Unilateral acute renal cortical necrosis: correlative imaging.

Bilateral acute cortical necrosis is a rare form of acute renal failure characterized by necrosis of the renal cortex and sparing of the medulla. Little information on the imaging presentation of bilateral acute renal cortical necrosis is available. The enhanced CT appearance is pathognomonic and diagnostic. The unilateral presentation of acute cortical necrosis is extremely rare, and no imaging methods have been described. The authors chose to apply scintigraphic evaluation to this unique condition complementary to CT to confirm the diagnosis. Mercaptoacetylglycine (T3) was selected to assess tubular damage, in contrast to the pure glomerular agent DTPA. Evidence of some tubular function and clear delineation of the shrunken kidney was found. Conversely, in the DTPA study the kidney was not visualized. A DMSA scan was performed for assessment of viability of the renal cortex and showed a photopenic halo around the small area of the viable cortex of the upper pole. The halo sign represents a cortical loss. The visualization of the upper pole as evidence of cortical viability as a consequence of collateral blood flow from capsular vessels was seen on angiography. Radiographic and scintigraphic correlation of this rare condition may be an effective means to confirm the diagnosis and to establish the extent of involvement. However, contrast CT remains the preferred method in the diagnosis of acute cortical necrosis.