Acute tubular necrosis: use of gadolinium-DTPA and fast MR imaging to evaluate renal function in the rabbit

Sequential fast magnetic resonance (MR) images (repetition time = 33 ms, echo time = 7 ms, alpha = 22 degrees, one image every 12 s) were acquired using gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) (10 or 100 mumol/kg) to study perfusion and concentrating ability in normal rabbit kidneys and in kidneys with HgCl2-induced acute tubular necrosis (ATN). In normal rabbits receiving 100 mumol Gd-DTPA/kg a concentric region of decreased MR signal was observed. In sequential images the dark ring pattern migrated centripetally through the kidney moving from the corticomedullary junction to the inner medulla. The decrease in MR signal intensity occurred as a consequence of T2 relaxation (magnetic susceptibility) due to high concentration of Gd-DTPA within the tubules. This suggests that the dark ring pattern may serve as a qualitative feature indicative of the ability of the kidneys to concentrate. With the onset of HgCl2-induced ATN the pattern of enhancement due to Gd-DTPA administration changed markedly. Although the kidneys with ATN did continue to be perfused, the concentric dark ring pattern seen in normal kidneys receiving 100 mumol Gd-DTPA/kg was not observed. These results suggest that Gd-DTPA and fast imaging MR may provide a method of assessing perfusion and concentrating ability within the healthy or diseased kidney.