Intracranial vertebrobasilar system: MR angiography

To determine the reliability of magnetic resonance (MR) angiography in depicting normal vascular anatomy and its usefulness in detecting vascular disease compared with those of digital subtraction angiography (DSA).

Sixty patients with symptoms referable to disease of the vertebrobasilar system were examined with MR angiography and DSA.

In patients with normal DSA results, all vertebral arteries (VAs) and basilar arteries (BAs) were also visualized with MR angiography. MR angiography demonstrated 117 of 120 superior cerebellar arteries and 80 of 90 posterior inferior cerebellar arteries but only 30 of 58 anterior inferior cerebellar arteries. MR angiography demonstrated disease of the VAs and BAs with 100% sensitivity. Stenoses were differentiated from occlusions in all cases. However, the degree of stenosis was overestimated in 63% of patients. In six patients with occlusive disease, collateral flow was correctly analyzed with selective saturation.

Despite its limitations, MR angiography is a clinically important noninvasive technique for screening patients for macroangiopathy of the posterior arterial supply to the brain.