fluids 4. If unresponsive: adrenaline 5. Corticosteroids Vagal reaction (hypotension and bradycardia) 1. Elevate child’s legs 2. Oxygen by mask (6–10 l/min) 3. Atropine intravenously 4. Intravenous fluids 5. Corticosteroids 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. Intramuscular adrenaline 6. Intravenous fluids 7. H1-blocker 8. β-2-agonist dose inhaler

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

The choice of imaging modality should always be strictly related to the clinical question to be answered. This is true in medicine in general, but particularly in paediatric patients, who are generally more sensitive to pharmacotoxicity and radiation and require special care. It should be remembered that often diagnostic imaging in children requires sedation, which increases the risk of side effects. Therefore it should be always considered whether the imaging method with the application of contrast medium is really necessary, and if it is the only possibility, the least invasive and risky diagnostic modality ought to be chosen.

References 1. ACR Practice guideline for the performance of pediatric contrast enema examinations, 1997 (res. 26), Revised 2001 (Res. 28) 2. ACR Practice guideline for the performance of pediatric contrast examinations of the upper gastrointestinal tract, 1997 (res. 25), Revised 2001 (Res. 29) 3. Auger JA (2001) Use of contrast material in pediatric magnetic resonance imaging. Applied Radiol (suppl) 23-29 4. Bhalla S, Siegel MJ, Multislice computed tomography in pediatrics. (2002) In: Silverman PM (Ed.), Multislice computed tomography. Lippincott Williams and Wilkins, ISBN: 0-7817-3312-X, pp 231-282 5. Board of the Faculty of Clinical Radiology, The Royal College of Radiologists (1996) Advice on the management of reactions to intravenous contrast media. London: Royal College of Radiologists 6 6. Cohen MD (1993) A review of the toxicity of nonionic contrast agents in children. Invest Radiol 28(suppl):87-93 7. Darge K, Bruchelt W, Roessling G, Troeger J (2003) Interaction of normal saline solution with ultrasound contrast medium: significant implication for sonographic diagnosis of vesicoureteral 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, Frush DP (2003) Pediatric multidetector body CT. Radiol Clin North Am 41:637-655 10. Hollingsworth C, Frush DP, Cross M, Lucaya J (2003) Helical CT of the body: a survey of techniques used for pediatric patients. AJR 180:401-406 11. Katayama H, Yamaguchi K, Kozuka T, Takashima T, Seez P. Matsuura K (1990) Adverse reactions to ionic and nonionic contrast media: a report from the Japanese Committee on the Safety of Contrast Media. Radiology 175:621-628 12. Kopitzko A, Cornely D, Reither D, Wolf KJ, Albrecht T (2004) Low contrast dose voiding urosonography in children with phase inversion imaging. Eur Radiol 14:2290–2296 13. Morcos SK, Thomsen HS (2001) Adverse reactions to iodinated 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) Off-label use and reimbursement of contrast media in MR. J Magn Reson Imaging 10:489-495 16. Runge VM, Parker JR (1997) Worldwide clinical safety 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 following intravascular administration of contrast media. Acta Radiol Diagn 26:457-461 19. Thomsen HS (2003) Guidelines for contrast media from the European Society of Urogenital Radiology; AJR 181:1463-7120 20. Thomsen HS, Morcos SK (2004) Management of acute adverse reactions to contrast media, Eur Radiol 14:476–481 21. Weissleder R, Rieumont MJ, Wittenberg J (1997) MR contrast 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 General information

Developmental anomalies result from an erroneous organogenesis, histiogenesis or cytogenesis of the central nervous system (CNS). Etiology is multifactorial including inherited or spontaneous genetic defects, intra-uterine destructive events, ischemia, infections and environmental agents. Developmental anomalies belong to the most frequent congenital malformations (1:100 births). The spectrum of malformations is wide, ranging from tiny focal cortical dysplasias to complex cerebral syndromes. Cerebral anomalies frequently have a significant impact on child development. An early 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-ray is of limited value to identify, characterize or classify cerebral malformations. In selected

syndromes the shape and ossification patterns of the skull can be helpful. The skull may predict the brain. Typically, a frontal and a lateral view are sufficient. In rare cases a town view (occipital) may be helpful.

Ultrasound Imaging technique Ultrasonography (US) can be used as a first-line imaging modality in neonates. The anterior fontanelle serves as acoustic window. Typically, coronal and sagittal views covering the entire brain are acquired. The posterior or temporal fontanelles allow additional views. The posterior fossa can be assessed by using a suboccipital view through the foramen magnum. Duplex sonography can be used to evaluate the circle of Willis. A 5.0–7.5 MHz curved or linear array transducer has to be used. A major advantage is that the neonates can be examined at the bed side usually without the need for sedation. A disadvantage is that US is rarely capable of identifying the exact extent of malformation, that cortical malformations are usually outside of the field of view and that tiny migrational abnormalities as well as myelination disorders are missed.

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Chapter 3 · Head and Neck

Possible findings

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▬ Hydrocephalus (symmetrical or asymmetrical) ▬ Midline defects (e.g. callosal agenesis or dysgenesis) ▬ Disorders of diverticulation or cleavage disorders (e.g. holoproscencephaly) ▬ Cerebral clefts (schizencephaly) ▬ Arachnoid 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 for examining cerebral malformations. Modern multislice CT scanners with isotropic three-dimensional data acquisition allow multiplanar reconstructions. Multiplanar reconstructions are essential to study complex malformations. Most cerebral anomalies can be identified satisfactorily by CT. Compared to MRI, the limited image contrast between white and grey matter may, however, prevent identification of subtle migrational disturbances. In addition, the use of ionizing radiation is a major disadvantage in the paediatric patient population. The use of intravenous contrast media has no value in examining cerebral malformations. The only exception is the evaluation of cerebral vascular malformations.

Possible findings All previously mentioned US findings can be identified by CT. The increased anatomical detail frequently allows a better delineation and characterization of the malformation. In particular, posterior fossa malformations are better identified by CT. The identification of subtle migrational anomalies or cortical organization disorders (e.g. polymicrogyria, pachygyria) may, however, be limited. In cases where CT findings do not explain neurologic findings, MRI should be performed. Finally, CT is limited in evaluating disorders of myelination.

Magnetic resonance imaging Imaging technique MRI offers the highest multiplanar spatial resolution in combination with a lack of ionizing radiation. Depend-

ing on the degree of cerebral maturation or myelination, T2- or T1-weighted sequences should be acquired. T2weighted sequences are especially advantageous in neonates and young children because the brain is still very »watery«. Typically, a slice thickness of 2–3 mm should be used. If available, functional imaging sequences like diffusion tensor imaging (DTI) or magnetic resonance spectroscopy (MRS) can 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 very sensitive to identify cortical malformations adjacent to the skull as well as to subtle migrational abnormalities within the white matter. Associated disorders of myelination can be assessed visually by using T1- and T2-weighted sequences or quantified by DTI and MRS. A minor disadvantage is that MRI is less sensitive for calcifications that may accompany migrational abnormalities. If calcifications are suspected T2*-weighted sequences should be added.

3.1.3 Diagnosis

Diagnosis relies on high-resolution neuroimaging. In the evaluation of developmental anomalies of the CNS, each radiologist should be aware that finding one lesion/malformation means looking for additional malformations. Frequently, the most obvious lesion is just the tip of the iceberg. Key information

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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), coronal (B), axial (C, D) T2-FSE MRI, axial fractional anisotropy map (E) and axial maximum-intensity 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 tracts connecting the anterior hemispheres. The fractional anisotropy map clearly visualizes the hyperintense white-matter

3.2

Hypoxic-ischemic encephalopathy in neonates

tracts that connect the frontal lobes while the posterior hemispheres are divided (small arrows). The anterior part of the ventricular system is deformed/narrowed. MRA shows the associated anomalous development of the circle of Willis with an unpaired anterior cerebral or azygos artery (arrowhead). The combined anatomical (MRI) and functional information (DTI and MRA) allow identification of the exact extent of cerebral anomaly

3.2.2 Imaging

Conventional X-ray 3.2.1 General information

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 well as the identification of the principal and supporting or mediating factors that determine the severity of brain injury are the focus of 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 the degree and extent of injury as early as possible in order to guide and monitor treatment (e.g. neuroprotection).

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 the sagittal and coronal plane. Care should be taken that the transducer is placed at the centre of the fontanelle. This will allow a symmetrical coronal view of the brain and prevents artefactual differences in the echogenity of the cerebral hemispheres. Duplex sonography allows examining the patency of the major arterial and venous intracra-

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

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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) ▬ Narrowed subarachnoid space ▬ Narrowed intracranial arteries ▬ Increased RI values ▬ Accompanying subependymal hemorrhages In the chronic phase ▬ Periventricular hypochogenic cysts (cavitations) ▬ Global 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 are rarely indicated. Different windowlevel setting can be useful to enhance identification of subtle HIE-related density changes.

Possible findings In the acute setting, CT as compared to US, is less sensitive for identifying subtle HIE-related global white matter injuries. The cortico-medullary junction may be obscured due to a hypodensity of the cortical ribbon or basal ganglia in HIE. Small intraparenchymal petechial hemorrhages or thrombosed intramedullary vessels appear 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 frequently the periventricular white matter is affected 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 ventriculomegaly with widening of

the subarachnoid space. The cortical ribbon may reach and impress the ventricles, resulting in a characteristic undulated margin of the ventricles. In addition, multiple periventricular hypodense cysts (periventricular leucomalacia, PVL) may be seen. If the basal ganglia were affected, the basal ganglia are frequently atrophic with disperse hyperdense calcifications.

Magnetic resonance imaging Imaging technique MRI is the preferred imaging modality in HIE. T2- and T1-weighted MR sequences (3 mm slice thickness) should be acquired. The T2-weighted sequences will show the anatomy best. T1- or T2*-weighted sequences are especially sensitive for petechial hemorrhages. Functional sequences including diffusion-weighted imaging (DWI) with reconstruction of apparent diffusion coefficient (ADC) maps are mandatory. DWI with ADC maps allows differentiating between potentially reversible vasogenic 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 cortical highlighting following the cortical ribbon is seen due to intracortical petechial hemorrhages. This T1 hyperintensity is matched by a T2 hypointensity. Additional cortical necrosis will result in a diminished corticomedullary differentiation. Moreover, signal alterations are seen within the basal ganglia/thalamus, hippocampus and posterior limb of the internal capsule (PLIC) (⊡ Fig. 3.2). Especially the loss of the normal T1-hyperintense signal of the white matter tracts within the PLIC has been shown to correlate with the degree of hypoxicischemic injury and outcome. On T2-weighted imaging a corresponding loss of the T2 hypointensity is observed. Finally, in many cases a linear, centripetal T2 hypo- and, T1 hyperintensity is seen 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 between cytotoxic oedema and vasogenic

17 3.2 · Hypoxic-ischemic encephalopathy in neonates

⊡ Fig. 3.2A-H. Preterm neonate (A–D) and term neonate (E–H) with severe perinatal asphyxia. In both neonates a series of T2-weighted FSE (A,E), T1-weighted SE (B,F), DWI (C,G) and ADC-maps (D,H) are presented. In the preterm neonate an asymmetric hypoxic ischemic injury to the hemispheric white-matter (arrow) (DWI-hyperintense, ADC hypointense) is seen in combination with injury of the white matter

tracts within the splenium of the corpus callosum and posterior 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 predominantly injury to the thalami and basal ganglia (arrowhead). The hemispheric white matter is spared. DWI is especially helpful due to its high lesion conspicuity

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oedema (⊡ Fig. 3.2). The quantitative analysis of the ADC values is especially helpful in global HIE. In chronic HIE, similarly to the CT findings, a focal or global volume loss of the white matter is observed. Periventricular cysts are easily identified. Disperse calcifications within the basal ganglia may appear T1-hyperintense.

Key information

3.2.3 Diagnosis

▬ DWI differentiates between cytotoxic and vasoge-

Diagnosis relies on the 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, congenital infections or malformations should be excluded. In addition, dual injury should be considered in complex or unexplained cases of neonatal encephalopathy. The combination of anatomical and functional MRI data progressively helps determining therapy and 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 intraparenchymal 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

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3.3

Intracranial hemorrhage in neonates


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Intracranial hemorrhage is one of the most common causes of acute focal neurological symptoms (e.g. seizures) in neonates. Multiple factors including location, extension and etiology of hemorrhage determine morbidity and mortality. Intracranial hemorrhages in neonates occur most frequently within the germinal matrix. The germinal matrix is a highly perfused site of neuronal proliferation. The germinal matrix is located along the lateral ventricles and is highly vulnerable for stress-related hemorrhages (e.g. perinatal hypoxia). Germinal matrix hemorrhages (GMH) are the most frequent 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 disorders. Extracerebral subarachnoidal, subdural and epidural haematomas may result from a traumatic birth.

3.3.2 Imaging

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

Ultrasound Imaging technique US is the primary modality to examine GMH. Coronal and sagittal views of the neonatal brain are acquired with a 5.0–7.5 MHz curved or linear array transducer through the anterior fontanelle (⊡ Fig. 3.3). Hemorrhages within the posterior fossa are very rare, suboccipital views are consequently seldom necessary. Serial examinations are mandatory to identify GMH complications like a hydrocephalus 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 are located at the level of the foramen of Monroi ▬ GMH extension into the choroid plexus will enlarge the plexus ▬ Venous infarction shows a fan-shaped hyperechogenity of the cerebral white matter on coronal views ▬ Complicating haemorrhagic transformations of venous 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 are classified into three grades: grade I: subependymal hemorrhage limited to the GM; grade II: intraventricular hemorrhage in which less than 50% of the ventricular volume is affected; grade III: intraventricular hemorrhage in which more than 50% of the ventricular volume is affected (⊡ Fig. 3.3). In previous classifications a grade-IV hemorrhage was defined as a GMH with extension into the adjacent cerebral hemispheres. This kind of neonatal hemorrhage is nowadays classified as »haemorrhagic venous infarction«. These hemorrhages result from an obliteration/compression of the subependymal deep venous system. The resulting venous stasis is believed to be causative for the frequently haemorrhagic venous cerebral infarction.

Computed tomography Imaging technique In general MRI is more sensitive than CT. Axial CT with 3–4-mm slice thickness is usually sufficient to identify GMHs and their complications. Intravenous contrast media are rarely necessary. However, if the etiology of hemorrhage is unclear, a contrast-enhanced sequence should be considered to rule out tumour, vascular malformation or dural venous thrombosis. CT is less sensitive than US to 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 suspected pathology within the posterior fossa (brainstem and cerebellum). Finally, in cases 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

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⊡ Fig. 3.3A,B. Coronal (A) and sagittal (B) US examination of the brain in a 3-day-old premature boy (29 weeks of gestation). US reveals a focal hyperechoic germinal matrix hemorrhage (grade II) with extension into the enlarged choroid plexus of the right lateral

ventricle (arrows). The sagittal view shows the extension of the GMH. In addition, the ventricles are enlarged with a hyperechoic lining indicating intraventricular hemorrhage. The gyration pattern is premature (29 weeks)

Possible findings

Possible findings

Hyperacute GMHs are isodense to normal brain tissue. Progressive blood clot retraction increases GMH density during the acute and early subacute phases, while 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 the hyperacute stage GMH is T1-iso or hypointense and T2 hyperintense; in the acute stage T1-iso or hypointense and T2 hypointense, in the early subacute stage T1-hyperintense and T2 hypointense, in the late subacute stage T1 and T2 hyperintense and finally in the chronic phase T1 hypointense and T2 centrally hyperintense surrounded by a rim of hypointensity (hemosiderin). On T2*-weighted sequences the GMH is strongly hypointense, in the case of an intraventricular extension the ventricular linings are frequently T2* hypointense. On DWI an acute venous ischemia frequently shows a mixed pattern of vasogenic and cytotoxic oedema. On PWI an increased CBV with a reduced CBF and a prolonged MTT may be observed.

Magnetic resonance imaging Imaging technique MRI is widely accepted as the most sensitive imaging modality to identify intracranial hemorrhage in general and GMH in particular. T1- and T2-weighted sequences should be combined with T2*-weighted sequences. Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) may be completed to increase sensitivity and specificity of findings. DWI and PWI are especially helpful in examining venous infarction.

3.3.3 Diagnosis

Clinically, GMH should be suspected and ruled out in preterm and term neonates who present with seizures, al-

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tered consciousness, bulging fontanelle, progressive head circumference or any kind of acute focal neurological deficit. GMHs are easily identified on US, CT or MRI. Imaging should identify secondary complications like hydrocephalus or haemorrhagic venous infarction. US is the primary imaging modality of choice. CT or MRI should be considered if US findings do not explain neurology. CT or MRI are indicated in neonatal hemorrhages other than GMH. Key information

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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

Cerebral infections


Most congenital cerebral infections results from infectious agents that are known by the TORCH acronym. They include Toxoplasmosis, Other (HIV), Rubella, Cytomegalovirus and Herpes simplex. Neonatal Herpes simplex type-II infection is typically acquired during birth while passing an infected birth canal. Pre- and postnatal Herpes simplex-II infections are rare. In the case of a complicating meningoencephalitis, prognosis is poor. Extensive perivascular infiltrates with ischemic and haemorrhagic infarction are usually fatal. Intra-uterine infections may interfere with normal brain development. Timing of infection in relation to the gestational age determines

the extent and kind of injury. Early in pregnancy, developmental brain anomalies occur with different degrees of migrational disturbances, microcephaly, cerebellar and brainstem hypoplasia as well as injuries/malformations of the eyes and inner ear. 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 structures into (1) parenchymal infections, (2) meningitis and (3) ventriculitis. Herpes simplex-I encephalitis is one of the most frequent acquired cerebral infections in children 6 months and older. Prognosis is frequently poor if not diagnosed and treated early. Usually a severe, necrotic haemorrhagic meningoencephalitis develops. The temporal lobes are predominantly affected. Meningitis can result from different organisms. The most frequent include Haemophilus influenzae and Streptococcus pneumoniae. Epidural empyemas, associated cerebral affection (meningoencephalitis) or septic dural sinus thrombosis are frightening complications. Ventriculitis frequently results from shunt placements.

3.4.2 Imaging

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

Ultrasound Imaging technique Coronal and sagittal views of the neonatal brain are acquired with a 5.0–7.5 MHz curved or linear array transducer through the anterior fontanelle. Duplex sonography may be helpful to differentiate between thalamic/basal ganglia calcifications and prominent thalamostriate vessels. In addition, complicating dural sinus thrombosis can be excluded.

Possible findings ▬ ▬ ▬ ▬ ▬ ▬

Periventricular and/or cortical calcifications Thalamic or basal ganglia calcifications Prominent 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 identify calcifications (⊡ Fig. 3.4) or hemorrhages (e.g. Herpes encephalitis). Postcontrast images may identify lesions with a disrupted blood-brain barrier, indicating active inflammation as well as a ventriculitis. Diagnosis of meningitis may be difficult on CT because an increased meningeal enhancement may be obscured by the overlying hyperdense skull. Postcontrast images are necessary to rule out complicating dural sinus thrombosis and will increase sensitivity for identifying subdural or epidural empyemas. Bone windows are necessary to study complicating inner ear 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 ▬ Encephaloclastic lesions ▬ Migrational disturbances (e.g. polymicrogyria, lissencephaly) ▬ Cerebellar and brain-stem hypoplasia ▬ Microcephaly ▬ Ventriculitis/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-weighted images are very useful to study active encephalitis, ventriculitis and meningeal inflammation. 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 dys- or de-myelination (⊡ Fig. 3.4). Alternatively, a T1-weighted inversion recovery sequence can be used. Magnetic resonance venography can be added to study patency of the dural sinuses. Diffusion-weighted imaging is very helpful for identifying active areas of inflammation (vasogenic oedema) as well as complicating ischemic (cytotoxic oedema) areas.

Possible findings

⊡ Fig. 3.4A-D. Axial non-enhanced CT (A) shows disperse cortical subcortical calcifications due to a cerebral toxoplasmosis infection. No migrational abnormalities are seen because infection occurred after completed migration. The second case (B) of a proven intra-uterine toxoplasmosis infection reveals on axial T2-weighted FSE extensive migrational abnormalities with lissencephaly and a double cortex. In addition, the ventricles are enlarged. The third case shows disperse hyperdense subcortical and white-matter calcifications on a non-enhanced CT (C) in a child with rubella infection. 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 to CT, higher sensitivity for migrational 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

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3.4.3 Diagnosis

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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 the 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 remain the first line imaging modality. If possible, MRI should follow US. Key information

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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 conspicuity ▬ DWI allows to differentiate between vasogenic and cytotoxic oedema ▬ MR venography should be added if dural 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 just small adults« is especially true for head injury. The kind of injury is related to the age of the child; TBI in children younger than 2 years result most frequently from falls, while in children older than 2 years, motor vehicle accidents are more frequent. The age of the child is also related to the location of force impact as well as the mechanism of trauma. In a small child who is hit by a car it is more 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 the impact of forces differs from adults. The skull is thinner, smoother and softer and the sutures may not be closed. The brain in young children absorbs the kinetic energy of an impact differently because the brain is more »watery« and more homogeneous in density. With progressive brain maturation (e.g. myelination) the brain becomes less »watery«. In addition, differences in densities between cerebral structures will increase with progressing maturation. Finally, children have a larger head-to-body proportion, the midface-to-skull proportion will increase and the paranasal sinuses are developing. The paranasal may function as a kind of »air bag« that absorbs much of the kinetic energy if an impact to the face occurs. In children, the transmission of the force of impact to the brain is not dampened by the paranasal sinuses. Finally, in neonates the weak neck muscles do not yet stabilize and support the neonates head in »shaken baby« trauma. Brain injury can be divided in primary injuries that 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 of diagnostic imaging should be to obtain 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 one of the leading causes of death and disability in children. Head trauma occurs in 3/1 000 children per year with a fatal outcome in 1/10 000 per year. The general rule that »children are

The value of conventional X-ray (skull AP and lateral) is an issue of ongoing discussions. In most European countries, conventional X-rays are performed because of legal concerns. However, the brain is much more important than the skull. A negative conventional X-ray does not

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 young children the cranial vault can be examined through the open fontanelle with a 5.0–7.5 MHz curved or linear array transducer. Osseous borders of the fontanelle prevent looking »around the corners«. Epidural or subdural haematomas that are located parasagittally can be overlooked. In addition, the visualization of the posterior fossa is limited.

Possible findings ▬ Acute, focal haemorrhagic brain contusions appear hyperechoic ▬ Chronic contusions are visualized as hypoechoic brain defects ▬ Intraventricular hemorrhage increases the echogenity of the ventricular lining; fluid-sedimentation levels are frequent ▬ Subarachnoid hemorrhage may be characterized by an increased echogenity of the subarachnoid spaces ▬ Midline shift due to an intracerebral haematoma or »hidden« extra-axial haematoma ▬ Brain oedema and an elevated intracranial pressure are characterized by a decreased resistive index value (duplex sonography) ▬ Occasionally, a skull fracture can be identified by ultrasonography

Computer tomography Imaging technique CT is sufficient to identify primary injuries that require emergency treatment (e.g. haematoma evacuation). 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 and obscuring beam-hardening artefacts within the posterior fossa. CT should be performed in children with an altered or deteriorating level of consciousness, if seizures or focal neurological symptoms occur, if the skull is depressed > 1 cm, in penetrating injuries, in children with an anisocoria, in children with a full fontanelle and in intubated children with an unclear trauma.

Soft tissue and bone algorithm with the appropriate window-level settings should be studied. Images should also be studied with a window-level setting that allows identifying hyperdense haematomas next to the hyperdense skull (e.g. Window 250 HU, level 75 HU). Coronal reconstructions are especially helpful for fractures that extend into the frontobasis or orbita. Contrast media is rarely necessary. If e.g. a fracture crosses a dural sinus, contrast media can identify a complicating dural sinus thrombosis.

Possible findings ▬ Extra-axial haematomas: subdural, epidural, subarachnoidal or intraventricular hemorrhage ▬ Intra-axial lesions: haemorrhagic and non-haemorrhagic brain contusions, lacerations, cortical hemorrhages, shearing injuries and coup/contre-coup contusions ▬ Brain oedema with a reduced grey-white matter differentiation, effaced subarachnoid spaces and compressed ventricles ▬ Midline shift ▬ Any kind of herniation ▬ Penetrating injuries with intracranial air inclusions ▬ Skull fractures ▬ Skull base and petrous bone fractures ▬ Complicating cerebral ischemia due to vascular 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 used if an unexplained discrepancy exists between CT findings and neurology. MRI is more sensitive for subtle findings like e.g. shearing injuries. T2*-weighted sequences are especially valuable. Compared to CT, MRI is more sensitive for identifying brainstem or cerebellar lesions. Functional techniques like DWI/DTI can serve as a biomarker of degree of tissue injury in intubated children. Imaging protocols should include T1-, T2- and T2*- weighted sequences (⊡ Fig. 3.5). DWI sequences are especially helpful because of the high lesion conspicuity. In addition, the differentiation between cytotoxic and vasogenic oedema gives information about potentially salvageable brain tissue (⊡ Fig. 3.5). The combination of

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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.

