Experience with volumetric (320 rows) pediatric CT.

The introduction of helical computer tomography (CT) and further progress to multi-slice CT enabled new applications. Most recent developments like the 320-row detector facilitate volume CT, which avoids the over-beaming effect of helical scanning. The 320-row multi-slice detector CT (MDCT) is based on a 16cm detector; a special acquisition mode allows reconstructing 640 slices from these 16cm. The shortest tube rotation time is in cardiac mode 0.35s, otherwise 0.4s and 0.5s used. At 0.5s the machine already reaches the maximum numbers of sub-second projections. Scan modes can be volume, helical and single slice mode. For image acquisition all dose savings technologies like variable tube position for scano-view, active collimation, automated exposure control, bolus and ECG tracking are available. Additionally special acquisition and post-processing techniques like head and body perfusion CT are ready for use on the console. For image reconstruction properties like filtered back projection as well as the latest development of iterative algorithms, an appropriate number of kernels and multi-planar reconstruction in all directions from the volume data at every increment are available. Volume CT allows sub second scanning of 16cm z-coverage which, however, makes administration of intravenous contrast medium to "hit or miss" event. The aim of this paper is to present the application of volume CT to body scanning in children. Representative examples of neck, cardiac and skeletal investigations are given.

[Modern imaging technology for childhood urinary tract infection]. / Moderne Bildgebung beim Harnweginfekt im Kindesalter.

Imaging in childhood urinary tract infection (UTI) is still a matter of debate. There are established guidelines, however new knowledge and the changed medical environment have enhanced this ongoing discussion. These new insights have impacted therapy and consequently the imaging algorithm. Modern imaging methods -- particularly MRI and modern ultrasound (US) -- are less invasive with a lower radiation burden. Additionally, it has been shown that VUR is a poor predictor for renal scarring out, which affects long-term results. Furthermore, the majority of UT malformations is depicted by prenatal US. The most crucial aspect of improving long-term outcome appears to be the early and reliable depiction of UTI and effective treatment to prevent renal scarring. This review tries to present this new knowledge and to discuss the potential of modern imaging. Recent changes in imaging algorithms are highlighted and an outcome-oriented algorithm that addresses these recent developments is proposed, without lightly abandoning established standards. It consists of an orienting US and -- for depiction of renal involvement -- amplitude coded color Doppler sonography or renal static scintigraphy (considered the gold standard, particularly for evaluating scars); in future MRI may play a role. Based on this concept, only patients with renal damage as well as patients with complex urinary tract malformations or intractable recurrent UTI may have to undergo VCUG.

[Functional disorders of the lower urinary tract in children]. / Funktionelle Störungen des unteren Harntrakts im Kindesalter.

Functional disorders of the lower urinary tract as well as vesicoureteral reflux involved in the disease complex of urinary tract infection/permanent renal parenchymal damage can be considered predisposing or risk factors. Two main forms can be distinguished, i.e., unstable bladder and dysfunctional voiding, while transitional forms between the two exist. Functional disorders of the lower urinary tract obstruct spontaneous resolution of vesicoureteral reflux. They are found in about 50% of cases in all children with urinary tract infection and are associated with an increased risk of developing renal parenchymal scars. They are observed during the newborn period up to school age. In the first few months of life, particularly boys with bilateral high-grade reflux and congenital renal parenchymal damage are affected. At later ages girls are also affected, but in this age group bladder instability predominates. Incontinence as the leading clinical symptom appears in approximately 70% of all cases and is closely correlated with chronic constipation. Imaging procedures in addition to urodynamic methods are of decisive importance for diagnosis and treatment, but noninvasive approaches such as sonography should be given preference.

Urinary tract infection in infants and children: an update with special regard to the changing role of reflux.

