MR Angiography in the Preoperative Evaluation of Abdominal Aortic Aneurysms: A Preliminary Study

The ability of magnetic resonance (MR) angiography to depict visceral and renal vessels was evaluated in patients with abdominal aortic aneurysms (AAAs). MR sequences (sagittal Tl-weighted, two-dimensional coronal, and three-dimensional axial time-of-flight) were compared in a prospective blinded fashion with conventional angiograms obtained preoperatively in 23 patients with AAAs. Results were correlated with surgical findings when available. Operative aortic clamp site was correctly predicted with conventional angiography in 95% of patients and with MR angiography in 86% ( P > .1). Aneurysm neck measurements obtained with the two modalities were within 1 cm in 91% of cases. With conventional angiography as the standard of reference, 96% of all renal arteries were identified on MR angiograms but 36% of accessory arteries were missed. MR angiography enabled identification of patients who had at least one renal artery stenosis greater than 50% with a sensitivity of 100% and specificity of 89%. For identifying individual renal artery, celiac artery, and superior mesenteric artery stenoses of similar severity, the sensitivity and specificity were 67% and in excess of 96%, respectively. The celiac artery could not be evaluated in one case. The results of this small study suggest that the role of MR angiography in the preoperative evaluation of AAA warrants further investigation.