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▬ Post-traumatic aneurysm ▬ Early signs of ischemia in e.g. herniation or vessel dissections ▬ Complicating meningitis/encephalitis

Possible findings ▬ All findings as seen by CT with exception of detailed information about osseous lesions, in particular petrous bone fractures ▬ Higher sensitivity for subtle post-traumatic lesions (e.g. shearing injuries) ▬ Higher sensitivity for lesions within the posterior 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 two (D–G) were examined by conventional and functional MRI. Axial T2-FSE (A) shows an extensive hyperintense injury to the splenium of the corpus 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 exact extent of the injury is best seen as a hyperintensity of the corpus callosum and basal

ganglia (arrows). In patient 2, a subdural and epidural haematoma 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 hypointense) indicating cytotoxic oedema within the right hemisphere (arrows). This functional information is essentially important to estimate prognosis

Diagnosis should be as early and as exact as possible. Detailed information about the mechanism of trauma and force impact is essential because this information tells the radiologist where to look. CT is the most frequently used primary imaging modality, MRI is a second-line imaging tool for those cases where CT findings do not explain neurology.

25 3.6 · Supra- and infratentorial tumours in children

Key information

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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 ▬ Complicating 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 injury is essential

3.6

Supra- and infratentorial tumours in children


Brain tumours are the second most common paediatric neoplasm after leukaemia. Clinical symptoms differ from adults because (1) different tumours are seen in children, (2) the location of paediatric brain tumours differs, (3) skull sutures may not yet be closed. Neonates with brain tumours may present with an increasing head circumference, failure to thrive and developmental delay. The intracranial pressure is rarely elevated because the skull sutures are not yet closed. On initial presentation, tumours are frequently large. Infants and children suffer more frequently from an increased intracranial pressure (headaches, nausea, vomiting and lethargy). In addition, depending on the location, the leading presenting symp-

tom in infants and children may be a decreased visual acuity, endocrine dysfunction, seizures, focal motor deficits and ataxia. The age of the child is closely related to the location and type of brain tumour. In children less than 2 years, most primary brain tumours are located supratentorially, between 2 and 10 years most tumours are infratentorially while in children older than 10 years supra- and infratentorial tumours occur equally frequently. Age and sex of the child limit differential diagnosis. Pilocytic astrocytomas (35%), PNET/medulloblastomas (25%), brainstem gliomas (25%) and ependymomas (12%) encompass 97% of all infratentorial tumours while astrocytomas (30%), craniopharyngeomas (15%) and hypothalamic/chiasmatic gliomas (15%) represent 60% of all supratentorial tumours. In children, surgery and chemotherapy are the primary treatment options. Radiotherapy is limited in neonates and young infants because of the deleterious effects of 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 of limited value in the diagnostic work-up of brain tumours. Imaging findings are non-specific and cannot be used in the 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 are difficult to recognize. Ultrasonography can be helpful in evaluating 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 hemorrhage or calcifications ▬ Perifocal, vasogenic oedema ▬ Focal or generalized enlargement of the ventricles

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▬ Postoperative, intracranial air inclusions ▬ Postoperative, subarachnoid hemorrhage

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Computer tomography Imaging technique Non-enhanced CT is essential to show intratumoural hemorrhage or calcification. Contrast-enhanced CT identifies areas with a disrupted blood-brain barrier and increases sensitivity and specificity of CT. Spatial resolution should be optimized to identify small lesions. The reconstructed slices should be between 3 and 5 mm slice thickness. Bone windows are necessary if the lesion is adjacent to the skull to rule out osseous infiltration, destruction or erosion.

tumour seeding should be excluded. In these cases, a spinal MRI is mandatory (⊡ Fig. 3.6). Postoperative MRI should be performed within 24 h. In most cases, blood-brain-barrier disruption due to reparative processes along the resection site does not occur within 24 h postoperative. Consequently, an early 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

Possible findings ▬ All the previously mentioned ultrasound imaging 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 components may be isodense or hyperdense depending on the protein content or possible intracystic hemorrhage ▬ Perifocal, vasogenic oedema is hypodense ▬ Vasogenic oedema is frequently restricted to the white matter ▬ The neoplasm may be non-enhancing, partially 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 using pre- and postcontrast T1-weighted sequences as well as T2-weighted high-resolution sequences for anatomical detail (⊡ Fig. 3.6). FLAIR sequences will differentiate between perifocal gliosis and vasogenic oedema. Functional techniques are helpful for estimating tumour grade. MRA and MRV show dilated supplying or draining vessels and displacement and patency of the intracranial vasculature. Intraventricular or subarachnoid

Diagnosis relies on a high-resolution imaging, evaluation of contrast enhancement pattern, location and functional information as e.g. supplied by MRI. Imaging findings should always be correlated with the age and sex of the patient. The location gives another clue to diagnosis. Imaging cannot give definite histology. Biopsies remain necessary in selected cases. Follow-up imaging is necessary to rule out transformation of tumour grade. Key information

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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

27 3.7 · Non accidental traumatic brain injury in children, child abuse

⊡ Fig. 3.6A-E. Axial and coronal contrast-enhanced T1-weighted MRI (A,B) in a child with an anaplastic astrocytoma of the left cerebellar hemisphere. Local tumour with inhomogeneous enhancement is revealed as well as intraventricular CSF-metastases within the left 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 frequently 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 be exposed to repetitive episodes of physical abuse. Early recognition of non-accidental injury is essential to limit injury, to prevent repetitive injuries and to »save« possible siblings for physical or psychological abuse. Unfortunately, child abuse is difficult to prove early. In addition, raising the suspicion of child abuse may have far reaching consequences.

tion of a IV-ventricle ependymoma shows 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 frequently a radiological diagnosis. Imaging findings like e.g. multiple long bone, rib or skull fractures, simultaneous occurrence of old and new fractures and chronic subdural hematomas are highly suggestive of child abuse. The radiologist plays an important role in the recognition and documentation of physical child abuse. He should be familiar with the different patterns of injury because the type and distribution of lesions are age related. Babies are more likely to have been shaken while 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, the compression of the thorax while shaking the baby may result in a hypoxic-ischemic injury of the brain. In older children, that are beaten, the direct impact of the forces may result in

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haemorrhagic brain contusions. In strangulated children, an additional hypoxic-ischemic injury may be seen. The radiologist should correlate the distribution and 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 different ages are seen, physical child abuse should be suspected and the referring physician should be alerted.

most frequent fractures encountered in child abuse. If child abuse is suspected, 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 and/or MRI, are necessary if the child presents with unexplained neurological symptoms.

3.7.2 Imaging

Ultrasound Imaging technique

Conventional X-ray Conventional X-ray is often the first line imaging modality. Physically abused children often present as trauma patients in emergency 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 array transducer should be used. US is limited 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 CT, precontrast (B) and postcontrast injection (C) in a child with a chronic, mixed isodense subdural hematoma on the right. After contrast injection the pial vessels facilitate demarcation of the hematoma from the isodense brain. Axial CT (D) and followup MRI (E) in a shaken baby syndrome. Initial CT shows an unusual collection of subacute, hyperdense blood within the Sylvian fissure

as well as bifrontal hygromas. Follow-up MRI shows the T2-hyperintense right subdural hygroma. Axial CT (F) and follow-up MRI (G) in a shaken baby with suffocation. Initial CT shows a hyodense 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 injuries in shaken baby injury are difficult to recognize. Localized intraparenchymal hematomas may be directly seen or suspected if midline structures are displaced. Epidural and subdural hematomas are usually difficult to recognize because the osseous borders of the fontanelle may prevent identification of hematomas along the lateral cerebral hemispheres. Diffuse brain oedema 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 structures due to subdural or epidural hematoma ▬ Hyperechoic, acute subdural or epidural hematoma ▬ Fluid-fluid levels within a chronic subdural or epidural hematoma ▬ Hyperechoic subarachnoid reflections due to subarachnoid hemorrhage ▬ Focal, hypoechoic, fluid filled brain defects (old contusion) ▬ Hyperechoic lining of ventricles (intraventricular hemorrhage)

Computer tomography Imaging technique Non-enhanced axial computer tomography (CT) should cover the entire brain from the skull base to the vertex. Multiple window-level settings should be studied including a bone algorithm reconstruction. A high-window level setting can be helpful to identify small subdural hematomas. Intravenous contrast injection is rarely necessary may however facilitate delineation of isodense chronic subdural hematomas (⊡ Fig. 3.7), may show fibrinoid »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 iso- or subacute hyperdense haemorrhagic brain contusion ▬ Chronic, hypodense brain contusion or brain defect

▬ Acute, isodense or subacute hyperdense subdural or epidural hematoma ▬ Chronic, hypodense subdural or epidural hematomas ▬ Subdural or epidural hematomas with multiple densities due to recurrent hemorrhages in repetitive trauma ▬ Subarachnoid hyperdense hemorrhage (⊡ Fig. 3.7) ▬ Intraventricular hemorrhage with fluid-sedimentation level ▬ Hypodense cerebrum with preserved hyperdense 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 fractures, petrous bone fractures, intracranial air-inclusions Occasionally retinal and subretinal hemorrhages can be seen

Magnetic resonance imaging Imaging technique Multiplanar T1-, T2- and T2*-weighted MR-sequences which cover the entire brain should be acquired. Image resolution, especially slice thickness should be adapted to the child’s age. Routinely, 2-4 mm slices with a fieldof-view between 160 and 200 mm are sufficient. T2*weighted images are especially helpful to identify hemosiderin. Diffusion weighted imaging may enhance the 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-hypointense petechial hemorrhages at the interface of gray and white matter and 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 subdural or epidural hematomas ▬ Chronic hematomas may be T1-hyperintense due to an elevated protein content.

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▬ Subdural or epidural hematomas with multiple intensities due to recurrent hemorrhages in repetitive trauma ▬ Subarachnoid hyperdense hemorrhage (⊡ Fig. 3.7) ▬ Intraventricular hemorrhage with fluid-sedimentation level ▬ T2-hyperintense, T1-hypointense cerebrum with preserved intensity of brainstem and cerebellum in hypoxic-ischemic injury (⊡ Fig. 3.7) ▬ Chronic cortical and subcortical atrophy with cortical T1-hypo or hyperintense, T2-hypointense calcifications ▬ Skull fractures, petrous bone fractures, intracranial hypointense air-inclusions with susceptibility artifacts ▬ Occasionally retinal and subretinal hemorrhages can be seen ▬ Diffusion weighted imaging may show lesions with 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 considered if the »story of trauma« does not match the neurological status of the child and/or the imaging findings. Imaging should include a skeletal survey with skull X-rays. CT can be applied in the emergency workup, MRI is however the most sensitive imaging modality. Radiological diagnosis of non-accidental injury should be combined with physical findings (bruises, scars, burns) and opthalmological findings (retinal hemorrhages). The radiologist should alert the clinician as early as possible to prevent additional assaults. In addition, siblings within the same household should not be forgotten. Key information

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

3.8

Intracranial cystic lesions in children


Most primary intracranial cysts are benign disorders of development. Cysts can also develop as complications of surgery, trauma or infection. Intracranial cysts may be incidental findings on imaging or the leading cause of focal neurological deficits. Hemorrhages within the cysts may result in a rapid increase in the size of the cysts. Arachnoid cysts are benign, fluid-filled lesions that are lined by a thin 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 adjacent skull by chronic compression. They should be differentiated from epidermoid cysts. Leptomeningeal cysts occur as complications of skull fractures due to an entrapment of lacerated meninges within the fracture. Meninges and underlying brain tissue may protrude through a growing skull defect. The skull defect may grow over time because the chronic propagation of 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 multiple locations and are named accordingly: intraventricular ependymal cysts, choroids plexus cysts and choroids fissure cysts. Cysts are also encountered in conjunction with tumours (e.g. pilocytic astrocytoma, haemangioblastoma) and after parenchymal hemorrhage or ischemia (porencephalic cysts).

3.8.2 Imaging

Conventional X-ray Conventional X-ray may reveal a thinning, scalloping or 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 identify cystic

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 cysts, US may show the dural defect ▬ In growing fractures, the skull defect can be used as acoustic window

▬ Uncomplicated cysts are anechoic or hypoechoic ▬ Uncomplicated cysts are well marginated with smooth borders ▬ Intracystic hemorrhage increases the echogenity of the cyst ▬ Fluid-sedimentation levels indicate intracystic hemorrhage ▬ Complicated cysts (after hemorrhage or infection) 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 arteries and veins may be displaced or compressed

Contrast-enhanced series are rarely necessary. In complicated, multiseptated cysts, injection of contrast media in the ventricular system and cisterns can be helpful to identify the different compartments of the cyst and their communications (⊡ Fig. 3.8). Measurement of the Hounsfield units can be helpful in differentiating arachnoid 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 hypoechoic arachnoidal cyst. Foetal T2-weighted MRI (B) and postnatal T1-SE MRI (C) confirm the arachnoidal cyst. Compres-

sion of the sylvian acquaduct results in a ventriculomegaly. Axial CT (D) and CT after intrathecal injection of contrast media (E,F) show that the shunted arachnoidal cyst does not communicate with the ventricles.

Computer tomography Imaging technique

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Possible findings

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▬ Hypodense, well-marginated lesions with smooth borders ▬ Intracystic hemorrhage increases the density of the cyst ▬ Fluid-sedimentation levels indicate intracystic hemorrhage ▬ Complicated cysts (after hemorrhage or infection) frequently display multiple septa and are consequently multicompartimentalized. The septa can be difficult to distinguish ▬ The cyst wall is usually thin 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 sufficient to image intracranial cystic lesions. FLAIR imaging is helpful to identify perifocal gliosis. Diffusion-weighted MR will confirm the fluid content and is especially helpful to differentiate arachnoid cysts from epidermoids. Contrast media are rarely necessary and should be used only if complications occur or infection is suspected.

Possible findings ▬ Uncomplicated cysts are T1-hypointense and T2-hyperintense, similar to CSF ▬ The cyst wall is thin, well-marginated and non-enhancing ▬ FLAIR sequences may reveal a hyperintense perifocal gliosis within the adjacent white matter ▬ On diffusion-weighted imaging the cyst is hypointense on DWI and hyperintense on ADC maps. ▬ Epidermoids are T1- and T2-isointense to uncomplicated cysts ▬ Epidermoids are DWI-hyperintense and ADC-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 cysts, pulsation artefacts with signal loss can be seen crossing the dural tear ▬ The high soft-tissue resolution and triplanar imaging are helpful in identifying small choroid-fissure neuron-epithelial cysts

3.8.3 Diagnosis

Arachnoid, leptomeningeal and neuro-epithelial cysts are symptomatic due to compression or displacement of the functional centre of the central nervous system (CNS). Depending on the location, focal neurological deficits, seizures or CSF circulation disturbances (hydrocephalus) are observed. In many instances, however, these cysts are clinically silent and are found only incidentally. Key information

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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 children

3.9

Cystic lesions of the head and neck in children

3.9.2 Imaging

Conventional X-ray 3.9.1 General information

Most cysts within the head and neck are benign disorders of development. Cysts can also result from infection, trauma and as a complication of surgery. Cysts of the head and neck region can be symptomatic due to compression of important functional structures. Large cysts can also interfere with the normal anatomical development of the viscerocranium. Aesthetic problems may also be a major concern. Hemorrhages within the cyst or complicating infection may result in a rapid increase in the size of the cysts. Rapid cyst enlargement can lead to life-threatening situations. Imaging should localize and characterize the cystic lesions. High-resolution imaging allows exact allocation of the lesion to the different anatomical spaces of the neck. Congenital cystic neck masses include branchial cleft cysts, thyroglossal duct cyst and lymphangiomas. These lesions should be differentiated from inflammatory or neoplastic cystic head and neck masses. Lymphangioma or cystic hygroma is a congenital malformation of the lymphatic channels within the neck. It can occur in combination with hemangiomas (lymphhaemangioma). Lymphangiomas can show multiple small cystic components (capillary lymphangioma), multiple medium-sized cysts (cavernous lymphangioma) or large fluid-filled compartments (cystic lymphangioma or hygroma). Branchial cleft anomalies include cysts, sinus tracts and fistula that result from an anomalous development of the branchial apparatus. Depending on the involved branchial component, different locations of the branchial cleft anomalies are encountered. Anomalies of the first and especially of the second branchial apparatus are most frequent. Anomalies of the third and fourth branchial apparatus are rare. Thyroglossal duct cysts are developmental anomalies that result from a failure of a segment of the thyroglossal duct to obliterate. The thyroglossal duct is the »path« that the thyroid gland follows during its descent from the foramen cecum at the tongue base to its final position in the infrahyoid neck. Cysts may occur at any location along the thyroglossal duct.

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 or compression of the air-filled larynx or trachea can be seen. Rarely, flebolites or complicating soft-tissue calcifications after hemorrhage or infection can be seen. Gas inclusions indicate severe inflammation. Calcified lymph nodes result from infections but should also raise the possibility of tuberculous lymph node infection.

Ultrasound Imaging technique Ultrasonography is the primary imaging modality for examining head and neck masses (⊡ Fig. 3.9). Imaging should be performed with 5.0–7.5 MHz curved array and linear transducer. The neck should be examined in a systematic fashion covering all anatomical spaces. Comparison with the contra lateral side is helpful. Duplex sonography and power Doppler sonography are necessary to study the neck vessels for their location and their patency. In addition, power Doppler sonography allows 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 cysts have an increased echogenity, 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 lymphhaemangiomas, the lymphangioma is hypoechoic, the haemangioma hyperechoic with an increased vascularity ▬ In infected cysts, enlarged lymph nodes within the 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 multicompartimentalized lymphangioma of the right neck. Ultrasonography (B) is especially sensitive to identify the multiple hyperechogenic septae within the hypoechogenic lymphangioma.

On CT (C,D) the lesion is hypodense and displaces/deforms the adjacent osseous structures. The contrast-enhanced neck vessels are patent but displaced. Conventional X-ray (E) confirms the osseous remodelling

▬ In thyroglossal duct cysts, the thyroid gland should be examined in detail. An ectopic thyroid gland should be excluded (thyreoid scan!) ▬ Inflammatory cystic masses (e.g. abscesses) should be suspected in the appropriate clinical symptomatology and identification of a generalized lymphadenitis colli ▬ Differentiation from cystic neoplasm can be difficult

Possible findings

Computer tomography Imaging technique Contrast-enhanced CT with coronal and sagittal reconstructions covering the neck from the skull base to the 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 into cutaneous fistulae prior to imaging can enhance identification of fistula tracts.

▬ Cystic neck masses are hypodense on CT and well marginated ▬ Cyst walls are thin and non-enhancing ▬ Intracystic septae may be difficult to identify. 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 lymphhaemangiomas, the haemangiomatous component will show a strong enhancement. Occasionally, dilated contrast enhancing intralesional vessels are seen ▬ Enlarged lymph nodes; displacement of anatomical 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 children

▬ Differentiation between lymphangioma, branchial cleft cyst and thyroglossal cyst relies on the exact anatomical lesion localization ▬ Calcified lymph nodes and cyst wall calcifications present hyperdense ▬ Abscesses in lymphadenitis colli are centrally hypodense with a strong peripheral enhancement ▬ Displacement of neck structures is easily identified by CT ▬ Bony erosion, remodelling and possible infectious affection (complicating osteomyelitis) ▬ Two- and three-dimensional bone reconstructions facilitate interpretation of complex osseous remodelling ▬ Enhancement patterns may differentiate between congenital and inflammatory cystic neck masses and cystic neck neoplasms

Magnetic resonance imaging Imaging technique The different imaging contrasts that can be generated, the functional imaging information (diffusion-weighted imaging) and the lack of ionizing radiation are advantageous (⊡ Fig. 3.9). Imaging should include pre- and postcontrast T1-weighted sequences as well as T2-weighted sequences. Fat saturation pulses will increase sensitivity of contrast-enhanced T1-weighted sequences. In selected cases, subtraction images (pre- and postcontrast sequences) are helpful. MR-angiography and MR-venography sequences should be added if vascular complications are suspected.

Possible findings ▬ Uncomplicated cysts are T1-hypo- and T2-hyperintense ▬ 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 cysts are T1-iso- or hyperintense and T2-iso- or hypointense ▬ Haemorrhagic cysts frequently reveal a fluid-sedimentation level on all MRI sequences ▬ Complicated cysts and especially abscesses are DWIhyperintense and ADC-hypointense due to the restricted 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 high anatomical detail and soft-tissue resolution facilitate differentiation between lymphangiomas, branchial cleft and thyroglossal duct cysts

3.9.3 Diagnosis

Diagnosis relies on the combination of a good clinical examination and high-resolution imaging. The differentiation between the different cystic neck masses is based on the proper identification of the anatomical landmarks. Ultrasonography can be especially valuable to differentiate between a uniloculated and multiloculated cystic neck lesion. Thin septa can be missed on CT or MRI. Finally, necrotic neoplastic lesions may mimic cystic lesions and should be considered and consequently ruled out. Key information

I

I

Cystic lesions of the head and neck in children ▬ 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

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3.10

Spinal cord neoplasm in children


3

Spinal cord neoplasm are rare, 0.5–1% of all central nervous system (CNS) tumours are located within the spinal cord. 2–4% of all glial CNS glial tumours are located in the spinal cord; 35% of all intraspinal tumours are intrinsic spinal cord neoplasm; 90% are glial tumours and most are malignant. All age groups are affected, but spinal cord neoplasm is more frequent toward the end of the first decade. There is no sex predilection. Spinal cord neoplasm is less common in children compared to adults. Children usually present (very) late because spinal cord tumours usually present with slowly progressive unspecific clinical findings. Retrospectively, there is frequently a long history of symptom exacerbations and remissions which is believed to result from peritumoural oedema fluctuation. Every child with persisting back pain should be taken seriously. 25-30% of all children with spinal cord neoplasm present with back pain. Additional symptoms include progressive motor weakness, progressive scoliosis, gait disturbance, rigidity and paraspinous muscle spasm. Sensory deficits are less common. 15% of children with spinal cord neoplasm present with symptoms of increased intracranial pressure. This may be related to an elevated cerebrospinal fluid (CSF) protein concentration, due to a blockage of the foramen magnum, a subarachnoid tumour hemorrhage or a subarachnoid tumour seeding. The same neoplasms are seen in adults and children. 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 hemangioblastoma, subependymoma, ganglioglioma, metastasis, lymphoma, neurocytoma, etc. As rule of thumb: In children, astrocytomas are much more frequent than ependymomas, while in adults the ependymomas are much more frequent than astrocytomas. Ependymomas are more frequent in neurofibromatosis 2, while 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 spinal X-ray has a very limited diagnostic value. If a scoliosis is seen without segmentation anoma-

lies, a spinal cord process should be excluded. If the spinal canal or the neuroforamina are widened a spinal cord process is likely. Spinal X-ray is still of 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 MHz linear array transducer. With progressing ossification of the dorsal spinal elements the diagnostic value declines. In our experience, US is of 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 ▬ Syringo-hydromyelia

Computer tomography Imaging technique Axial contrast-enhanced CT with secondary sagittal and 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 ▬ Peritumoural hypodense cysts which may enhance peripherally

37 3.10 · Spinal cord neoplasm in children

▬ Perifocal hypodense spinal cord oedema and/or venous stasis ▬ Variable contrast-enhancement of the tumour ▬ Enlarged adjacent tumour vessels (e.g. in hemangioblastoma) ▬ Syringo-hydromyelia ▬ Cerebro spinal fluid (CSF) tumour seeding ▬ Tumour extension through the neuroforamina ▬ Erosion and/or widening and/or scalloping of the spinal canal or neuroforamina

Magnetic resonance imaging Imaging technique Sagittal and axial pre- and postcontrast T1-weighted images should be combined with T2-weighted sequences. Coronal images may be added. Thin-sliced three dimensional heavily T2-weighted (long echo train) images may be helpful to identify intramedullary cysts, to study the central canal and to evaluate the narrowing of the perimedullary subarachnoid space. Three 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 infiltrating tumour without a clear cleavage plane between tumour and normal spinal cord ▬ Tumour is T2-hyperintense, T1-hypo or iso-intense, rarely haemorrhagic ▬ Variable, mild to moderate contrast enhancement ▬ 20-40% have peri- or intratumoural cysts as well as a syrinx (caudal or rostral) ▬ Tumour is usually excentric in location with asymmetric cord expansion ▬ Spinal canal may be enlarged/widened ▬ CSF-seeding presents as nodular intradural enhancement, most frequently in the dependent spinal canal (⊡ Fig. 3.10b) Spinal ependymoma ▬ Most frequently in cervical cord ▬ Central location (arises frequently from ependym of central canal). Symmetric spinal cord enlargement.

