Wiltrud K. Rohrschneider

Combined static-dynamic MR urography for the simultaneous evaluation of morphology and function in urinary tract obstruction. I. Evaluation of the normal status in an animal model.

Objective. A new approach, combined static-dynamic MR urography is evaluated to determine its potential utility for the functional-morphological diagnosis of paediatric urinary tract obstruction. In this initial investigation we sought to evaluate the procedure by imaging the urinary tract of piglets. Materials and methods. Twenty-nine healthy piglets were studied with MR urography (MRU), 99 mTc-MAG3 diuretic renal scintigraphy (DRS), ultrasound (US) and excretory urography (EU). The functional and morphological findings were compared. For MRU we combined a respiration-triggered 3D-IR-TSE sequence and a dynamic 2D-FFE sequence after Gd-DTPA injection. Results. MRU depicted the complete urinary tract with superior image quality compared to EU. Calculation of time-intensity curves from the dynamic sequence permitted determination of single kidney function from parenchymal ROIs and urinary excretion using the whole kidney ROI. MRU and DRS showed significant agreement in the assessment of both single kidney function and urinary excretion. Disturbances of urinary drainage were generally caused by an overfilled bladder. Conclusions. Combined static-dynamic MRU is well suited for the depiction of the complete urinary tract and for the determination of individual kidney function and urinary excretion in the piglet.

Combined static-dynamic MR urography for the simultaneous evaluation of morphology and function in urinary tract obstruction. II. Findings in experimentally induced ureteric stenosis.

Purpose. To assess the diagnostic value of combined static-dynamic MR urography (MRU) for the functional-morphological evaluation of experimentally induced urinary tract obstruction in the piglet. Materials and methods. In 20 piglets unilateral ureteric stenosis was created operatively. Post-surgery repeated comparative examinations were obtained with MRU, diuretic renal scintigraphy (DRS), excretory urography (EU) and ultrasound (US). MRU was performed as a combination study with a static 3D-IR-TSE sequence and a dynamic 2D-FFE sequence after Gd-DTPA with frusemide administration. Results. MRU allowed complete depiction of the prestenotic urinary tract and of the stenosis in all cases. In 43 comparative studies MRU was superior to EU in 36, EU to MRU in 2. When single kidney function was calculated with both MRU and DRS, results were highly correlated (r = 0.92). When urinary excretion was compared, significant agreement was achieved with concordant findings in 86 % and slightly discordant results in 12 %. Conclusions. Static-dynamic MR urography permits excellent depiction of experimentally induced urinary tract obstruction in piglets and reliable assessment of individual renal function and urinary excretion. Two advantages of the method stand out – it does not require radiation and it permits functional-morphological correlation.

Hydrostatic reduction of intussusception under US guidance

The current nonoperative management of ileocolic intussusception includes hydrostatic and pneumatic reduction, both performed under fluoroscopic monitoring. Recently, a new technique — ultrasoundguided reduction — replaced the conventional approach in our institution. Over a 20-month period, 46 intussusceptions were diagnosed sonographically in 40 patients. In all cases, reduction was attempted under ultrasound guidance by means of a normal saline enema. In 42 cases (91%) reduction was successful and only four patients had to be operated (two resections, two manual reductions). Complications did not occur. this technique permits distinct visualization of the entire process, providing a clear and detailed echogram of the fluid-filled large and small intestine. We established the following definite criteria of reduction: disappearance of the target, demonstration of the ileocecal valve, visualization of the fluid reflux, and fluid filling of small bowel loops. The presented technique for the reduction of intussusception without radiation exposure is reliable and safe, and appears to be one of the most promising methods for the nonoperative treatment of ileocolic intussusception.

MR to assess renal function in children

Abstract.Renal function evaluation in the pediatric patient is generally based on scintigraphic examinations where a baseline gamma-camera renography is used to determine single kidney function, and diuresis renography is obtained to assess urinary drainage from the pelvicalyceal system. Magnetic resonance imaging also permits the evaluation of renal functional processes using fast dynamic sequences. Principally, an agent cleared by renal excretion is intravenously injected and its cortical uptake, parenchymal transport, and eventually its urinary excretion are followed with serial images. Different approaches have been presented most of which are based on T1-weighted gradient-recalled echo sequences with short TR and TE and a low flip angle obtained after intravenous injection of Gd-DTPA or Gd-DOTA. These techniques permit renal functional assessment using different qualitative and quantitative parameters; however, most of these methods are not suitable for the evaluation of urinary tract dilatation in infants and children. For the diagnostic work-up of children with congenital urinary tract obstruction and malformation a technique was developed which permits quantitative determination of single kidney function, in addition to evaluating urinary excretion disturbances analogous to that possible with scintigraphy.

