"Segmental" prolonged cortical nephrogram as a result of radiation damage to the kidneys.

We present two cases showing bilateral segmental delayed nephrograms secondary to radiation injury which occurred during radiation therapy for retroperitoneal adenopathy. The abnormal areas in the affected kidneys were not devoid of a nephrogram, but rather showed a persistent corticomedullary separation indicative of slowed perfusion. Linear margins not conforming to the normal renal lobular configuration were a confirmatory feature. Radiation injury should be included in the differential of both the asymmetric prolonged nephrogram and the "segmental" nephrogram.