Application of simple ultrasound Doppler hemodynamic parameters in the diagnosis of severe renal artery stenosis in routine clinical practice.

Background: Doppler ultrasound (DUS) is recommended in first-line imaging for the diagnosis of renal artery stenosis (RAS). However, the correct selection of Doppler direct or indirect parameters and their optimal thresholds remain controversial. This study explored simple ultrasound Doppler parameters to diagnose severe RAS (RAS ≥70%) in routine clinical practice. Methods: In this retrospective study, patients with clinically suspected renovascular hypertension who first underwent renal artery DUS and contrast-enhanced ultrasound (CEUS) and subsequent digital subtraction angiography (DSA) or computed tomography angiography (CTA) were consecutively included. Clinical characteristics and ultrasound Doppler hemodynamic parameters were collected, including peak systolic velocity (PSV), the ratio of the peak velocities in the renal artery and the aorta (RAR), the ratio of the peak velocities in the renal artery and the segmental artery (RSR), and the ratio of the peak velocities in the renal artery and the interlobar artery (RIR). All enrolled patients were divided into two groups based on the degree of diameter reduction: a severe stenosis group (diameter reduction ≥70%) and a non-severe stenosis group (diameter reduction <70%). Logistic regression analysis was performed to determine the independent predictors for severe stenosis. Receiver operating characteristic curves and areas under the curve were used to evaluate the diagnostic performance of the ultrasound Doppler parameters. Results: A total of 85 patients (106 renal arteries) with RAS were included in this study. The optimal thresholds of PSV in the main renal artery and the PSV ratios for diagnosing severe RAS obtained via receiver operating characteristic curves were 249.5 cm/s for PSV, 2.94 for RAR, 5.1 for RSR, and 7.5 for RIR. The areas under the curve of PSV and the ratios all exhibited good diagnostic efficiency (all >0.8). The combination of these four Doppler variables demonstrated a significant benefit to the overall diagnostic value compared with any factor alone [area under the curve (AUC) =0.962; 95% confidence interval (CI): 0.906-0.989; P<0.05]. The combination of PSV and RSR (AUC =0.925; 95% CI: 0.858-0.967) exhibited comparable diagnostic efficiency to the combination of four ultrasonographic variables (z statistic =1.882; P=0.06). Conclusions: This simple and accurate method to evaluate severe RAS based on the velocity obtained via basic DUS may facilitate the detection of severe RAS in the majority of medical institutions and provide a reliable basis for the selection of proper candidates for further angiography or revascularization.