▬ Less infiltrating, predominantly compression of adjacent non-affected spinal cord. Often clear cleavage plane ▬ Peritumoural cysts common, Intratumoural cysts less common ▬ Tumour frequently T2 hyperintense, T1 hypo- or isointense ▬ Strong contrast enhancement, small tumour vessels 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 producing, polylobulated tumour that may scallop osseous spinal canal ▬ T2-hyperintense, T1 hypo- or iso-intense, strongly enhancing tumour

3.10.3 Diagnosis

Children with back-pain, progressive scoliosis, progressive 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: Diagnose aggressively, treat conservatively. Frequently, unnecessary, non-diagnostic tests and imaging is performed delaying diagnosis. MRI is the most sensitive imaging modality for spinal cord lesions and should be used early in diagnose making. Diagnostic CSF-taps should be done after MRI is performed. A CSF-tap frequently results in a dural enhancement which may mimic subarachnoid tumour seeding. Key information

I

Spinal cord neoplasm in children ▬ Spinal cord neoplasm ▬ Astrocytoma ▬ Ependymoma ▬ Myxopapillary ependymoma ▬ Hemangioblastoma ▬ Back pain ▬ Tumour cysts ▬ Syringo-hydromyelia

I

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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 shows an expanding T2-hyperintense, slightly T1-hypointense, strongly enhancing intramedullary astrocytoma. The thin sliced heavily T2-weighted image shows peritumoural cysts along the cranial 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 contrast enhancing metastatic nodules due to CSF-seeding in a child with an anaplastic spinal cord astrocytoma

Barkovich AJ (2000) Pediatric neuroimaging, 3rd edn. Lippincott Williams & Wilkens, Philadelphia Osborn AG (2004) Diagnostic imaging: brain. Amirsys, Salt Lake City Tortori-Donati P (2005) Pediatric neuroradiology: 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 imaging. 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) Pediatric neuroradiology. Philadelphia-New York, Lippincott-Raven

4 Thoracic disorders Donald P. Frush

4.1

Introduction

The thorax is the most common region to undergo imaging evaluation in children. While a chest radiograph (or chest X-ray) is the most frequently performed procedure, computed tomography (CT), ultra sonography (US) and magnetic resonance (MR) imaging also provide important diagnostic information for paediatric thoracic and intrathoracic abnormalities. Knowledge of the relative 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 the traditional classification scheme, consisting of congenital (including neonatal) abnormalities, infectious/inflammatory conditions, tumour and tumour-like conditions, traumatic abnormalities or toxic/metabolic disorders, which includes thoracic manifestations of systemic disorders. Alternatively, disorders could be classified based on the presentation, such as fever, mass or wheezing. However, the signs or symptoms of thoracic disorders in children are relatively non-specific and often overlap the individual disorder classifications noted above. For example, wheezing can be caused by infection (viral or bacterial), toxic exposure (inhalation), trauma (aspirated foreign body) or congenital anomalies (such as tracheal compression by a vascular ring such as a double

aortic arch). Therefore, the following material will be divided based on the traditional classification scheme, and subclassified by region (chest wall, airway, lung 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) with more in-depth discussion and illustration of the more common of the disorders. The reader is referred to several other excellent references for a more in-depth discussion [2,3].

4.2

Imaging modalities

The standard imaging modalities for evaluation of thoracic and intrathoracic disorders in infants and children as well as the benefits and relative disadvantages are found in ⊡ Table 4.1 [1]. With few exceptions, chest radiography is the first (and often only, e.g. for pneumonia) imaging modality used to assess thoracic signs or symptoms. Because the radiograph is a relatively low -radiation dose, inexpensive, widely available and relatively consistently performed, it provides an excellent survey of lung parenchyma, cardiovascular structures, mediastinum and chest wall structures. Fluoroscopy has a limited role but is used to assess 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

41 4.2 · Imaging modalities

in the setting of aspiration of a foreign body), contrast evaluation of the oesophagus, and to assess diaphragm motion in the setting of possible hemidiaphragm paralysis or paresis. Disorders of the oesophagus are assessed using either barium or water-soluble contrast during fluoroscopic evaluation. The water-soluble media are 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 and gastroesophageal reflux), as well as structural evaluation is provided by contrast-enhanced fluoroscopic evaluation of the oesophagus. Ultrasonography should always be considered as a second-line modality for evaluation of those processes which are considered intrathoracic but peripheral in nature (recall, there is no coherent sound transmission and ability to form a sonographic image through air-filled structures such as the lung) [2]. This includes assessment of the presence or characteristics of pleural effusions [e.g. septations or loculations), chest wall masses or evaluation of potential mediastinal masses in the neonate or infant (⊡ Fig. 4.1). One type of sonography is echocardiography. This is in general reserved for evaluation of the heart and great vessels. If there is a suspicion of congenital heart disease, echocardiography should be used in conjunction with chest radiography. In these circumstances, CT angiographic and MR angiographic techniques would 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 single detector (single-slice CT), or, currently, from 4–64 arrays of detectors [all called multidetector array or MDCT). Much of CT today is performed using MDCT technology [3,8]. Overall, CT gives the best global assessment of all thoracic and intrathoracic structures. In particular, the highest level of anatomical information regarding lung parenchyma is provided by a CT examination, especially if high-resolution CT (HRCT) (thin-slice and high-detail) techniques are used. In addition, CT provides excellent morphological and anatomical information for mediastinal or cardiovascular structures (especially if angiographic technique, or CT angiography—CTA—is utilized) and osseous abnormalities. Because of its relatively wide availability, fast examination times (with new 64slice technology chest CT examinations can be performed in under 0.5 s in neonates and in under a few seconds in adult-sized teenagers) and consistent examination detail,

⊡ Fig. 4.1. Transverse view of normal infant thymus (thymus). Borrowed with permission Academy of Medicine, Singapore

CT is often the second-line evaluation when radiography does not provide sufficient information for diagnosis or management (such as surgical 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 of the equivalent of 100 chest X-rays for a single CT examination. MR imaging is usually reserved for a problem-solving tool when radiography is insufficient, sonography is unlikely to result in sufficient diagnostic information, and evaluation of lung parenchyma is not critical. In particular, MR provides excellent evaluation of the chest wall, spinal and paraspinal region, the remainder of the mediastinum and cardiovascular structures. With non-IV contrast-enhanced cardiac-gated information (or blackblood techniques) or with IV contrast media (MR angiography), excellent cardiovascular assessment is achieved including functional information that is unavailable from a CT examination.

4

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4.3

Congenital abnormalities/ neonatal anomalies

4.3.1 Introduction

4

There is a variety of disorders which are of congenital nature or associated with birth. This is a particularly unique category since these abnormalities either do not exist in adults or are extremely rare (for example pulmonary 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 abnormalities of the shape, size or configuration of the thorax, particularly in the neonate with respiratory distress or potential skeletal dysplasia, or in the setting of pectus excavatum. In addition, the presence of focal abnormalities such as congenital masses including haemangiomas or vascular malformations is well addressed by diagnostic imaging [4].

⊡ Fig. 4.2. Radiograph of chest wall mass in a young child which was a congenital rib anomaly fully demonstrated 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 abnormalities, including the shoulder region (including the clavicle) which may account for abnormalities in size or configuration of the thorax. This information may be diagnostic. Of note, suspected masses in children often reflect insignificant congenital anomalies or asymmetry in chondro-osseous structures (⊡ Fig. 4.2) [4]. Ultrasonography, or sonography, can be used there is a suspicion of an anomaly of the ribs or costovertebral region. Sonography is also useful in assessing the presence or absence of a congenital chest wall mass. Sonography can also be useful in detecting the nature of other chest wall masses such as the general category of vascular masses composed of either haemangiomas or vascular malformations (such as lymphatic or venous malformations), inflammatory masses (such as adenitis, abscess or cellulitis) or cyst or cyst-like conditions. However, if assessing the total extent of a lesion, cross-sectional imag-

ing (such as CT or MR evaluation) is often indicated for evaluation of masses.

Sonography technique ▬ High-resolution linear transducer (10–17 MHz) ▬ Orthogonal 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 congenital mass is or is not present. CT may be diagnostic for congenital variations of the vertebrae, ribs or sternum, of which the latter two frequently are the cause of concern in adolescent patients. CT will also indicate the presence of a mass although 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 only a skeletal and lung parenchyma detail is necessary. As is the case in other regions of the body including the brain, spinal cord and musculoskeletal system, MR imaging provides the best soft-tissue contrast information, and is very useful in assessing masses not otherwise addressed adequately by radiography or sonography. When sedation is required for MR imaging, CT may be considered as the next modality in children for whom sedation for CT would not be required. In this case, a IV contrast CT examination is indicated. For sonography of the chest wall, a high-resolution transducer (10–17 MHz) is generally indicated. For CT examination, depending on the type of abnormality, either a non-contrast-enhanced or IV contrast-enhanced examination may be performed. If there is suspicion of a tumour or tumour-like condition as a cause for a mass, then IV contrast is indicated. 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 then be distinguished from congenital airway disorders such as an aberrant bronchus or tracheo-oesophageal fistula. Fluoroscopic evaluation of congenital anomalies is generally limited to assessment of trachea abnormalities and diaphragm motion (sonography is an alternative). Airway disorders can be divided into large and small airway disorders. Most congenital abnormalities of the 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 fistula. Malacia is best addressed by bronchoscopy, but MDCT performed during respiration and subsequently segmented to depict cycles of respiration can show the dynamic nature of airway collapse. Branching anomalies are best depicted by CT. For example, CT best demonstrates the anomalous airway branching patterns of a tracheal (or pig) bronchus where an upper lobe bronchus arises directly from the trachea. The airway can also be secondarily involved due to other congenital lesions such 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 general, IV contrast-enhanced CT examination is best in addressing airway abnormalities because it better outlines adjacent vascular structures from potential masses and better defines airway abnormalities. Newer multidetector (MDCT) technology affords multiplanar and volume three-dimensional reconstructions with excellent depiction of airway morphology with some functional information [5].

4.3.3 Airway

4.3.4

The role of radiography is both 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 also has a critical role in assessing other conditions which may mimic airway abnormalities, as signs and

Introduction

⊡ Fig. 4.3. Pectus excavatum evaluation by CT. The degree of anteroposterior narrowing (in addition to sternal tilt) is well assessed using this modality. Borrowed with permission Elsevier

Lung parenchyma

The spectrum of congenital lung lesions includes a variety of disorders (⊡ Table 4.2) [6]. These 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 1. Airway a. Trachea i. Tracheomalacia ii. Congenital stenosis b. More distal large airway i. Bronchogenic cyst ii. Bronchial atresia

4

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

nique to optimally opacify the arterial supply and venous drainage is preferred (⊡ Fig. 4.4). CT also gives important information in other mass lesions such as the bronchogenic cysts, where the attenuation will be that of fluid and the wall is typically thin or imperceptible (⊡ Fig. 4.5). Congenital lobar emphysema presents as hyperinflation of a lobe, particularly an upper lobe (⊡ Fig. 4.6). Care must be taken to rule out causes of acquired emphysema, such as compression 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 these congenital lung abnormalities is limited due to the intraparenchymal nature of the congenital lesions. While peripheral abnormalities might be detected by sonography, information obtained is usually insufficient for management, usually surgical resection. MR imaging is useful in assessment of mass lesions 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 disorders is generally covered by mass and mass-like conditions (see below).

Imaging Evaluation The initial modality for suspected congenital lung abnormalities is radiography. These disorders can also be detected in utero either by sonography or MR imaging. Radiography should be performed when a mass or abnormal aeration persists over approximately three examinations. For example, pulmonary sequestration can mimic recurrent pneumonia. After the second pneumonia in an identical location, it is worthwhile to obtain a followup radiograph once an appropriate period of antibiotic treatment has ensued (e.g. after 3–4 weeks) to make sure that this resolves. If the opacity persists, IV contrast CT is warranted. This principle of follow-up is also 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-

4.3.6 Cardiovascular system

With the advent of echocardiography and, more recently, improved spatial information obtained with contrastenhanced CT and MR, the role of radiography in the diagnosis of specific lesions in congenital cardiovascular disease in children has changed 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 heart disease, or as a baseline modality (for example to determine if pulmonary oedema or pleural effusion develop) or for detecting other anomalies associated with congenital heart disease such as a rib or vertebral anomalies. When echocardiography is insufficient, then contrast-enhanced MR or CT is indicated (⊡ Figs. 4.7, 4.8) [7,8]. The relative benefits of these modalities are listed below.


⊡ Fig. 4.4. Pulmonary sequestration. Arterial supply (arrow, upper left) and venous drainage (arrow, lower right) eventually into the pulmonary vein are demonstrated. Borrowed with permission Elsevier

⊡ Fig. 4.5. Bronchogenic cyst in a young child. CT examination demonstrates the fluid density cyst (arrow) in the middle mediastinum

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

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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 ▬ No radiation ▬ Functional information (e.g. cardiac output, ejection fraction; determination of pressure gradients across stenoses; resurgent fractions pulmonary-to-systemic flow ratio) One group of congenital lesions in which radiography 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 the airway, with radiography provides important clues to the presence and type of vascular ring. These include deviation of the trachea to the left from a right-sided aortic arch, often with an aberrant left subclavian artery, or double aortic arch, or anterior bowing of the trachea on the lateral examination suggesting a left aortic arch with aberrant right subclavian artery (in addition to aberrant left subclavian artery with a rightsided arch). Occasionally, other lesions are not clinically evident in the neonatal period and these may present

⊡ Fig. 4.8. Axial contrast enhanced CT examination. Right-sided aortic arch with aberrant left subclavian artery (arrow) Note mild tracheal narrowing (short arrow). Borrowed with permission Springer

later in childhood including pulmonary artery stenosis, (increased main pulmonary artery segment), aortic stenosis (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 ventricular septal defect or atrial septal defect. These will have enlargement of specific chambers or overall cardiomegaly which should prompt echocardiographic evaluation. Radiography is also useful in the postoperative period for congenital heart disease.

4.3.7 Thoracic imaging unique to neonates

⊡ Fig. 4.7. Pulmonary embolism. Contrast enhanced CT with coronal reformation demonstrates the emboli (arrows) bilaterally. Borrowed with permission Springer

While all the imaging modalities have some application to thoracic disorders in the neonate, radiography is by far the most often performed in this age group. The neonate with respiratory distress can have either a primary intrathoracic abnormality, or an extrathoracic condition which manifests with pulmonary symptoms. In this latter case, the normal radiograph is helpful in focusing attention on extrathoracic conditions (e.g. birth-related central nervous system injury such as hypoxic ischemic insult, or urosepsis), or in providing reassurance for conservative treatment such as oxygen for central depression from administration of medication to the mother. For those conditions which are thoracic and the cause of respiratory distress, the major conditions, and differentiating features, are found below. These four conditions will account


A ⊡ Fig. 4.10. Hyaline membrane disease in a preterm infant. Radiograph 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 arch. B Axial image from contrast enhanced chest CT shows posterior junction of the arches (arrow), and C the narrowing of the left bronchus (A descending (midline) thoracic aorte)

for the vast majority of thoracic aetiologies of neonatal respiratory distress (⊡ Figs. 4.10, 4.11) 1. Surfactant deficiency disease (or respiratory distress syndrome, RDS, or hyaline membrane disease, HMD) a. Preterm b. Diffuse ground glass opacities c. Effusion is very rare d. Traditionally low volume, but this is rarer currently with administration of surface acting agent prior to the first radiograph 2. Neonatal pneumonia a. Any pattern possible (focal opacity, multifocal opacity, focal or diffuse ground glass opacities) b. Term or preterm appearing child c. Small to moderate pleural effusion is much more common 3. Aspiration: can be amniotic fluid alone, blood, or fluid with meconium—the latter results in most severe changes) a. Generally, term neonate b. Areas of hyperinflation and atelectasis (or other heterogeneous opacities), c. Pneumothorax or pneumomediastinum d. Effusion is not typical 4. Transient tachypnea of the newborn (TTN) or retained foetal lung fluid a. Term neonate b. Streaky, predominantly central opacities c. Small pleural effusion

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impossible especially in a preverbal child with respiratory distress and fever [10]. The imaging evaluation of the immunocompromised 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, and fungal processes) as well as development of other disorders such as primary malignancy or post-transplant lymphoproliferative disorder in certain populations.

4

4.4.2 Chest wall

⊡ Fig. 4.11. Group B streptococcal pneumonia in an infant. Radiograph shows diffuse ground glass granularity but, what is not typical for hyaline membrane disease, the main differential consideration, is the presence of small bilateral pleural fluid collections (arrows)

Causes of diffuse granularity in the neonate ▬ ▬ ▬ ▬ ▬ ▬

Hyaline membrane disease Pneumonia Oedema Microatelectasis Chronic lung disease (bronchopulmonary dysplasia) Bilateral hypoplasia

Cardiovascular anomalies also can result in neonatal respiratory distress although as a group they are much less common than those listed immediately above. In general, when there is a suspicion of a cardiac anomaly, echocardiography is indicated and is often performed prior to radiography for diagnostic purposes. The role of CT and MR angiography is thus very limited.

4.4

Chest wall infections such as adenitis, cellulitis or phlegmon or abscess formation are best addressed by sonography if limited in extent, or by contrast-enhanced CT or MR if the extent is adjacent to structures such as the bone or intrathoracic regions. Radiography has a limited role in suspected chest wall infection. For cases of cellulitis, with possible abscess formation, sonography is sufficient to exclude fluid collections which may be accessed for drainage. If this is a clinical question, then sonography is the sufficient examination. A bone scan can be obtained for suspicion of chest bony involvement in cases where infection is known or suspected elsewhere in the body, but usually sonography or cross-sectional imaging is indicated for assessment of regional or focal infection of the chest wall. Radionuclide imaging has a limited role but could be used in assessment of perhaps a multifocal infectious process such as chronic recurrent multifocal osteomyelitis. In addition, in the setting of a potentially haematogenous origin of osteomyelitis with several regions which may be affected within or outside the chest a bone scan is an excellent survey. MR imaging can also provide excellent evaluation of bones and soft tissues if the infectious process is limited to the thorax (⊡ Fig. 4.12)

Infectious/inflammatory 4.4.3 Airway

4.4.1 Introduction

Infection is the most common disorder involving the 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, and viral processes. The clinical distinction between these two aetiologies can be quite difficult or

Infectious complications in the airway in the paediatric population consist mostly of viral etiologies (tracheobronchitis) due to a variety of pathogens. Primary bacterial processes are rare. Involvement of the intrathoracic trachea from bacterial tracheitis (or pseudomembranous tracheitis) is usually due to extension from the subglottic airway and manifests usually with upper airway signs and

49 4.4 · Infectious/inflammatory

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

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

symptoms (for example stridor, drooling). Subtle abnormalities of the trachea will be difficult to see radiographically. Bronchoscopy is usually applied when additional 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 Lung parenchyma

Radiography is the first modality in cases of suspected lung infection [10]. In an appropriate clinical scenario, a normal chest X-ray can help in excluding pneumonia as a cause for the symptoms; this may obviate antibiotics. Excluding pneumonia is probably the most important role for radiography. Technique is critical, since poor positioning may obscure pathology and poor inspiration may mimic pathology. Radiography can help differentiate viral from bacterial processes (see below), but is not reliable for determining specific types of organisms. Typical radiograph findings in pneumonia are well recognized, consisting of consolidation (airspace disease with hallmark air bronchograms; ⊡ Fig. 4.13), ill-defined margins and pleural effusions. Adenopathy can occasionally be present but is relatively 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. Left lower lobe pneumonia with effusion presenting in a child with abdominal pain which is why the abdominal radiograph was obtained

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A

A

B ⊡ Fig. 4.15A,B. Complicated pneumonia. A Frontal chest radiograph shows right upper lung airspace disease and small fluid collection. The child did not respond to antibiotics. B Several views of the IV contrast-enhanced CT examination show loculated pleural fluid collection with some enhancement. Pleural stripping was necessary to 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 can occur. In this, the airways are affected, manifesting with different radiographic features consisting of abnormalities in aeration particularly in air trapping, peribronchial thickening seen on the face as a »doughnut« appearance or in profile, 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-defined margin – Exception is round pneumonia which is usually seen only in the first decade ▬ Air space involvement: air bronchogram (this is a hallmark of airspace disease) ▬ Normal lung volumes

51 4.4 · Infectious/inflammatory

Viral pneumonitis ▬ Generally symmetric: centralized or diffuse ▬ Interstitial Involvement – Peribronchial thickening – Streaky hilar opacities – On lateral, these superimpose to create full looking hila – Pitfall: may look like adenopathy ▬ Hyperinflated lungs ▬ Atelectasis

Mimics of pneumonia ▬ Normal thymus (⊡ Fig. 4.17) ▬ Atelectasis ▬ Congenital lesions – Bronchogenic cyst, sequestration, congenital cystic adenomatoid malformation ▬ Artefact ▬ Contusion ▬ Inhalation ▬ Hemorrhage ▬ Focal oedema ▬ Pulmonary embolism ▬ Langerhans cell histiocytosis, alveolar proteinosis, collagen vascular disease, vasculitis

A

B

CT is used in evaluation of parenchymal infections that are not responsive to therapy (⊡ Fig. 4.15). Findings that CT provides include necrosis, cavitation, pleural abnormalities (bronchopleural fistulae, fluid collections) or chest wall involvement. In general, a IV contrast-enhanced CT examination is indicated in the 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 examination also gives the best assessment of the nature and extent of infection, including the presence of pneumatocele formation. For these reasons, in the setting of complicated pneumonia (i.e. unresponsive to antibiotics, or progressive consolidation or development for large pleural fluid collection), CT examination is usually the second-line modality in evaluation following serial radiographs. Septic emboli can occur as a sequela of remote infection. Radiography can demonstrate the multiple illdefined nodules and display cavitation. This may be sufficient with a strong clinical history. However, CT

⊡ 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 treated with antibiotics, being mistaken for pneumonia. A CT was performed after follow-up X-ray was unchanged and after discussion that this was most likely thymus. B Contrastenhanced examination of the CT examination demonstrates normal thymic tissue T

evaluation provides superior morphological evaluation, particularly for associated complications including necrosis or empyema. CT is not able to define the nature of pleural fluid as well as sonography. The role of sonography for assessment of infectious processes is primarily limited to evaluation of the presence and of characteristics of pleural fluid, or in confirming that an opacity is parenchymal and not pleural [2]. Sonography is helpful in determining whether a pleural effusion is present or not and may be all that is needed prior to aspiration or catheter drainage of fluid. Sometimes consolidation with or without atelectasis can make

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the chest X-ray appearance one that mimics effusion. In this case, sonography can demonstrate the presence of consolidated lung in the absence of effusion. It is well recognized that sonography will provide more detailed information about the nature of pleural fluid such as the number, thickness and extent of septations or loculations, and the presence of debris. While these features do not always indicate an empyema, their absence is helpful in that the fluid is most likely not an empyema. Decubital radiographs can help determine the presence of pleural fluid, and whether or not this fluid is free-flowing (supporting a transudate more than an exudative empyema); however, sonography provides more information and is less cumbersome to perform. If a thoracostomy tube is anticipated, one should obtain a sonographic evaluation after the CT to help define the character of the fluid; highly septated and thickwalled collections are more difficult to drain and may require operative intervention. MR imaging has a limited 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 children is rare, especially compared with adults. Mediastinitis in children is usually seen in the postoperative setting. Either CT or MR will identify the extent and nature of the process and can be used to monitor therapy.


For cardiac and pericardial infections, echocardiography is indicated. For the great vessels, such as mycotic aneurysms, CT angiography or MR angiography best depict 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 Takayasu’s arteritis), in which case CT or MR imaging best displays the involvement, or small vessel

disease with a variety of patterns in the lung from ground glass opacities to nodular, ill-defined areas of parenchymal involvement, including cavitation, to airspace opacities. Radiography can suggest the nodular involvement, but the above patterns are best depicted by CT.

4.5

Mass or mass-like conditions

4.5.1 Introduction

Mass or mass-like conditions can occur in the chest wall, airway, lung or mediastinum. While masses may also occur within the heart or vessels, in general echocardiography is the first-line modality for these. Both benign and malignant masses comprise the spectrum of mass and mass-like conditions. Specific imaging features (discussed in greater detail below) can help in distinguishing between these two general categories. One example is lesion location. When a mass is within the lung in children, this is rarely cancer, unlike in adults. In addition, most endotracheal masses in children are going to be benign, primarily consisting of papillomas. The primary objective of imaging mass and mass-like condition is first to identify whether or not the mass is present. When present, the next step is to define the nature or the lesion (i.e. specific imaging features), the extent of the abnormality and the mass effect on adjacent structures. Radiography is often the first modality used in the setting of thoracic masses. These are usually discovered incidentally as a result of imaging for non-specific respiratory symptoms (⊡ Fig. 4.18). Once detected, the location is important for further follow-up. For example, intra parenchyma lung masses may be treated with antibiotics, if there is a history of fever or other signs of pulmonary infection. Radiographic follow-up is not warranted but may be obtained to assure resolution. For those masses detected within the mediastinum, cross-sectional imaging is usually warranted. In a neonate or infant, where a potential abnormality of the anterior mediastinum is present, sonography may help to determine whether a mass is present or not and some features of this mass, such as calcification or areas of necrosis or cyst. As in most thoracic evaluation, contrast-enhanced chest CT gives optimal evaluation. Evaluation of anterior of middle mediastinum masses or pulmonary parenchyma masses is best afforded by CT (see congenital lung abnormalities below).

53 4.5 · Mass or mass-like conditions

For posterior masses, MR imaging is the primary modality given the fact that 80-90% of these masses are neurogenic in origin. Because of this, optimal evaluation of the intraspinal contents and vertebral column is warranted. This is best afforded by MR imaging. For middle and anterior mediastinal masses, CT can give sufficient information for diagnosis, or limited differential considerations. In addition, CT provides adequate information for surgical planning.

