Paul G J, Stephenson T F
Radiology. 1977 Feb;122(2):338. doi: 10.1148/122.2.338.
The authors describe a case of unilateral renal artery occlusion in which a thin, dense rim was seen on infusion pyelography with subsequent marked atrophy of the kidney. This "cortical rim sign" appears to be due to collateral blood supply from the renal capsule, preserving a thin rim of viable cortex.
