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Purpose: To determine the importance of MRI with contrast-enhanced MRA for the detection or exclusion of aberrant or obstructing renal arteries in ureteropelvic junction obstruction in children. Materials and Methods: Key word-based search in RIS database (ureteropelvic junction obstruction/ MRI) and retrospective comparison of arterial findings from preoperative contrast -enhanced MRA and intra-operative inspection. From 2007 to 2013, 19 children with ureteropelvic junction obstruction underwent contrast-enhanced MRA. Based on the results of the MRI scan and MAG3 scintigraphy, the children were referred to surgery (Anderson-Hynes-pyeloplasty). Results: An aberrant renal artery was diagnosed with MRI in 14 of 19 children, and intra-operative inspection confirmed 13 of those 14. In the remaining 5 children, no aberrant vessel could be observed in MRI and this was confirmed intra-operatively in 3 of the 5 cases, while in the remaining 2, an aberrant vessel was found. Of the 14 children with aberrant vessels, 12 underwent surgery due to assumed ureteral obstruction, which was confirmed by surgery in 11 cases. In one case, an aberrant artery was found intra-operatively, but obstruction could not be confirmed. In one of the 14 children, the vessel was found in MRI, but its obstructing character was negated via MRA, which was confirmed intra-operatively. In the diagnosis of aberrant and obstructing renal arteries, contrast-enhanced MRA presents 85 % sensitivity and 80 % specificity, with a positive predictive value of 0.8. Conclusion: MRI with contrast-enhanced MRA is suitable to detect aberrant and obstructing renal arteries. An obstructive effect of the aberrant vessel is to be assumed if the vessel has a close relationship to the ureteropelvic junction and if it is linearly stretched. Key Points: • MRI with contrast-enhanced MRA is a sure method for the detection of aberrant renal arteries in children with ureteropelvic junction obstruction • the obstructive effect of the aberrant vessel can be derived from the close proximity of the vessel to the ureteropelvic junction and from the streched course of the vessel Citation Format: • Ritter L, Gotz G, Sorge I et al. Significance of MR Angiography in the Diagnosis of Aberrant Renal Arteries as the Cause of Ureteropelvic Junction Obstruction in Children. Fortschr Rontgenstr 2015; 187: 42 – 48

PURPOSE: To evaluate the predictive value of MR imaging criteria, the biopsy Gleason score, and preoperative PSA levels for differentiating between T2 and T3 prostate carcinomas. MATERIALS AND METHODS: Endorectal MR images of 81 patients (median age: 65 years, range: 48 to 81 years) who had biopsy-proven prostate cancer and underwent a radical prostatectomy were analyzed retrospectively. The existence of different imaging features were recorded for each patient. A radiological analysis comprising all used imaging criteria was also performed for every patient. Optimal cut-off levels for the biopsy Gleason score and preoperative PSA levels were obtained using ROC analyses. Subsequently, a logistic regression analysis was performed to identify features which make a significant contribution to the prediction of the tumor stage. RESULTS: Histological examination showed that 24 patients (29.6 %) had a T3 tumor and 57 patients (70.4 %) had a T2 tumor. The mean preoperative PSA level was 9.4 ng/ml (+/- 7 ng/ml), and the median Gleason score was 6 with a range of 4 to 8. The radiological judgment comprising all imaging criteria led to a sensitivity of 54.2 % and specificity of 79 % for the detection of a T3 tumor. The obliteration of the rectoprostatic angle (regression coefficient B = 2.30; standard error (se) = 0.80; p = 0.002) and the biopsy Gleason score (B = 1.16; se = 0.3; p = 0.001) were the parameters with the highest independent predictive value for the diagnosis of an extracapsular tumor spread. The other radiological criteria and the preoperative PSA level were not statistically significant. A combination of the parameters "obliteration of the rectoprostatic angle" and "biopsy Gleason score" led to a sensitivity and specificity of 75 % and 79 %, respectively (existence of one parameter sufficient). The optimal cut-off value was a Gleason score of 7 for the differentiation between T2 and T3 prostate carcinomas. CONCLUSION: In our study, only the criteria "obliteration of the rectoprostatic angle" and "biopsy Gleason score" were of predictive value for the diagnosis of a T3 prostate carcinoma. The other MR imaging criteria and the preoperative PSA levels had no additional benefit.