A

4.5.2 Chest wall

Most chest wall masses are usually identified or suspected by clinical examination. Within the chest wall, masses may arise from any of the tissues, including bone, muscle, skin or vascular structures, including lymphatic abnormalities (⊡ Fig. 4.19) [4, 11]. In certain situations, a chest radiograph may help to define an osseous abnormality which is congenital in nature and simply not manifest until late infancy or childhood. Ultrasonography can be used to confirm the presence of a mass. In a setting where the mass is potentially 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 used for evaluation of breast abnormalities in infants and children, both male and female. Since radiography is very 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 regarding the extent and character of osseous masses (e.g. chondroid or osteoid matrix, periosteal reaction, calcification), but MR gives more information

B ⊡ Fig. 4.18A,B. Posterior mediastinal mass (ganglioneuroma). A Frontal chest radiograph in this teenage girl shows large mass with slight effect on subjacent ribs (arrows). B Contrast-enhanced chest CT examination shows fairly homogenous soft tissue attenuation mass in the posterior mediastinum with scattered punctate calcifications. Borrowed with permission American College of Radiology

⊡ Fig. 4.19. Coronal T2-weighted MR imaging of neurofibromas (arrows) in the distribution of the brachial plexus

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on the presence and extent of marrow involvement and associated soft-tissue abnormalities.

4.5.3 Airway abnormalities

4

Tracheal masses are relatively rare and consist predominantly of papillomas. Other masses include granulomas such as after endotracheal intubation, or foreign bodies.


Within the lungs, the majority of mass or mass-like conditions are due to either congenital abnormalities (for example bronchogenic cyst, sequestration, congenital cystic adenomatoid malformation previously discussed under congenital lung abnormalities (⊡ Fig. 4.20) or round pneumonia. Other conditions include pseudotumours (loculated pleural fluid projected over the lung), or contusion. Primary lung malignancies in children are extremely rare.

Congenital lung malformations Solid mass-like ▬ Bronchogenic cyst ▬ Pulmonary sequestration ▬ Rarely, congenital cystic adenomatoid malformation (CCAM): more often air-filled ▬ Hybrid of above lesions

A

Air-filled mass-like ▬ Congenital cystic adenomatoid malformation ▬ Congenital diaphragmatic hernia ▬ Diaphragm elevation ▬ Pneumatocele 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 indicated for posterior mediastinal processes while either CT or MR is useful for evaluation of masses within the anterior or middle mediastinum (⊡ Fig. 4.21). CT is helpful in de-

B ⊡ Fig. 4.20A,B. Congenital cystic adenomatoid formation in a young child presenting with respiratory distress. A Frontal chest radiograph 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 a

Hypertrophy

Cyst Thymic carcinoma

Lymphomaa

Thymoma

Hyperplasia

Cystic dysplasia

Thymolipoma / fibrolipoma 2. LYMPHOMAa

Nerve cell (ganglion) Neuroblastoma (including ganglioneuroblastoma)

Ganglioneuroma

Nerve sheath Neurofibroma Benign schwannoma (neurilemmoma)

Malignant schwannoma

Teratomaa / teratocarcinoma

Choriocarcinoma

Other (rare) Paraganglioma (alternate terms chemodectoma, pheochromocytoma)

Seminoma

Embryonal carcinoma

2. NON NEURAL (< 15%)

Endodermal sinus tumour

Mixed types

Foregut Bronchogenic cyst Oesophageal duplication

3. GERM CELL TUMOURS

4. OTHER Abnormally (e.g. aneurysm)

Thyroid ectopia

Vascular malformations

Langerhans cell histiocytosis

Metastases

Extension of paracardiac tumours / pericardial cysts

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 limiting the differential considerations of mediastinal masses. 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 by 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.

Vascular Aortic aneurysm Azygos/haemiazygos enlargement

Neurenteric cyst Oesophageal dilation Haemangioma

Lymphatic Lymphoma

Lymphangioma

Paravertebral Hematoma Extramedullary haematopoiesis

Abscess Metastases

Diaphragmatic Bochdalek hernia Paraesophageal or hiatal hernia Other Mesenchymal tumours (sarcoma, 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

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this technique may be used for morphological assessment in these cases.

4.6

Trauma

4.6.1 Introduction

4

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

Virtually all thoracic trauma consist of ingested foreign bodies, such as swallowed coins, aspirated material, or a blunt or penetrating injury. The selection of the imaging modality and algorithm will depend on the type of trauma. Radiography is often used both for aspirated and swallowed material, as well as in penetrating and blunt trauma. Chest radiography is often sufficient for minor blunt trauma and is also the initial modality in the setting of severe penetrating or blunt trauma before additional evaluation and imaging is performed. 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 left ventricle (arrow)


Echocardiography is the initial modality for evaluation of cardiac masses. Contrast-enhanced MRI can be helpful in assessing intracardiac masses not sufficiently evaluated by echocardiography, and for assessment of paracardiac masses and cardiac involvement by extracardiac masses (⊡ Fig. 4.22). The dynamic information afforded by MR is an advantage compared with CT, and

Radiography helps in assessment of minor blunt trauma. While detecting a potential rib fracture is often the clinical question, the more important task is to detect the sequelae of these fractures consisting of a fluid collection (haemothorax) or pneumothorax. The radiograph is also usually sufficient for detection of clavicular fractures. For complex trauma to the chest wall, imaging plays only a minor role, aside from 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 soft-tissue injury is best addressed using MR. One important exception to the above is the presence of posterior rib fractures, particularly in infancy and young childhood. These have a high association with non-accidental injury (infant or child abuse; ⊡ Fig. 4.23). Diaphragm injury can be included in the chest wall category. Injury to the diaphragm can occur with either penetrating or blunt trauma, including blunt abdominal trauma. Diaphragm injury can easily be overlooked given other confounding findings including contusion or aspiration. MDCT with coronal and sagittal reformations can display herniation of intra-abdominal contents into the thorax.

57 4.6 · Trauma

help in detecting a radio-opaque foreign body, or asymmetric aeration (either atelectasis or air trapping), which is a secondary finding. CT is more sensitive in detecting an aspirated foreign body although bronchoscopy is often the next step with strong clinical suspicion or supportive findings on radiography (atelectasis or air trapping). Fluoroscopy can be used if there is a question of obstruction, demonstrating decreased change in lung volume on the affected side (⊡ Fig. 4.24). With a history of blunt or penetrating injury, particularly in the setting of a persistent pneumothorax with a thoracostomy tube present, CT may demonstrate the injury to the trachea or bronchus.


⊡ 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 ▬ Posterior rib fractures ▬ Sternal fractures ▬ Scapular fractures ▬ Fractures of posterior elements ▬ Proximal humeral metaphyseal corner fractures Moderate risk ▬ Multiple fractures ▬ Fractures of varying ages ▬ Vertebral body fractures Low risk ▬ Clavicle fractures ▬ Humeral diaphyseal fractures 4.6.3 Airway abnormalities

Trauma to the airway consists of aspirated material, such as a foreign body or direct injury with penetrating or severe blunt injury (shearing forces). Radiography can

There is little role for any other modality in assessing lung parenchymal trauma than CT. Radiography is insensitive to the presence and extent of injury, and the other modalities, likewise, do not give sufficient parenchymal detail. CT can depict lung injury including pleural disease (pneumothorax and haemothorax), contusion, laceration, haematoma, pneumatocele, fat emboli (from large, long bone fractures) and aspiration (⊡ Fig. 4.25).

4.6.5 Mediastinum

Mediastinal trauma is also best addressed by CT initially. For injury, particularly penetrating, near the oesophagus, a water-soluble contrast swallow is indicated to exclude oesophageal injury. Radiography in the setting of acute trauma is indicated to assess secondary signs of aortic injury (addressed below), including mediastinal haematoma, and can also show mediastinal haematoma from spine fractures.


CT angiography is indicated to assess vascular injury, including the aorta and branch vessels in the acute setting (⊡ Fig. 4.26). Injury includes dissection, transaction and thrombosis. MR angiography can also be used to assess vascular injury, but because CT is used for assessment of head, spine and intra-abdominal and pelvic injury, in addition to injury to the lung or airway, CT is the preferred modality for assessment of arterial injury as well. In the subacute or chronic setting, for assessment of vascular

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*

4

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

⊡ Fig. 4.25. Teenage female following motor vehicle collision. CT shows anterior pneumothorax (arrowheads), dense right lung consolidation, 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.

59 4.7 · Toxic/metabolic and thoracic evaluation of systemic disorders

trauma including aneurysm, stenosis or trauma-related thrombosis, MR angiography or venography should be the initial consideration (if ultrasonography is not useful) because there is no radiation involved as with CT. Radiography is helpful in assessing for secondary signs of vascular (usually aortic) injury. Traditional features include widening of the superior mediastinum, left apical cap, blurring of the aortic arch, widening of the left paravertebral stripe and rightward deviation of the distal trachea or oesophagus at the same level. Some of these findings (visualization of the aortic arch and mediastinal widening) are less reliable in young children given the presence of a radiographically visible thymus. The decision about further imaging must be made based on clinical concern, including mechanism of injury, other evidence of at least moderately severe chest trauma, and some or all of the above radiographic features.

4.7

Toxic/metabolic and thoracic evaluation of systemic disorders

4.7.1 Introduction

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 the setting of both primary or acquired immunodeficiency (i.e. due to antibiotics or cancer chemotherapy) or acquired immunodeficiencies, sepsis, bleeding disorders, embolic phenomena, metastatic disease (which includes both cancer and other multiorgan disorders such as Langerhans cell histiocytosis—or eosinophilic granuloma—and consists of chest wall involvement, mediastinal masses, hilar adenopathy, and pulmonary metastases; ⊡ Fig. 4.27), vasculitides, connective tissue disorders, congenital disorders such as cystic fibrosis and pulmonary manifestations of metabolic disorders such as glycogen storage disease (cardiomegaly) or Niemann Pick disease (interstitial lung disease). Radiography is usually the initial imaging modality. If further information is necessary, CT is generally 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 pulmonary manifestations of systemic disorders include oedema, well or poorly defined pulmonary nodules, airspace opacities or interstitial disease (such as bronchiectasis), Interstitial lung disease (ILD) has a variety of

⊡ Fig. 4.27. Metastatic osteosarcoma with large pulmonary masses and nodules, including areas 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 children. In fact, it is presently a poorly classified and rapidly evolving group of 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 examination. HRCT is indicated for the definition of suspected interstitial lung disease (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. bronchiectasis in a child suspected of being immunodeficient), assessment of pulmonary function abnormalities in the setting of normal chest X-ray, or if there is known systemic disease of which ILD may be manifestation (e.g. sarcoid or systemic lupus erythematosis) in which the HRCT is used to assess the severity of disease or as a baseline as a measure of therapeutic response. It is extremely important to obtain HRCT images without respiratory motion as this may obscure important findings. Children should be able to breath hold (they can rest between slices) or be intubated or have some other technique (such as controlled assisted ventilation). With the newest very fast CT, HRCT images may be relatively motion-free at the end of inspiration or expiration; however, the images in between are usually non-diagnostic due to motion. Interstitial lung disease is seen with hemosiderosis (airspace opacities, fibrosis), alveolar proteinosis (airspace opacities, interstitial thickening), lymphangioleiomyomatosis (interstitial thickening), interstitial

4

60


4

A

⊡ Fig. 4.29. Chest CT examination in child with cystic fibrosis. Note scattered bronchiectasis

B ⊡ Fig. 4.28A,B. High-resolution CT at two levels near the carina (A,B) of a young child with Langerhans cell histiocytosis demonstrating multiple cystic regions. Detail is sufficient even when scanning while breathing

pneumonias [2] and Langerhans cell histiocytosis (small nodules, cavitation, cysts) (⊡ Fig. 4.28).

Common causes of bronchiectasis in children ▬ ▬ ▬ ▬

Cystic fibrosis (most common) (⊡ Fig. 4.29) Recurrent infection (includes immunodeficiencies) Foreign body Other – Congenital/syndromic: Kartegaener’s syndrome (ciliary dyskinesia)

Pulmonary manifestations are the most common for cystic fibrosis (CF). Thoracic manifestations include bronchiectasis, airspace disease, adenopathy, pneumothorax and pneumomediastinum. Radiography is used to assess acute signs or symptoms. CT is a better modality for assessing (e.g. CF scoring system) disease progression or 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 the congenital or primary immune deficiency, 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 usually warranted, usually CT examination (⊡ Fig. 4.30). Image-guided biopsy also plays a role, 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 process (e.g. mucous, tumour, foreign body) – Exobronchial process (extrinsic compression such as mediastinal mass or vascular ring), – Bronchiolitis obliterans

61 References

3. 4.

5.

6.

7. 8.

9. 10.

11. 12. ⊡ Fig. 4.30. Young child with severe combined immune deficiency (SCID) with candida pneumonia and secondary chest wall involvement. Borrowed with permission American Journal of Roentgenology

13.

14.

– Patient rotation – Pneumothorax – Lung cyst – Chest wall deformities – Contralateral volume loss or hypoplasia B. Volume loss/small/opaque hemithorax – Atelectasis (including endobronchial and exobronchial processes – Layering effusion – Hypoplasia (e.g. primary hypoplasia, space occupying mass such as congenital diaphragmatic hernia) – Contralateral hyperinflation or asymmetrically 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, Frush DP (2003) Pediatric multidetector body CT. Radiol Clin North Am. 41:637-655 Fefferman NR, Pinkney LP (2005) Imaging evaluation of chest wall disorders in children. In: Frush DP (ed) Pediatric chest imaging, 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) Imaging evaluation of congenital lung abnormalities in infants and children. In: Frush DP (ed) Pediatric chest imaging, W.B. Saunders, Philadelphia, PA, pp 303-323 Frush DP, Herlong RJ (2005) Pediatric thoracic CT angiography. Pediatr Radiol 35:11-25 Chung T (2005) Magnetic resonance angiography of the body in pediatric patients: experience with a contrast-enhanced time-resolved technique. Pediatr Radiol 35:3-10 Hernanz-Schulman M. (2005) Vascular rings: a practical approach to imaging diagnosis. Pediatr Radiol. 35(10):961-79 Donnelly LF (2005) Imaging in immunocompetent children who have pneumonia. In: Frush DP (ed) Pediatric chest imaging, 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) Pediatric chest imaging, W.B. Saunders, Philadelphia, PA, pp 325-353 Westra SJ, Wallace EC (2005) Imaging evaluation of pediatric chest trauma. In: Frush DP (ed) Pediatric chest imaging, W.B. Saunders, Philadelphia, PA, pp 267-281 Brody AS (2002) Thoracic manifestations of systemic diseases. In: Lucaya J and Strife JL (eds) Pediatric chest imaging, Springer, Berlin Heidelberg New York, pp 245-264 Brody AS (2005) Imaging considerations: interstitial lung disease in children. In: Frush DP (ed) Pediatric chest imaging, W.B. Saunders, Philadelphia, PA, pp 391-403 Hollingsworth CL (2005) Thoracic disorders in the immunocompromised child. In: Frush DP (ed) Pediatric chest imaging, W.B. Saunders, Philadelphia, PA, pp 435-477 Yin EZ, Frush DP, Donnelly LF, Buckley RH (2001) Primary immunodeficiency disorders in pediatric patients: clinical features and imaging findings. AJR 176:1541-1552

4

5 Abdomen Jochen Tröger

5.1

Hepatobiliary system, spleen, pancreas

Hyun Soo Ko 5.1.1 Hepatobiliary system

Congenital and neonatal abnormalities Biliary atresia and neonatal hepatitis Neonatal jaundice that persists beyond 4 weeks 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 infection with mostly normal appearance of the liver on US, MRI and CT (sometimes gall bladder thickening is seen in patients with hepatitis). Biliary atresia and neonatal hepatitis have similar clinical, biochemical and histological findings, hence diagnostic imaging plays an important role in differentiating patients with biliary atresia who undergo prompt laparatomy and patients with neonatal hepatitis who will be treated medically. The distinction between biliary atresia and neonatal 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 obstruction, the proximal intrahepatic ducts are usually small. In neonatal hepatitis the intra- and extrahepatic bile duct system is patent but small. The initial imaging procedure is US to exclude choledochal cyst and dilatation of the extrahepatic bile duct system. Only about 20% of patients with biliary atresia

have an identifiable gallbladder, thus the finding of a normal gallbladder only is able to support the diagnosis of neonatal hepatitis. Hepatobiliary scintigraphy with 99Tc-labelled iminodiacetic acid (IDA) derivates provides accurate diagnosis with evidence of gastro-intestinal excretion of tracer in patients with neonatal hepatitis and lack of gastro-intestinal excretion of tracer (often associated with an increased urinary excretion) in neonates with biliary atresia.

Choledochal cyst and Caroli disease A choledochal cyst is an uncommon diagnosis, with higher incidence in females and orientals and half of the patients being 1-10 years old. It is a localized dilatation of the bile duct system with five types (modified Todani classification, see ⊡ Table 5.1). Choledochal cysts can be subdivided into two groups: one group with neonatal jaundice caused by stenosis or atresia of the biliary tree and the other, diagnosed later in life, being associated with common duct stones and pancreatitis. Complications: cholangitis, pancreatitis, stone formation and liver cirrhosis. US, hepatobiliary scintigraphy with 99Tc-labelled iminodiacetic acid (IDA), MRI and ERCP allow a specific diagnosis. Differential diagnosis includes the whole spectrum of other fluid-filled masses (e.g. hepatic cyst, pancreatic 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 abscesses are very rare in children (usually 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 often diagnosed in association with obstructive congenital biliary anomaly, total parenteral nutrition, 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 diagnostic gold standard for biliary stones is US. The typical appearance on US echogenic opacities within the gallbladder that shift with gravity and show an acoustic shadowing. The distinction between small nonshadowing gallstones and biliary sludge may be difficult. Neonatal cholelithiasis may resolve spontaneously. Persisting (> 6 h) right upper quadrant pain with typical sonographic findings suggests acute calculous (85%) or acalculous (15%) cholecystitis. Acalculous cholecystitis is often associated with recent surgery. US has up to 100% sensitivity and specificity in diagnosing acute cholecystitis, demonstrating a gallbladder wall thickening (> 3 m), a positive sonographic Murphy sign (abdominal pain during US scanning of the gallbladder) and hydrops of the gallbladder (distension > 5 cm in AP diameter 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, contrast enhanced CT and MRI may give additional information, e.g. gallbladder function, pericholic morphology. Complications of acute cholecystitis are gallbladder gangrene, pericholecystic abscess, impacted gallstone leading to cystic duct obstruction (Mirizzi syndrome), emphysematous cholecystitis, empyema, duodenal obstruction due to eroded gallstone (Bouveret syndrome) or gallstone ileus.

Hepatobiliary tumours A

B

The liver is, after the kidney and adrenal glands, the third most common site of origin of abdominal malignancies. Approximately 5-10% of all abdominal tumours are situated in the liver and about one third of all primary liver tumours in children are benign (see ⊡ Table 5.2). The main role of imaging is the differentiation between benign and malign tumours, their extension and thus resectability and response to treatment. Precise diagnosis usually can be made with clinical presentation, age, laboratory results and imaging. US with colour Doppler examination is useful for assessing the solid and fluid nature and vascularity of the lesion; however, MRI and CT are best for evaluating the preoperative localization and resectability. MRI shows a slight advantage over CT and CT is superior in postoperative follow-up in detecting recurrences.

⊡ Fig. 5.3A,B. MRI (Haste, transversal plane) of a 20-year-old female 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 the most common benign hepatic tumour during the first 6 months of life (⊡ Fig. 5.5). The nomenclature of cavernous haemangioma and haemangioendothelioma is not consistent, and it is probable that they belong to the same entity in different phases of evolution. US demonstrates heterogeneous, predominantly hypoechoic, hepatic lesions with vascular components and calcifications in 50%. MRI shows a heterogeneous, predominantly hypointense, lesion on T1-weighted images and varying degrees of hyperintensity on T2-weighted images with early peripheral rim enhancement, while CT shows a hypo-attenuating mass with early peripheral rim enhancement and variable delayed central enhancement. Main complications are congestive heart failure due to AV shunting haemorrhagic diathesis (Kasabach-Merritt syndrome), obstructive jaundice, rupture of tumour (haemoperitoneum) and, rarely, malignant transformation into angiosarcoma.

5

66


⊡ Table 5.2. Paediatric hepatic tumours Tumour

Prevalence

Benign Epithelial

5

Focal nodular hyperplasia

3%

Adenoma

1%

Mesenchymal

Haemangioendothelioma/ cavernous haemangioma

18%

Other

e.g. Mesenchymal hamartoma

4%

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 (elevated alpha foetoprotein, heterogeneous mass, low vascularity) ▬ mesenchymal hamartoma (usually multilocular cystic mass) ▬ metastatic neuroblastoma (elevated catecholamines, adrenal mass)

B

Hepatic adenoma It is the most common hepatic tumour in young 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 with variable echogenicity while MRI shows a round mass of decreased intensity (except in those cases with fresh intratumoural haemorrhage presenting as a hyperintense mass on T1w images). Contrast-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 rare benign congenital hamartomatous malformation and congenital arteriovenous malformation; triggering focal hepatocellular hyperplasia is postulated as its cause. Oral contraceptives do not cause but stimulate its growth. FNH is usually 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 partly solid, partly cystic abdominal mass (transversal plane). B T2w MRI (transversal plane). C T1w contrastenhanced MRI (coronal plane) demonstrating contrast enhancement of the solid part of the tumor


A

B

C

D

⊡ Fig. 5.6A–D. MRI and CT of a 21-year-old male with hypopharynx carcinoma and incidentally diagnosed hepatic adenomas (segment 3 of the left lobe and segment 6/7 of the right lobe). MRI: T1 axial plane A Unenhanced phase with iso- to slightly hyperintense adenomas. B Equilibrium contrast-enhanced phase with hypointense masses and

a peripheral rim enhancement of the adenoma of the right lobe). CT axial plane demonstrating the hepatic adenomas with contrast enhancement during the arterial phase (C) and iso- to hypodense signal during the equilibrium phase (D)

while liver function is normal. Most FNHs are well circumscribed, non-encapsulated with a nodular cirrhoticlike mass, and are highly vascularised. A central scar is common whereas calcifications are extremely rare. US demonstrates a homogeneous mass with a varying 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 usually homogeneous

with iso- or hypointense appearance on T1-weighted images and slightly hyper- to iso-intense appearance on T2weighted images compared to normal liver parenchyma. Contrast-enhanced MRI studies show analogous enhancement during arterial, portal venous and delayed phases. Differential diagnoses include hepatic adenoma, haemangioma, hepatoblastoma and hepatocellular carcinoma, and may still be hard to be distinguished by US, CT or MRI. Nuclear sulphur colloid scintigraphy scan can lead to final diagnosis with a pathognomonic normal (5070%) to »hot« (elevated up to 10%) uptake, whereas other differential diagnoses show no significant uptake.

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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 (arterial phase) demonstrating a high flow supplying artery. Arrows supplying artery (B) powerDopper, (D) MRI

Hepatoblastoma Hepatoblastoma (⊡ Fig. 5.8) is the third most common abdominal tumour and the most common primary hepatic tumour in children. Hemihypertrophy and the Beckwith-Wiedemann Syndrome, trisomy 18 and familial adenomatous polyposis are often associated with hepatoblastoma. Most patients are < 3 years old and there is a higher incidence among males. The tumour is usually large, solitary, and well-delineated with a pseudocapsule. Serum AFP is elevated in 90% of cases. US demonstrates a large heterogeneous, echogenic, hypervascular mass, often with calcifications, occasionally with cystic areas (hemorrhage, necrosis). CT shows an inhomogeneous mass with a peripheral rim enhancement. On MRI, hepatoblastoma presents as hypointense on T1-weighted and hyperintense with hypointense fibrous septa on T2-weighted images. Inhomogeneous areas of hemorrhage with typical appearance

(hyperintense on T1w and hypointense on T2w) may be seen. Differential diagnosis: ▬ haemangioendothelioma ▬ metastatic neuroblastoma ▬ mesenchymal hamartoma ▬ hepatocellular carcinoma

Hepatocellular carcinoma (HCC) HCC is the second most common malignant hepatic 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 diffusely infiltrating mass that is inhomogeneous, with variable echogenicity and rarely with calcifications on US. On MRI and CT HCC presents as a heterogeneous mass with contrast enhancement. Except for age, clinical symptoms


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 years. The tumour presents as a large, hypovascular mass with well-delineated borders with a fibrous pseudocapsule and cystic areas. Necrosis and hemorrhage are common, whereas usually no calcifications are seen. The tumour may infiltrate into the diaphragm, the lung and other locoregional structures. US, MRI and CT show a heterogeneous, partially cystic mass with contrast enhancement of fibrous septa.

Hepatic metastases

A

The most common hepatic metastases are from neuroblastoma (⊡ Fig. 5.9), Wilms tumour, leukaemia and lymphoma. They usually present as solitary or multiple solid nodules within the liver parenchyma. Their echogenicity, density and intensity may vary, but they often show an 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 and seldom lobulated intraluminal masses may be seen with all imaging modalities.

Trauma of the liver

B ⊡ Fig. 5.8A,B. 3-year-old boy with abdominal pain due to hepatoblastoma with intratumoral hemorrhage and highly inhomogeneous parenchymal pattern (coronal TIRM MRI (A) and transversal US (B))

are similar to hepatoblastoma, and with imaging alone a differentiation between hepatocellular carcinoma and 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 years) and has no association with chronic liver disease. The hallmark of this variant is a central hyperechoic scar.

