Stroke Mechanism Subtypes and Prognosis in Patients With Symptomatic Intracranial Atherosclerosis Based on Multiparametric MRI.

Background: Different stroke mechanisms present with distinct imaging characteristics and prognosis. Multiparametric MRI can characterize these variations and may contribute to stroke secondary prevention.

Purpose: To investigate the stroke mechanism subtypes and prognosis in patients with symptomatic intracranial atherosclerosis using multiparametric MRI.

Study type: Retrospective.

Population: Two hundred and seventeen ischemic stroke patients (147 males; age 55.5 ± 11.7 years) with intracranial atherosclerosis.

Field strength/sequence: 3-T, dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI); High-resolution vessel wall imaging (HR-VWI): three-dimensional (3D) T1-weighted Sampling Perfection with Application optimized Contrast using different flip angle Evolution (SPACE) and contrast-enhanced T1-SPACE.

Assessment: All patients underwent multiparametric MRI within 7 days of stroke symptom onset. The stroke mechanisms included branch occlusive disease (BOD), artery-to-artery embolism, hypoperfusion, and mixed mechanisms. The following imaging characteristics were assessed by three radiologists independently. HR-VWI plaque characteristics included plaque area, lipid area, lipid ratio, occlusive thrombus, degree of stenosis, plaque burden, enhancement ratio, remodeling index, and intraplaque hemorrhage (IPH). The mean transit time-Alberta Stroke Program Early Computed Tomography score (MTT-ASPECTS) based on DSC-PWI was used to evaluate perfusion impairment. During a median follow-up period of 15 months, the correlation between different stroke mechanisms and prognosis was analyzed.

Statistical tests: Chi-squared or Fisher's exact, Kruskal-Wallis H-tests, multivariate logistic regression, and Kaplan-Meier curves. All p-values were corrected by Bonferroni correction, and p-values < 0.05 were considered statistically significant.

Results: Mixed mechanism was the most common subtype (32.7%). Significant differences were observed in perfusion impairment, degree of stenosis, plaque burden, enhancement ratio, IPH, and remodeling among stroke mechanisms. Of these characteristics, MTT-ASPECTS (odds ratio [OR] 0.70, 95% CI 0.562-0.863) and IPH (OR 2.30, 95% CI 1.042-5.051) were significantly associated with non-BOD mechanisms. Hypoperfusion mechanism was associated with a higher risk of stroke recurrence during a median follow-up of 15 months (hazard ratio 3.97, 95% CI 1.43-11.03).

Data conclusion: Multiparametric MRI may reveal differences in imaging characteristics among stroke mechanisms. Hypoperfusion may be associated with an increased risk of stroke recurrence.

Evidence level: 3. Technical Efficacy: Stage 3.