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Case Presentation A patient with a history of liver transplantation was referred for ultrasound due to an acute on chronic renal insufficiency. Color Doppler ultrasound demonstrated dilated tortuous blood vessels in the upper pole of the left kidney with pulsatile arterialized flow in the segmental draining vein, suggesting an anomalous renal arteriovenous communication. In the adjacent renal cortex, a rounded structure with highly turbulent flow was noted in connection with this arteriovenous fistula (Figure 1). Computed tomography (CT) angiography confirmed a renal arteriovenous fistula with an associated pseudoaneurysm (asterisk on Figure 2a) and early opacification of the left renal vein (Figures 2b and 3). The arteriovenous fistula was probably iatrogenic as it was not seen on the ultrasound at the time of renal biopsy a few years earlier. Comment Renal arteriovenous (AV) shunts, a rare pathologic condition, are divided into two categories, traumatic and nontraumatic, and can cause massive hematuria, retroperitoneal hemorrhage, pain and high-output heart failure. Traumatic renal AV shunts are caused by penetrating or blunt trauma, percutaneous or open biopsy, or surgery. The most common cause of traumatic renal AV shunts is iatrogenic injury, especially percutaneous renal biopsy. Several studies reported incidences of 7.4%-11% after renal biopsy. A majority of traumatic renal AV shunts due to renal biopsy are asymptomatic and resolve spontaneously within two years, but some can be symptomatic and require interventional treatment. They are usually solitary, involving a single direct communication between the renal artery and adjacent vein, so-called traumatic AV fistulas. Pseudoaneurysms occasionally coexist with traumatic renal AV shunts. Color Doppler US is useful for screening for renal AV shunts, especially following renal biopsy, because of its convenience and minimally invasive

e16535 Background: Muscle invasive bladder cancer (MIBC) is a life-threatening disease. Treatment is multimodal combining neo-adjuvant cisplatin-based chemotherapy (NAC) and radical cystectomy (RC). Accurately predicting complete pathologic response (pCR) using multiparametric MRI (mpMRI) could impact peri-operatively treatment. Methods: MIBC patients receiving NAC were evaluated at our institution with mpMRI before, after 2 cycles and after 4 cycles of dose dense MVAC (ddMVAC). Response after 4 cycles was retrospectively assessed using the method earlier described by Necchi et al with blinding of the readers for the pathological result of RC. Two radiologists independently evaluated 3 questions: residual disease at T1/T2-weighted images, presence of spots of restrictive diffusion within the bladder wall on diffusion-weighted imaging, and presence of focal contrast enhancement in the bladder wall on dynamic contrast enhanced images. Radiographic complete response (rCR) was defined as “No” on all three questions. Results: A total of 46 patients were identified having received ddMVAC for urothelial MIBC. Six patients did not undergo RC after NAC and were excluded from this analysis. Eleven out of 40 (28%) patients showed a complete pathologic response (ypT0). Baseline characteristics were similar compared to non-complete pathologic responders ( > ypT0), with the exception of hydronephrosis (9% in ypT0 vs. 52% in > ypT0). mpMRI questions could be assessed in 37 of 40 patients (93%). rCR was seen in 5 patients and was significantly associated with pCR (1-sided p value 0.021). Although sensitivity was low (36%), specificity was very high (96%) of this 3-step assessment. Positive likelihood ratio was 9.45, negative likelihood ratio 0.66. Concordance of assessment was very high. Conclusions: Using the 3-step imaging approach of Necchi et al, mpMRI can predict pCR after neo-adjuvant cisplatin-based chemotherapy with high specificity but low sensitivity. mpMRI should be included in future trials of multimodal management of MIBC and is an important predictive asset in routine clinical management.[Table: see text]