Blunt trauma of the liver is the second most common abdominal injury after trauma of the spleen. Contrastenhanced CT is the major tool to evaluate a blunt abdominal trauma (⊡ Fig. 5.10). CT shows a hypoattenuating haematoma with variable shape (depending on type of liver injury), hypodense wedge-shaped areas as focal hepatic devascularization and focal contrast enhancement as site of active bleeding. A haemoperitoneum, intrahepatic/ subcapsular gas and rupture of spleen are often associated with these findings. US demonstrates a heterogeneous liver with lack of normal vascular pattern and localized echogenic areas of hemorrhage.

Vascular abnormalities Portal hypertension Portal hypertension is in most cases 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. 5.10A,B. US and CT of a 6-year-old boy with hepatic rupture after blunt abdominal trauma, demonstrating the ruptured area in the longitudinal. (A) US and transversal (B) contrast enhanced CT view of the liver

⊡ 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 decreased portal venous blood flow may be due to prehepatic (e.g. portal vein thrombosis or portal vein compression), intrahepatic (e.g. liver fibrosis, liver cirrhosis, hepatitis) or posthepatic obstruction (e.g. Budd-Chiari syndrome, heart failure). Prehepatic portal obstruction, especially due to portal vein occlusion, is more common in children (approx. 70%) than in adults. Portoportal and portosystemic collaterals develop with an increased portal resistance. During childhood the most common complication of portal vein thrombosis is splenomegaly and acute gastrointestinal, often oesophageal, hemorrhage. Other complications include renal enlargement and portal venous collaterals. Portal vein thrombosis mainly occurs between the ages of 3 and 10. A small group can be related directly to

previous umbilical catheterization or ascending omphalitis but in most cases portal vein thrombosis is idiopathic. In children with liver cirrhosis, portal hypertension is often detected through abnormal laboratory results of liver function, hence gastro-intestinal hemorrhage is a rather rare complication. Doppler US should determine the diameter of the portal vein, portal venous blood flow and flow direction and evaluation of present collaterals. One of the first signs of portal hypertension is the loss of blood flow variation during respiration. Portal vein branch occlusions are difficult to define by US. After portosystemic shunts, portal venous blood flow is inversed with a continuous hepatofugal blood flow. MRI and CT are useful techniques to determine portal vein thrombosis, cavernous transformation of the portal vein and portal collaterals (⊡ Fig. 5.11).


Budd-Chiari syndrome The Budd-Chiari syndrome (hepatic venous obstruction) is uncommon during childhood and in about two-thirds of cases idiopathic. In one third it is caused by thrombosis (e.g. sickle cell disease, leukaemia) or non-thrombotic obstruction (e.g. tumour, constrictive pericarditis, right heart failure). Doppler sonography is a useful, non-invasive method for evaluating the Budd-Chiari syndrome. Typical findings are the small diameter and absence of blood flow in hepatic veins and in up to 90% a hypertrophy of the caudate lobe, with prominent hepatic veins draining the caudate lobe into the inferior vena cava. MRI and CT also demonstrate the absence of blood flow in hepatic veins and may provide additional information about collaterals and anatomical structures.

A

Hepatic veno-occlusive disease (HVOD) HVOD is defined by obstruction of the hepatic venous system at the level of the central and sublobular veins. The majority of cases are due to previous chemotherapy or certain medication (e.g. alkaloids), hepatic radiation and bone marrow transplantation. Imaging is capable to exclude the Budd-Chiari syndrome (patent major hepatic veins), but definitive diagnosis requires biopsy and histological evaluation. HVOD is often associated with a gallbladder wall thickening, ascites, hepatosplenomegaly, decreased diameter of the major hepatic veins, increased diameter of the portal vein and portal venous collaterals.

Diffuse hepatic parenchymal disease Hepatitis Except for neonatal hepatitis, viral infections are the most common cause of hepatitis. Radiology is very rarely requested because US, MRI and CT usually show a normal appearance. Gallbladder wall thickening is sometimes seen.

Congenital hepatic cyst Congenital hepatic cysts (⊡ Fig. 5.12) are the second most common benign hepatic lesion after haemangioma. 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-year-old girl with portal vein thrombosis consecutive splenomegaly and venous collaterals due to idiopathic liver fibrosis. A CT portal venous phase with contrast-enhanced aorta and hepatic arteries but non-enhanced portal vein (white arrows). B Reformatted CT demonstrates splenomegaly and multiple venous collaterals

Polycystic liver disease is an autosomal dominant disease with a female predominance that is combined with polycystic kidney disease in up to 50% of cases. The cysts are usually located throughout both lobes of the liver. US shows a typical cystic structure that may contain fluidfluid levels and typical attenuation is seen with CT and 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) shows focal or diffused increased echogenicity, whereas CT imaging shows markedly decreased attenuation. MRI (⊡ Fig. 5.13B) findings 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 the liver is due to metabolic diseases such as haemachromatosis or after multiple blood transfusion or major thalasemia with haemosiderosis. The liver usually appears normal to hypoechoic on US, whereas CT demonstrates a markedly diffuse and increased attenuation of liver parenchyma. On MRI T2w sequences, the liver parenchyma is hypointense.

Cirrhosis Cirrhosis (⊡ Fig. 5.14) is a chronic liver disease with irreversible widespread hepatic fibrosis, diffuse parenchymal necrosis and nodular parenchymal regeneration. There are multiple aetiologies, and in children the most common causes are chronic cholestasis (e.g. in cystic fibrosis, biliary atresia, inflammatory bowel disease, hepatitis), hereditary diseases (e.g. tyrosinemia, galactosemia, alpha1-antitrypsin deficiency, Wilson disease) and iatrogenic 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 detected on US, CT and MRI. Regenerative liver nodules usually have signal intensity similar to normal liver parenchyma on MRI and therefore may be differentiated from HCC nodules in the cirrhotic usually have a similar signal intensity compared to normal liver parenchyma and therefore may be differentiated from HCC nodules. 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 are several indications for liver transplantation in children. Assessment of portal vein size, hepatic blood flow, detection of portosystemic shunts, unsuspected tumours and anatomical abnormalities are important pre-operative information that may be provided by US. In children with complex anatomical structures or in whom US does not 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 on the type of transplantation (whole-organ versus split-organ), hepatic localization and vascular anatomy may vary. Portal vein and hepatic artery anastomosis are usually performed end to end whereas the recipient 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 postoperative complications are hepatic artery thrombosis resulting in infarction, biliary anastomosis leaks and strictures. Periportal oedema is an early finding, caused by a lymphedema due to lack of normal lymphatic drainage which presents as hyperechoic on US


and as a »periportal collar« of high intensity on T2w images on MRI and low attenuation on CT. Doppler US is essential in postoperative evaluation because of its non-invasive assessment of hepatic haemodynamics. MRI T2w fat-saturated sequences or contrast enhanced T1w sequences with hepatobiliary contrast agents may be helpful in diagnosing 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 to biliary atresia or neonatal hepatitis ▬ Hepatobiliary scintigraphy allows to diagnose biliary atresia

▬ ▬

A

A

B

B

⊡ Fig. 5.13A,B. 1-month-old boy with coagulopathy, hepatosplenomagly and fatty replacement of the liver. A US: longitudinal view of the liver demonstrating diffused increased echogenicity of the parenchyma. B MRI: coronal STIR sequence showing 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 portal 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 cystic 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

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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 and US, MRI and radionuclide scintigraphy with 99TC-labelled sulphur colloid lead to confirmation of asplenia.

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Polysplenia A

Poysplenia (⊡ Fig. 5.16) may also be associated with less severe cardiac problems, hemihypertrophy and biliary atresia. Polysplenia should not be confused with accessory splenic tissue or post-traumatic fragmentation of spleen.

Accessory spleen An accessory spleen (⊡ Fig. 5.17) is a very common variant with an incidence of 10-30%. It is a small, round, softtissue mass that is localized 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 malpositioned spleen that is usually diagnosed incidentally. However, torsion and thus vascular thrombosis/infarction may occur, leading to inhomogenous echogenicity on US and 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 haste sequence (periportal »collar«). B CT reformatted coronal view (periportal »collar« and splenomegaly, collaterals). C Transversal MRI contrast-enhanced T1 sequence (collaterals)

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 cyst) or secondary (usually pseudocysts, except for parasitic lesions) to vascular (laceration/haematoma, cystic degeneration of infarct), infectious (abscess, tubercu-


A ⊡ Fig. 5.17. US of a 5-year-old boy with incidentally diagnosed 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

Trauma

Splenic rupture, splenic haemorrhage

Others

Haemodialysis, autoimmune lymphoproliferative syndrome, sarcoidosis

B ⊡ Fig. 5.16A,B. US of an 8-year-old girl with incidentally diagnosed polysplenia. A Longitudinal view B Transversal view and situs inversus

losis, parasitic) or benign/ malignant tumorous (cavernous haemangioma, lymphangioma, lymphoma, necrotic metastases) reasons. Splenic cysts are usually surrounded by normal splenic parenchyma. They may be echogenic on US (⊡ Fig. 5.19) or hyperdense on CT if they contain fat, cholesterol or debris due to previous hemorrhage or infection. A pyogenic abscess is a sonolucent mass and may be septated or contain gas that is highly echogenic on US. MRI and CT demonstrate a typical cystic appearance (high signal on T2w and varying intensity on T1w images, depending on protein and solid content on MRI and low attenuating mass on CT).

Solid splenic lesions Leukaemia and lymphoma are the most common causes for solid lesions of the spleen (⊡ Fig. 5.20). Lymphatic nodules may vary in echogenicity and size, ranging from

a miliary pattern to asymmetric, solitary affection up to 10 cm in diameter. Arteriovenous and lymphatic malformations often show some cystic-like components. Lymphatic malformations of the spleen are often associated with lymphatic malformations at other sites of the body. A healed splenic infarction is hyperechoic on US and may lead to shrinkage und calcification of the spleen.

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5 A

B A ⊡ Fig. 5.19A,B. US of the spleen (longitudinal view) of a 10-year-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 the most common abdominal injury (⊡ Fig. 5.21). Contrast-enhanced CT is the major tool to evaluate a blunt abdominal trauma. CT

shows a hypoattenuating haematoma with variable shape associated with hypodense wedge-shaped areas of focal splenic devascularization and focal contrast enhancement as site of active bleeding. Free splenic fluid is often noted. US demonstrates a heterogeneous spleen with localized echogenic areas of hemorrhage. Key information

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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


A

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⊡ 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

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⊡ 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 CT

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5.1.3 Pancreas

Pancreatic developmental abnormalities Pancreas divisum

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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, especially MRCP, may show the separate ventral and dorsal portions with their ducts in some cases, whereas conventional ERCP is still 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 usually associated with intrinsic duodenal stenosis or atresia and often diagnosed during infancy because of intermittent vomiting. US is neither sensitive nor specific in diagnosing annular pancreas, thus MRI with MRCP or thin-sectional CT is necessary in order to achieve an accurate diagnosis.

Pancreatic parenchymal disease Pancreatitis There are multiple diseases and abnormalities that can cause acute pancreatitis (see ⊡ Table 5.4), yet some cases of pancreatites are idiopathic. Diagnosis is mainly based on clinical findings and laboratory results. US is generally the first radiological modality to evaluate acute pancreatitis (⊡ Fig. 5.22) and is able to show pancreatic enlargement, dilatation of the pancreatic duct, abnormal echogenicity and peripancreatic fluid collection. However, the pancreas may also appear normal on 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 the pancreas that leads to irreversible damage to its anatomy and function. Aetiology may be classified in chronic calcifying pancreatitis (Kwashiokor, metabolic disorders, hyperlipidemia and hypercalcemia) and in chronic obstructive pancreatitis (e.g. cystic fibrosis, developmental abnormalities, trauma). Plain film may reveal multiple irregular calcifications. Typical radiological findings on US, MRI and CT are irregular pancreatic margins with irregular duct dilatation, pancreatic calcifications, small and sometimes atrophic

pancreatic parenchyma, pancreatic pseudocysts and mild 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 fibrosis (⊡ Fig. 5.23) may lead to pancreatic dysfunction ranging from mild mucus accumulation in the ducts to severe mucus plugging and pancreatic atrophy, fibrosis and cyst formation. Due to fibrous and fatty infiltration, the pancreas appears echogenic and small on US, and also has a fat-equivalent signal on MRI and CT. Calcifications and small cysts may be seen in addition; however, large, macroscopic cystic replacement should not be mistaken for a cystic tumour.

Other Differential diagnoses of an echogenic and/or inhomogeneous pancreas on US, on MRI and CT include the Schwachmann syndrome (exocrine pancreatic insufficiency and bone marrow dysfunction), haemosiderosis 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 pseudocyst has only a fibrous wall and is most commonly 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.


A

B

C

D

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

Pancreatic tumours Pancreatic tumours are extremely rare in children and include rhabdomyosarcoma, carcinoma, mucinous cystadenoma, 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

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▬ 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

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5.2

Urogenital tract

Jens-Peter Schenk 5.2.1 Renal dysmorphology and anomalies

Renal agenesis and hypoplasia Renal agenesis

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Renal agenesis is a rare anomaly and is usually unilateral. If a compensatory hypertrophy of the contralateral kidney is seen, at least a functional unilateral kidney is highly 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.

Possible findings in renal hypoplasia ▬ ▬ ▬ ▬

Normal structure Volume < 3rd percentile Unilateral or bilateral hypoplasia Segmental 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 differentiated. MR urography is indicated in all cases with combined genito-urinary tract malformations or suspicious vaginal urinary output (ureteral ectopia). Scintigraphy

Renal hypoplasia Renal hypoplasia is defined as a reduction in the number of nephrons. The kidneys are small (< 3 percentile) with a normal parenchyma structure. Renal hypoplasia may be bilateral or unilateral. Segmental hypoplasia in unilateral kidney is possible (Ask-Upmark kidney). Bilateral hypoplasia presents in chronic renal failure.

Imaging Ultrasound

If a kidney is neither orthotopic nor in atypical dystopic location, it is indicative of unilateral renal agenesis. Because of possible accompanying anomalies of the uterus 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 decisive. 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 ▬ Pelvic kidney ▬ Lumbal dystopic kidney covered by intestinal air ▬ Clumb kidney

Functional kidney parenchyma can be documented with renal scintigraphy. Scintigraphy proves functional single kidney but not kidney agenesis. Scintigraphy can be necessary in complicated disease with clinical symptoms. Key information

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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 the collecting system is a consequence of the development of two ureteric buds in the mesonephric duct. Two ascending buds lead to a ureter duplex, a premature division of the ureteric bud leads to a ureter fissus. The ureter draining the lower segment migrates

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more cephalad and lateral than the ureter draining the upper segment. There is often reflux to the ureter of the lower collecting system. Upper pole ureter is prone to ureteral ectopia and obstruction. Ectopic ureterocele is due to cystic ballooning of the distal ureter between mucosa and bladder muscle. In girls, urinary dribbling, in boys, 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 ▬ Ectopic ureter ▬ Ureterocele ▬ Megaureter ▬ Dysplasia of the upper pole ▬ Signs of urinary tract infection or VUR

Ultrasound

Pitfalls

Routine ultrasound usually detects a duplication of the collecting system by dilatation of the upper or lower pole due to reflux or obstruction. Ultrasound examination can suggest duplication of the urinary tract and ectopic ureteral insertion, but cannot prove it.

▬ Single dilatation of a calix ▬ Missing the ureterocele due to bladder ▬ A cone of normal parenchyma central in the renal 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

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so that and an obstruction can be missed. Upper pole obstruction leads to a displacement of the lower pole, 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 VCUG. To detect reflux in the upper or more often in the lower renal pelvis of the duplex kidney, VCUG can be replaced by VCUS. The sensitivity of reflux detection is higher in VCUS than in VCUG. Especially in repetitive examinations for follow-up studies, VCUS can avoid radiation exposure to the gonads.

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Key information

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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 bilateral duplex kidney, megaureters in both upper poles and ectopic ureter ostium of the left side. Normal size of both lower poles (arrows)

MRUrography MRU demonstrates anatomical details, even in non-functioning poles (3-D T2/HASTE sequence) (⊡ Fig. 5.25). Ectopic ureteral orifices are best visualized in MRU. Contrast-enhanced MRU with 2-D or 3-D T1 sequences combine the information of contrast excretion in the kidney with documentation of the ureters. Information of partial renal function (%) and urodynamic information can be achieved (⊡ Fig. 5.24).

Intravenous pyelogramm (IVP) Experience with this method showed a lack of information in non-functioning poles of a duplex system,

Horseshoe kidneys are the most common type of renal fusion. Usually, both lower poles connect across the midline by an isthmus lying next to the aorta and inferior vena cava. Horseshoe kidneys are usually in lumbal dystopic position and are frequently found in Turner’s syndrome and Trisomie 18. Hydronephrosis can be associated when ureteropelvic junction obstruction is caused by high ureteral insertion or anomalous vessels. In crossed ectopic kidneys, one kidney lies on the opposite side from ureteral insertion of the bladder. The most common type in crossed ectopy is the unilateral fused type with inferior ectopia. Crossed renal ectopia may be associated with VUR.

Imaging Imaging modalities are similar to those of duplex kidneys. US can detect anomalies of the renal position in crossed ectopia; it often cannot distinguish between ectopy with or without fusion. The isthmus in horseshoe kidneys is usually detectable by US.


Key information

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Fusions anomalies ▬ Crossed ectopy ▬ Incomplete 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

5.2.2 Cystic renal diseases

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

Multicystic dysplastic kidney (MCDK) MCDK is the most common cystic disease. It is most commonly unilateral, with a contralateral normal kidney. A segmental manifestation is very rare. The ipsilateral ureter is abnormal or absent. Association with ipsilateral genital anomalies is possible. As primary volume differs, MCDK often appears as an abdominal mass in neonates. 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 usually achieved solely by sonography. Follow-up monitoring is necessary to exclude complications. 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

Scintigram, VCUG and MRUrography Other imaging modalities become necessary in complications or association with other renal anomalies, such as duplex kidneys with MCDK or in patients with urinary tract dilatation of the contralateral kidney. MRUrography is the preferred modality in differential diagnosis of complex anomalies with MCDK. Key information

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

Renal dysplasia A disturbed renal ontogenesis results in renal dysplasia, which can be focal (e.g. in duplex kidneys) or present as a diffuse renal disease. Clinical symptoms depend on the underlying disease or syndrome. In patients with bilateral dysplasia, renal failure determines the clinical course of the disease.

Imaging Ultrasound

Pitfalls ▬ ▬ ▬ ▬

Hydronephrosis Cystic renal tumours Ovarian cysts in newborn Polycystic kidney disease

In general, dysplastic kidneys are small. US shows a hyperechogenic kidney with a reduced corticomedullary differentiation. In renal cystic dyplasia cysts of varying size infiltrate the renal parenchyma. Associated VUR can be diagnosed with VCUS.

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Renal scintigram Evaluation of kidney function is necessary in patients with complications (obstruction, VUR) and before surgical interventions.

Polycystic kidney disease

5

Polycystic kidney disease includes multiple hereditary diseases: autosomal recessive polycystic kidney disease (ARPKD), autosomal dominant polycystic kidney disease (ADPKD), juvenile nephronophthisis and medullary cystic disease complex (MCDC), congenital nephrotic syndrome and syndromal cysts. The spectrum of these diseases reaches from isolated cysts to diffuse and progressive disease of the kidney parenchyma. In the following, only ARPKD, ADPKD, MCDC and juvenile nephronophthisis will be described.

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

ARPKD Manifestation and course of ARPKD varies, and usually the disease is diagnosed in early infancy. Dilatations of the collecting ducts lead to multiple cysts in cortex and medulla. Bilateral masses are typical after birth. Hepatic cysts are frequently associated, liver cirrhosis and portal hypertension are seen in severe cases. This disorder is diagnosed prenatally with oligohydramnion and is often associated with lung hypoplasia. Severe renal involvement in the neonatal period leads to early death.

⊡ Fig. 5.28. ARPKD, transverse scan

Imaging Ultrasound

Markedly enlarged and uniformly hyperechogenic kidneys are typical at birth. US may fail to define the cysts if they are too small. A typical finding is a bilaterally speckled increased echogenicity of renal tissue with inhomogeneously reduced tissue differentiation (»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 rarely used imaging technique. Because the collecting ducts run from cortex to medulla, radial streaks and tubular striation are the typical findings in ARPKD.

MRU Muliple cysts of the renal parenchyma are best visible in highly T2-weighted sequences. In demonstration of

⊡ Fig. 5.29. Coronal MRI (3-D-T2-SPIR) in polycystic kidney disease with multiple cysts in both kidneys

kidney disease together with liver involvement and lung hypoplasia, MRI is also a useful tool in planning surgical therapy.


⊡ Fig. 5.30. Transverse MRI (ceT1SPIR) with contrast enhancement in residual parenchyma in both kidneys (polycystic kidney disease)

⊡ Fig. 5.31. ADPKD, sonography with longitudinal scan. Parenchymal cyst (arrow)

ADPKD

from dilatated distal tubules and collecting ducts, but some of the cysts can also be found in the renal cortex. Interstitial fibrosis, glomerular sclerosis and cortical atrophy lead to renal insufficiency. Clinically, patients show all symptoms of renal failure.

ADPKD is a cause of end-stage renal failure in adults, but manifestation of the disease often takes place during childhood. Initially, only a few cysts exist; in the course of the disease both kidneys are enlarged and more cysts develop in cortex and medulla. Children may present with hematuria or unilateral or bilateral flank masses. Hypertension is possible. Further secondary complications of the cysts are hemorrhage, sedimentation and infection. Ultrasound examinations of the children’s family (parents) help to differentiate between ADPKD and other cystic renal diseases (⊡ Fig. 5.31).

Imaging Ultrasound

US demonstrates cysts in various size. In small infants usually the renal parenchyma looks normal, only single cysts may be detectable. Positive family screening is considered diagnostic. In later childhood the number of cysts with varying size increases. Hyperechoic parenchyma in bilaterally enlarged kidneys is possible.

MRI In very rare cases with complications and differentiation of complicated cysts, MRI can be helpful, but it is not a routine diagnostic tool.

Imaging Ultrasound

Typical findings in US are small kidneys. In early MCDC no specific signs exist. In the later course of the disease, multiple cysts lying in the renal parechmya, loss of corticomedullary differentiation and hyperechoic parenchyma can be found. 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.

Juvenile nephronophthisis Familial juvenile nephronophthisis is inherited recessively. This disease is a sclerosing tubulo-interstitial nephropathy with small tubular and glomerular cysts. Chronic renal failure determines the course of the disease.

Imaging Ultrasound

MCDC MCDC is an autosomal dominant inherited disease. Typical age of manifestation is in older children and adolescents. Cysts are located in the medulla. Cysts develop

In US corticomedullary differentiation is reduced and a slight hyperechogenicity is observed. Kidneys are small or size decreases in the course of the disease. Cysts are located in the corticomedullary junction zone. Cysts are

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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

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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 vessel in Doppler sonography next to the ureteropelvic junction

Pitfalls ▬ Cystic kidney disease may mimic severe renal pelvic dilatation ▬ VUR with intermittent renal pelvic dilatation ▬ Ureteral stenosis ▬ Infravesical stenosis

5.2.3 Obstructive uropathy

Ureteropelvic junction obstruction

⊡ Fig. 5.32. Ureteropelvic junction obstruction with enlargement of renal pelvis, longitudinal scan

Renal pelvic dilatation can occur as a dilated renal pelvis with or without calyceal dilatation. Special focus is on calyceal dilatation, because pelvic dilatation without calyceal dilatation can be a normal variant. Renal pelvic dilatation can occur in obstructive disease or without obstruction.

Imaging Ultrasound

In prenatal diagnosed pelvic dilatation, ultrasound must confirm the diagnosis after birth. Because of decreased postnatal diuresis, US should 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 urinary tract obstruction. 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


MAG3 Tc99m diuretic renogram

Magnetic resonance urography (MRU)

Urodynamic studies are classified according to the O’Reilly classification and aid in determining between surgical and medical treatment. Diuretic renograms demonstrate function and drainage (⊡ Fig. 5.34). A scintigram should not be performed before the 6th week of life as the kidney’s function is still immature.

MRU is necessary in patients with complex anatomical findings or uncertain ultrasound interpretations. Especially when the location of the obstruction is not clear, further MRI is necessary. Static-dynamic MRU can replace scintigram and IVP.

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

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Key information

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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 newborn. About 20% are bilateral. The obstructive component can return to 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 important, for this reason it is important to perform the study after the first 2 days of life (⊡ Fig. 5.35–5.36).


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

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

Pitfalls ▬ ▬ ▬ ▬ ▬ ▬ ▬

Low hydratation Confound with ovaries in females Peristaltic wave of the ureters Intermittent vesico-ureteral reflux Obstructive uropathy in duplex kidneys Infravesical obstruction with megaureters Megaureter-megacystic syndrome

VCUG Is indicated to differentiate obstructive megaureter from VUR (See Vesico-ureteral reflux, below)

MAG3 Tc99m diuretic renogram The scintigraphy is performed similarly to ureteropelvic junction obstruction (⊡ Fig. 5.37).

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

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


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

Vesico-ureteral reflux

Imaging

Reflux of urine from the bladder to the ureter and renal pelvis due to insufficient valvular mechanism at the ureterovesical junction leads to intermittent or chronic dilatation of the urinary tract. The bacterial inflow from the bladder in the kidneys can result in an urinary tract infection with pyelonephritis. Recurrent infections are responsible for renal scarring and loss of function.

