“Segmental” prolonged cortical nephrogram as a result of radiation damage to the kidneys

Abstract

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.

FDG PET/CT Appearance of Radiation Nephritis

“…CT findings of radiation-induced changes in the kidneys have also been described. 3,[7][8][9] While the irradiated renal tissue shows low attenuation during the early nephrogram phase as noted in our case and those reported in the literature, 3 the delayed ceCT demonstrated persistent nephrogram in the irradiated regions with clearance of contrast from nonirradiated regions. 7,9 This persistent nephrogram resembles iFDG and the increased 99m Tc-MDP activity at 1 to 3 hours after injection.…”

“…3,[7][8][9] While the irradiated renal tissue shows low attenuation during the early nephrogram phase as noted in our case and those reported in the literature, 3 the delayed ceCT demonstrated persistent nephrogram in the irradiated regions with clearance of contrast from nonirradiated regions. 7,9 This persistent nephrogram resembles iFDG and the increased 99m Tc-MDP activity at 1 to 3 hours after injection. Given the similarities, it is conceivable that the accumulation of 99m Tc-MDP, FDG, and CT contrast in the irradiated region during the delayed phase may share a common mechanism, that is, delayed excretion from injured renal tissue as also suggested by some of these authors, 4,5 while there may be additional mechanisms for different compounds.…”