Reduction in voiding cystourethrographies after the introduction of contrast enhanced sonographic reflux diagnosis.

Abstract.Background: Voiding urosonography (VUS) using the intravesical application of an US contrast medium (Levovist) has been shown to have very high sensitivity and specificity in the diagnosis of vesicoureteric reflux (VUR) compared to voiding cystourethrography (VCUG). Objective: To determine the extent of reduction of VCUGs after adding VUS to the diagnostic algorithm of VUR. Materials and methods: Over 2 years, 449 children (162 boys, 287 girls) were referred for diagnosis of possible VUR. The selection of a particular reflux examination was based on pre-defined criteria. VUS was performed primarily in girls and follow-up cases. The indications for VCUG were as follows: (a) boys – first examination for VUR, (b) specific request for urethra or bladder imaging, (c) girls – when VUR was diagnosed in the VUS and no VCUG had been done previously, and (d) inadequate VUS. Results: VCUGs were primarily carried out in 141 cases. VUSs were performed in 308 patients. In 69 of these patients a VCUG followed during the same examination session. Thus 239 of 449 patients underwent only VUS, resulting in reduction of the VCUGs by 53 %. Conclusions: The number of VCUGs was significantly reduced as a result of the implementation of VUS as part of the routine diagnostic imaging modality for VUR. Consequently, the number of children that would have been exposed to ionising radiation was reduced by over half.

Intestinal intussusception survey about diagnostic and nonsurgical therapeutic procedures

Objective. To provide an overview of the diagnostic and therapeutic procedures performed by European paediatric radiologists in the management of intussusception. Materials and methods. A postal survey was sent to the European members of ESPR. Items surveyed included diagnostic imaging procedures (plain films, US, contrast enema [CE]), contrast medium used (barium, iodine, air, saline solution), and imaging technique used for monitoring during reduction (films, fluoroscopy, US). Multiple answers were possible. Other data, including contraindications, maximum pressure, pressure and irradiation monitoring, presence of a surgeon, sedation, number and duration of attempts, and hospitalisation were also obtained and analysed. Results. There were 204 respondents (60.2 %). Regarding diagnosis, 72.5 % of respondents used plain radiographs, 93 % US, and 34 % CE. Reduction was performed using air (55 %), a barium suspension (32 %), iodinated contrast medium (24 %), or a saline solution (10 %). Reduction was monitored using fluoroscopy alone (46 %), fluoroscopy and radiographs (49.5 %), US alone (9.5 %), or a combination of radiology and US (18 %). Pressure was monitored by 81 % of respondents. Most respondents (82.4 %) used a maximum pressure between 100 and 120 mm Hg. Conclusions. US is widely used for diagnosing intussusception. For treatment, contrast medium and air reduction are used almost equally. A large number of radiologists are now performing intussusception reduction using US monitoring.

Pyloric muscle in asymptomatic infants: sonographic evaluation and discrimination from idiopathic hypertrophic pyloric stenosis

Objective. To compare the morphological and functional US appearance of the pylorus in healthy infants with those suffering from idiopathic hypertrophic pyloric stenosis (IHPS) in order to determine the pathological limits and to find out the most discriminating morphometric parameter. Materials and methods. The pylorus of 84 asymptomatic infants was prospectively evaluated with respect to morphology (pyloric length, pyloric diameter, muscle thickness and pyloric volume) and function (gastric peristalsis and emptying, pyloric opening and the fluid passage). Results were compared with 85 patients with proven IHPS. Results. In every normal infant we observed frequent pyloric opening with passage of gastric contents and quick gastric emptying. All infants with proven IHPS presented with a permanently closed pylorus and exaggerated, retrograde gastric peristalsis. For each of the four parameters, highly significant differences (P < 0.0001) were found between the control and IHPS groups. Pathological limits were 3 mm for muscle thickness (accuracy 100 %), 15 mm for pyloric length (accuracy 94 %), 11 mm for pyloric diameter (accuracy 92 %) and 12 ml for pyloric volume (accuracy 96 %). Conclusions. Evaluation of pyloric function plays an important role in the diagnosis of IHPS. The morphometric parameters are highly accurate in differentiating IHPS from a normal pylorus, muscle thickness being the most discriminating parameter.

