Duplex evaluation of distal renal artery to predict the presence of proximal significative acceleration: An experience of 2,200 explorations

Purpose: Detection of renal artery stenosis (RAS) (diameter reduction ≥60%) by means of duplex Doppler ultrasound with direct scanning of the main renal arteries is subject to numerous limitations. The aim of this study was to determine the accuracy of indirect hemadynamic parameters obtained by evaluation of the segmental or interlobal arteries within the kidney as predictors of the presence of hemodynamically significative proximal renal artery stenosis.

Material and methods: We performed a retrospective analysis of all consecutively studied patients at our center with suspected RAS. Direct hemodynamical measures (renal peak systolic velocity-RPSV- and end diastolic velocity-EDV-) determined in the proximal an middle segments of the main renal artery where measured with the association of four indirect doppler parameters obtained in the renal hilium (Resistive Index- RI-Acceleration Inde – AI-, Systolic Acceleration Time – AT- and Pulsatility Index – PI-). The population was classified by the presence or absence of direct hemodynamical criteria of RAS (RPSV ≥200 cm/s) and the distal indirect parameters were compared in these two populations.

Results: A total of 2200 explorations in 1419 patients were analyzed. A predictive binary logistic regression model was developed in order to determine the accuracy of distal indirect parameters to predict the presence of a proximal significative RPSV. The Area Under the Curve of the Receiver Operating Characteristic analysis of the predictive model was 0.84 (95% Confidence Interval [CI] 0.703 – 0.924), indicating good discrimination power between those with and without significative proximal values of RPSV. Only PI (Prevalence Odds Ratio [POR] 4,109 95% CI 1.74 – 9,695) and AT (POR 1,031 95% CI 1,021 – 1,041) were significatively associated with highest RPSV.

Conclusion: These results suggest that distal indirect hemodynamic parameters PI and TA could provide good diagnostic accuracy in the prediction of proximal significative RPSV values, being useful when main-vessel velocities cannot be determined reliably.