Posterior Circulation Thrombectomy—pc-ASPECT Score Applied to Preintervention Magnetic Resonance Imaging Can Accurately Predict Functional Outcome

Abstract

There are currently no imaging criteria to identify patients who would benefit from endovascular recanalization of posterior circulation strokes. Applying the Posterior Circulation Alberta Stroke Program Early Computed Tomography Score (pc-ASPECTS) to magnetic resonance imaging (MRI) has been demonstrated to be an accurate predictor of functional outcome. Here, we aimed to evaluate the accuracy of the pc-ASPECTS with preintervention MRI as a predictor of functional outcome in a cohort undergoing endovascular recanalization. This is a 15-year retrospective study of patients undergoing endovascular recanalization of posterior circulation with baseline MRI or computed tomography. We analyzed baseline imaging, clinical data, and type and timing of intervention to the functional outcome at 90 days. Using MRI pc-ASPECTS, we evaluated interrater reliability and accuracy in predicting functional outcome and compared them to the use of single-anatomic location for this function. Door-to-recanalization time in the MRI cohort was significantly longer (median: 8.7 vs. 2.7 hours, P= 0.03); however, functional outcome was not different. Within the MRI cohort, pc-ASPECTS and National Institutes of Health Stroke Scale were the only factors that were significantly different between the groups with good and bad functional outcome (P < 0.001). The area under the receiver operating characteristic curve for the pc-ASPECTS and good functional outcome was 0.96, with the optimal threshold of ≥8 resulting in positive predictive value of 90% and negative predictive value of 100%. Despite longer time to intervention with MRI as the initial imaging modality in posterior circulation strokes, it does not negatively affect the functional outcome. Pc-ASPECTS is an easy to use and accurate prognostic tool for the real-time evaluation of preintervention MRI in this population.