Rim sign can be seen in major renal vascular compromise including:
- renal artery obstruction from embolism, thrombosis or dissection
- renal vein thrombosis
- acute tubular necrosis
At contrast-enhanced CT or MRI, a thin (1-3 mm) rim of subcapsular enhancement is seen paralleling the renal margin. This is considered to be as a result of preserved perfusion of the outer renal cortex by capsular perforating vessels. The finding may be partial or total depending on the level of vascular occlusion.