Comprehensive Assessment of Hemodynamics in Intracranial Atherosclerotic Disease

Intracranial atherosclerotic disease (ICAD) is one of the most common causes of ischemic stroke worldwide, and patients with ICAD have a high risk of stroke recurrence. Thus, careful patient surveillance, risk stratification, and treatment planning are crucial for secondary prevention. Currently, ICAD is treated with aggressive medical management, yet the rate of stroke in patients with ICAD remains high. Hemodynamic failure is a known risk factor for stroke in a subset of patients with ICAD. A true assessment of hemodynamic impacts of the disease, however, requires a complete characterization of cerebral artery hemodynamics and brain tissue perfusion. A diagnostic framework which can provide such a comprehensive investigation of cerebral macro- and microvascular hemodynamics has yet to be developed. To fill this technical gap, we propose the synergistic combination of a non-invasive MRI technique (4D flow MRI) and specially tailored analysis tools to assess the hemodynamics in the entire cerebral vasculature. We plan to quantify hemodynamic biomarkers including velocity, flow and pressure gradient as well as perfusion in cerebral vascular territories. We will investigate the potential of using pressure gradient as a biomarker for determining the hemodynamic significance of atherosclerotic stenosis, compared to current clinical evaluation based on the degree of lumen narrowing. Furthermore, we investigate the relationship between blood flow redistribution in the cerebrovascular network and brain tissue perfusion in vascular territories, in order to determine the hemodynamic contribution to the pathophysiology of stroke in the setting of ICAD. The successful completion of this project can provide the diagnostic techniques required for future investigations of the utility of cerebral hemodynamics as a prognostic factor for the stratification of stroke recurrence risk.