Ultrasound

US detects indirect signs of VUR, to prove that VUR contrast studies are necessary. When intermittent dilatation of the renal pelvis or different diameters of the renal pelvis before and after micturition are observed, think of VUR!

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

⊡ Fig. 5.39. VCUG, normal urethra

Possible findings

Possible findings

▬ ▬ ▬ ▬

▬ Contrast media before or during micturition in the ureter or renal pelvis ▬ Associated bladder diverticulum ▬ Subvesical obstruction, e.g. urethral valve ▬ Uni- or bilateral VUR ▬ Refluxing megaureter

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 remains the gold-standard examination for imaging the bladder and urethra in suspected VUR. Anatomical details are best visualized in VCUG. VCUG is necessary to exclude an urethral obstruction through an urethral valve (⊡ Fig. 5.39–5.41).

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


Contrast-enhanced voiding cysturosonography (VCUS) VCUS has already proven to be a valuable alternative in the diagnosis of VCUG. Concordance between VCUS and VCUG is about 90%. Contrast enhancement is achieved with the use of microbubbles. Harmonic imaging is recommended, to increase sensitivity and specifity (⊡ Fig. 5.42–5.45).

Possible findings ▬ Microbubble regurgitation into the terminal ureters or renal pelvis ▬ Intrarenal 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 imaging before contrast application. Ureter (arrow)

⊡ Fig. 5.41. VCUG with vesico-ureteral reflux in the left ureter (arrow)

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

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5.2.4 Urinary tract infections

Acute pyelonephritis

5 ⊡ Fig. 5.44. Longitudinal scan of the kidney before reflux (anechoic renal pelvis)

In symptomatic infections upper urinary tract infection (acute pyelonephritis) must be distinguished from lower tract infection (acute cystitis). If the renal pelvis and parenchyma are involved, inflammatory oedema and microabscesses develop. Colliquation of infectious foci results 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. Complicated urinary tract infections are based on abnormalities of the kidney, VUR or bladder dysfunction. Upper urinary tract infections present with high fever and generalized symptoms, depending on age. Hematogenic infections of the kidneys are possible, but less common.

Imaging Ultrasound

The primary examination should be obtained to rule out hydronephrosis or other renal anomalies. Furthermore, in pyelonephritis a careful examination of the kidney parenchyma is necessary. The correct measurement of the kidney volume should be performed, an increase of the renal parenchyma of up to double its volume is possible in young children.

Possible findings

⊡ Fig. 5.45. Longitudinal scan of the kidney with harmonic imaging and reflux in the renal pelvis (arrows) after micturition (hyperechoic renal pelvis)

▬

Pitfalls ▬ Intravaginal reflux mimicking reflux in the ureters ▬ Echo-enhancement from air in the bowel loops ▬ Strong acoustic shadow due to a high microbubble concentration in the bladder obscures reflux in the terminal ureters Key information

▬ ▬ ▬ ▬

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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 echogenicity of the parenchyma, especially the renal cortex Hypo- or non-echogenic foci representing microabscesses 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 Increased perirenal echogenicity

Pitfalls ▬ Pelvic wall thickening in VUR, postoperative ureteropelvic obstruction or renal transplant rejection possible


▬ Loss of corticomedullary differentiation in dysplasia or other chronic renal disorders ▬ Hypoechogenic foci in lymphoma or nephroblastomatosis ▬ Diffuse enlargement of the kidney in leukaemia or 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 be achieved through the use of amplitude modified Doppler (power Doppler).

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

CT An indication for uro-CT in childhood is given in combined severe trauma and infection, complex disease with urolithiasis or in special situations with uncertain abscess formation or tumour diagnosis. Best demonstration is in the late postinjection phase with contrast medication. CT is a helpful method in clinical progression under the appropriate therapy.

Possible findings Possible findings ▬ ▬ ▬ ▬ ▬

Segmental perfusion defects Areas of devascularization Non-perfusion in abscess formations Adjacent hyperperfusion Displacement of normal vessels by adjacent inflammation

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

▬ Hypodense striated triangular-shaped areas within the renal parenchyma ▬ Hyperdensitiy of urolithiasis or calcifications ▬ Abscess formation ▬ Contrast-enhancement of the abscess membrane ▬ Air-fluid level in abscess formations ▬ Sedimentation in the pyelon ▬ Loss of corticomedullary differentiation in contrast phase ▬ Perirenal retroperitoneal edema (hyperdense in comparison to the perirenal fat)

Pitfalls MRI MRI can detect renal scarring and acute edema. A great advantage is the possibility of visualizing the complete renal collecting system in relation to the inflammation. A safe detection of renal abscess formations is another advantage and in pre-operative planning MRI is a very useful tool. In addition, the technique of magnetic resonance urography (MRU), with visualization of the urinary tract or renal function analysis, helps to plan the next therapeutic decisions.

Possible findings ▬ ▬ ▬ ▬ ▬ ▬

Enlargement of the kidney Perirenal edema Loss of corticomedullary differentiation Fluid collection Renal and perirenal abscess formation Renal pelvic dilatation in relation to inflammatory foci

▬ Underestimation of the disease in early postinjection phase ▬ Missed inflammatory foci in arterial or early venous phase ▬ Without early injection phase or native scans, differentiation of urolithiasis versus contrast excretion 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 routine use of DMSA scans in acute pyelonephritis is unnecessary, but is indicated in complex situations before therapeutic decisions.

Possible finding ▬ Decreased focal uptake

Pitfall ▬ No differentiation between new lesion and old lesion

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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

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Permanent inflammation of the renal parenchyma in recurrent upper urinary tract infections and delayed treatment in pyelonephritis results in chronic pyelonephritis (called reflux nephropathy). Complications are multiple scarring of the kidney, resulting in renal hypertension, renal failure or end-stage renal disease.

Imaging Ultrasound

Kidneys can appear with diffuse or local scarring. Through the diffuse scarring the echogenicity increases and a lost of cortical-medullary differentiation is observed. Volume measurements are of high importance in a growing child to detect a stagnation of growth in the renal parenchyma.

DMSA scan und MAG3 renogram Both methods can be necessary, depending on clinical conditions and therapy planning.

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 ▬ Normal size possible ▬ Additional CDI can show the perfusion of the renal parenchyma (important for microthrombotic diseases, e.g. haemolytic uremic syndrome or for peripheral reduced flow, e.g. in glomerulonephritis) ▬ Because of systemic involvement, sonography of the whole abdominal situs is important to detect ascites, pleural and cardial effusions, liver, bowel and pancreas 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 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 possible in inherited diseases or in systemic diseases, e.g. infections, auto-immune diseases, malignant diseases, metabolic changes or storage diseases. Symptoms may be proteinuria, hematuria, nephritic or nephrotic syndrome, hypertension and renal failure. Some special entities of renal parenchyma disease are Schönlein-Henoch nephritis, rapidly progressive glomerulonephritis (GN), acute postinfectious GN, vasculitis syndromes, IgA nephropathy, haemolytic-uremic syndromes or systemic lupus erythematosis.

IVU, CT, MRT are not specific in renal parenchyma disease. IVU and CT with intravenous iodinated contrast enhancement should be avoided in renal insufficiency.

Imaging Ultrasound

US is the primary imaging modality in all parenchyma diseases of the kidneys. Sonography is important to rule

⊡ Fig. 5.46. Schoenlein’s purpura with hyperechoic renal cortex, longitudinal scan


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

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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) ▬ Hydronephrosis

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

Radiography Plain film radiography is the secondary method when symptoms caused by kidney stones are not explicable.

5.2.6 Nephrocalcinosis

Urolithiasis Renal calculus is a complication of nephrocalcinosis and a possible finding in recurrent pyelonephritis. Kidney stones can present in acute flank pain. Urolithiasis must be excluded in patients with uncertain hematuria, unilateral hydronephrosis and abdominal pain.

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

Imaging Ultrasound

US must localize the calculus in the kidney parenchyma (e.g. cortical or medullary calcifications), the collecting system (e.g. renal calices or renal pelvis), the ureter (e.g pelvi-ureteric junction, distal ureter) or in the bladder. US of nephrolithiasis in the renal pelvis is very sensitive. Detection of ureterovesical urolithiasis demands patience and is important in the 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 ▬ Acoustic shadow

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

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⊡ Fig. 5.50. Same patient after contrast application in late phase radiogram. Contrast collection in the dilatated renal pelvis and ureter 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 gives the best visualization and is the best method in localizing a kidney and ureter calculus. CT should be performed as a low-dose CT. MRI is not an imaging modality for visualization of calcifications or calculus, but is necessary in imaging of complex diseases with inflammatory pseudotumour. Key information

IVP Routine IVP is not indicated in all cases of urolithiasis. IVP is necessary for planning of pyelotomy, endoscopic therapy or lithotripsy in renal calculus of the size more than 5 mm (⊡ Fig. 5.49–5.50).

Possible findings ▬ Radiopaque 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 complicated calculus in complex diseases, e.g. abscess-forming pyelonephritis or xantho-

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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, corticomedullary and medullary calcification must be distinguished in parenchymal calcifications of the kidney. Medullary calicifications are found in, e.g. renal tubular acidosis, Bartter syndroma or furosemid therapy. Cortical manifestation is found after renal vein thrombosis or primary hyperoxaluria. Vitamin D therapy can result in corticomedullary calcification.


⊡ 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 thrombosis in a newborn. Shrinkage of the kidney with small hyperechoic peripheral calcifications in the renal cortex

Imaging

Imaging

Ultrasound

Ultrasound demonstrates renal enlargement and replacement of the normal corticomedullary relationship in the acute phase. Increased echogenicity can be generalized or in focal areas. In follow-up studies the kidney becomes shrunken and calcified (⊡ Fig. 5.52). CDI demonstrates loss of venous Doppler signal in renal veins. Decrease in systolic flow velocity and 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, annular hyperechoic region between cortex and medulla ▬ Complete hyperechogenicity of the renal medulla

Pitfalls ▬ Urolithiasis ▬ Necrotizing renal papillitis ▬ Renal vessels

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

Pitfalls ▬ Nephritis ▬ Diffuse renal parenchyma disease

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

Pitfalls ▬ Acute infectious nephritis ▬ Nephrocalcinosis ▬ Hypoplastic-dysplastic kidney 5.2.8 Renal tumours

5.2.7 Renal vein thrombosis

Patchy thrombosis of the intrarenal veins of both kidneys causes severe congestion and hematuria. One or both kidneys become enlarged. Renal vein thrombosis can follow after respiratory distress, severe dehydration or shock.

The nephroblastoma (Wilms’ tumour) is the most common renal tumour in childhood. The tumour tend to occur mainly in children of less than 5 years. Preferred locations for metastases are the locoregional lymph nodes and the lung. Liver metastases are possible. Other distant metastases, e.g. in the skeletal system, are

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rare. Association with clinical syndromes (WiedemannBeckwith, Denys-Drash, WAGR syndrome) should be considered. Renal cell carcinoma, clear cell sarcoma, rhabdoid tumour occur in less than about 10% of malign renal tumours in childhood. Mesonephric adenoma is a very rare benign renal tumour. In the first 6 months of life, mesoblastic nephroma occurs more often than Wilms’ tumour. Complicated renal cysts, cystic dysplasia and multilocular cystic nephroma can make diagnostic problems and must be differentiated from cystic nephroblastoma.

MRI MRI is the standard procedure before therapy. MRI gives a global view of the abdomen (⊡ Fig. 5.53–5.54). Contrast sequences are necessary to distinguish between tumour and renal parenchyma.

Imaging Ultrasound

Ultrasound is the fundamental imaging method. Nephroblastomas present as a renal mass with displacement of the renal pelvis and neighbouring organs, including retroperitoneal vessels. Detection of renal vessels is improved by CDI. Renal vein displacement must be distinguished from tumour invasion with tumour thrombus. Panorama imaging is a useful tool for volume measurement of the tumor. Because bilateral tumours are possible, it is important to exclude a second mass in the contralateral kidney. Next to the main tumour nephrogenic rests are possible 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 bleeding with central fluid/sedimentation levels ▬ Cystic tumours with tumour parenchyma are found in the case of cystic nephroblastoma ▬ Complete cystic tumours are found in multilocular 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 nephroma cannot be distinguished from cystic partial differentiated nephroblastoma by imaging methods

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


Lymph node metastases are best visible in MRI, which is superior to CT in detection 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 bleeding in the tumour in T1w sequences ▬ 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

tion and hypo-adrenalism. Most frequently, hemorrhage is asymptomatic. Because of differentiation to neuroblastoma in newborns, catecholamine metabolites in urine can help. In the case of unclear diagnosis, further diagnostics can be interrupted for the next weeks and sonographic follow-up examinations are necessary to demonstrate the volume regression of the lesion. Another cause of bleeding into adrenal glands is the shock from meningococcemia, the Waterhouse-Friderichsen syndrome.

Imaging Ultrasound

Ultrasound is the method of choice to detect adrenal hemorrhage in newborn. Mostly hemorrhage is detected 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. Fluid-fluid levels can occur. In later examinations the volume of the adrenal gland decreases, calcifications occur after resorption of the bleeding (⊡ Fig. 5.55–5.56).

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

Pitfalls ▬ Low-contrast enhancement of the inferior vena cava in early phase studies can make detection of tumour thrombus impossible Key information

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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

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 becomes necessary. Hyperintense T1w signal is indicative of hemorrhage. Key information

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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

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-

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 neuroblastomas arise in the abdomen. A typical location (about 50%) is the adrenal gland. The tumour extends to surrounding tissue by local invasion and to regional lymph nodes. Metastatic spread in bone marrow, skeleton

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Imaging Ultrasound

In any case of suspicious neuroblastoma, sonography of 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: ▬ Adrenal bleeding ▬ Nephroblastoma

MRI

⊡ Fig. 5.56. Hypoechoic oval mass (arrow) above the kidney in the case of a adrenal hemorrhage in a newborn, longitudinal scan

and liver is frequent. Tumours localized to one side of the abdomen often cross the midline. Neuroblastomas frequently secrete neurogenically derived substances, e.g. catecholamine metabolites or neuron-specific enolase. More than 50% of patients have metastatic disease. Primary diagnosis is performed 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 demonstrate tumour response to chemotherapy. Radiological diagnosis must be confirmed by tissue biopsy. Other tumour entities in the adrenal glands such as pheochromocytoma or adrenal carcinoma in childhood are very rare diseases. The main differential diagnosis to neuroblastoma is the Wilms’ tumour in the upper renal pole.

MRI is the best method to diagnose the relation of the 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 can demonstrate tumour necrosis and vital tumour areas. In the case of tumour invasion into the neuroforamina, sagittal sequences of the spine are required. Spinal cord compression has to be excluded. Volume-rendering techniques in post processing allow exact tumour volume measurement.


Encasement of retroperitoneal vessel structures Ventral displacement of aorta and vena cava Infiltration of adjacent organs Infiltration into neuroforamen

Pitfalls ▬ Differentiation to nephroblastoma ▬ Adrenal bleeding in newborn 123

Jod-meta-iodobenzylguanidine (MIBG)scintigram

MIBG as an analogon of catecholamine precursors is taken up in neuroblastoma and other neuro-endocrine tissue (⊡ Fig. 5.59). Primary tumour and metastases can be demonstrated. Physiological uptake can be found in the adrenal gland, liver, spleen, intestine, myocardium,


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

Bone scan A V

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 increase of metabolic activity in locations of bone metastases.

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

Size of osteolytic metastases in bone scan-positive lesions can be determined by radiography. In follow-up examinations, therapy results can be documented. Stability of the bone can be estimated in conventionel X-ray images. Key information

⊡ Fig. 5.58. Neuroblastoma in MRI. Encasement of the mesenteric artery, aorta and vena cava with hyperintense tumour mass

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

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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

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5.2.10 Female gonads

Developmental anomalies of the uterus and vagina

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Vagina and uterus are formed by the Müllerian duct. Common Müllerian duct anomalies are hydrocolpos, hydrosalpinx, hematometra, didelphic, bicornuate or unicornuate uterus. Müllerian anomalies are associated with heritable disorders, e.g. Mayer-Rokitansky-Kuster-Hauser syndrome or Kaufman-McCusick syndrome. Anomalies of the gonads are often associated with renal anomalies. In hydrocolpos the vagina becomes distended with fluid. The uterus is pushed above the fluid-filled vagina or can be distended in the case of hydrometrocolpos. 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 an acoustic window and allows, together with tissue harmonic imaging, a high-resolution imaging of upper vagina, uterus and ovaries (⊡ Fig. 5.60). CDI makes it possible to distinguish between non-perfused fluid collections and perfused masses.

⊡ 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 is necessary. Intermittent sharp abdominal pain is characteristic. Single cysts must be differentiated from teratoma, which is usually benign; but malignant teratomas can occur. Malignant ovarian tumours, e.g. germ cell tumours can be a solid mass or occur as a more cystic mass.

Imaging Typical findings in hydrocolpos

Ultrasound

▬ 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

In ultrasound ovarian cysts present as non-echogenic masses in the lower abdomen, frequently larger than 2 cm. In the case of hemorrhage in the cyst, the sonographic appearance can change in follow-up studies. Hyperechoic inhomogeneous structure can cause diagnostic problems. Fluid-fluid levels indicate hemorrhage. CDI demonstrates no central perfusion. Often ovarian rest tissue with small follicles is normal. Because of the varying location of the ovaries in the abdomen, especially in babies, the contralateral ovary is sometimes difficult to find. A secure differentiation of ovarian cysts and paroophoron cysts is not possible in ultrasound. A typical sign for teratoma is calcification with acoustic shadow in a thickened wall or tissue nodule. 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).

Pitfalls ▬ Anatomical localization can be difficult, e.g. in ovarian 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 disappear spontaneously. Especially in newborn, large ovarian cysts are observed. In general,



Unechoic mass in single ovarian cysts Mixed echogenicity in hemorrhage Loss of total perfusion in torsion of the adnexa. Free fluid in the abdomen in the case of ovarian torsion or malignancy ▬ Thickening of the wall or tissue nodule in the wall of the cyst with calcification indicates teratoma ▬ Inhomogeneous perfused tissue in solid and partial cystic masses in malignant masses

Pitfalls ⊡ Fig. 5.61. Hemorrhage in the ovary during normal menstrual cycle as an accidental finding. CDI in longitudinal view.

▬ All other cystic masses of the abdomen can 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 indicated to exclude ileus or perforation of hollow viscus with free air in the abdomen. Calcifications in different ovarian neoplasms or tooth buds in the 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 hyperechoic spots demonstrate 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 images or sequences with fat saturation fatty tissue can be separated and indicate teratoma. MRI can identify hemorrhage and vital tissue can be differentiated through contrast enhancement (⊡ Fig. 5.64–5.66).

⊡ Fig. 5.64. MRI (transverse T1 TSE) before contrast application. Hypointense mass in the lower abdomen in germ cell tumour

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5.2.11 Male gonads

Testicular torsion

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Acute testicular torsion has to be diagnosed urgently and is an emergency. Testicular torsion presents with scrotal swelling, reddening and pain (acute scrotum). 1:4000 boys is affected. Testicular torsion is defined as a rotation of the longitudinal axis of the spermatic cord. Strangulation of the vessels results in irreversible damage of the testicular parenchym after 6 h of ischaemia. About 30% of patients with acute scrotum have a testicular torsion. ⊡ Fig. 5.65. MRI (transverse T1 SPIR) after contrast application. Contrast enhancement of the solid areas in the tumour, lack of enhancement in liquid areas

Imaging Imaging methods concentrate on morphological and perfusion parameters. Detection of testicular torsion is possible in dynamic contrast studies in MRI or scintigraphy. In routine clinical work, sonography with CDI has become an adequate method to replace surgical exploration in the case of hydated torsion or epididymitis

Ultrasound Sonography with CDI and pulsed Doppler, have become the only method of high clinical value. Description of tissue structure and echogenicity in comparison of both testes, volumetry and assessment of central and peripheral blood flow and documentation of arterial and venous blood flow in triplex mode is necessary. If available within a short time after clinical examination, CDI is of high clinical value in acute scrotum. Maximal systolic velocity in intratesticular arteries is 4-12 cm/s. After puberty, lowflow resistance with RI between 0.48 und 0.75 is normal. Before puberty, diastolic flow is uncertainly visible. In the case of doubt, surgical exploration is still indicated (⊡ Fig. 5.67). ⊡ Fig. 5.66. Coronal MRI ( ceT1 SPIR) in acute torsion of the adnexe. Contrast enhancement in the uterus, but lack of enhancement in the left ovary after haemorrhagic infarction (arrow)

Key information

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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 perfusion signals in comparison to the other side ▬ Hyperperfusion after retorsion


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

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

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⊡ Fig. 5.67. Acute torsion of the left swollen testicle. Power Doppler sonography 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 diseases of the scrotum are responsible in approximately 60% of acute scrotum in infants. Mostly acute hydatid torsion causes a painful inflammatory reaction of the epididymis and scrotum. In clinical examination the so-called blue dot sign can 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 and adolescents acute scrotum with vasculitis in Schoenlein’s purpura are rare diseases with acute scrotal swelling. Painless swelling of the scrotum is observed in scrotal oedema, e.g in nephritic syndrome. Inflammation due to injury of the scrotum can be observed after a stab wound with bacterial infection.

⊡ Fig. 5.68. Hydatide torsion with hyperechoic nodule (arrows) next to the testicle

are found with or without reactive hyperperfusion of the testes. In the case of hydatid torsion a small hyperechoic nodule can be demonstrated in some cases (⊡ Fig. 5.68). This diagnostic sign is insecure and not always found in hydatid torsion. Concomitant hydrocele is frequent. If bacterial infection is considered voiding cysturethrogram is indicated to exclude urethral obstruction.

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

Possible findings in sonography ▬ Swelling of epididymis or testes ▬ Concomitant hydrocele

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▬ ▬ ▬ ▬ ▬ ▬

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

It must be defined whether the patient has a vagina and a urogenital sinus. Location of connection of these structures in relation to the perineum must be demonstrated. Often a voiding cysturethrogram 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.

Pitfalls

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▬ Reactive hyperperfusion after testicular torsion or in intermittent torsion ▬ Scrotal tumours ▬ Scrotal hernia ▬ Varicocele with hyperperfusion dependent on Valsalva’s manoeuver

5.2.12 Congenital genital anomalies

Anomalies of sex differentiation have various etiologies. Genital disturbances are determined by endocrinic or chromosomal disorders and impaired biochemical processes in embryological development. Patients can have consistency or inconsistency between their gonadal and genetical sex. A child with ambiguous external genitals needs exact morphological evaluation of the genitalia to classify the anomaly and to define surgical treatment. Anomalies are found in hermaphroditism, congenital adrenal hyperplasia, testicular feminization and gonadal dysgenesis.

Possible findings ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬

Tract of sinus urogenitalis Impression of uterine cervix on the vaginal vault Hypospadia Perineal urethral ostium Utricle Blind-ending vagina Pseudovagina Contrast material opacifying the uterine canal Key information

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Congenital genital anomalies ▬ Sonography ▬ Genitography ▬ Catheter technique ▬ Retrograde filling of Müllerian structures in voiding cysturethrogram ▬ MRI in complex anomalies

Imaging Imaging studies are performed to define the relation between urinary tract and internal genital anatomy. The aim of radiological methods is the identification of uterus, vagina, bladder and urethra. Urogenital sinus is the most common appearance in adrenogenital syndrome. Urethra and vagina flow into a common sinus tract, which ends perineal mostly near a prominent phallus or enlarged clitoris. In addition to sonography, the most important diagnostic technique is genitography. 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, and a voiding cysto-urethrogram is conducted.

⊡ Fig. 5.69. Patient with adrenogenital syndrome. Genitogram performed as voiding cysturethrogram in urogenital sinus


5.2.13 Persistence of urachus

Inflammation in the umbilical region are observed in umbilical granuloma, persistent structures of the umbilical cord or inflammation of the persistent urachus. If there is a urine-like discharge from the umbilicus, persistent urachus should be suspected. Persistent urachus or urachus cyst is associated with dysfunction of the bladder outlet.

Imaging Ultrasound

In sonography the urachus fistula is found directly below the abdominal wall in the midline between bladder and umbilicus. Mostly thickening of the urachus wall indicates the inflammatory reaction of the fistula. Midline diverticula of the bladder can remains of the urachus and differ in size, dependent on the bladder volume. Fluoroscopy of a suspected fistula with iodine contrast medication is not a routine method. In the case of seropurulent secretion of the umbilicus or failed treatment with cauterization with silver nitrate of the umbilicus in granulomas, a surgical exploration is in any case indicated. Next to remains of the urachus, a persitent remain of the omphalo-enteric duct must be excluded additionally (⊡ Fig. 5.70–5.72).

