OBJECTIVETo evaluate the thrombus length on CT perfusion imaging and to assess its predictive value for recanalization and clinical outcome after intravenous thrombolysis therapy (IVT).

METHODSFifty-six consecutive acute ischemic stroke patients with proximal middle cerebral artery (M1 segment) occlusion underwent CT perfusion imaging examination before IVT between June 2009 and May 2015. The onset-to needle time was (214.3 ± 82.0) min, and the pretreatment NIHSS score of patients was 13 (IQR 8-17). The thrombus length was determined as the distance between the proximal and distal thrombus end delineated on dynamic angiography, which was reconstructed from CT perfusion source images. Recanalization was evaluated according to Arterial Occlusive Lesion (AOL) scale, and functional outcome was based on modified Rankin scale (mRS) 3 months after IVT. Logistic regression model was used to investigate the relationship between thrombus length and recanalization, and the optimal cut-off points were determined by receiver operating characteristic curve (ROC).

RESULTSAmong 56 patients, 42 (75%) achieved recanalization 24 h after IVT with mean thrombus length of (9.0 ± 4.7) mm; and 14 (25%) patients remained occlusion with mean thrombus length of (10.0 ± 5.4) mm. Logistic regression analysis demonstrated that thrombus length was an independent predictor for both recanalization (OR=0.869; 95% CI:0.764-0.987; P=0.031) and unfavorable outcome (OR=1.180;95% CI:1.023-1.362; P=0.023). Thrombus length of 11.3 mm was identified as the optimal cut-off value for recanalization (AUC=0.697, sensitivity 71.4%, specificity 76.2%), while thrombus length of 9.9 mm was the optimal cut-off value for unfavorable functional outcome (AUC=0.689, sensitivity 64.7%, specificity 71.4%).

CONCLUSIONThe thrombus length evaluated on CT perfusion imaging is an effective predictor for recanalization and unfavorable outcome after IVT in acute ischemic stroke patients with middle cerebral artery occlusion.