USPIO-ENHANCED MR-IMAGING OF GLYCEROL-INDUCED ACUTE-RENAL-FAILURE IN THE RABBIT

Enhanced-MR imaging in combination with ultrasmall superparamagnetic i ron oxide (USPIO) was used in the glycerol-induced model of acute rena l failure (ARF) in the rabbit to detect renal perfusion abnormalities. A control group (n = 5) and an ARF group (n = 5) were studied after i ntramuscular injection of glycerol (10 ml/kg) with T-2-weighted spin-e cho sequence at 1.5 T and a 27 mu mol/kg IV dose of iron. The signal i ntensity (SI) was quantified in the cortex, the outer medulla (OM), an d the inner medulla (IM). In control rabbits, the maximum SI decrease after USPIO injection was in the OM (76% +/- 3.6), as this is the regi on of maximal vascular density, then in the IM (73.4% +/- 2.9). In the glycerol group, SI loss in the OM (61% +/- 12.6) and the IM (45.2% +/ - 16.24) was significant less than in the control group (p < .05). Pat hology results showed fibrinous thrombus in the efferent arterioles an d congestive aspect of the vasa recta in the medulla. We argue that a reduced medullary concentration of USPIO in the renal failure group is indicative of medullary hypoperfusion.