Intracranial artery dissections: serial evaluation with MR imaging, MR angiography, and source images of MR angiography.

BACKGROUND AND PURPOSE:To assess chronological change in intracranial artery dissections with magnetic resonance imaging (MRI), MR angiography (MRA), and source images of MRA, and to determine whether the source images of MRA provide additional useful information to the combined evaluation of MRI and MRA. MATERIALS AND METHODS:Seven consecutive patients with intracranial artery dissections who were diagnosed by clinical history and conventional angiography were followed sequentially with MRI and MRA (mean follow-up duration, 8.8 months). Two observers independently reviewed the signal intensity of the arterial wall on T1-weighted images, luminal structures on MRA, and source images of MRA. RESULTS:In three (43%) of seven patients, the affected arterial wall had high signal intensity area from 4 to 62 days after onset on T-weighted images. Double lumen on MRA wasobserved only in one patient during the course of the study, whereas a definite low-intensity linear area in the lumen on source images of MRA was seen from 0 to 773 days after onset in all patients. When information from the source images of MRA was added to evaluation with both MRI and MRA, detectability increased to 100% from day 0 to day 3 and 67% from day 4 to day 30. CONCLUSION:The signal intensity of the dissected wall and the luminal structures on MRA and its source images vary according to chronological age. The use of source images from MRA in addition to the combined evaluation of MRI and MRA may provide more accurate diagnosis and follow-up study of intracranial artery dissections.