From the case: Retroperitoneal fibrosis
Axial C+ via nephrostomy catheters
Contrast administered using the nephrostomy catheters (no intravenous contrast due to impaired renal function). There is a mass surrounding, but not displacing, the abdominal aorta and part of the inferior vena cava. At the location of the mass there is ureteral stenosis on the right and occlusion of the left ureter.