Multimodal CT And MR Imaging For Early Warning Of Ischemic Stroke

ObjectiveTo explore the application value of multimodal CT and MR imaging in early warning of acute ischemic stroke(AIS)in patients with chronic cerebral circulation insufficiency(CCCI).MethodsPatients with CCCI of anterior circulation were retrospectively analyzed and divided into two groups: a total of 30 cases in the non-AIS group and a total of 19 cases in the AIS group.Clinical baseline data were collected.The degree of intracranial and extracranial artery stenosis was evaluated by CT angiography(CTA).Cerebral perfusion parameters were obtained by brain CT perfusion(CTP)and arterial spin labeling(ASL)imaging,including cerebral blood flow(CBF),cerebral blood volume(CBV),mean transit time(MTT),time to peak(TTP),time to maximum of the residual function(Tmax),time to drain(TTD)and relative values(r CBF,r CBV,r MTT,r TTP,r Tmax,r TTD).Difference test was used to analyze the differences of baseline characteristics between the two groups,and the differences of perfusion parameters between different degrees of vascular stenosis in the non-AIS group.Paired t-test,intraclass correlation efficient(ICC)and Bland-Altman method were used to evaluate the consistency between ASL and CTP.Binary logistic regression was used to screen the influencing factors of AIS.Receiver operating characteristic curve(ROC)was used to analyze the efficacy of CTP parameters in diagnosing AIS,and the combined diagnostic efficacy based on Tmax and TTD.Results1.Except for the factor of alcohol consumption(P = 0.033),there was no statistically significant difference in clinical baseline characteristics between the two groups.2.ASL-r CBF and CTP-r CBF had good consistency: paired t-test(P = 0.101),ICC =0.880(P < 0.001),all cases were within the 95% limits of agreement(Lo As)and were not beyond clinical tolerance.3.Tmax and TTD were statistically different between severely stenose-occluded blood vessels and lightly or moderately stenotic blood vessels(P values were 0.023,0.022 and0.035,0.026).ASL-CBF only had a statistical difference between severe stenosis-occlusion and mild stenosis(P = 0.034).4.After adjusting for multiple factors such as age and gender,the degree of vascular stenosis(OR = 2.240,P = 0.017)and alcohol consumption(OR = 9.035,P = 0.034)were independent risk factors for AIS in CCCI patients.5.The r CBF and r CBV were the most effective in diagnosing AIS,and the best cut-off value of r CBF was 21%.There was no statistically significant difference in the area under the curve(AUC)between the diagnosis of r Tmax alone,r Tmax combined the degree of vascular stenosis,r Tmax combined the degree of vascular stenosis and alcohol consumption(P values were 0.793,0.793,0.567).Similarly,there was no statistical difference between r TTD and the two combined diagnoses(P values were 0.683,0.480,0.591).ConclusionMultimodal CT and MR imaging can be a reliable examination method for early warning of ischemic stroke,as follows:1.ASL is expected to become a non-invasive,non-radiation,and non-contrast medium perfusion method to replace CTP,which can be used to monitor changes in cerebral hemodynamics when vascular stenosis progresses rapidly.2.Tmax and TTD are sensitive imaging biomarkers that reflect the ability of cerebral blood flow reserve in the pre-ischemic stroke.3.The degree of vascular stenosis assessed by CTA is an independent risk factor for AIS in CCCI patients.4.The r CBF and r CBV are conducive to the early diagnosis of AIS.