Computed Tomography Perfusion after Thrombectomy: An Immediate Surrogate Marker of Outcome after Recanalization in Acute Stroke

Background and Purpose - Despite recanalization, almost 50% of patients undergoing endovascular treatment (EVT) experience poor outcome. We aim to evaluate the value of computed tomography perfusion as immediate outcome predictor postendovascular treatment. Methods - Consecutive patients receiving endovascular treatment who achieved recanalization (modified Thrombolysis in Cerebral Ischemia [mTICI] 2a-3) underwent computed tomography perfusion within 30 minutes from recanalization (CTPpost). Hypoperfusion was defined as the Tmax>6 second volume; hyperperfusion as visually increased cerebral blood flow/cerebral blood volume with reduced Tmax compared with unaffected hemisphere. Dramatic clinical recovery (DCR) was defined as 24-hour National Institutes of Health Stroke Scale score ≤2 or ≥8 points drop. Delayed recovery was defined as no-DCR with favorable outcome (modified Rankin Scale score 0-2) at 3 months. Results - We included 151 patients: median National Institutes of Health Stroke Scale score 16 (interquartile range, 10-21), median admission ASPECTS 9 (interquartile range, 8-10). Final recanalization was the following: mTICI2a 11 (7.3%), mTICI2b 46 (30.5%), and mTICI3 94 (62.3%). On CTPpost, 80 (52.9%) patients showed hypoperfusion (median Tmax>6 seconds: 4 cc [0-25]) and 32 (21.2%) hyperperfusion. There was an association between final TICI and CTPpost hypoperfusion(median Tmax>6: 91 [56-117], 15 [0-37.5], and 0 [0-7] cc, for mTICI 2a, 2b, and 3, respectively, P<0.01). Smaller hypoperfusion volumes on CTPpost were observed in patients with DCR (0 cc [0-13] versus non-DCR 8 cc [0-56]; P<0.01) or favorable outcome (modified Rankin Scale score 0-2: 0 cc [0-13] versus 7 [0-56] cc; P<0.01). No associations were detected with hyperperfusion pattern. An hypoperfusion volume <3.5 cc emerged as independent predictor of DCR (OR, 4.1 [95% CI, 2.0-8.3]; P<0.01) and 3 months favorable outcome (OR, 3.5 [95% CI, 1.6-7.8]; P<0.01). Conclusions - Hypoperfusion on CTPpost constitutes an immediate accurate surrogate marker of success after endovascular treatment and identifies those patients with delayed recovery and favorable outcome.