Value Of The Combination Of CT Angiography With CT Perfusion For Assessment Of Collateral Circulation In Acute Ischemic Stroke

Objective:Good collateral circulation helps to maintain the viability of low perfusion brain tissue,and slow down the speed of infarction.Accurate evaluation of collateral status will help to predict the prognosis of patients with acute ischemic stroke.The purpose of our research is to compare collateral status on single-phase CT angiography(sCTA)and multiphase CT angiography(mCTA)and the CT perfusion parameters in patients with AIS,and to explore their inter rater reliability and intra-observer agreement in assessing collateral circulation and ability of predicting clinical outcomes.Method:Consecutive patients who underwent multimodal CT examination(including NCCT,CTP,and CTA)presenting to our institution within 24 hours after onset of stroke.In this study,acute stroke imaging and clinical outcome data were obtained.The peak arterial phases reconstructed from CTP original image is defined as single-phase CTA(sCTA).The peak arterial phase,the peak venous phase,and late venous phases were defined as Multi-phase CT angiography(mCTA).The statuses of collateral circulation were scored on a scale of 0-5 according to the system described by Menon,and evaluate the reliability of inter-raters.The magnitude of ischemic core volume,hypoperfusion volume,and final infarct volume between different scores of sCTA and mCTA and the correlation between them were compared.The sCTA and mCTA were divided into good collateral status group and poor collateral status group,and the differences in ischemic core volume,hypoperfusion volume,final infarct volume,National Institutes of Health Stroke Scale(NIHSS)score,onset-to-scan time,and modified Rankin Scale at 3 months score(m RS)were counted and analyzed between the two groups.Results:The final analysis included 77 patients(53man,median age 64.29±12.94years).The median onset-to-scan time was 330 minutes(IQR,214.00-480.00).The median of baseline NIHSS score was 7(IQR,3.00-12.00).Compared with patients with poor outcomes,patients with good outcomes were younger(P=0.028).Inter-rater reliability for sCTA and mCTA are excellent(the Kappa values were 0.808 and 0.791).Compared with mCTA,sCTA underestimated collateral status.sCTA showed that 24patients(31.2%)had good collateral status,while 46 patients(59.7%)with mCTA had good collateral status,and the 10 of 22 patients had a good functional outcomes.According to mCTA,good collateral status(46/77)was significantly associated with more favorable functional outcomes(P<0.05).Single-and multi-phase CT angiography scores were negatively correlated with ischemic core volume(r_s=-0.333,P=0.000;r_s=-0.506,P=0.000).Both single-and multiple-phase CT angiography scores had a moderate negative correlation with final infarct volume(r_s=-0.429,P=0.000;r_s=-0.575,P=0.000).Single-and multi-phase CTA scores are negatively correlated with three-month m Rs scores(r_s=-0.269,P=0.018;r_s=-0.320,P=0.005).Conclusion:For patients with anterior circulation acute ischemic stroke,multi-phase CT angiography performed better than single-phase CT angiography in assessing collateral circulation condition,and the accurate collateral circulation status assessed with multiple-phase CT angiography can be a good predictor of patients’functional prognosis.