Angiomyolipoma (AML) are the most common benign solid renal mass. Differentiation from malignant tumours is essential. Imaging features in ultrasound may overlap between malignant lesions, especially between renal cell carcinoma (RCC) and AML. So far, sectional imaging has been necessary for reliable differentiation. The aim of this study is to evaluate the use of the ultrasound-guided attenuation parameter (UGAP), a recently established tool for assessing hepatic steatosis, in the differentiation of AMLs from other renal masses. Therefore, 27 patients with unknown solid renal masses were examined by ultrasound including UGAP. The attenuation was assessed qualitatively by attenuation map and quantitatively in comparison to the surrounding renal tissue. UGAP was applicable in 26/27 patients. Findings were compared with CT/MRI as the current imaging standard. A total of 18 AML and 9 other renal tumours were found. The diagnostic performance of B-Mode (hyperechogenic lesion) ultrasound was 77.8% in identifying AML. The diagnostic performance of the attenuation map showed a diagnostic performance of 92.6%, whereby UGAP measurements were successful in 76.9% of cases. Quantitatively, we found a significant difference (p < 0.034) in mean measured attenuation between AML (0.764 ± 0.162 dB/cm/MHz) vs. other renal tumours (0.658 ± 0.155 dB/cm/MHz). The best performance was found by a combined parameter of a hyperechogenic lesion with a positive attenuation map with an accuracy of 95.0%. In conclusion, UGAP may represent a possibility for differentiating solid renal lesions more accurately by ultrasound, especially classic hyperechoic AMLs from other renal lesions. Further studies are needed to increase the diagnostic reliability further.

Background/Objectives: Early graft loss within the first year is a rare complication of renal transplantations. In some cases, venous congestion may cause renal dysfunction, but, so far, this syndrome has been assessed by the presence of the triad of an unexplained decrease in renal function together with severe volume overload, relevant heart disease, and a typical histopathological pattern of tubular injury. This study aimed to determine the proportion of patients with early allograft loss due to venous congestion within the first year after transplantation. Additionally, we characterized typical renal vein flow profiles to identify patients at risk of early graft loss due to postrenal venous congestion and prerenal perfusion deficit. Methods: In this retrospective, single-center study, patients who underwent kidney transplantations between 2010 and 2020 and experienced early graft loss within the first year after transplantation were included. Clinical data and renal vein blood flow profiles were collected retrospectively. Results: A total of 579 patients received kidney transplants between 2010 and 2020. Of these, 43 patients (7.4%) lost their grafts within the first year of transplantation. Nine of these 43 patients (20.9% with early graft loss) lost their graft due to a suspected cardiorenal syndrome. Besides graft loss, cardiorenal patients had a significantly higher risk of death than other patients. All cardiorenal patients could be identified using a distinct renal vein blood flow profile (100%). Conclusions: We characterized the typical renal vein blood flow profiles in patients at risk of premature graft loss due to venous congestion. The early identification of such patients is crucial in improving outcomes after renal transplantation.