⊡ Fig. 5.70. Longitudinal scan between 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 flow signals in CDI in inflammatory disease

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

Pitfalls ▬ Physiological urachus rest in preterm infants and newborn ▬ Umbilical granuloma ▬ Bowel structures ▬ Omphalo-enteric cysts Key information

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Persistence of urachus ▬ Sonography ▬ Urachus cysts ▬ Urachus diverticulum ▬ Urachus fistula

I ⊡ Fig. 5.72. Longitudinal view of the bladder. Urachus diverticulum (arrow) above the bladder

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5.3

Gastro-intestinal tract

Michael Kimpel

5.3.1 Oesophagus (Oesophageal atresia

Fluoroscopy

To provide further information to the surgeon and to 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.

and tracheo-esophageal fistula) Postoperative radiology

General Information

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Oesophageal atresia usually occurs at the upper/middle third of the oesophagus, with or without presence of tracheo-esophageal fistula (TEF). The length of the gap varies and is generally longest in the absence of a fistula. Oesophageal atresia and TEF are classified as follows (Vogt classification), showing the approximate frequency of appearance: Vogt I: Complete absence of oesophagus Vogt II (): Atresia without fistula Vogt IIIa (): Atresia with proximal fistula Vogt IIIb (): Atresia with distal fistula Vogt IIIc (): Atresia with proximal and distal fistula Vogt IV (): 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.

The risk of anastomotic leakage or recurrent TEF is up to 10%. In some cases, if surgery is performed without preoperative fluoroscopy, a proximal fistula (in Vogt IIIc atresia) may be not detected intra-operatively and so still persists (⊡ Fig. 5.74). For these reasons a postoperative control of the oesophagus with low-osmolar contrast agent is recommended before the first admittance of oral alimentation. Key information

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Oesophageal atresia

▬ 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

Imaging

and duodenum

Radiography

The initial images often show the inefficient attempt to place a nasogastral tube, so one will see the tube in the proximal oesophageal pouch. It is helpful to inflate air 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).

General information Obstruction of the stomach

Congenital obstruction of the stomach is very rare. Agastria is described in single cases. Microgastria is uncommon and may exist isolated or with complex malformation. Although atresia of the stomach near the antrum or pylorus exists, in most cases the reason for gastric obstruction is a mucosal web or diaphragm.

109 5.3 · Gastro-intestinal tract

⊡ Fig. 5.73. Oesophageal atresia with distal TEF, showing the tube in the upper oesophageal pouch, which is filled with inflated air. Air in the stomach indicates the presence of distal tracheo-esophageal fistula

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Obstruction of the duodenum

The most common reason for high intestinal obstruction is the duodenal stenosis or atresia (while atresia is more 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 segment before and the loss of intestinal air behind the obstruction. In duodenal atresia the classic finding is the »doublebubble sign«, showing air in the stomach and the dilated proximal duodenum (⊡ Fig. 5.76). If plain radiography detects duodenal atresia, no further examination is necessary, as air is a sufficient contrast media and positive contrast provides no further information. If the stomach and/or duodenum is decompressed

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

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

Key information

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Obstructions of stomach and duodenum ⊡ Fig. 5.75. Postoperative anastomotic leak and mild stenosis after oesophageal repair (same patient as Fig. 5.74, now after second 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 incomplete obstruction (stenosis) plain radiography may show a normal air distribution.

5.3.3 High intestinal obstruction

Fluoroscopy

General Information

In some cases, usually in stenosis, not atresia, fluoroscopy and admittance of low osmolar water-soluble contrast agent can be useful to locate the stenosis preoperatively.

Jejunal atresia and stenosis

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


⊡ 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 absence 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 (Kirks): Type I membranous atresia Type II blind ends separated by fibrous cord Type IIIa blind ends separated with an associated Vshaped mesenteric gap Type IIIb apple-peel small-bowel atresia Type IV multiple atresias

Imaging Radiography

In complete obstruction, plain radiography will show dilated, air-filled bowel loops, often with a bulbous end just before the obstruction. The situation may be 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 intestinal obstruction means an obstruction in the distal ileum or in the colon. The most common reasons are: ▬ Meconium plug syndrome ▬ Meconium ileus ▬ Ileal atresia ▬ Hirschsprung disease ▬ Anorectal malformations / anal atresia

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Imaging Radiography

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

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Contrast enema should be performed using low-osmolar water-soluble contrast agents, to avoid fluid shiftings into the bowel. Barium should only be used in Hirschsprung disease. In the case of a distal small bowel obstruction, the contrast enema will show the typical aspect of an unused colon, the microcolon, which usually has a diameter of 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 syndrome is characterized by delayed passage (> 24-48 h) of meconium and intestinal dilatation. A contrast enema (water-soluble contrast media) shows meconium retention, often visualized as a »plug«. In many cases the meconium plug is dislodged after the enema study. In some cases the left colon appears small (small

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

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left colon syndrome). The pathophysiological mechanism is assumed to be an immaturity of the myenteric plexus nerve cells, so the clinical and radiological features may be similar to Hirschsprung’s disease. Meconium ileus

The meconium ileus has to be strictly differentiated from the above described functional immaturity of the colon. In meconium ileus a low intestinal obstruction is present, resulting by the inspissation of abnormal meconium 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 (water-soluble contrast agent) will show an (empty) microcolon. Meconium pellets are found in the distal ileum, showing multiple round, filling defects. Ileum loops are distended. Hirschsprung’s disease

In Hirschsprung’s disease (⊡ Fig. 5.80) intramural ganglion cells of the distal colon are absent. As the neuronal cells migrate in proximal direction, the narrow segment (caused by permanent contraction of the circular muscle layer) extends distally from the migration arrest to the anus, so it is only necessary to examine the distal, colon up to the splenic flexura. Proximal to this point, the colon is dilated. It is important to know that in newborn contrast enema may look

B


normal. As the narrow segment could be distended while filling the colon, late X-ray controls should be obtained 24 h after contrast enema to evaluate an unusual retention of barium. If there is only an ultrashort aganglionar segment, the radiological findings usually are the same as in obstipation!

▬ Male: rectobulbar fistula oder anal agenesia without fistula Low atresia: ▬ Female: anovestibular fistula, anocutaneous fistula, anal stenosis ▬ Male: anocutaneous fistula, anal stenosis

Anal atresia

Anal atresia exists with or without fistula. In most of the cases the atretic rectum communicates with the genitourinary tract or shows a rectocutaneous fistula. Anal atresia is usually classified as high or low atresia (rectum ending below or above the puborectalis sling), which has therapeutic and prognostic significance. As patients with low atresia have higher incidence of genito-urinary anomalies, pre-operative renal ultrasound is mandatory. International classification of anorectal malformations (Wingspread 1984): High atresia: ▬ Female: anorectal agenesia with or without rectovaginal fistula, rectal atresia ▬ Male: anorectal agenesia with or without rectoprostatic fistula, rectal atresia

In anal atresia with fistula a contrast enema using lowosmolar water-soluble contrast agent can be performed to demonstrate the length of the fistula and probable communications with the urinary tract (⊡ Fig. 5.81). Transperineal sonography

In addition, or in cases with imperforate anus, a transperineal sonography can be performed in order to measure the distance between perineum and rectal ending (⊡ Fig. 5.82).

Intermediate atresia: ▬ Female: rectovestibular-rectovaginal fistula or anal agenesia without fistula

⊡ Fig. 5.80. Hirschsprung’s disease

⊡ Fig. 5.81. Anal atresia with fistula to the vestibule (marked with a lead button)

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MRI of the pelvis

As anorectal malformations are often associated with other anomalies, especially with those of the lumbar spine or the genito-urinary tract, an MRI of the pelvis should be performed. The sectional images also allow a detailed pre-operative planning, as one can see the pelvic and sphincter muscles. Transversal, coronar and sagittal images should be acquired (⊡ Fig. 5.83). Key information

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Low intestinal obstruction

▬ Contrast enema will be necessary in most of the cases

▬ Water-soluble, low-osmolar contrast agent A

▬ ▬

▬ ▬

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5.3.5 Rotation anomalies of the midgut

B ⊡ Fig. 5.82A,B. Anal atresia: distance between the markers from rectum to perineal skin is 1 cm

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should be used to avoid fluid shifts 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)

B

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

General information Malrotation

During normal development the bowel will rotate counterclockwise three times 90° around the superior mesenteric artery (SMA) to its final position. If the bowel does not rotate completely during embryonic development, 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 of a patient with intestinal malrotation depends on age at presentation and degree of intestinal obstruction. Signs and symptoms are often presented as intermittent and incomplete. Symptoms may be bilious vomiting and feeding intolerance, some may also have upper abdominal distension.


Volvulus

Radiography

If volvulus occurs in patients with intestinal malrotation, the obstruction is typically complete, and blood supply of the midgut is reduced. The symptoms depend on the degree of ischaemia. It can range from lymphatic and venous congestion with simple oedema to full intestinal necrosis.

Plain film radiography can show the classical signs of 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 likely when inversion of the SMA and the superior mesenteric vein (SMV) is shown. Volvulus is highly probable if the SMV is shown to be coiling around the SMA (»whirlpool sign«). Other findings may be fixed midline bowel loops and duodenal dilation with distal tapering.

Fluoroscopy

Upper gastro-intestinal series using barium is the study of choice to obtain the diagnosis. If imminent surgery is necessary, water-soluble contrast agents should be used. If the anatomy is normal, the duodenal C-loop crosses the midline and the duodenojejunal junction is located left of the spine. If contrast ends abruptly or tapers in a corkscrew pattern, midgut volvulus or some other form of proximal obstruction may be present.

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B

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⊡ 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)

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Lower gastro-intestinal series (barium enema) may 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 duplications may occur anywhere from oesophagus to rectum, but are mostly located in the small bowel (35% distal ileum). Usually, the wall contains gastric mucose, covered by a circular muscle layer. Duplication cysts may be asymptomatic or cause abdominal bleeding, compression of the bowel, obstruction or invagination.

Imaging

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Radiography

Abdominal radiograph can show dislocation of bowel loops by an opaque mass or, in the case of obstruction, dilated loops. Ultrasound

The classical appearance is a cystic mass (⊡ Fig. 5.86), tubular structures are less common. Sometimes a hypoechogenic ring (smooth muscle) with an inner, hyperechogenic layer (mucosa) can be identified. In the case 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 Achalasia

General information ⊡ Fig. 5.85. Contrast enema in malrotation: the colon is positioned abnormally, with cecum (arrow) and terminal ileum in the upper left quadrant

A

The failure of relaxation of the lower oesophagus sphincter (achalasia) causes a functional obstruction of the 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)


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⊡ 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 children the oesophagogram shows the classic »beak appearance« of the distal esophagus. In younger children the findings may be subtle. Key information

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

General information Gastro-esophageal reflux (GER) is a very common disorder. One can distinguish between the functional, physiological 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 of the cases, the diagnosis can be obtained from the history and physical examination. In newborn abdominal ultrasound is the imaging study of choice to detect GER (⊡ Fig. 5.88). In a longitudinal section the oesophagogastral junction is viewed (after feeding the infant in order to assure adequate filling of the stomach). Usually a hiatal hernia can be diagnosed if present. 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.

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

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Fluoroscopy

Upper GI series help to evaluate the anatomy of the oesophagus and may show GER in older infants and children (where ultrasound is no longer useful any more or if required for presurgical planning), even when sensitivity and specificity are low for the diagnosis of GER. GER may occur spontaneously in oesophagography, but as it is an episodic event it may not show during the examination. In older children barium can be used, in infants and if there is a risk of aspiration, water-soluble contrast agents should be used. An axial hernia (⊡ Fig. 5.90) will be recognised in fluoroscopy 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). Emptying of the stomach should be documented at the end of the examination. If the patient cannot swallow (e.g. due to mental deficiency) the examination can be performed using a nasogastral tube, placed in the oesophagus.

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Key information

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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


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⊡ 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 the objects pass the gastro-intestinal tract without complications and leave the body in the normal way. In some cases, these objects may lodge in the oesophagus, usually at the thoracic inlet/upper oesophageal sphincter, at the level of the aortic arch or at the lower oesophageal sphincter. Patients with oesophageal foreign bodies usually present as acutely symptomatic. Objects in the oesophagus need to be removed (endoscopically) to prevent ulcera and consecutive perforation with mediastinitis. If a foreign body passes the lower oesophageal sphincter, it will usually pass the rest of the gastro-intestinal tract as well and in most cases no invasive treatment is necessary.

Imaging Radiography

Most of the swallowed objects are opaque und will be identified on plain radiographs (⊡ Fig. 5.91). If possible, it is helpful to have a sample of the ingested foreign body.

After foreign body ingestion the radiography should show the entire GI tract, including the nasopharynx. The standard thorax X-ray is insufficient, because after the stomach the upper oesophageal sphincter is one of the most common sites where foreign bodies lodge. Fluoroscopy

A quickly performed pulsed, low-dose fluoroscopy using the last-image-hold technique for documentation usually leads to lower radiation doses than plain film radiographs of the same regions. For this reason it should be preferred, being perfomed by an experienced examiner. If there is evidence for a non-opaque foreign object in the oesophagus, a contrast examination using watersoluble, 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 of the ingested foreign objects do not get stuck, and pass the whole gastro-intestinal tract to leave the human body in the natural way. So in absence of complications and clinical symptoms it is usually not necessary to prove radiologically that the object has left the intestine.

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B

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⊡ Fig. 5.91A–C. Foreign body. A,B Coin lodged at upper oesophageal sphincter. C Allen key lodged in the stomach

Of course the parents often want to know if the foreign body has been evacuated after a period of time, but without clinical symptoms this should be no indication for the application of additional radiation. It is better to examine the faeces.

Appendix: magnets, magnetic toys If more than one magnet is swallowed, they have to be evacuated immediately. If the magnets pass the pylorus, they usually have to be extracted surgically. Magnets stick together and so may provide necrosis and perforation of the bowel, resulting in severe peritonitis. Cases with fatal outcome have been reported! Key information

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Foreign body ingestion

▬ Usually foreign bodies pass the intestine with

⊡ Fig. 5.92. Non-opaque oesophageal foreign body located in the upper 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


▬ 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!

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5.3.9 Intussusception

General nformation Intussusception is the invagination of an intestinal segment into the contiguous distal segment, leading to consecutive mechanical obstruction and ischaemia of the bowel segment involved. While ileoileal intussusceptions usually devaginate spontaneously, most of the intussusceptions are ileocolic (90% of the cases) and need to be treated. The classical patient with spontaneous ileocolic invagination is a boy (twice as frequently as girls) under 2 years of age (most common age is 3 months to 1 year). As in about 10% of all cases the intussusception is secondary to some other pathology (e.g. Meckel diverticulum, lymphoma of the bowel, duplication cysts and 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%.

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

The appearance of the intussusception is classical (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

Imaging Ultrasound

An intussusception is an emergency in paediatric radiology and needs immediate treatment (⊡ Fig. 5.93). The procedure of choice is an abdominal ultrasound of the abdomen and especially of the bowel. For this procedure a linear probe (7.5 MHz or higher) should be used. Every sector of the abdomen should be examined carefully.

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).

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ways be documentated (⊡ Fig. 5.95C). The oedamatous ileocecal valve is usually visible and has to be distinguished from residual intussusception. Results using air instead of water for reduction of intussusception are equal to hydrostatic devagination, but as the examination is performed under fluoroscopy control, ultrasound should be preferred (no radiation dose). If the procedure fails to reduce the invagination, a second attempt after a break is suitable. If the hydrostatic devagination does not work out properly, the reduction 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 to coecum

5

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

In 5-10% re-invagination after successful hydrostatic reduction will occur, usually within 72 h of the treatment. The treatment of the recurrent intussusception is the same as decribed above, but one should remember that intussusceptions can be a secondary phenomenon due to pathological lead points. Perforation as a complication to hydrostatic reduction is seldom (< 0.5%).

Therapy When the patient is haemodynamically stable and not decompensated, hydrostatic reduction should be given a try before admitting the patient to surgery. Contra-indications are electrolyte derailment or clinical evidence of perforation and/or peritonitis. Hydrostatic devagination can be performed in ultrasound as well as in fluoroscopy, according to the less radiation, the sonographyically controlled hydrostatic reduction should be the treatment of first choice (⊡ Fig. 5.95). The patient should be prepared adequately, getting intravenous access, a nasogastral tube and a mild sedation (e.g. chloralhydrate). A catheter is placed through the anus and held by assisting personnel, baloon catheters should not be used due to the risk of perforation. Warm saline solution is now admitted from an enema bag under ultrasound control. 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-

Key information

I

I

Intussusception

▬ 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


5.3.10 Hypertrophic pyloric stenosis

General information Infantile hypertrophic pyloric stenosis is the most common cause of intestinal obstruction in infancy. Hypertrophy and hyperplasia of the pyloric muscular layers lead to secondary stenosis. Clinical symptoms show a classic 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 usually leads to the diagnosis. If the sonography is inconclusive (which should be very seldom) and alternative diagnoses are considered, a contrast examination of the upper GI tract can be performed. The typical appearance is an elongated pyloric channel (string sign) and a bulge of the pyloric muscle into the antrum (shoulder sign) and lack of pyloric passage. B

Key information

I

I

Infantile hypertrophic pyloric stenosis

▬ 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 Necrotizing enterocolitis

General information

C ⊡ Fig. 5.95A–C. Devagination procedure under ultrasound guidance (A,B). Oedematous valve of Bauhin after successful hydrostatic reduction (C)

Necrotizing enterocolitis (NEC) is a mural or transmural necrosis of segments of the intestine, mostly affecting the terminal ileum or proximal colon, with an onset 2 weeks up to several months postpartum. The major risk for development of NEC is premature of birth.

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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 thickness of the pyloric muscle)

Ultrasound

The characteristic ultrasound appearance is thick-walled loops of bowel with hypomotility. Free intraperitoneal fluid is a common finding. In the presence of pneumatosis intestinalis, gas reflexes can be identified in the thickened intestinal walls and gas may be present in the portal 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 studies. An enlarged distance between the gas-filled loops indicates wall thickening. In early stages the findings are unspecific, but later often characteristic submucosal / subserosal air occurs: pneumatosis intestinalis (⊡ Fig. 5.97). Pneumatosis is found in 50–75% of the cases. Portal venous gas and gallbladder gas are pathognomonical signs and indicate severe disease. A pneumoperitoneum is an indicator for perforation and leads to 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 important imaging modality ▬ Uncharacteristic findings in early stage: distended, separated bowel loops ▬ Pneumatosis intestinalis and gas in the portal 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


⊡ 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 and UC, the less specific term inflammatory bowel disease is in common use.

5.99). Power Doppler sonography can often demonstrate hyperperfusion (⊡ Fig. 5.99B). Free peritoneal fluid may

be another sign of inflammation. Stenoses lead to dilated proximal bowel segments (more often in CD than in UC).

Crohn’s disease (CD)

CD is a transmural granulomatous inflammation of unknown aetiology which may occur in every part of the gastro-intestinal tract. The prevalently affected segment is the terminal ileum; most children show affections of the distal ileum and the right hemicolon. Ulcerative colitis (UC)

The inflammation of UC is usually limited to the mucosal layer. It commonly begins at the rectal mucosa and spreads proximally without skip lesions. UC shows a variety of extra-intestinal manifestations like arthritis and sclerosing cholangitis.

Imaging Ultrasound

Patients with inflammatory bowel disease often present with a variety of abdominal symptoms including, pain, (bloody) diarrhoea, GI passage problems up to ileus, maldigestion etc. The imaging method depends on the patient’s complaints, but an initial ultrasound will be one of the first imaging techniques. Of course, a complete abdominal scan has to be performed, but the main region of interest will be the bowel structures, which should be examined with a linear probe of at least 7.5 MHz. The inflamed bowel commonly shows a wall thickening; diameters above 3 mm are pathological (⊡ Fig. 5.98 and

Radiography

The indication to plain film radiographs depends on the clinical symptoms. If the patient presents with transit problems or ileus, plain film radiographs of the abdomen are helpful to detect air-fluid levels and dilated bowel segments. If a perforation is considered, plain radiography shows free peritoneal air. Fluoroscopy

Nowadays, with increasing possibilities of MRI techniques, fluoroscopy plays a minor role in the diagnosis of inflammatory bowel disease, especially as the extent of inflammation is detected in an endoscopy. Nevertheless, a variety of contrast studies may be performed according to clinical symptoms and complications. Enterocutaneous fistulae can be visualized by injection of water-soluble contrast agent. Upper GE series and small-bowel follow-through (prefered by Sellink-procedure) can localize stenosis and entero-enteral fistulae. In patients with colitis involvement of the small bowel, detection of skip lesions help to lead to the diagnosis CD.

MRI An elegant imaging method to document the extent of inflammatory bowel disease is the so-called hydro-MRI (⊡ Fig. 5.100). The bowel structures will be distended by water filling transanal and peroral and so become evaluable. A bowel paralysis is achieved with Buscopane i.v. Native

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and contrast-enhanced transverse and coronar scans are performed. Best distension of the small bowels is achieved by not drinking the water, but applying it via a nasojejunal

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 the case of MRI contra-indications or in emergency situations an abdominal CT can be indicated.

I

Key information

5

I

Inflammatory bowel disease

▬ Abdominal ultrasound detects wall thickening of the bowel (a linear probe of at least 7.5 MHz 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 Appendicitis

General information B ⊡ Fig. 5.99A,B. Wall thickening and hyperperfusion of the terminal ileum in Crohn’s disease

A

B

Appendicitis is the most common reason for surgery 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)


While in older children the pain is mostly located to the lower right quadrant, especially younger children do often not localize the pain to the right lower abdomen.

While clinical diagnosis and US become more difficult after perforation, radiographic findings often become more distinctive, so it could be helpful on suspicion of perforation.

Imaging Ultrasound

Possible findings

US should be the first preferred modality. The sensitivity 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 applied compression may displace other loops of the bowel. Longitudinal and transverse scans are performed (⊡ Fig. 5.101). If the appendix cannot be identified, a complete scan of the whole abdomen should be performed because of the variability of the appendiceal position and in order to exclude other reasons for the abdominal pain.

▬ ▬ ▬ ▬ ▬

Appendicoliths Small bowel obstruction Paralytic ileus Free peritoneal (subphrenic) air is uncommon Extraluminal air, located between caecum and the peritoneal fat line are seen in some cases

Possible Findings ▬ ▬ ▬ ▬ ▬ ▬ ▬

Transversal: target sign Diameter > 6 mm, not compressible Longitudinal: tubular structure, blind end Hyperperfusion Appendicoliths Periappendiceal / intraperitoneal fluid Abscess formation

Pitfalls

A

▬ Retrocecal appendix is difficult or even not visible ▬ After perforation the appendix is no longer distended and is difficult to visualize; the patient feels sometimes better after perforation ▬ Many other diseases may mimic appendicitis, such as yersiniosis, Crohn’s disease, distal intestinal obstruction in cystic fibrosis and even gastro-enteritis with mesenteric adenitis ▬ Most serious differential diagnosis in female is the torsion of the right ovary, so the ovaries have to be visualized in the examination ▬ The first menstruation in young girls often causes pain similar to an appendicitis Radiography

Plain film radiography is not standard procedure in uncomplicated appendicitis, as it may look completely normal in acute appendicitis. An appendicolith may be seen in 5-10% of the cases.

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

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Computed tomography

CT gives the best visualization of an appendicitis and its possible complications, as it not only shows the appendicitis and peri-appendiceal region, but also the effect of inflammation on other structures and any abdominal extensions (⊡ Fig. 5.102). As one of the major targets of paediatric radiology is the reduction of radiation in childhood, CT scans in appendicitis are reserved for the unclear cases.

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Note

In our opinion, the dose reduction aspect should be valued before economical aspects and CT scans should remain an exception.

Key information

I

A

I

▬ Ultrasound first ▬ On special indications: – Radiography – Computed tomography (CT)

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

▬ Evidence for complications: – Abscess formation – Paracecal or free peritoneal fluid – Paralysis

▬ 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 diagnosis«; physical examination by surgeon is mandatory!

5.3.14 Gastro-intestinal tumours and

tumour-like lesions Not every entity of gastro-intestinal tumours will be discussed in this manual. Serving as an example the nonHodgkin lymphoma (exemplary for malignant tumours) and the lymphangioma / haemangioma (exemplary for a benign tumour) are shown.

Non-Hodgkin-lymphoma General information As neoplasms of the lymphoid system, lymphomas can occur in almost every organ system. The non-Hodgkin-lymphoma (presenting as lymphoblastic, small noncleaved cell: Burkitt; ⊡ Fig. 5.103 or Burkitt-like, or largecell lymphomas, LCLs) may occur in the small bowel, 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 often hardly visible. The intestinal wall usually seems


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 often not possible to distinguish between ileal lymphoma and inflammatory bowel disease by sonographic appearance, but additional clinical symptoms and laboratory findings usually lead the way.

Additional staging imaging

If a lymphoma is most likely, a complete staging has to 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.

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Key information

I

I

Non-Hodgkin-lymphoma

▬ 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 lymphangiomas are vascular malformations as a result of abnormal (lymph)angiogenesis and can be located on almost every site of the body. Both mostly occur sporadically, but in some cases haemangiomas are inherited in an autosomal dominant way, or are part of syndromes. A major complication of large haemangiomas is congestive heart failure due to significant arteriovenous shunting.

Imaging

A

Ultrasound

Abdominal ultrasound is a cost effective screening modality to detect these malformations in the mesenterium or the parenchymatous organs (⊡ Fig. 5.105), but cannot exclude the presence of haemangioma/lymphangioma. The relation to other relevant structures often cannot be depicted accurately. Colour-flow and PW Doppler demonstrate the perfusion and may identify feeding vessels in case of haemangioma, lymphangiomas may look nearly the same in B-mode ultrasound, but will show no perfusion 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 surrounding tissue, organs and vessels (⊡ Fig. 5.106). Three plane sections in T1 and T2 weightings and contrast-enhanced studies should be performed. An MR angiography is very helpful to show the vascular anatomy in haemangiomas.

