Serial Multimodal Imaging Change And Its Effects In Acute Ischemic Stroke Patients Who Achieved Recanalization

Part 1 Dynamic changes of perfusion status and cerebral injury after reperfusion therapy in acute ischemic stroke patients who achieved recanalizationObjectives: To evaluate the dynamic changes of perfusion status and subsequent injury of cerebral tissue in acute ischemic stroke(AIS)patients after reperfusion therapy.Methods: We retrospectively analyzed patients with anterior circulation large artery occlusion who received endovascular treatment,achieved recanalization and underwent CT perfusion(CTP)-1 at admission and CTP-2 immediately after endovascular treatment at our department from November 2013 to March 2019.Recanalization was assessed based on arterial occlusive lesion(AOL),which was defined as AOL score of 3.Hypoperfusion was identified with Tmax>6s.Infarct core was identified as relative cerebral blood flow(r CBF)<30%.The hypoperfusion-core mismatch(abbreviated as “mismatch”)was identified by removing the infarct core of the hypoperfusion area.Reperfusion region was defined as the regions presenting mismatch on CTP-1 and not hypoperfusion on CTP-2.Persistent hypoperfusion region was defined as the regions presenting mismatch on CTP-1 and hypoperfusion on CTP-2.Complete reperfusion was defined as persistent hypoperfusion volume of 0 ml.The final infarct lesion was identified on 24-hour diffusion-weighted imaging or non-contrast CT,whereas the hemorrhagic lesion was evaluated on 24-hour susceptibility-weighted imaging or non-contrast CT.Binary logistic regression was used to analyze relative factors of incomplete reperfusion.Results: 139 patients were included in the final analysis.The volume of baseline mismatch area was 57.0(36.8-80.0)ml.Reperfusion rate was 100.0(90.9-100.0)%.96(69.1%)patients achieved complete reperfusion.Multivariate analysis showed that diabetes(OR,2.947;95% CI,1.206-7.207;p=0.018)and baseline hypoperfusion volume(OR,1.009;95% CI,1.003-1.016;p=0.004)was independently related to incomplete reperfusion.81(58.3%)patients had injury in the reperfusion area,with 10(7.2%)of pure hemorrhage,55(39.6%)of pure infarction,and 16(11.5%)of both infarction and hemorrhage.The injury volume in the reperfusion area was 19.0(6.7-32.1)ml.Conclusion: Most of AIS patients could achieve reperfusion,but there's incomplete reperfusion after recanalization.Patients with diabetes and larger volume of baseline hypoperfusion were more likely to have incomplete reperfusion after recanalization.More than half of AIS patients developed injury within reperfusion region.Part 2 The impact of cerebral injury after reperfusion on outcome of AIS patientsObjectives: To to evaluate the impact of cerebral injury after reperfusion on the outcome of AIS patients who received reperfusion therapy.Methods: We retrospectively analyzed patients with anterior circulation large artery occlusion who received endovascular treatment,achieved recanalization and underwent CTP-1 and CTP-2 at our department from November 2013 to March 2019.Image observed ischemic reperfusion injury(IOIRI)was defined as 24-hour injury(infart or hemorrhagic lesion)within the reperfusion area.IOIRI degree was defined as volume ratio of reperfusion-injury region to reperfusion region.Edema was evaluated on baseline and 24-hour non-contrast CT or DWI with a scale of 7 grades(0-6 points).Edema expansion was defined as the increase of edema score from baseline to 24 hours.The neurological outcome was assessed by a modified Rankin Scale(m RS)at 3 month.Good and poor outcome were defined as m RS of 0-2 and 3-6,respectively.Linear regression was used to analyze the independent predictors for edema expansion,and binary logistic regression for poor outcome.Receiver operating characteristic(ROC)curve analysis was used to determine predicted value.Results: 139 patients were included in the final analysis.Median IOIRI degree was 9.2(0.0-46.2)%.Multivariate analysis showed that IOIRI degree was independently correlated with edema expansion(standard coefficient=0.559,p<0.001)and poor outcome(OR,1.279 per 10%;95% CI,1.108-1.478,p=0.001).Cut-off of reperfusion injury degree for predict poor outcome was 51.6%(area under the curve,0.661;95% CI,0.571-0.751),with sensitivity and specificity of 37.0% and 92.4% respectively.Conclusion: IOIRI degree was associated with poor outcome and edema expansion in AIS patients who achieved recanalization.Part 3 Investigation of mechanisms of image observed ischemic reperfusion injuryI.Relationship between baseline perfusion status and image observed ischemic reperfusion injuryObjectives: To explore the relationship between baseline perfusion status and IOIRI.Methods: We retrospectively analyzed patients with anterior circulation large artery occlusion who received endovascular treatment,achieved recanalization and underwent CTP-1 and CTP-2 at our department from November 2013 to March 2019.Image observed ischemic reperfusion injury(IOIRI)was defined as 24-hour injury