Utility of intrarenal Doppler ultrasound in the diagnosis of renal artery stenosis

Purpose: To determine the utility of intrarenal Doppler parameters and waveform analysis in a hypertensive population screened for renal artery stenosis (RAS). Materials and methods: Sixty five patients were studied (122 kidneys) with intrarenal Doppler sonography. Doppler waveforms of three different areas from each kidney were obtained (superior, middle and inferior level). Waveform morphology, acceleration time (AT), acceleration (Ac) and resistive index (RI) were evaluated in each kidney, comparing retrospectively the Doppler findings with the angiographic results. Results: Arteriography demonstrated 33 (27.2%) renal arteries with stenosis (18 with RAS>75%). Statistically significant differences for AT and Ac were found among the patients with RAS>75% and the other groups (P<0.01). An AT>80 ms and an Ac≤1 m/s2 showed a sensitivity of 89% and a specificity of 99%, for the diagnosis of RAS>75%. Better results were obtained in patients less than 50 years old (100% of sensitivity and specificity). The morphologic analysis of the Doppler waveform had poor results but the detection of a waveform grade 0 had a high specificity (98%). An additional comparison of both kidneys didn't improve the results. Conclusion: Intrarenal Doppler waveform analysis using quantitative measurements (AT and Ac) is an adequate technique for the diagnosis of severe RAS in previously selected patients, especially in younger patients (<50 years)