Contrast-Enhanced MR Angiography at 3T in the Evaluation of Intracranial Aneurysms: A Comparison with Time-of-Flight MR Angiography

A, Coronal MIP projection from contrast-enhanced MRA shows the supra-aortic arteries with voxel dimensions of 0.7 × 0.6 × 0.8 during 20 seconds. B, Sagittal and axial MIPs from contrast-enhanced MRA (upper row) and TOF-MRA (lower row) show a 20 × 16 mm aneurysm arising from the basilar artery tip. Note the only portion of the aneurysm sac that is visualized on the TOF-MRA study is the superior portion (inflow zone) of the dome (arrows). The loss of signal intensity and incomplete enhancement of the aneurysm sac at TOF-MRA make the full sac size and geometry difficult to perceive.

Coronal oblique MIP and volume-rendered projections from contrast-enhanced MRA (upper row) and TOF-MRA (lower row) show a large (16 × 12 mm) aneurysm arising from the cavernous portion of the right internal carotid artery. Note loss of signal intensity and incomplete flow-related enhancement of the aneurysm sac at TOF-MRA, which limits definition of the border of the aneurysm.