Dynamic CT angiography in evaluation of collateral flow and outcome of acute ischemic stroke patients after intravenous thrombolysis

Objective: To evaluate the collateral flow of patients with acute ischemic stroke by dynamic CT angiography( CTA) and to analyze the relationship between collateral flow and outcome after intravenous thrombolysis. Methods: We retrospectively analyzed CT perfusion( CTP) imaging of 22 acute ischemic stroke patients with middle cerebral artery( MCA) or internal carotid artery( ICA) occlusion undergoing intravenous thrombolysis,and reconstructed the images for dynamic CTA in the Second Affiliated Hospital,Zhejiang University School of Medicine from June 2009to October 2013. The total extent and flow speed of collateral flow based on dynamic CTA images of these patients were evaluated. The scores of National Institute of Health stroke scale( NIHSS) in different collateral flows were compared with repeated measuring. The nonparametric Spearman 's rank correlation was used to assess the relationship between collateral flow and modified Rankin scale( mRS) at 3 months after thrombolytic therapy. Results: Compared with the poor collateral flow group,patients with good collateral flow had lower NIHSS at 1 month after thrombolysis( 4. 7 ± 5. 0 vs25. 1 ± 15. 1,P = 0. 001) and higher reperfusion percentage( 69% ± 32% vs 23% ±54%,P = 0. 044). The total condition score of collateral flow was positively correlated with mRS at 3 months after treatment( r = 0. 450,P = 0. 001). Conclusion: Acute ischemic stroke patients with good collateral flow after intravenous thrombolysis have a better outcome. The dynamic CTA can be used to evaluate the collateral flow and to predict clinical outcomes in patients with acute ischemic stroke after thrombolysis therapy.