Computed Tomography–Based Imaging Scores in Basilar Artery Occlusions: A Comparison of Predictive Abilities for Functional Outcomes

BACKGROUND: Posterior circulation large-vessel occlusion strokes have significant morbidity and mortality, but patient selection for acute interventions remains understudied. Multiple computed tomography (CT)–based scores exist, including the CT perfusion–based critical area perfusion score (CAPS), CT angiography–based basilar artery treatment management and posterior circulation CT angiography scores, and CT angiography source image or noncontrast CT–based posterior circulation Alberta Stroke Program Early CT Score, but their predictive values for long-term outcomes after thrombectomy have not been directly compared. METHODS: We conducted a retrospective multicenter cohort study of patients with basilar artery occlusions treated with endovascular thrombectomy. Four CT-based scores were assessed: posterior circulation Alberta Stroke Program Early CT Score, basilar artery treatment management score, posterior circulation CT angiography score, and CAPS. The primary outcome of interest for the study was a favorable functional outcome at 3 months (modified Rankin Scale score, 0–3). We calculated sensitivity, specificity, positive and negative predictive values, and generated receiver operating characteristic curves measuring area under the curve (AUC), which were compared with nonparametric methods. RESULTS: Ninety-eight patients were included for analysis, with an average age of 64.9 ± 15.6 years. The median National Institutes of Health Stroke Scale score was 13.5 (interquartile range, 7.0–23.0). AUC values were highest for the CAPS (AUC, 0.72 [95% CI, 0.63–82]) and lowest for the posterior circulation CT angiography score (AUC, 0.57 [95% CI, 0.45–0.68]; P =0.019). There was a trend toward the CAPS outperforming the basilar artery treatment management score (AUC, 0.66 [95% CI, 0.55–0.77]) and posterior circulation Alberta Stroke Program Early CT Score (AUC, 0.63 [95% CI, 0.52–0.75]) though this was not statistically significant ( P =0.29 and P =0.23, respectively). CAPS ≤3 demonstrated 100% sensitivity and negative predictive value (95% CI, 92.6–100.0%; 95% CI, 75.7–100.0%, respectively) for good outcome but had low specificity (24.0% [95% CI, 14.3–37.4]). CONCLUSIONS: The CT perfusion–based CAPS had the best performance for predicting good functional outcome at 3 months and had high sensitivity and negative predictive values though our finding is limited by the small number of patients who had CAPS >3. The CAPS should be validated in prospective studies.