Detection of main renal artery stenosis using phase-contrast cine MR angiography

OBJECTIVE: The purpose of our study was to assess the ability of phase-contrast cine MR angiography to detect the presence of main renal artery stenosis. SUBJECTS AND METHODS: We prospectively evaluated 75 hypertensive patients form main renal artery stenosis using phase-contrast cine MR angiography. Each main renal artery was evaluated as normal or abnormal. Thirty-seven of the 75 patients underwent conventional arteriography or intraarterial digital subtraction arteriography; these results were compared with the MR angiographic interpretations. Only those patients who had confirmatory arteriography were included in the statistical analysis. RESULTS: Thirty-six main renal arteries interpreted as normal by MR angiography were found to be without a focal stenosis on invasive arteriography. MR angiography suggested 32 main renal artery stenoses; invasive arteriography showed 29 of these as stenoses. Three main renal arteries that were interpreted as having focal stenoses by MR angiography were shown to be not stenotic by invasive arteriography. Three other patients had diffusely narrowed main renal arteries bilaterally without a focal stenosis on MR angiography; bilateral proximal renal artery stenoses were seen at arteriography in two of these patients, and diffusely narrowed main renal arteries were seen in the third patient. Thus, the sensitivity of phase-contrast cine MR angiography for detecting a focal stenosis or abnormal main renal artery was 100% (95% confidence interval, 88-100%) and the specificity was 93% (95% confidence interval, 80-99%). The kappa coefficient was 0.85 with a standard error of 0.08. CONCLUSION: Phase-contrast cine MR angiography had a high degree of accuracy and a high negative predictive value in detecting the presence of main renal artery stenoses and may be a good screening technique for renovascular hypertension.