Diagnostik des vesikoureteralen Refluxes mit der echoverstärkten Miktionsurosonographie

ZusammenfassungEinleitung: Ziel der Arbeit war es, zu prüfen, ob die echoverstärkte Miktionsurosonographie (MUS) der Röntgen-Miktionszystourethrographie (MCU) in der Diagnostik des vesikoureteralen Refluxes (VUR) vergleichbar ist. Methodik: Eine echoverstärkte MUS und eine MCU wurden bei 114 Patienten nacheinander in der gleichen Sitzung zum Nachweis oder Ausschluß eines vesikoureteralen Refluxes (VUR) durchgeführt. Nach einer Sonographie des Harntrakts erfolgte die Füllung der Blase mit Kochsalzlösung und Levovist® (Schering AG, Berlin). Ein Reflux wurde diagnostiziert, wenn sich im Harnleiter oder Nierenbecken hyperechogene, flottierende Mikrobläschen darstellten. Ergebnisse: Es standen 226 Nieren-Harnleiter-Einheiten zur Analyse zur Verfügung. Ein Reflux wurde in 80 Einheiten diagnostiziert. Alle Refluxgrade kamen vor. In 15 Einheiten wurde in der MUS ein VUR diagnostiziert, aber nicht in der MCU. Das Gegenteil war in 3 Einheiten der Fall. Die echoverstärkte MUS hat damit im Vergleich zur Referenzmethode MCU eine hohe Sensitivität und Spezifität. Die lange Kontrastdauer von Levovist® ermöglicht überzeugende Bilder und eine hohe diagnostische Sicherheit. Schlußfolgerung: Die echoverstärkte MUS ist der MCU in der Diagnostik des VUR gleichwertig.SummaryAim: To ascertain the diagnostic efficacy of reflux sonography with the application of the echo-enhancing agent Levovist® in comparison with X-ray voiding cystourethrography (VCUG). Patients and methods: Echo-enhanced voiding urosonography (VUS) and VCUG were performed successively in one examination session in 114 children referred for the investigation of possible vesicoureteral reflux (VUR). After sonography of the urinary tract the bladder was filled with normal saline and Levovist® was administered. Reflux was diagnosed when hyperechogenic, floating microbubbles appeared in the ureters or renal pelvises. Results: A total of 226 kidney-ureter units were available for analysis. Reflux was diagnosed in 80 units. All grades of reflux were represented. In 15 kidney-ureter units VUR was diagnosed with echo-enhanced VUS but was not seen at VCUG. The contrary was true in 3 units. High sensitivity and specificity in comparison to the VCUG could be attributed to the echo-enhanced VUS. The long imaging window attainable with Levovist® makes the documentation of convincing images possible, contributing to the high diagnostic efficacy. Conclusion: Echo-enhanced VUS is comparable to VCUG in the diagnosis of reflux.

Eosinophilic gastroenteritis mimicking idiopathic hypertrophic pyloric stenosis

Abstract We report two infants with eosinophilic gastroenteritis (EG). This rare disease can mimic the clinical symptoms and US appearance of idiopathic hypertrophic pyloric stenosis (IHPS). US examination of the antropyloric region with a high-frequency linear transducer can assist in the differentiation of EG from IHPS, which is important because the therapeutic approaches are completely different. Eosinophilic gastroenteritis should be considered in the differential diagnosis of IHPS, especially when there has been an ineffective pyloromyotomy.

Sonomorphology and involution of the normal urachus in asymptomatic newborns.

Background. The number of reports on the sonomorphology of the urachus or urachal remnants in neonates and the pattern of involution is limited. Objective. To determine whether a sonographically visible urachus in the first months of life is a pathologic condition and whether postnatal involution can be demonstrated by ultrasound. Materials and methods. A total of 102 asymptomatic infants (premature and term newborns) were examined with a high-resolution 7.5-MHz linear transducer between 0 and 60 days of age. In 70 infants, a second examination followed 3–5 months later. Results. In all infants, the urachus could be identified on the first examination. Different morphological types were differentiated. There was no difference between premature and term newborns in the morphology of the urachus. Spontaneous involution of the urachus was observed in all infants receiving a second examination, and they most often showed a fusiform urachal remnant at the apex of the bladder. Conclusion. Involution of the urachus is not complete at birth and can be followed up sonographically in the first months of life. This knowledge should prompt a new strategy in young infants with a discharging umbilicus or even an infected urachus. Instead of early surgery, a conservative approach under sonographic control seems reasonable, because there is a chance of spontaneous involution and any abnormal development can be detected by ultrasound.