Renal artery duplex ultrasonography as a screening and surveillance tool to detect renal artery stenosis: a comparison with current reference standard imaging.

OBJECTIVE

Digital subtraction angiography quantitative vessel analysis (QVA) to assess percent renal arterial stenosis (RAS) is the reference standard. Quantitative vessel analysis is not ideal for screening purposes. Renal artery duplex ultrasonography (RADUS) is a noninvasive method to screen for RAS using well-known parameters. We investigated the direct correlation between several RADUS parameters and QVA to evaluate the acceptability of RADUS as a RAS screening and surveillance tool.

METHODS

We performed a multicenter retrospective study. Stenoses were evaluated in all patients with arteriograms and RADUS examinations within 30 days of each other in the span of 1 year. Percent stenosis of each stenotic renal artery segment was calculated digitally with QVA and correlated with the corresponding peak systolic velocity (PSV) and renal-aortic ratio (RAR) obtained with RADUS. Descriptive statistics and receiver operating characteristic curves were calculated. Correlation of percent stenosis, PSV, and RAR was performed. Sensitivity, specificity, and accuracy of diagnostic cut points for each RADUS parameter were calculated.

RESULTS

Sixty-seven renal arteries were included. Thirty-three arteries had less than 60% stenosis; 34 had stenosis of 60% or greater. The mean values were PSV, 272.791 cm/s; RAR, 3.716; and angiographic percent stenosis, 51.731%. Receiver operating characteristic curves showed higher accuracy for RAR with stenoses of 60% or greater versus PSV.

CONCLUSIONS

Renal artery duplex ultrasonographic parameters for 60% or greater RAS correlate well with QVA. For detecting stenosis of 60% or greater, RAR is the most accurate parameter at a threshold of 2.5. Renal-aortic ratio is more accurate than PSV. Peak systolic velocity may be a useful RADUS alternative parameter for hemodynamically important stenoses in the setting of aortic disease when aortic velocities are less than 40 or greater than 100 cm/s.