The aim of this study was to present current theories of pathogenesis and prognosis in urinary tract infection (UTI) and renal scarring during infancy and childhood, with special regard to new insights concerning the role of vesico-ureteral reflux (VUR). For a long time VUR and UTI were considered the only risk factors for renal scarring in childhood. Now a wider spectrum of contributing conditions is commonly accepted, which all may pose different clinical consequences and require different imaging approaches. Particularly bilateral renal scarring causes long-term sequalae; therefore, renal involvement in UTI with potential scarring has become the clinical and imaging focus, and proper diagnosis of UTI as the key factor for further management has become even more important. The VUR still remains one issue on a list of important factors such as treatment onset and response, bacterial virulence, immunological factors, genetic disposition, anatomical variants, and lower urinary tract dysfunction. Recent advances in knowledge leading to changed patho-physiological concepts, and new imaging techniques, may consecutively impact the presently established standard imaging algorithms. New, advanced imaging techniques offer improved and accelerated comprehensive imaging of the paediatric urinary tract. At present, this is complimentary to the established gold standard techniques. Strong research efforts have to be made before suggesting significant changes of current imaging concepts; however, based on recent technical advances and new insight on the natural history of paediatric urological diseases, potential changes of established imaging algorithms need to be discussed and evaluated.

Feasibility of MR urography in neonates and infants with anomalies of the upper urinary tract.

The aim of this study was to evaluate the feasibility and diagnostic potential of dynamic MR urography (MRU) in neonates and infants with sonographically detected abnormalities of the upper urinary tract. Thirty infants (age range 5 days to 3 years, mean age 7.9 months; male:female: 22:8) underwent MRU using T2 and contrast-enhanced dynamic T1-weighted sequences. The results were compared with the findings of ultrasound ( n=30), intravenous urography (IVU, n=19) and/or scintigraphy ( n=25) based on the criteria suggestive of obstructive uropathy. Oral sedation was sufficient to perform MRU with diagnostic quality in 20 of 21 patients younger than 1 year; 9 older patients needed intravenous sedation. Diagnosis of the 66 renal units (58 kidneys, 29 successful examinations) included normal systems (contralateral units), duplex systems, vesico-ureteral reflux, obstructive megaureter, ureteropelvic junction obstruction and accompanying renal parenchymal disease, with complex pathology in 10 patients. Magnetic resonance urography demonstrated anatomy better than IVU, particularly the renal parenchyma, (ectopic) ureters, and poorly functioning dilated systems. Magnetic resonance urography was superior to US in showing ureteral pathology. Tiny cysts in dysplastic kidneys were better seen by US. Gadolinium-enhanced dynamic MRU allowed accurate assessment of obstruction applying IVU criteria. Here MRU matched IVU results, and most of the scintigraphic findings. Magnetic resonance urography can be performed in young infants with diagnostic quality using oral sedation. Magnetic resonance urography correctly depicts anatomy and allows assessment of the urinary tract better than US and IVU, with additional functional information. Magnetic resonance urography thus has the potential to replace IVU for many indications.

Echo-enhanced color Doppler sonography in children and adolescents.

Fifty-one patients, with a range of underlying pathologic conditions, were studied prospectively to assess the diagnostic value of echo-enhanced color Doppler sonography in the pediatric and adolescent population Their diagnoses included various tumors, vascular disorders, cerebral bleeding, pathologic conditions of small parts, and focal lesions of parenchymal organs. All patients underwent color Doppler sonography before proceeding to echo-enhanced color Doppler sonography. Diagnoses were confirmed by additional imaging (computed tomography, magnetic resonance imaging, angiography, and scintigraphy) performed as appropriate, with or without histologic study. An additional 20 children did not proceed to echoenhanced color Doppler sonography as color Doppler sonography alone was found to be sufficiently diagnostic. Levovist (SHU 508A), a contrast agent based on galactose-encapsulated air microbubbles, is approved for pediatric applications in Austria and was used as the echo-enhancing agent. Echo-enhanced color Doppler sonography was performed a total of 63 times in 51 patients (mean age, 9.8 years). Compared to color Doppler sonography, echo-enhanced color Doppler sonography either detected or enhanced visualization of pathologic conditions in 55 investigations (87.3%), yielding an overall accuracy of 95.2% (sensitivity, 95%), versus 65.7% with color Doppler sonography. One spinal arteriovenous malformation, one cerebral cavernoma, and one liver lesion were missed. The contrast material was easy to administer; no adverse reactions were observed. We conclude that echoenhanced color Doppler sonography is beneficial in pediatric sonography. It enhances visualization of vessels and perfusion, thus offering a nonionizing imaging tool for detection and follow-up evaluation of pathologic conditions with disturbed vasculature in specific cases. In infants and in persons with superficial lesions it did not offer significant advantages over color Doppler sonography.

