Accuracy of "At Risk" Tissue Predictions Using CT Perfusion in Acute Large Vessel Occlusions

BACKGROUND AND PURPOSE The validity of CT perfusion (CTP) predictions of expected infarction volume (“at risk” tissue) without rapid recanalization remains poorly characterized. METHODS From the MR CLEAN trial, we included patients who underwent CTP without successful recanalization. “At risk” volume was defined as Tmax > 6 seconds and ischemic core as relative CBF < 30 (Olea Sphere). Coprimary outcomes were follow‐up infarct volume (FIV) on CT at 1‐5 days and 90‐day mRS. Data are presented as median [IQR] or OR [95% CI] unless otherwise specified. RESULTS Among 37 patients who met criteria, 14 (38%) were women, median age was 61 years [52‐69], NIHSS was 19 [15‐21], ASPECTS was 8 [7‐9], and onset to imaging was 160 minutes [39‐200]. Occlusion location was M1 for 22 (59%), ICA‐T in 10 (27%), and M2 in 4 (11%). In univariable analysis, “at risk” volume correlated poorly with FIV (r = .06, P = .77). Among patients with predicted “at risk” volume < 100 mL, 36% had FIV > 200 mL. In adjusted linear regression, NIHSS but not “at risk” volume was associated with FIV (Coef 12, P = .045; Coef –.15, P = .8). In adjusted logistic regression, NIHSS but not “at risk” volume was associated with mRS 0‐2 at 90 days (OR .7 [.5‐.99]; OR 1.0 [.99‐1.04]). CONCLUSION Predictions of “at‐risk” tissue using CTP may underestimate the natural history of infarction from acute large vessel occlusions. NIHSS may perform better as a predictor of clinical outcomes in patients without rapid recanalization.

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