Extracranial Carotid Plaque Length and Parent Vessel Diameter Significantly Affect Baseline Ipsilateral Intracranial Blood Flow

BACKGROUND: The degree of carotid artery stenosis has traditionally been used as a marker of hemodynamic compromise and increased stroke risk. However, the hemodynamic effect of carotid atherosclerotic plaque length on cerebral blood flow has not previously been studied. OBJECTIVE: To determine whether carotid plaque length, in addition to degree of stenosis, significantly affects carotid blood flow in patients with >65% carotid stenosis. METHODS: Consecutively treated surgical patients with unilateral >65% carotid stenosis at a single institution were analyzed. Quantitative measurements of plaque length, internal carotid artery (ICA) vessel diameter, and degree of stenosis were made from magnetic resonance angiography images. Quantitative phase-contrast magnetic resonance angiography flow maps were generated to estimate ICA flow compromise by calculating a ratio of the ipsilateral/contralateral ICA flow rates. RESULTS: Of 38 eligible patients, 23 had full anatomic and ICA flow data sets available for analysis. Univariate regression analysis demonstrated that longer carotid plaques and increasing percentage carotid stenosis were associated with a significant decline in ipsilateral ICA flow (P = .008 and P = .02, respectively). A multivariate regression identified both plaque length and vessel diameter as independent predictors of ICA flow (P = .001 and P = .002, respectively). CONCLUSION: Carotid plaque length and vessel diameter appear to be significant variables, in addition to degree of stenosis, in predicting ipsilateral carotid blood flow compromise in patients undergoing carotid revascularization.