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.