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[Visualization of renal arteries and value of color-coded duplex sonography in renal artery stenoses using an ultrasound signal enhancing agent].

PURPOSE
To assess whether the use of an echo-enhancing agent reliably allows the diagnosis of renal artery stenosis with colour-coded Doppler sonography.


MATERIALS AND METHODS
We examined the main, segmental, and, if present, the accessory renal arteries of 31 patients before and after intravenous injection of Levovist using colour-coded Doppler sonography and compared the results with digital subtraction angiography. A rise in peak systolic velocity in the main renal artery and a reduction of the acceleration index in segmental arteries were used as parameters to detect renal artery stenosis.


RESULTS
After i.v. administration of Levovist the main stem of the renal arteries could be well delineated in 36 of 62 cases (58%) during colour-coded Doppler sonography against 31 cases without Levovist. Taking only the visible cases in account the sensitivity of native as well as of enhanced colour-coded Doppler sonography of the renal main stem was 100%, the specificity was 96% and 94%, respectively. Only one of 11 accessory renal arteries was identified after echo enhancement. The segmental arteries were seen only after echo enhancement in 12 cases so that 60 of the total of 62 renal arteries (95%) could be evaluated. The sensitivity and specificity of the native examination were 67% and 70%. After echo enhancement sensitivity was 75% and specificity was 81%.


CONCLUSION
Using an echo-enhancing agent the sensitivity and specificity for detection of relevant renal artery stenosis could only be slightly improved compared to the native examination.