PURPOSE: To evaluate the efficacy of power Doppler ultrasonography (PDUS) in depicting renal infarction inrabbits during experimental renal segmental arterial occlusion, and to compare the results with those of CTscanning. MATERIALS AND METHODS: In 28 rabbits weighing 2.5-4kg, the segmental renal artery was occluded throughthe left main renal artery by embolization with Ivalon (Nycomed, Paris, France). Power Doppler ultrasonography andspiral CT scanning were performed before and at 2, 5, 8, 15, and 24 hours, and 3 and 7 days after occlusion of thesegmental renal artery. The location of infarcted areas and collaterals, as seen on PDUS and CT scans, wasevaluated by two radiologists. RESULTS: In all cases, as seen on power Doppler ultrasonography, infaretedareas-when compared with normal parenchyma, clearly demonstrated wedge-shaped perfusion defects in the kidney. Thelocation of the lesion closely corresponded to the location seen during CT scanning. After renal arterialocclusion, transiently congested capsular arteries, which were named 'capsular sign', were seen in 63% ofrabbits in the two and five-hour groups. No significant cortical rim sign was demonstrated on power Dopplerultrasonography, though it was noted on spiral CT at 15 and 24 hours, and 3 and 7 days after renal arterialocclusion. CONCLUSION: Power Doppler ultrasonography was useful for the diagnosis of renal infarction. Congestedcapsular artery seen in the early stage of renal infarction might be a characteristic finding of this condition,as seen on power Doppler ultrasonography.