Helical CT angiography with maximum intensity projection in the assessment of aortic coarctation after surgery.

OBJECTIVE: The value of CT angiography and three-dimensional (3D) reconstructions was investigated in the postoperative care after surgical repair of aortic coarctation and compared with conventional angiography. SUBJECTS AND METHODS: Twenty-five patients referred because of suspicion of stenosis in the area of former coarctation were prospectively studied with CT angiography and catheter angiography. We determined the morphometric and morphologic findings such as aortic diameter, stenosis, aneurysm, intimal flaps, circumscribed pouch, or arteriosclerotic plaques with 3D reconstructions, using maximum-intensity-projection (MIP) technique and catheter angiography. The results of both techniques were compared. The ratio of the narrowest diameters of the former coarctation and the descending aorta was correlated with the systolic pullback blood pressure gradient in all patients. RESULTS: The former coarctation was normal in 11 patients, (44%), group A; narrowed in 12 children (48%), group B; and dilated in two children (8%), group C. An intimal flap and a circumscribed pouch were delineated in four subjects. MIP reconstructions and catheter angiography revealed identical results regarding the classification into groups A, B, C; intimal flaps; and circumscribed pouches. Statistical analysis revealed good correlation between the narrowest aortic diameters measured on MIP reconstructions and catheter angiography, whereas no correlation between the systolic pullback blood pressure gradient and the diameter ratio of the former coarctation and the descending aorta was found. CONCLUSION: CT angiography and 3D reconstructions using MIP represent a reliable noninvasive technique to replace diagnostic catheter angiography in the postoperative care of patients with coarctation and provide the clinician with valuable information concerning further invasive procedures.

[Neonatal gastrointestinal emergencies]. / Gastrointestinaler Notfall im Neugeborenenalter.

UNLABELLED: Gastrointestinal emergencies in neonates often demand a quick and efficient diagnostic imaging. The procedures have to take the special diseases and conditions in these babies and preterm children into account. CONCLUSION: This paper summarises the most common causes for gastrointestinal neonatal emergencies and discusses the indication and performance as well as the diagnostic value of the commonly used modalities, giving some suggestions for an efficient imaging algorithm. Most of the time conventional plain abdominal films and sonography can answer the clinically important questions, however, in certain conditions fluoroscopy with contrast administration (enema, etc.) is mandatory. Only rarely is CT, MRI or Angiography indicated.

[Neonatal segmental cystic nephroma. A case report]. / Neonatales segmental-zystisches Nephrom. Eine Kasuistik.

UNLABELLED: Multicystic segmental renal dysplasia is rare in early childhood. We report a case with prenatally recognized renal malformation. Prenatally a cystic renal malformation was detected sonographically; postnatally further evaluation was performed by Doppler sonography, contrast enhanced CT and voiding cysto-urethrography leading to the diagnosis of a multicystic segmental nephroma. Due to increasing size in spite of therapeutic and diagnostic sonographic guided punctures and the atypic manifestation the baby underwent heminephrectomy. The final histological diagnosis confirmed preoperativ findings. CONCLUSION: Prenatally recognised cystiform renal malformations should be reevaluated postpartally by ultrasound and--as doubtful findings are found--further imaging might be necessary for follow up and for the decision on conservative or operative treatment.

The reliability of bone age determination in central European children using the Greulich and Pyle method.

