Aim (2). CVR, as measured using the blood oxygenation level-dependent (BOLD) MRI signal change in response to hypercarbia, will be used to assess cerebrovascular reserve. The inflow vascular-space-occupancy with dynamic subtraction (iVASO-DS) approach, which we have developed and demonstrated in patients, will be applied to assess baseline aCBV. For the same patients as in Aim 1, CVR dynamics and aCBV will be statistically assessed for unique relationships with two-year stroke incidence.