PURPOSE To evaluate the diagnostic quality and minimum required dose to obtain acceptable images for diagnostic purposes in the field of musculoskeletal radiology. MATERIALS AND METHODS A critical comparison of the image quality produced by a novel flat panel detector and the conventional screen/film system using a contrast-detail phantom was performed in phase I. Images from both systems were obtained with the same dose and displayed with similar contrast and density. In phase II images of significant anatomical structures in cadaver extremities obtained using the digital detector system and the standard film/screen system were critically evaluated. After a successive reduction in the X-ray dose for 84 patients in phase III, eight independent radiologists compared the image quality of the screen/film system to that of the novel flat panel detector. RESULTS Phases I and II revealed a difference in the image quality achieved by the standard screen/film system and the digital detector system to the advantage of the digital detector system. In 77 of 84 patients (91.7 %), phase III showed equal image quality after a 50 % reduction in the X-ray dose. In 3 cases (3.6 %) the image quality and the level of contrast were better. No unified statement could be made for 4 patients (4.7 %). CONCLUSION Digital imaging of skeletal disorders using the novel flat panel detector makes it possible to reduce the X-ray dose by 50 % with equal or even better image quality.

Poster: "ECR 2013 / C-2392 / Adding the third dimension to high resolution MR-imaging of the inner ear: an answer waiting for a question" by: "N. N. N. Naguib, N.-E. A. Nour-Eldin, T. Lehnert, T. Gruber-Rouh, R. Hammerstingl, T. J. Vogl; Frankfurt a. Main/DE"

Aim Colour Doppler imaging (CDI) is a useful tool for non-invasive diagnosis and treatment of postcatheterisation lesions of the femoral artery. The aim of the present study was to evaluate success and limitations of the method in unselected patients. Material and methods A total of 29 patients, including 24 patients with pseudoaneurysms and 5 patients with arteriovenous fistulas, were treated by CDI-guided compression therapy. Results 17 of 24 (71%) pseudoaneurysms, but only 1 of 5 (20%) arteriovenous fistulas were successfully occluded. Successful treatment of pseudoaneurysms was limited by continuous anticoagulation and local pain during compression. However, arteriovenous fistulas, except one, could not be occluded due to high flow velocities in the shunt. Conclusion CDI-guided compression therapy is the treatment of choice for postcatheterisation pseudoaneurysms, while arteriovenous fistulas should be repaired surgically. If possible, anticoagulation therapy should be discontinued and analgesic drugs should be prescribed.

Ziele: Zur Bestimmung des Nutzens von MRT mit Kontrastmittel zur besseren Beurteilung des follow-up des Tumoransprechens nach Mikrowellenablation von pulmonalen Metastasen. Methode: Diese prospektive Studie beinhaltete 130 Ablationsitzung fur pulmonale Metastasen bei 80 Patienten. MRTs des Thorax mit Kontrastmittel wurden jeweils eine Woche vor der Ablation sowie 24 Stunden, 3, 6, 9 und 12 Monate nach der Ablation durchgefuhrt. In Dunnschicht-CT-Untersuchungen wurde das Lasionsvolumen im gleichen Zeitabstand zum Vergleich als zweite Kenngrose ausgemessen. Die Intensitat der Bildkontrastverstarkung der Lasion wurde jeweils beurteilt und im Verhaltnis zur Intensitat der Bildkontrastverstarkung der paraspinalen Muskeln auf gleicher Hohe erfasst (Lesion Muscle Signal ratio (LMS)). Die Korrelation zwischen dem Volumen der Lasion im post-Ablations-CT (follow-up) und des LMS im MRT mit Kontrastmittel zur gleichen Zeit wurde berechnet. Ergebnis: Das Praablationsvolumen der Tumore reichte von 0,26–5,29cm (Mittelwert 1,75cm3, Standardabweichung 1,59). Ein LMS ˂ 1 stand in Zusammenhang mit einer Reduktion des Tumorvolumens post-ablativ, wahrend ein LMS ˃ 1 auftrat: pra-ablativ infolge einer hohen Kontraststeigerung des Tumors, 24 Stunden nach der Ablation infolge einem entzundlichen Geschehen im Zusammenhang mit der Thermoablation und infolge einer Regresses oder Progresses des Tumors. Es lies sich eine leichte Korrelation zwischen dem der Anderung des LMS und des Volumens im CT nach 24 Stunden feststellen. Ein starker Zusammenhang bestand zwischen den Anderungen des LMS im follow-up nach 3 Monaten (SpearmanR:0,62, p=0,0021), 6 Monaten (SpearmanR:0,66, p=0,001), 9 Monaten (SpearmanR:0,61,p˂ 0,001) und 12 Monaten (SpearmanR:0,7,p˂ 0,00001). Schlussfolgerung: Das MRT mit Kontrastmittel als follow-up Untersuchung nach Mikrowellenablation von Lungentumoren kann, unter Einsatz des LMS ratio als Kenngrose, effektiv genutzt werden um das Tumoransprechen zu bewerten. Keywords: MRT, Thorax, Mikrowelle, Ablation Korrespondierender Autor: Nour-Eldin Mohammed N Johann Wolfgang Goethe Universitatsklinikum, Institut fur diagnostische und interventionelle Radiologie, Theodor-Stern-Kai 7, 60590 Frankfurt am Main E-Mail: nour410@hotmail.com