Middle cerebral artery intraplaque hemorrhage: prevalence and clinical relevance.

OBJECTIVE: Little is known about the composition of middle cerebral artery (MCA) plaques and how they relate to clinical status. Using high-resolution magnetic resonance imaging (HR-MRI), we aimed to examine the occurrence of high signal on T1-weighted fat-suppressed images (HST1) of MCA plaques, which are highly suggestive of fresh or recent intraplaque hemorrhage. METHODS: We retrospectively analyzed the HR-MRI and clinical data of 107 adult patients with high-grade (>70%) MCA stenosis. On HR-MRI, HST1 within an MCA plaque was defined as an area with an intensity >150% of the signal of adjacent muscles. The relationship between HST1 and clinical presentations was analyzed. RESULTS: A total of 109 stenotic MCAs (46 symptomatic and 63 asymptomatic) on 981 image slices were analyzed. HST1 was revealed on HR-MRI in 11 vessels (10.1%, 9 symptomatic and 2 asymptomatic). The occurrence rate of HST1 between symptomatic and asymptomatic MCAs was significantly different (19.6% vs 3.2%, p = 0.01). INTERPRETATION: HST1 within MCA plaque on HR-MRI is associated with ipsilateral stroke. Our results provide new insight into the vascular biology of MCA atherosclerosis.