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Renal artery stenosis: evaluation with colour duplex ultrasonography
J Riehl1, H Schmitt, D Bongartz
1Department of Internal Medicine II, Technical University of Aachen, Germany.
Summary
Duplex Doppler ultrasound of intrarenal arteries effectively detects renal artery stenosis (RAS) using resistive index (RI) and delta RI. This non-invasive method offers high sensitivity and specificity for diagnosing hemodynamically significant RAS.
Area of Science:
- Cardiovascular Medicine
- Diagnostic Imaging
- Nephrology
Background:
- Direct renal artery scanning via duplex Doppler ultrasound has limitations for detecting renal artery stenosis (RAS).
- Intrarenal Doppler curve analysis offers a semiquantitative approach to detect RAS, overcoming direct scanning challenges.
Purpose of the Study:
- To evaluate the efficacy of colour duplex ultrasonography (US) in detecting hemodynamically effective renal artery stenosis (RAS).
- To compare Doppler-derived indices with angiography, the gold standard for RAS diagnosis.
Main Methods:
- 214 patients with severe arterial hypertension underwent renal angiography and intrarenal colour duplex US.
- Resistive index (RI) and side-to-side differences in RI (delta RI) of interlobar arteries were calculated.
- Angiography defined RAS as >70% diameter reduction; Doppler results were correlated with angiography findings.
Main Results:
- Angiography identified 59 RAS in 53 patients.
- Significant differences in RI (0.48 vs 0.63) and delta RI (24.4% vs 3.6%) were observed between kidneys with and without RAS (P < 0.001).
- Combined RI and delta RI thresholds achieved 92.5% sensitivity and 95.7% specificity for detecting effective RAS.
Conclusions:
- Colour duplex US with RI and delta RI calculation is a valuable non-invasive test for assessing RAS hemodynamic effects.
- The Doppler technique is safe, cost-effective, and suitable for screening renovascular disease.