Predicting Impaired Cerebrovascular Reactivity and Hyperperfusion Syndrome with BeamSAT MRI in Carotid Artery Stenosis

Background We evaluated the impact of collateral flow of the middle cerebral artery (MCA) territory and cross flow visualized with internal carotid artery (ICA)-selective Magnetic resonance angiography (MRA) constructed by pencil beam presaturation (BeamSAT) pulse on preoperative cerebral hemodynamic status and postoperative hyperperfusion syndrome. Methods Fourty-eight patients who underwent carotid artery stenting or carotid endarterectomy were included. The preoperative status of collateral flow in the MCA territory and crossflow was assessed using ICA-selective MRA. Cerebral blood flow and cerebrovascular reactivity (CVR) were assessed using single-photon emission computed tomography. Potential signs of hyperperfusion syndrome (HPS) were retrospectively assessed by reviewing medical charts. Results Patients who either demonstrated mismatch in MCA signal intensity (MCA-MRA grade) between ICA-selective MRA by BeamSAT magnetic resonance imaging (MRI) and conventional MRA or whose MRA crossflow was visualized on BeamSAT MRI were placed in the developed collateral (DC) group (n=19). All other patients were placed in the undeveloped collateral (UC) group (n = 29). Preoperative ipsilateral CVR was significantly lower in the DC group than in the UC group (18.0±20.0% versus 48.3±19.5%; P<0.0001). Multivariate logistic regression analysis revealed that the DC group was significantly associated with impaired CVR (odds ratio [OR] = 17.7, [95%confidence interval [CI]: 1.82 to 171]; P = 0.013). The partial area under curves (AUCs) of BeamSAT logisitic model (0.843) were significantly larger than those of the conventional logistic model (0.626) over the range of high sensitivity (0.6-1) (p = 0.04). The incidence of postoperative symptoms suggestive of HPS was significantly higher in the DC group than in the UC group (8/19 vs. 1/29; P=0.001). Conclusions The differences in the MCA-MRA grade and crossflow between ICA-selective and conventional MRA were associated with impaired CVR. BeamSAT MRI may be a valuable and non-invasive tool for assessing of cerebral hemodynamics and predicting postoperative HPS.