Abstract Body: Background: Intracranial atherosclerosis (ICAS) is the leading, global cause of stroke. ICAS patients with 70-99% arterial stenosis have a first-year recurrent stroke rate as high as 19.7%, a major cause of death and disability. In contrast, first-year recurrence for non-ICAS stroke patients is less than 5%. Furthermore, compared to extracranial vessels, intracranial arteries have distinct physiological and structural characteristics. These two points underscore the critical need for targeted research specific to ICAS and to identify biomarkers associated with recurrent stroke and treatment failure.

Method: CAPTIVA-MRI is a multicenter, observational study, ancillary to the CAPTIVA Trial and operated under the StrokeNet infrastructure. CAPTIVA-MRI aims to determine if advanced multimodal MRI biomarkers can identify ICAS patients who fail optimal medical management in the CAPTIVA trial. In CAPTIVA-MRI, we will measure regional flow with quantitative MRA, wall shear stress with computational fluid dynamics, and plaque inflammation with vessel wall MRI. We plan to recruit 300 concurrently enrolled participants in the CAPTIVA Trial from up to 30 participating sites. All participants will undergo baseline MRI within 21 days of CAPTIVA randomization and follow-up MRI at 1-year.

Result: The primary outcome is the rate of recurrent symptomatic stroke in the vascular territory of the index stroke parent artery. Secondary outcomes include: asymptomatic ischemic events (measured using a follow-up MRI at 1-year), a composite outcome of all ischemic events, and change of cortical thickness and white matter hyperintensities between the baseline and 1-year follow-up MRI.

Conclusion: CAPTIVA-MRI will validate MRI biomarkers related to functional blood flow and plaque composition to deliver essential insights for risk stratification in patients with ICAS. These biomarkers are expected to enhance the understanding of disease progression and assist in identifying patients at higher risk for recurrent stroke, ultimately guiding more personalized treatment approaches.