MR angiography of ruptured aneurysms in acute subarachnoid hemorrhage.

PURPOSE To determine the efficacy of high-resolution MR angiography for the prospective diagnosis of ruptured aneurysms in acute subarachnoid hemorrhage. METHODS We used 3-D time-of-flight MR angiography with a large image matrix (193 x 512 frequency-encoding steps), magnetization transfer saturation, and a variable flip-angle excitation (tilted optimized nonsaturating excitation [TONE]) to study 28 patients with acute subarachnoid hemorrhage. The MR angiograms were compared with intraarterial digital subtraction angiographic (IA-DSA) images. RESULTS Thirty-five (90%) of 39 aneurysms were detected prospectively with MR angiography. At least one aneurysm was identified with MR angiography in 25 (96%) of 26 patients with aneurysms proved by IA-DSA. Although four aneurysms were missed prospectively, three of these were detected retrospectively with MR angiography. Six aneurysms (18%) of those evident on MR angiograms were 3 mm or less in diameter. In one patient, additional targeted maximum intensity projections were greatly helpful for the ensuing IA-DSA by determining the optimial projection angle by which to depict a ruptured aneurysm that neither routine MR angiography nor routine IA-DSA detected. CONCLUSION High-resolution MR angiography may be a useful diagnostic technique for detecting ruptured aneurysms, even in patients with acute subarachnoid hemorrhage. Initial MR angiography offers valuable and reliable information on ruptured aneurysms in acute subarachnoid hemorrhage, allowing the optimization of projection angles at conventional angiography.