MAGNETIC-RESONANCE-IMAGING STUDY OF INTRACRANIAL VERTEBROBASILAR ARTERY DISSECTIONS

Background and Purpose The purpose of this study is to demonstrate the magnetic resonance features of intracranial vertebrobasilar artery di ssections and to determine the potential and limitations of magnetic r esonance imaging in their diagnosis. Methods We studied five consecuti ve patients with angiographically verified intracranial vertebrobasila r artery dissection with magnetic resonance imaging (0.5 T) in regard to the shapes of the intramural hematoma and the chronological change of its signal intensity. We also estimated the sensitivity of magnetic resonance imaging for diagnosing dissection. Results We observed intr amural hematoma in four patients on the first magnetic resonance scan and in all five patients during the course of the study. The shapes of the intramural hematomas were curvilinear, crescentic, ''bamboo-cut,' ' ''band-like,'' and spotty. The intensity of the intramural hematoma varied according to its age. On the T-1-weighted and the proton images , the intramural hematomas appeared isointense to slightly hyperintens e in the first few days and became hyperintense thereafter. The intram ural hematomas became isointense or unrecognizable 2 months after onse t. The T-1-weighted image and the proton images were superior to the T -2-weighted image in demonstrating the intramural hematomas. Conclusio ns Magnetic resonance imaging is a sensitive tool for diagnosing intra cranial vertebrobasilar artery dissection, particularly in the subacut e to early chronic stage. Magnetic resonance imaging is complementary to angiography in that it can directly visualize intramural hematomas.