This study assessed the reliability of bone age determination in normal central European children using the Greulich and Pyle method and determined the effects of readers' experience on the measured bone ages. Plain hand radiographs of 47 children (aged 2 months to 18.8 years) with normal growth were analysed by four radiologists (two experienced paediatric radiologists and two radiology residents). The readers were blinded to the age of the children. The images were re-read by the same readers 2 months later. The mean intraobserver and interobserver variations were lower for experienced readers than for radiology residents. However, these differences were not statistically significant at the 5% level. The difference between the chronological age and the measured bone age was -1.5 +/- 7.6 months (p = 0.20) for the experienced readers and 2.7 +/- 10.3 months (p = 0.09) for the radiology residents. The differences between the measured bone age and chronological age were statistically significant (p = 0.04) for only one of the two radiology residents. Although the measurements by all four readers underestimated the chronological age, the differences between chronological age and bone age were within the normal variations of skeletal maturation as reported by Greulich and Pyle. Our data suggest that the reliability of bone age measurements increases with experience and that the Greulich and Pyle method may be used for central European children.

Cytomegalovirus associated neonatal pneumonia and Wilson-Mikity syndrome: a causal relationship?

Lung injury caused by intrauterine inflammation has recently been strongly implicated in the pathogenesis of Wilson-Mikity syndrome (WMS). This article supports this theory by suggesting a causative role of intrauterine cytomegalovirus (CMV) infection for the development of WMS. A male premature infant, born at 33 weeks of gestational age, developed chronic lung disease compatible with WMS and diagnostic evaluation was positive for CMV infection. High-resolution computed tomography scan and lung histology revealed typical features of WMS in association with signs of interstitial pneumonia. CMV was found in urine, breastmilk, bronchoalveolar lavage material and lung tissue from open lung biopsy. Follow-up after treatment with ganciclovir and steroids showed resolving lung disease at the age of 6, 10 and 16 months, with lung function signs of mild obstruction. Assuming that a chance coexistence of cytomegalovirus pneumonia and Wilson-Mikity syndrome is rather unlikely, it is possible that intrauterine cytomegalovirus infection caused a pattern of lung injury consistent with Wilson-Mikity syndrome. Further cases of Wilson-Mikity syndrome should be investigated as to a possible role of congenital infection.

High-resolution CT findings in Wilson-Mikity syndrome: a case report.

Wilson-Mikity syndrome (WMS), an uncommon cause of respiratory distress presenting after birth, is radiologically characterised by varying degrees of interstitial thickening and bilateral cyst-like foci of hyperinflation. Aetiology and pathogenesis are still unknown. There are few reports of WMS in the paediatric literature and none describing the features and value of high-resolution CT. The purpose of this report is to describe the radiographic findings and high-resolution CT appearance of WMS and to correlate them with the histopathological findings.

Imaging of constipation in infants and children.

The aims of this review article are to present epidemiology, important definitions, clinical considerations, and etiologic and pathogenetic aspects of constipation in infants and children. Anatomy, physiology, and pathophysiology of the the anorectum are described. Special attention is given to the indications for diagnostic imaging, imaging techniques, and imaging findings with different causes of constipation. Other diagnostic modalities, such as anorectal manometry, electromyography, and biopsy techniques are briefly discussed. The central question as to whether diagnostic imaging is needed for the diagnostic workup of infants and children suffering from constipation can be answered affirmatively. Especially the combination of barium enema or defecography and anorectal manometry allows definition of those infants and children who do not need biopsy and surgery for Hirschsprung's disease. The special role of defecography in this context is underlined.

The sonographically thickened wall of the upper urinary tract system: correlation with other imaging methods.

