High‐Resolution <scp>MRI</scp> Revealed Different Etiology‐Specific Associations With Cerebral Infarction in Adult Moyamoya Vasculopathy

OBJECTIVE: High-resolution MRI enables detailed assessment of intracranial vessel wall pathology in moyamoya vasculopathy. We aimed to classify adult moyamoya vasculopathy etiologies using high-resolution MRI and to examine subtype-specific associations between high-resolution MRI features and ischemic infarction. METHODS: We enrolled 398 adult patients with moyamoya vasculopathy. According to high-resolution MRI characteristics, 340 patients were classified as moyamoya disease (n = 279) or atherosclerosis-associated moyamoya vasculopathy (n = 61). Hemisphere-level analyses were performed using generalized estimating equations logistic models with patients as clusters to evaluate associations between high-resolution MRI measures and ischemic hemispheres. RESULTS: Compared with atherosclerosis-associated moyamoya vasculopathy, moyamoya disease patients were more often female and more likely to have a family history of early-onset stroke and posterior cerebral artery involvement. In the moyamoya disease group, greater middle cerebral artery stenosis, higher Suzuki stage, and more severe internal carotid artery, middle cerebral artery, and posterior cerebral artery involvement were independently associated with ischemic hemispheres, whereas a higher middle cerebral artery remodeling index was inversely associated with ischemia. In the atherosclerosis-associated moyamoya vasculopathy group, higher middle cerebral artery remodeling index and more severe anterior cerebral artery involvement were independently associated with ischemic hemispheres, while other high-resolution MRI metrics showed no significant associations. INTERPRETATION: High-resolution MRI-derived quantitative vascular metrics show distinct ischemia-related patterns in moyamoya disease and atherosclerosis-associated moyamoya vasculopathy. Global steno-occlusive burden with impaired middle cerebral artery remodeling characterizes ischemic hemispheres in moyamoya disease, whereas adverse middle cerebral artery remodeling and anterior cerebral artery involvement are key correlates of ischemia in atherosclerosis-associated moyamoya vasculopathy.