Duplex ultrasound as first-line screening test for patients suspected of renal artery stenosis: prospective evaluation in high-risk group.
Our objective was to assess how far the progress in ultrasound devices has increased feasibility and accuracy of Duplex ultrasound (DUS) for the diagnosis of renal artery stenosis (RAS), in a population with high prevalence of atherosclerotic renovascular lesions. Ninety-one hypertensive patients with atherosclerotic disease were prospectively evaluated by both DUS and digital subtraction angiography (DSA) of the renal arteries. Only proximal criteria (peak systolic velocity >180 mm/s or renal-to-aortic ratio >3.5) were used for the diagnosis of significant RAS (>60% narrowing). For both techniques, two readers were involved for interobserver variability study. Two hundred one arteries were demonstrated by DSA on 182 available kidneys. The prevalence of RAS among the study group was 37%. Sixteen of the 19 accessory arteries were not seen at DUS; in 8 patients, one renal artery was not seen at DUS (feasibility 91%). On the 177 arteries assessed, in comparison with DSA, DUS yielded 96, 91, and 97% mean values of accuracy, sensitivity, and specificity, respectively. Kappa for interobserver agreement was 0.95 for DUS and 0.92 for DSA. Although still unreliable for the detection of accessory arteries, DUS is in our experience an accurate and reproducible diagnostic test for RAS.