BACKGROUND: Sonographically detected, upper urinary tract wall thickening (UUTWT) was reported to occur in urinary tract infection, urinary tract stone disease, rejection after renal transplantation and vesico-ureteral reflux (VUR). A possible association with obstruction can be hypothesized. OBJECTIVE: The assessment of a potential relationship of UUTWT with VUR or obstruction in patients without one of the above-mentioned conditions. MATERIALS AND METHODS: We analyzed 38 patients (74 upper urinary tracts) with at least unilateral UUTWT and concomitant imaging studies such as voiding cystourethrography (VCU), intravenous urography (IVU) and diuretic renography (DR). RESULTS: At sonography 49 urinary tracts showed UUTWT. In 33, ipsilateral VUR could be demonstrated at VCU, 11 revealed obstruction at IVU and/or DR, and 4 showed non-obstructive pelvicalyceal dilatation at IVU and DR. In one patient, all imaging studies were normal. The positive predictive value of UUTWT for the presence of VUR was 67.4 % and for obstruction it was 22.5 %. Altogether, UUTWT indicated pathology in 98 % of urinary tracts. CONCLUSION: After exclusion of urinary tract infection, urinary stone disease and prior renal transplantation, the most common associated findings in UUTWT are VUR and obstruction. Therefore, VCU seems to be justified in all cases of UUTWT. Nonrefluxing systems should be further evaluated with DR and/or IVU for exclusion of obstruction.

Power Doppler imaging and evaluation of the resistive index in focal nodular hyperplasia of the liver.

Focal lesions of the liver represent a significant diagnostic problem for various imaging modalities. The aim of this study was to assess the value of power Doppler sonography versus conventional color Doppler imaging in the depiction of hypervascular focal nodular hyperplasia (FNH) of the liver and to investigate the resistive index (RI) in the lesions' feeding arteries. Eighteen histologically proved FNHs in 14 patients were evaluated by gray-scale ultrasound, conventional color Doppler, and power Doppler sonography. With conventional color Doppler, a feeding arterial vessel could be depicted in only 4/18 lesions and hypervascularization was detected in 6/18 lesions. Power Doppler was more sensitive in detecting feeding arteries (16/18) within hypervascular lesions (15/18). RI values in the feeding arteries (mean = 0.51) significantly differed from those in the main hepatic artery or its intraparenchymal branches (mean = 0.68) in the same patient. The mean RI-difference was 0.19, suggesting hemodynamically significant arteriovenous shunting. Power Doppler sonography significantly increases sensitivity in the diagnosis of focal nodular hyperplasia of the liver and reliably permits the distinction of these lesions from hepatocellular carcinomas.

Multiphasic helical CT of the kidney: increased conspicuity for detection and characterization of small (< 3-cm) renal masses.

PURPOSE: To evaluate the potential of thin-section multiphasic helical computed tomography (CT) in the detection and characterization of small (< 3.0-cm) renal masses. MATERIALS AND METHODS: Identically collimated helical CT of the kidney was performed before and after administration of contrast material in 93 patients with small renal masses. Helical CT scans were obtained during the corticomedullary and nephrographic phases. Differences between attenuation of the lesion and that of the kidney were measured quantitatively. The presence of a mass or absence of disease was confirmed with clinical, imaging, and histologic findings. RESULTS: The number of masses smaller than 3.0 cm detected on corticomedullary-phase scans (n = 211) was statistically significantly fewer than those on nephrographic-phase scans (n = 295) (P < .01). Mean differences in enhancement between the renal cortex and masses were 148 HU +/- 54 and 137 HU +/- 44 during the corticomedullary and nephrographic phases, respectively, and the difference in attenuation of the renal medulla and that of the masses was statistically significantly greater during the nephrographic phase (P < .01). False-positive results (n = 9) occurred only on corticomedullary-phase scans because of lack of enhancement of the renal medulla. CONCLUSION: Nephrographic-phase scans enabled greater lesion detection and better characterization of small renal masses than corticomedullary-phase scans. Nephrographic-phase scans should be obtained when only monophasic scanning is used to detect small renal masses.

HRCT features in a 5-year-old child with follicular bronchiolitis.

High-resolution CT (HRCT) is the most sensitive radiographic method to image small airways disease. We discuss the HRCT features of follicular bronchiolitis in a 5-year-old boy and correlate them with the histopathological findings. The changes described include centrilobular nodules, bronchiectasis and bronchiolectasis, branching opacities and areas of reduced lung attenuation.