A validation study on the intraobserver and interobserver reproducibility of renal artery duplex ultrasound.

Aim of the present study was to evaluate intraobserver and interobserver reproducibility of direct renal artery Doppler velocimetry. Healthy volunteers were evaluated by one examiner on three separate occasions and by three different examiners in a single day. Peak systolic velocities of the aorta (PSV.Ao) and proximal renal arteries (PSV.RA) were taken at an optimal angle below 60 degrees. The renal-to-aortic ratio (RAR) was calculated dividing PSV.RA by PSV.Ao. Mean values +/- 2 SD were 85 +/- 34 (49-150) cm/s for the PSV.RA, 38 +/- 20 (0-60 degrees) for the Doppler angle of insonation, 102 +/- 37 (63-153) cm/s for the PSV.Ao, and 0.85 +/- 0.41 (0.49-1.58) for the RAR. Correlation coefficients and coefficient of variation were 0.64-0.82/7.8%-10.1% (PSV.RA), 0.75-0.82/9.9%-13.8% (RAR) for intraobserver evaluations; and 0.79-0.80/7.7%-12.5% (PSV-RA), 0.65-0.78/9.5%-12.3% (RAR) for interobserver evaluations. Reliable results of direct renal artery Doppler velocimetry confirm clinical applicability and suitability for repeated measurements after catheter-based interventions or surveillance of low-grade stenoses.