CBV-ASPECTS Improvement over CT-ASPECTS on Determining Irreversible Ischemic Lesion Decreases over Time

The Alberta Stroke Program Early CT Score (ASPECTS) is a useful scoring system for assessing early ischemic signs on noncontrast computed tomography (CT). Cerebral blood volume (CBV) on CT perfusion defines the core lesion assumed to be irreversibly damaged. We aim to explore the advantages of CBV-ASPECTS over CT-ASPECTS in the prediction of final infarct volume according to time. Methods: Consecutive patients with anterior circulation stroke who underwent endovascular reperfusion according to initial CT-ASPECTS ≥7 were studied. CBV-ASPECTS was assessed blindly later on. Recanalization was defined as thrombolysis in cerebral ischemia score 2b-3. Final infarct volumes were measured on follow-up imaging. We compared ASPECTS on CBV and CT images, and defined ASPECTS agreement as: CT-ASPECTS - CBV-ASPECTS ≤1. Results: Sixty-five patients, with a mean age of 67 ± 14 years and a median National Institutes of Health Stroke Scale score of 16 (range 10-20), were studied. The recanalization rate was 78.5%. The median CT-ASPECTS was 9 (range 8-10), and the CBV-ASPECTS was 8 (range 8-10). The mean time from symptoms to CT was 219 ± 143 min. Fifty patients (76.9%) showed ASPECTS agreement. The ASPECTS difference was inversely correlated to the time from symptoms to CT (r = -0.36, p < 0.01). A ROC curve defined 120 min as the best cutoff point after which the ASPECTS difference becomes more frequently ≤1. After 120 min, 89.5% of the patients showed ASPECTS agreement (as compared with 37.5% for <120 min, p < 0.01). CBV-ASPECTS but not CT-ASPECTS correlated with final infarct (r = -0.33, p < 0.01). However, if CT was done >2 h after symptom onset, CT-ASPECTS also correlated to final infarct (r = -0.39, p = 0.01). Conclusions: In acute stroke, CBV-ASPECTS correlates with the final infarct volume. However, when CT is performed after 120 min from symptom onset, CBV-ASPECTS does not add relevant information to CT-ASPECTS.