Computed tomography of renal emergencies: A comprehensive diagnostic guide for radiology residents

Figure 4 Grade IV renal injury. A: Axial computed tomography of the abdomen in corticomedullary phase demonstrating renal hilar injury with diffuse hypoattenuating fluid collection in the hilum, concerning for collecting system involvement (white arrow); B: On delayed phase imaging, note the contrast extravasation from the renal collecting system into the hypoattenuating collection consistent with urine extravasation (white arrow). These findings correspond to grade IV renal injury.