within the reperfusion area.IOIRI degree was defined as volume ratio of reperfusion-injury region to reperfusion region.Related Wilcoxon test was used to compare perfusion parameters between two relevant groups.Receiver operating characteristic(ROC)curve analysis was used to determine predicted value.Results: 139 patients were included in the final analysis.Baseline mean transit time(MTT)within reperfusion-injury region was longer than reperfusion non-injury region(p=0.012),and there was no significant difference of other perfusion parameters between the two groups.Cut-off of MTT for predict IOIRI was 16.19s(area under the curve,0.596;95% CI,0.517-0.675),with sensitivity of 53.0% and specificity of 67.2%.Conclusion: We found that tissues with longer baseline MTT are more likely to develop injury within ischemic-reperfusion region.It may indicate the importance of severe ischemia in the pathogenesis of cerebral injury after reperfusion.II.Relationship between venous drainage status and image observed ischemic repefusion injuryObjectives: To investigate the status of venous drainage before and after recanalization in AIS patients,and to explore its association with IOIRI at baseline and post reperfusion therapy.Methods: We retrospectively analyzed patients with anterior circulation large artery occlusion who received endovascular treatment,achieved recanalization and underwent CTP-1 and CTP-2 at our department from November 2013 to March 2019.Patients with poor quality image that could not be used to reconstruct vein map were excluded.IOIRI degree was defined as volume ratio of reperfusion-injury region to reperfusion region.Severe IOIRI was defined as IOIRI>50%.Three ipsilateral anastomotic veins were evaluated based on four-dimensional CT angiography.Presence of the targeted vein was defined as the appearance of contrast flow in the target vein at any time point of venous phase.Absence of targeted vein was defined as no contrast filling of the vein across the whole venous phase.We evaluated vein on both CTP-1 and CTP-2.Absence vein on CTP-1 that presence on CTP-2 was defined as vein reappearence.Vein reappearance ratio was defined as ratio of number of reappeared vein to absent vein.Binary logistic regression was used to analyze the independent predictors for SIOIRI.Results: 134 patients were included in the final analysis.Absent veins of 0,1,2 and 3 were observed in 80(59.7%),44(32.8%),9(6.7%)and 1(0.7%)patients at baseline,respectiveluy.After adjusting for baseline NIHSS,baseline hypoperfusion volume,and antiplatelet drug usage,the number of absent veins at baseline was independently correlated with SIOIRI(OR,2.033;95% CI,1.055-3.918;p=0.034).11(8.5%)patients had 1 absent vein after reperfusion therapy,and the rest patients' absent veins all reapppeared.Low vein reappearance ratio was independently associated with SIOIRI after adjusting for baseline NIHSS,baseline hypoperfusion volume and antiplatelet drug usage(OR,0.124;95% CI,0.027-0.984;p=0.048).Conclusion: Venous drainage disturbance could recover after recanalization.The venous drainage disturbance was associated with cerebral injury after reperfusion,and venous drainage recovery could reduce the injuryIII Relationship between blood-brain barrier permeability(BBBP)and image observed ischemic repefusion injuryObjectives: To explore the relationship between BBBP and IOIRI.Methods: We retrospectively analyzed patients with anterior circulation large artery occlusion who received endovascular treatment,achieved recanalization and underwent CTP-1 and CTP-2 at our department from November 2013 to March 2019.Patients with CTP-1 that could not reconstruct permeability surface area product(PS)maps were excluded.IOIRI degree was defined as the volume ratio of reperfusion-injury region to reperfusion region.Severe IOIRI was defined as IOIRI>50%.CTP images were used to reconstruct CBF and PS maps.ROI of hypoperfusion area was imported into CBF and PS maps to calculate mean PS and CBF,respectively.Relative PS()was used to represent the permeability of blood-brain barrier.Then we could calculated baseline according to the formula: =(PS/CBF)* 100%.Linear regression model was used to analyze the impact factors for baseline .Binary logistic regression was used to analyze the independent predictors for SIOIRI.Results: 54 patients were finally included.Baseline was 62.83(41.95-107.08)%.Multivariate analysis showed that hypertension(standard coefficient=0.289,p=0.014),atrial fibrillation(standard coefficient=0.383,p=0.002)and larger number of absent veins at baseline(standard coefficient=0.335,p=0.005)were associated with higher baseline .Binary logistic regression analysis showed that after adjusting for baseline NIHSS,baseline hypoperfusion volume,antiplatelet drug useage and the number of absent veins at baseline,higher baseline was independently associated to SIOIRI(OR,1.022;95%CI,1.006-1.038;p=0.008).Conclusion: Baseline BBB damage was associated with cerebral injury after ischemicreperfusion in AIS patients.