Histomorphological Changes after Renal X-Ray Arteriography Using Iodine and Gadolinium Contrast Media in an Ischemic Porcine Model.

Background: Gadolinium contrast media (Gd-CM) are regarded as non-nephrotoxic or considerably less nephrotoxic than iodine contrast media (I-CM), and have therefore come to be used as a substitute for I-CM in patients with renal insufficiency in a variety of radiographic examinations.

Purpose: To investigate renal histomorphological changes caused by Gd-CM in comparison with I-CM after renal X-ray arteriography in an ischemic porcine model, and to evaluate these changes in relation to the nephrotoxicity of the CM used.

Material and Methods: Test solutions: gadopentetate, gadodiamide, iohexol, gadobutrol, iopromide, iodixanol, mannitol, and saline. The experiments were performed on 152 animals. Each pig was randomized to receive one test solution injected into the balloon-occluded (10 min) right renal artery. The kidneys were evaluated histomorphologically. The severity of histomorphological changes was graded subjectively: 1 = minimal, 2 = mild, 3 = moderate, and 4 = marked.

Results: The main histological changes were 1) proximal tubular and glomerular necrosis, 2) hemorrhage/congestion of the cortex, medulla, and glomeruli, 3) proximal tubular vacuolation, and 4) protein-filled tubules in the cortex and medulla. Necrosis and hemorrhage/congestion were more frequent after injections with gadopentetate, mannitol solution iso-osmotic to gadopentetate, and gadobutrol compared to all other groups (P<0.001). The degree of necrosis and hemorrhage/congestion was related to the degree of impairment of renal function, but inversely related to vacuolation and tubular protein filling.

Conclusion: In ischemic porcine kidneys, the histomorphological changes caused by Gd-CM are similar to those caused by I-CM. Vacuolation appears to be independent of the osmolality and viscosity of the CM, and does not seem to be an indicator of renal impairment. “High-osmolal” Gd-CM are more nephrotoxic than “low- and iso-osmolal” I-CM when compared in equal volumes of concentrations, resulting in equal X-ray attenuation.