Correlation of volumetric mismatch and mismatch of Alberta Stroke Program Early CT Scores on CT perfusion maps

We aimed to determine if volumetric mismatch between tissue at risk and tissue destined to infarct on computed tomography perfusion (CTP) can be described by the mismatch of Alberta Stroke Program Early CT Score (ASPECTS). Forty patients with nonlacunar middle cerebral artery infarct < 6 h old who had CTP on admission were retrospectively reviewed. Two raters segmented the lesion volume on mean transit time (MTT) and cerebral blood volume (CBV) maps using thresholds of > 6 s and < 2.0 mL per 100 g, respectively. Two other raters assigned ASPECTS to the same MTT and CBV maps while blinded to the volumetric data. Volumetric mismatch was deemed present if a parts per thousand yen20%. ASPECTS mismatch (=CBV ASPECTS -aEuro parts per thousand MTT ASPECTS) was deemed present if a parts per thousand yen1. Correlation between the two types of mismatches was assessed by Spearman's coefficient (rho). ROC curve analyses were performed to determine the optimal ASPECTS mismatch cut point for volumetric mismatch a parts per thousand yen20%, a parts per thousand yen50%, a parts per thousand yen100%, and a parts per thousand yen150%. Median volumetric mismatch was 130% (range 10.9-2,031%) with 31 (77.5%) being a parts per thousand yen20%. Median ASPECTS mismatch was 2 (range 0-6) with 26 (65%) being a parts per thousand yen1. ASPECTS mismatch correlated strongly with volumetric mismatch with rho = 0.763 [95% CI 0.585-0.870], p < 0.0001. Sensitivity and specificity for volumetric mismatch a parts per thousand yen20% was 83.9% [95% CI 65.5-93.5] and 100% [95% CI 65.9-100], respectively, using ASPECTS mismatch a parts per thousand yen1. Volumetric mismatch a parts per thousand yen50%, a parts per thousand yen100%, and a parts per thousand yen150% were optimally identified using ASPECTS mismatch a parts per thousand yen1, a parts per thousand yen2, and a parts per thousand yen2, respectively. On CTP, ASPECTS mismatch showed strong correlation to volumetric mismatch. ASPECTS mismatch a parts per thousand yen1 was the optimal cut point for volumetric mismatch a parts per thousand yen20%.