Evaluation of renal artery stenosis by magnetic resonance angiography

Accurate identification of patients with surgically correctable renovascular hypertension has been difficult by noninvasive means. Advances in the technique of magnetic resonance angiography (MRA) have begun to provide detailed, accurate imaging of the vascular system. This study reports our recent experience in the evaluation of the renal arteries by this technique.

MRA and contrast arteriography were performed in 32 arteries (16 adult patients) for evaluation of hypertension, abdominal aortic aneurysm, mesenteric vascular disease, and aorto-iliac occlusive disease. Luminal diameter reduction (%) was determined from two-dimensional time-of-flight (TOF) axial images. Contrast arteriography served as the gold standard for comparison.

Contrast arteriography revealed a 50% or greater stenosis in 11 of 32 vessels studied (34%). As a screening test for detection of greater than 50% diameter reduction, MRA had a sensitivity of 91%, a negative predictive value of 94%, and an overall accuracy of 81%. Linear regression analysis demonstrated significant correlation between MRA and arteriographic measurements (r = 0.8; P < 0.001).

This study demonstrates the ability of MRA to accurately assess the main renal arteries for the presence of critical stenosis. This noninvasive evaluation compares well with conventional angiography and may have increasing application in the screening of patients with suspected renovascular disease.