ABILITY OF A PHASE-SHIFT US CONTRAST AGENT TO IMPROVE IMAGING OF THE MAIN RENAL-ARTERIES

PURPOSE: To evaluate the ability of a phase shift contrast agent to im prove Doppler sonographic imaging of the main renal arteries in cases of suspected renal artery stenosis. MATERIALS AND METHODS: In 25 patie nts in whom renal artery stenosis was suspected, baseline Doppler sono graphy was performed followed by two studies performed after blinded a dministration of contrast material or placebo (saline). Each kidney (n = 45) was evaluated for (n) visualization of the main renal artery on a scale of 0-4, (b) presence of accessory renal arteries, and (c) dir ect Doppler sonographic findings suggestive of renal artery stenosis. Correlative magnetic resonance angiography was performed in 24 patient s, and angiograms were obtained in eight kidneys with stenosis at one or both imaging studies. RESULTS: Contrast enhancement was observed in 23 patients. Enhancement was 8-20 minutes. Renal artery visualization scores improved from a mean of 2.56 and 2.71 on baseline and noncontr ast scans, respectively, to 3.69 after administration of contrast mate rial. Contrast-enhanced images depicted seven kidneys with accessory r enal arteries not seen at other studies. Two of eight cases of stenosi s were seen only with contrast-enhanced sonography. CONCLUSION: Use of the phase shift contrast agent appears to enable a reduction in the n umber of equivocal findings of renal artery stenosis.