B ⊡ Fig. 5.106A,B. Left retroperitoneal lymphangioma (MRI T2w)


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 performed pre-operatively if surgery is required, and should include MR angiography

5

6 Musculoskeletal system Harvey Teo, David Stringer

6.1

Common bone dysplasias

6.1.1 Achondroplasia

General information Achondroplasia is the commonest form of short-limb dwarfism. It is a non-lethal autosomal dominant condition characterized by short stature with disproportionately 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 the gene for fibroblast growth factor receptor-3 (FGFR3) resulting in the characteristic clinical and radiological features.

Clinical features ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬ ▬

Short stature Rhizomelic shortening of the arms and legs Limitation of elbow extension Trident hands Genu varum (bow legs) Thoracolumbar gibbus in infancy Exaggerated lumbar lordosis Large head with frontal bossing Midface hypoplasia

Imaging Prenatal ultrasound Prenatal detection of homozygous achondroplasia is possible but is still challenging even in expert hands. Prenatal diagnosis of heterozygous achondroplasia is even more difficult because femoral shortening generally manifests only in the third trimester. However, with increasing use of 3-D US imaging and foetal MRI, more accurate diagnosis may be possible in the future.

Plain radiographs Skeletal surveys show the following characteristic features: ▬ Midface hypoplasia, enlarged calvaria with frontal bone prominence and shortening of the base of the skull. The foramen magnum is diminished in size. ▬ Narrowing of the interpedicular distances from proximal to distal in L1-L5 is seen on a anteroposterior radiograph of the lumbosacral spine. ▬ The lateral view reveals shortening of the pedicles and vertebral bodies with posterior scalloping. Thoracolumbar 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 sacrosciatic notch is small,

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Chapter 6 · Musculoskeletal system

6.1.2 Thanatophoric dysplasia

General information Thanatophoric dysplasia (TD) is the commonest form of lethal short-limb dwarfism occurring in the neonatal period. The condition is caused by de nuovo mutations in the gene for fibroblast growth factor receptor-3 (FGFR3) located on chromosome 4p16. Histopathologically there 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 sacro-sciatic notch (small arrow), flat acetabulum (large arrow), short femoral neck (n) and coxa vara (cv)

and the acetabular roof is horizontal. The femoral neck is short and an apparent coxa vara may be seen. ▬ Metaphyseal flaring of the long bones is present. 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 distal femoral physes have an inverted-V shaped configuration.

Affected neonates are characterized by: ▬ Growth deficiency with an average length of 40 cm at term ▬ Macrocephaly with frontal bossing, a flattened nasal bridge, and proptotic eyes ▬ Hydrocephalus also contributes to the macrocephaly ▬ Narrow thorax with small ribs and a protuberant abdomen ▬ Small, short limbs There are two clinically defined subtypes due to differences in the mutation pattern on the abnormal gene. Type 1 is characterized by a normal skull with curved short long bones, whilst type 2 is characterized by a clovershaped skull due to premature closure of the sutures and straight femurs.

Neuroimaging Cervical cord compression at the cervicomedullary junction due to narrowing of the formanen magnum is a common cause of death in infancy. MRI of the brain is the modality of choice to assess cervicomedullary compression at the foramen magnum, fusion of C1 or isolated subaxial cervical stenosis, myelomalacia, intramedullary cyst, or angulation at the craniocervical junction. Hydrocephalus may also be detected. MRI can assess the degree of spinal stenosis of the lower lumbar segements. Ultrasound can be used in the neonate to detect ventricle size and other abnormalities.

Imaging Prenatal Imaging Prenatal ultrasound can be made in the 2nd or 3rd trimester and reveals polyhydramnios, generalized micromelia, a narrow thorax, flattened, hypoplastic vertebrae, shortened limbs with short curved or straight femora, large or cloverleaf head, small hands, feet and frontal bossing. However, differentiation from other skeletal dysplasias like fibrochondrogenesis or atelosteogenesis is difficult.

References

Plain radiographs

Gordon N (2000): The neurological complications of achondroplasia. Brain Dev 22(1): 3-7 Krakow D, Williams J 3rd, Poehl M, Rimoin DL, Platt LD (2003) Use of three-dimensional ultrasound imaging in the diagnosis of prenatal-onset skeletal dysplasias. Ultrasound Obstet Gynecol. 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 »French telephone receiver« aspect of the femora and humeri is typical for the type 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 Asphyxiating thoracic dysplasia

The condition is lethal and death results from respiratory failure in all cases.

General information

Sahinoglu Z, Uludogan M, Gurbuz A, Karateke A (2003) Prenatal diagnosis of thanatophoric dysplasia in the second trimester: ultrasonography and other diagnostic modalities. Arch Gynecol Obstet. 269(1):57-61

Jeune’s asphyxiating thoracic dystrophy (ATD) is a shortlimbed short-rib polydactyly dwarfism that is characterized by thoracic cage deformity and severe respiratory distress at birth. The syndrome is inherited in an autosomal recessive manner and the locus has been mapped to chromosome 15q13.

Clinical features ▬ The chest is narrow, elongated and bell-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 patients may suffer from renal failure due to juvenile nephronophthisis, liver dysfunction due to cholangiopathy or retinal dystrophy

Imaging Prenatal imaging Prenatal ultrasound diagnosis should be suspected if the ratio of the thoracic circumference to the abdominal circumference is less than normal or if there is discordance between the gestational age and thoracic circumference.

Plain radiographs

⊡ Fig. 6.2. Babygram of a thanatophoric dwarf showing a narrow 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 clavicles are horizontal in orientation. The ribs are short and horizontal with expansion of the costochondral junctions. The thorax is bell-shaped ▬ The long bones are short but not to the same degree as in achondroplasia 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 wings and underdeveloped pelvic bones are present. The proximal femoral epiphyses are prematurely visible, which is highly suggestive of ATD

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Prognosis This condition is usually lethal, but sporadic cases surviving to childhood have been reported.

References den Hollander NS, Robben SG, Hoogeboom AJ, 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, Kaitila I (2001) Familial asphyxiating thoracic dysplasia: clinical variability and impact of improved neonatal intensive care. J Pediatr 139(1):130-3

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6.1.4 Osteogenesis imperfecta

General information Osteogenesis imperfecta (OI) is a genetic disorder of increased bone fragility, low bone mass, and other connective-tissue manifestations. The underlying pathophysiology is the production of abnormal collagen I molecules as well as a decrease in the production of normal collagen I molecules. This results from mutations in the loci coding for pro-α 1 and pro-α 2 chains which form the helical structure of collagen 1.

⊡ Fig. 6.3. Chest radiograph illustrating horizontal clavicles (c), short, horizontal ribs with expansion of the costochondral 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 type-1 form has the best prognosis and bone fragility is mild. Ligamentous laxity is common. The type-2 form has the worst prognosis with many dying in utero or in the neonatal period. Type 3 has severe bone fragility and osteopenia. The bones are usually markedly deformed at birth. Individuals survive to childhood. Type 4 is the 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 and gracile with thin cortices (⊡ Fig. 6.4a). The skull vault may be normal ▬ In the more severe forms of OI such as types 2 and 3, the bones are thick and short with multiple fractures and hyperplastic callus formation. The skull is osteopenic and multiple wormian bones are 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 and cross-sectional imaging is reserved for specific indications only.

Prenatal Ultrasound OI, especially type 2, can be diagnosed on prenatal ultrasonography by the second trimester. Findings include bowing, shortening and angulation of the long bones due to fractures and easy visualization of intracranial structures due to decreased ossification of the skull vault.

B ⊡ Fig. 6.4A,B. A Type-1 osteogenesis imperfecta. Plain X-ray of the right tibia and fibula showing thin gracile bones and cortices. Healing fractures of the mid-tibial shaft and upper fibula are seen. B Type-2 osteogenesis imperfecta. Newborn with congenital fractures, callous formation and bowing of the femurs, tibias and fibulas (arrows)

Treatment Physiotherapy, rehabilitation, and orthopaedic surgery are the mainstay of treatment for patients with osteogenesis imperfecta. In recent years, biphosphonate therapy has been used with success.

6.1.5 Osteopetrosis

General information References Rauch F, Glorieux FH (2004) Osteogenesis imperfecta 24;363(9418):137785 Ablin DS (1998) Osteogenesis imperfecta: a review. Can Assoc Radiol J 49(2): 110-23

Osteopetrosis is a heterogeneous group of hereditary conditions in which there is a failure of bone resorption by osteoclasts. This decrease in osteoclast activity results in generalized osteosclerosis and obliteration of marrow spaces and cranial foramina. This results in bone brittleness and decreased bone marrow function.

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Clinical features The classical clinical features are: ▬ Pathological fractures ▬ Visual impairment ▬ Bone marrow failure There are three major forms of the disease: ▬ Malignant infantile ▬ Intermediate ▬ Adult form

6

The malignant infantile form is autosomal recessive and clinically most severe with patients suffering from growth retardation and failure to thrive due to bone marrow failure. The adult form is mild, occurring in adults between 20 and 40 years old. It is autosomal dominant and may be detected incidentally. Patients suffer from frequent fractures, which heal with difficulty, and no bone marrow suppression is present.

Imaging Plain radiographs Radiological findings vary depending on the form of disease. The bones are generally uniformly sclerotic, but alternating sclerotic and lucent bands may be noted in the iliac wings and near the ends of long bones (⊡ Fig. 6.5). A bone-within-bone appearance may be seen. The entire skull is thickened and dense, especially at the base. Sinuses are small and underpneumatized. Vertebrae are extremely radio dense or may show alternating bands, known as the »rugger-jersey« sign. Evidence of fractures or osteomyelitis may be present.

⊡ Fig. 6.5. Plain radiograph of the lower limbs showing generalized increased density of the bones due to osteopetrosis

6.2

Developmental dysplasia of the hip

Cross-sectional imaging The diagnosis is made on plain radiographs but CT and MR imaging can aid in the evaluation of facial, skull base, intracranial and cranial nerve involvement. In addition, MR imaging can be useful in assessing the degree of the marrow involvement in the malignant infantile form of the disease.

General information Developmental dysplasia of the hip (DDH) comprises a spectrum of abnormality ranging from acetabular dysplasia to frank dislocation of the hip. Breech presentation, skull moulding deformities at birth, neuromuscular disorders, congenital torticollis, congenital foot deformities and a family history are risk factors. DDH is bilateral in up to one-third of patients.

References Tolar, J, Teitelbaum, SL, Orchard, PJ (2004) Osteopetrosis. N Engl J Med 351: 2839-2849 Stoker DJ (2002) Osteopetrosis. Semin Musculoskelet Radiol 6(4):299305

Clinical features DDH can be detected on physical examination by performing the Barlow’s and the Ortolani’s manoeuvre.

6

139 6.2 · Developmental dysplasia of the hip

⊡ Fig. 6.6. Frontal pelvic radiograph showing a superiorly dislocated right hip. Hilgenreiner’s (H) line is a horizontal line drawn through the triradiate cartilages and Perkin’s (P) line is perpendicular to Hilgenreiner’s line from the outer edge of the acetabulum. The normally located femoral head (F) on the left is situated inferior and medial to Hilgenreiner’s and Perkin’s lines respectively. The acetabular angle or index (i) is formed by the Hilgenreiner’s line and a line along the acetabular 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 than 3 months of age because the unossified epiphyseal cartilaginous portions of the hip joint cannot be visualized ▬ Radiographs can be used once the femoral head has ossified which is 3 to 6 months in females and 4 to 7 months in males. The acetabular index, Perkin’s and Hilgenreiner’s lines are used in the evaluation of DDH (⊡ Fig. 6.6)

Ultrasound US is optimally performed when the patient is 4 to 6 weeks of age, allowing for resolution of physiological hip instabilities that may occur in the first month of life. In 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 limited two or three-slice low-dose CT may be performed within 24 h after 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 triradiate cartilage join in the medial part of the acetabulum (small arrow). The labrum is also seen (thick arrow). B Transverse dynamic views of the left (Lt) hip performed prior and after the application of stress in an attempt to piston the femoral head (H) out of the acetabulum (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 Osteomyelitis

Anatomy and pathology

6

Osteomyelitis is defined as infection of the bone and bone marrow. Organisms spread via the bloodstream to lodge in the slow-flowing sinusoids in the metaphyseal regions of the long bones. In infants, transphyseal vessels enable spread of the organisms into the epiphysis. After 1 year of age, the transepiphyseal vessels close and the infection cannot cross the growth plate. In older adolescent and adults, fusion of the growth plate re-establishes the vascular continuity between the epiphysis and metaphysis and infection may again spread from the metaphysis to the epiphysis. Spread of the infective process into the joint causes septic arthritis. Complications in osteomyelitis may lead to growth plate damage with subsequent growth arrest and deformity. Other complications include septicaemia, persistent metaphyseal cartilage, leg lengthening due to chronic hyperaemia, avascular necrosis, osteolysis and, in rare cases, systemic amyloidosis. Staphylococcus aureus causes greater than 90% of all cases across all age groups.

Scintigraphy The sensitivity of Tc99m MDP has an accuracy of 90% in detecting the presence of osteomyelitis. Osteomyelitis shows increased uptake in all three phases of the technetium 99m methylene disphonate (Tc99m MDP) threephase bone scan which comprises the blood flow (angiographic phase), early tracer uptake within bone (blood pool phase) and delayed uptake 2 to 4 h later (delayed phase). Cellulitis or soft-tissue inflammation show increased uptake in the 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 evident with discharging sinuses at the affected site and low-grade fever

Plain radiography ▬ Deep soft tissue swelling is the initial finding ▬ Bony changes such as osteopenia, bony destruction and cortical erosion are only seen after loss of 30 to 50% of bone mineralization and diagnosis may be delayed (⊡ Fig. 6.8) ▬ In chronic osteomyelitis a mixed pattern of bony erosion and sclerosis is seen. Thick cortical lamellar periostitis due to involucrum formation and medullary sclerosis are noted

⊡ Fig. 6.8. Plain X-ray of the right lower leg of a newborn showing a lucency (arrow) in the distal tibia due to osteomyelitis

141 6.3 · Infection and inflammatory

Ultrasonography US is able to detect soft tissue swelling, thickening of the periosteum and the presence of subperiosteal fluid before plain radiographic changes are evident. In later disease, cloaca can also be seen on US.

excellent images albeit with increased cost. The choice between MRI and bone scintigraphy thus depends on local factors.

References Computed tomography CT is useful in evaluating the subacute and chronic stages of infection. The sequestra, involucrum, cloaca, abscesses and soft tissue extension of the disease is well assessed (⊡ Fig. 6.9).

Saigal G, Azouz EM, Abdenour G (2004) Imaging of osteomyelitis with special reference to children. Semin Musculoskelet Radiol. 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 Septic arthritis

Magnetic resonance imaging The sensitivity of MRI for detecting and evaluating the extent of osteomyelitis ranges from 88 to 100%. Infected marrow is low in signal intensity on T1-weighted imaging and high on T2-weighted and STIR imaging. Infected marrow enhances after the administration of gadoliniumdiethylenetriamine-penta-acetic acid (Gd-DTPA) on T1weighted sequences. Subperiosteal collections, abscesses, cortical thickening and fibrotic devascularized sequestra may be seen. MRI and bone scintigraphy are equally sensitive in diagnosing early osteomyelitis but MRI is able to provide

General information Septic arthritis is an infectious inflammation of a joint. Modes of infection include haematogenous spread, contiguous spread from osteomyelitis, direct implantation or post-surgical. The commonest organism is Staphylococcal aureus.

Clinical features ▬ Fever, erythema and joint swelling may be seen 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 count and the C-reactive protein are often 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: ▬ Osteomyelitis ▬ Soft-tissue swelling and widening of the joint space ▬ Periarticular osteopenia in later stages

Ultrasound

⊡ Fig. 6.9. Axial CT image of a newborn with osteomyelitis of the upper metaphyseal region of the right humerus with bony destruction (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 also useful in guiding needle placement joint aspiration procedures

6

142


References Lee SK, Suh KJ, Kim YW, Ryeom HK, Kim YS, Lee JM, Chang Y, Kim YJ, Kang DS (1999) Septic arthritis versus transient synovitis at MR imaging: preliminary assessment with signal intensity alterations in bone marrow. Radiology 211(2):459-65 Malleson PN (1997) Management of childhood arthritis. Part 1: Acute arthritis. Arch Dis Child. 76(5):460-2. Review

6.3.3 Juvenile 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 defined by the presence of joint swelling or two of the following: joint tenderness, decreased range of motion (ROM), pain on ROM, or joint warmth for at least 6 weeks without another cause, in children younger than 16 years of age. ⊡ Fig. 6.10. US of the right hip showing an echogenic effusion due to septic arthritis (arrow)

CT and MRI ▬ Cross-sectional imaging with CT and MRI should be used only in more complex cases where evaluation of the surrounding structures is important ▬ Joint effusions, synovial enhancement, swelling and hypertrophy of the joint may also be seen on MRI ▬ Septic arthritis may also show signal abnormalities in the adjacent bone marrow on fat-suppressed GdDTPA enhanced T1 and on T2 weighted images. These features are not seen on transient synovitis ▬ CT may show bony destruction in cases due to contiguous spread from adjacent osteomyelitis

Treatment and complications Treatment of septic arthritis is an emergency. Complications such as avascular necrosis, bony ankylosis and growth deformity may result. Open surgical drainage of the joint or repeated joint aspirations may need to be carried out.

Classification The classification task force in childhood rheumatologic disease of the International League for Rheumatology standardized classification of childhood inflammatory arthritis to provide a solid basis for collaborative research and clinical guidance. JIA has six sub-types: ▬ Systemic arthritis (extra-articular manifestations including rash, fever, lymphadenopathy, hepatosplenomegaly and serositis predominate at onset) ▬ Oligoarthritis (< five joints involved in the first 6 months) – Persistent – Extended ▬ Polyarthritis (five or more joints involved in the first 6 months) – RF-positive – RF-negative ▬ Enthesitis-related arthritis (including juvenile ankylosing spondylitis and arthritis associated with inflammatory bowel disease) ▬ Psoriatic arthritis ▬ Others – this category accommodates disease fitting the definition of JIA but not fulfilling any of the

143 6.4 · Neoplasm

defined subtypes or fitting into two or more of the defined subtypes

Imaging Plain radiographs Plain radiographs frequently show the following findings: ▬ Soft-tissue swelling and widening of the joint space ▬ Late stage joint space narrowing and ankylosis (⊡ Fig. 6.11) ▬ Articular surface erosions ▬ Peri-articular osteopenia in later stages However, these features lack sensitivity and specificity. Several radiological grading systems have been formalized to score the degree of severity of radiographical findings, but these are limited in children because of the cartilaginous structure of the epiphyses, which may mask the real timing of development of bone erosions

hypertrophy, soft tissue swelling, articular cartilage, joint integrity and bone marrow changes. Fast spin-echo T2 or intermediate-weighted imaging and 3D-spoiled gradient echo (SPGR) T1-weighted sequence 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 sensitive in the detection of joint effusion and 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, there is an increasing use of MRI and US in this regard. Patients should be managed on a caseby-case basis due to the higher cost of these modalities.

MRI MRI is recommended to monitor JIA progression and response to therapy because of its ability to assess synovial

References Petty RE, Southwood TR, Manners P, Baum J, Glass DN, Goldenberg J, He X, Maldonado-Cocco J, Orozco-Alcala J, Prieur AM, SuarezAlmazor ME, Woo P (2004) International League of Associations for Rheumatology. International League of Associations for Rheumatology classification of juvenile idiopathic arthritis: second revision, Edmonton, 2001. J Rheumatol.31(2):390-2. Gylys-Morin VM, Graham TB, Blebea JS, Dardzinski 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 of bone lesions consists of lesion detection, characterization, staging, biopsy guidance and identification of residual or recurrent disease post-treatment.

Imaging Plain radiographs ⊡ Fig. 6.11. Plain wrist radiograph showing ankylosis of the carpal bones (arrow) due to long-standing JIA

Radiographic evaluation of the following characteristics provide information regarding the aggressiveness and diagnosis of bone lesions (⊡ Fig. 6.12; ⊡ Table 6.2).

6

144


Evaluation of the lesion matrix may provide evidence of the tissue of origin. E.g. Chondroid tumours usually show evidence of irregular, punctate calcification, which may take the shape of rings or arcs. Fibrous dysplasia may give rise to a »ground-glass« density.

CT CT provides the following information regarding the lesion and is especially useful in complex-shaped bones such as the spine and pelvis. CT is also useful in evaluat-

ing the extent of cortical involvement and breakthrough and matrix calcification.

Scintigraphy Technetium (Tc)-99m-labelled diphosphonate bone scintigraphy is used in the staging of bone tumours to evaluate for the presence of metastases and skip lesions. PET imaging is playing an increasing role in the 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

MRI

6.4.2 Langerhan cell histiocytosis

MR imaging is used in the local staging of bone tumours. This is achieved by evaluating the extra- or 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 Enneking system of surgical staging of bone and soft tissue tumors is based on grade (G), site (T), and metastasis (M) and uses histological, radiological, and clinical criteria. It is the most widely used staging system and has been adopted by the Musculoskeletal Tumour Society (⊡ Table 6.3). ▬ Grade – G0 – benign lesion – G1 – low-grade malignant lesion – G2 – high-grade malignant lesion ▬ Site – T0 – benign intracapsular and intracompartmental lesion – T1 – intracompartmental lesion – T2 – extracompartmental lesion ▬ Metastasis – M0 – no regional or distant metastasis – M1 – regional or distant metastasis The surgical stage of the tumour determines management.

General information Langerhans cell histiocytosis (LCH) is a group of idiopathic disorders characterized by the proliferation of specialized bone marrow-derived Langerhans cells (LCs) and mature eosinophils. The peak incidence is between 1 and 4 years.

Clinical features There are three clinical variants of LCH known as eosinophilic granuloma (EG), Letterer-Siwe disease (LS) and Hand-Schüller-Christian (HSC) disease: ▬ EG is a benign, indolent form affecting children between the ages of 5 and 15 years. A single or a few skeletal lesions are seen. The most commonly affected sites are the skull, mandible, spine, ribs and long bones. Patients may present with local pain, swelling and tenderness or pathological fractures. ▬ LS is an acute, fulminant form affecting children less than 2 years of age. It is characterized by hepatosplenomegaly, lymphadenopathy, skin lesion, otitis media, lung involvement, anaemia, leukopenia and thrombocytopenia. ▬ HSC is an intermediate clinical form affecting children between the ages of 2 and 10 years. This form is characterized by multifocal, chronic involvement and classically presents as the triad of diabetes insipidus, proptosis and lytic bone lesions.

References O’Donnell, P (2003) Evaluation of focal bone lesions: basic principles and clinical scenarios. Imaging 15: 298-323 Teo HE, Peh WC (2004) The role of imaging in the staging and treatment 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

Imaging Plain radiographs ▬ Early stage skeletal lesions have an aggressive, permeative appearance. In later stages they appear as well-defined, punched out, lytic lesions with little periosteal reaction. Surrounding sclerosis is seen only in the healing stage of the disease. ▬ Widespread osteopaenia, cortical thinning and trabeculae prominence may be seen in diffuse bony involvement ▬ A lesion with a beveled edge may be seen in the skull vault due to differential destruction of the inner and outer tables of the skull vault. A button sequestion is a description given to a rounded lytic lesion with a central area of intact bone ▬ A solitary collapsed vertebral body known as vertebra plana is characteristic of LCH (⊡ Fig. 6.13)

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Once the diagnosis is achieved, skeletal surveys and/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 the quality of gamma cameras and imaging techniques have produced better results in recent reports. Both methods are complimentary.

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 whilst bone marrow and soft-tissue involvment is better demonstrated on MRI. Lesions are

typically low in signal intensity on T1-weighted imaging, high in STIR and T2-weighted imaging and demonstrate enhancement after the administration of gadolinium. 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 have an excellent prognosis. The prognosis in patients with HSC is related to the extent and 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, Podda A (2005). Langerhans’ cell histiocytosis: pathology, imaging and treatment of skeletal involvement. Pediatr Radiol 35(2):103-15 Kilborn TN, Teh J, Goodman TR (2003) Paediatric manifestations of Langerhans cell histiocytosis: a review of the clinical and radiological findings. Clin Radiol 58(4):269-78

6.5

Trauma

6.5.1 Paediatric fractures

General information Musculoskeletal injuries account for 12% of paediatric visits to the emergency department, with fractures making up a large proportion of these numbers. Paediatric bone is more elastic than adult bone and can bend without breaking. This results in unique 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 of a long bone. With increasing force, microfractures occur and the bone then loses its capacity to regain its original shape and remains bowed.

147 6.5 · Trauma

This fracture occurs most commonly in the radius and ulna ▬ Torus fractures are also known as buckle fractures and are incomplete fractures occurring on the concave 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 complete fracture occurs when the fracture line propogates completely through the bone and most commonly involve the diaphyseal region

Physeal fractures The Salter-Harris classification of physeal fractures is the most widely accepted classification and it relates the 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

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