| Background:Intracranial atherosclerotic disease (ICAD) is the leading cause of stroke in Asian. High resolution vessel wall imaging (HRVWI) can observe the intracranial vessel wall, the lumen and the morphology and component of the plaque non-invasively. It has great potential to identify the plaque vulnerability and clinical prognosis in ICAD patients.Objective:Explore the association among the infarct pattern, stenosis rate, the features of plaque, vessel wall and remodeling in middle cerebral artery (MCA), to demonstrate the pathophysiology mechanism of stroke in ICAD.Methods:This study retrospectively analyzed consecutive patients with and without stroke history. The symptomatic group included MCA territory stroke patients with stroke onset less than 2 weeks, who had eccentric plaque on Ml segment of ipsilateral MCA on HRVWI. The asymptomatic group included candidates without history of stroke, who had eccentric plaque on M1 segment of ipsilateral MCA on HRVWI. According to the infarct pattern, the symptomatic group was classified into penetrating artery infarction group, embolic infarction group and single white matter infarction group (not included in final analysis). Imaging markers include the lumen area, outer wall area, plaque distribution (includes superior, inferior, anterior and posterior quadrant), plaque length, plaque thickness, plaque signal and plaque discontinuity were measured on the slice of the most stenotic plaque. The reference lumen area and reference outer wall area were measured on the slice of relatively normal artery. Then the plaque index (the number of the quadrants that a plaque involves), vessel wall area, stenosis rate and remodeling rate were calculated. Univariate analysis and logistic regression analysis were performed.Results:232 patients were included in this study, of which,113 were in symptomatic group, 119 were in asymptomatic group. In symptomatic group,54 were penetrating artery infarctions,52 were embolic infarctions. Among all three groups, the plaque length, plaque thickness and plaque index were significantly associated with stenosis rate (p<0.05). In penetrating artery infarction group and asymptomatic group, the constrictive remodeling was significantly related with stenosis rate (p<0.05). In embolic infarction group and asymptomatic group, the vessel wall area was significantly related with stenosis rate (p<0.05). The penetrating artery infarction group had less inferior, anterior and posterior wall involvement, more superior located plaque (the thickest part is located at the superior wall), larger lumen area and smaller plaque index (p<0.05). According to the logistic regression analysis, superior located plaque (p=0.003, OR 3.158,95%CI 1.490-6.690), lumen area (p=0.005, OR 1.315,95%CI 1.089-1.589) and plaque index (p=0.010, OR 0.575,95%CI 0.378-0.874) were the independent predicting factors. The embolic infarction group had more anterior and posterior wall involving, larger plaque length and thickness, more mixed signal plaque and discontinuity, higher stenosis rate, more expansive remodeling, larger wall area, smaller lumen area and larger plaque index (p<0.05) than asymptomatic group. The logistic regression analysis indicated the stenosis rate (p=0.008, OR 9.996,95%CI 2.141-46.665), plaque length (p=0.003, OR 1.295, 95%CI 1.068-1.569) and expansive remodeling (p=0.002, OR 3.785,95%CI 1.601-8.947) as the independent predicting factors. In mild stenosis group, the embolic infarction group had more plaque discontinuity and expansive remodeling (p<0.05), and the plaque discontinuity was the independent predictor of embolic infarction (p=0.016, OR 5.146, 95%CI 1.354-19.533).Conclusions:1) As the stenosis rate increases, the change of vessel wall area and remodeling pattern is different among three groups.2) Compared to asymptomatic group, the independent predicting factors of penetrating artery infarction are superior wall located plaque, plaque index and lumen area, indicating that the superior located plaque might be a high-risk plaque of a special category other than vulnerability. the plaque whose border involves superior wall is not likely to occur penetrating artery infarction; and the diffuse remodeling may play a role in stroke mechanism.3) The independent predicting factors of embolic infarction are stenosis rate, plaque length and expansive remodeling; in patients with mild stenosis, the plaque discontinuity is the independent predictor of embolic infarction, indicating that the embolic infarction may be an important mechanism in mild ICAD patients. This may be helpful for analyzing the etiology of cryptogenic stroke.
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