Purpose: The aim of this study was to determine whether the ratio of blood flow contralateral-to-affected asymmetry in the cerebellar hemisphere to blood flow affected-to-contralateral asymmetry in the middle cerebral artery (MCA) territory (ARcbl/ARMCA) on preoperative brain perfusion SPECT could identify patients at risk for new cerebral ischemic events after carotid endarterectomy (CEA) for symptomatic unilateral cervical carotid stenosis. For the purposes of this study, new cerebral ischemic events included neurological deficits and cerebral ischemic lesions on diffusion-weighted MRI.
Methods: Brain blood flow was assessed using 123I-IMP SPECT in 101 patients. A region of interest was automatically placed in the bilateral MCA territories and in the bilateral cerebellar hemispheres using a 3-dimensional stereotaxic region-of-interest template, and the ARcbl/ARMCA was calculated. Diffusion-weighted MRI was performed within 3 days before and 24 hours after surgery. Patients were neurologically tested before induction of general anesthesia and after recovery from general anesthesia.
Results: New cerebral ischemic events after CEA were observed in 12 patients (12%). Multivariate analysis revealed that only high ARcbl/ARMCA was significantly associated with the development of new postoperative cerebral ischemic events (95% confidence interval, 1.945–8.452; P = 0.0070). The ARcbl/ARMCA provided 75% sensitivity, 84% specificity, and 39% positive and 96% negative predictive values in predicting development of new postoperative cerebral ischemic events.
Conclusions: The ARcbl/ARMCA on preoperative brain perfusion SPECT could identify patients at risk for new cerebral ischemic events after CEA for unilateral cervical carotid stenosis.