Carotid revascularization can significantly reduce the risk of stroke in patients with severe carotid stenosis; however, it has been associated with cognitive decline in 25% of the older adults who undergo the procedure. Characterizing risk factors for cognitive decline following carotid interventions and individualizing treatment strategy based on those risks can minimize procedure-associated cognitive dysfunction. Neuroimaging techniques that characterize white matter integrity and regional hypoperfusion have the potential to provide sensitive brain structure indicators that may be associated with memory decline following revascularization procedures. In this protocol, we hope to determine how cerebral blood flow and baseline white matter abnormality in the vulnerable region modify the frequency and cognitive effect of microembolization following carotid revascularization procedures.