Atherosclerosis of middle cerebral artery: evaluation with high-resolution MR imaging at 3T.

OBJECTIVE: Three-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) has been wildly used in the diagnosis of intracranial artery diseases, but it only shows the arterial lumen and does not delineate the vessel wall. The aim of this study was to assess whether high resolution cross sectional magnetic resonance imaging (HRMRI) could compensate the limitation of 3D TOF MRA in the atherosclerotic disease of middle cerebral artery (MCA).

METHODS: Fourty-eight suspected patients with atherosclerotic stenosis of MCA underwent 3D TOF MRA and HRMRI with a 3T scanner. The HRMRI was performed in 49 MCAs perpendicular to the M1 segment with T2-weighted imaging. Findings of HRMRI were compared with that of 3D MRA.

RESULTS: HRMRI displayed the artery wall clearly, and showed 37 abnormalities, including 20 plaques and 17 wall thickening. The inter-observer reproducibility was moderate for wall abnormalities with k=0.75 (95% CI 0.59-0.91), and excellent for plaques with k=0.91 (95% CI 0.80-1.03). 3D TOF MRA showed 34 stenoses at the M1 segment. Five normal MCAs on 3D TOF MRA had abnormal wall (3 plaques and 2 wall-thickening) on HRMRI. Two stenoses on 3D TOF MRA showed normal wall structure on HRMRI, indicating a possible negative remodeling phenomenon.

CONCLUSIONS: High-resolution MR imaging can clearly depict the wall structure of middle cerebral arteries. As a complementary method, HRMRI may compensate the limitation of 3D TOF MRA and help to detect atherosclerotic lesions not visualized by MRA.