Objectives: We aimed to investigate the geometric characteristics of middle cerebral artery (MCA) atherosclerosis and their clinical relevance.
Methods: Vessel wall magnetic resonance imaging was obtained in patients with recent stroke in MCA territory or suspected asymptomatic MCA atherosclerosis without cardioembolism or carotid artery stenosis. MCAs were classified as atherosclerotic or plaque-free based on whether plaque was present. Atherosclerotic MCAs were divided into MCAs with or without stroke. Geometric characteristics including M1 segment shape (Fig.1), plaque location, plaque length, plaque thickness, stenosis degree, and remodeling ratio were assessed. These geometric characteristics were compared between the groups.
Results: A total of 1006 MCAs were analyzed, including 577 atherosclerotic MCAs (124 MCAs with stroke and 457 MCAs without stroke) and 429 plaque-free MCAs. Curvy MCAs were more prevalent than straight MCAs (79.2% vs 20.2%). The inferior-oriented M1 curve was the most prevalent (61.5%). In 90.4% of curvy atherosclerotic MCAs, the inner side of the M1 curve was involved by plaque. Only 9.6% of curvy atherosclerotic MCAs had no plaque involving the inner sides. Inferior and anterior plaque were found in 67.3% of atherosclerotic MCAs while superior and posterior plaque were found in 32.7%. The absence of an inferior-oriented M1 curve (OR 0.54, 95%CI 0.35-0.83), presence of superior plaque (OR 2.42, 95%CI 1.52-3.86), greater plaque length (OR 1.14, 95%CI 1.07-1.22), greater plaque thickness (OR 2.55, 95%CI 1.49-4.36), higher remodeling ratio (OR 1.15, 95%CI 1.04-1.27), and fewer quadrants involved by plaque (OR 0.68, 95%CI 0.51-0.91) were independently associated with MCAs with clinical stroke.
Conclusions: MCA plaque tended to develop in the same orientation as the M1 inner curve. In addition, the inferior-oriented M1 curve was associated with MCAs without stroke, while superior plaque was associated with MCAs with stroke.