Colour Doppler ultrasound: a new index improves the diagnosis of renal artery stenosis.

The description of a new index, the renal-segmental ratio (RSR), and the comparison of its performance with other conventional Doppler parameters for the detection of renal artery stenosis (RAS). A total of 96 renal units were studied with angiography and colour Doppler ultrasound (US) independently. The Doppler parameters applied were: 1. renal artery peak systolic velocity (RE-PSV), 2. renal-aortic ratio (RAR), 3. early systolic acceleration (ESA), and 4. renal-segmental ratio (RSR). The angiographic study was used as the "gold standard" for the identification of > or = 50% RAS. The results indicate that RSR (sensitivity: 93.33%, specificity: 89.47%) and RE-PSV (sensitivity: 83.33%, specificity: 89.47%) were the best criteria for RAS diagnosis (p values <0.05). The results show that colour Doppler US is a reliable diagnostic modality for RAS diagnosis. The new index (RSR) improves the effectiveness of the method.