PURPOSE: To assess the usefulness of diffusion-weighted imaging(DWI) in evaluating serial parenchymal changesin renal infarction induced by renal artery ligation, by comparing this with the conventional spin echo techniqueand correlating the results with the histopathological findings. MATERIALS AND METHODS: In 22 rabbits, renalinfarction was induced by ligation of the renal artery. Spin-echo T1-weighted imaging(T1WI), turbo spin-echo(TSE)T2-weighted imaging(T2WI), and DWI were performed, using a 1.5-T superconductive unit, at 30 minutes, 1 hour, 2,3, 6, 12 and 24 hours, and 2, 3, 7 and 20 days after left renal artery ligation. Changes in signal intensity onT1WI, T2WI, and DWI were correlated with histopathologic findings. RESULTS: On MR images obtained 30 minutesafter ligation, the signal intensity of affected kidney was not significantly different from that of contralateralkidney, as seen on T1WI and T2WI, but was noticeably higher on DWI. On T2WI, the signal intensity ratio(SIR) wasslightly higher over time from 30 minutes to 2 days after ligation, and then decreased slightly. The SIR on DWIincreased abruptly at 30 minutes, remained high until 12 hours, and then fell, returning to close to the normalrange at between 2 and 3 days. It fell further, below the normal range, until 20 days after ligation. The mainhistopathologic findings after ligation were congestion and swelling of renal tubules (1-6 hours after ligation),degeneration and necrosis of renal tubules (12 hours - 2 days), coagulation necrosis of renal tubules(3 days),collection of cellular debris between renal tubules (7 days), and proliferation of fibroblast between renaltubules (20 days). CONCLUSION: Diffusion-weighted imaging is useful for the detection of hyperacute renalinfarction, and the apparent diffusion coefficient may provide additional information concerning its evolution.