Magnetic Resonance Imaging Of Collateral Circulation In Intracranial Arterial Stenosis

Part 1: The correlation analysis between cerebral small vessel disease burden and the collateral circulation in acute ischemic strokeObjective: The correlation between cerebral small vessel disease(CSVD)burden and collateral circulation and remaining antegrade flow in acute ischemic stroke(AIS)reached different conclusions.We utilized perfusion-based collateral quantitative method to analyze the relationship between CSVD burden and collateral circulation and antegrade flow after stroke onset.Methods: This study prospectively enrolled patients with AIS within 24 h after symptom onset.All patients underwent 3D pseudo-continuous arterial spin labeling with post-labeling delays(PLDs)of 1.5s and 2.5s.CSVD was evaluated regarding four separate features: white matter hyperintensity,perivascular space,lacunes and cerebral microbleed.Total CSVD burden(t SVD score)was calculated.The mean cerebral blood flow(CBF)of the middle cerebral artery territory was calculated and recorded.Collateral perfusion was defined as(CBF 2.5s-CBF 1.5s)at lesion side minus(CBF 2.5s-CBF 1.5s)at normal side as the quantitative value of collateral circulation and antegrade flow.Results: From 2018.11 to 2020.3,a total of 682 patients with AIS from nine centers were enrolled in this study.According to the inclusion and exclusion criteria,eighty patients with anterior circulation AIS were finally analyzed after screening.Compared with patients with no CSVD burden(N = 26),those with any CSVD(N = 54)showed higher incidence of hypertension(χ2 = 9.5,p = 0.002)and smoking history(χ2 = 5.09,p = 0.02).In addition,patients with any CSVD demonstrated lower CBF at PLDs 2.5s(t = 2.44,p = 0.02)and collateral perfusion(t = 3.11,p = 0.03).Multi-variable linear regression showed that t SVD score could serve as one independent variable to reflect collateral perfusion(b =-1.37,p = 0.005).Among the four separate features of CSVD,the collateral perfusion was lower in patients with lacunes compared to those without(F = 5.23,p = 0.03).Conclusion: The current study indicated that the t SVD score could serve as an independent factor to reflect the collateral perfusion after stroke onset.Furthermore,patients with lacunes tend to show poor collateral perfusion than those without.This study could help clinicians to distinguish patients with AIS who were at higher risk of developing poor collaterals.Part 2: The correlation analysis between cerebral small vessel disease burden and the collateral circulation in symptomatic intracranial large vessel stenosisObjective: We sought to identify whether the cerebral small vessel disease(CSVD)burden correlates with collateral circulation and antegrade flow in patients with symptomatic intracranial large vessel severe stenosis or occlusion.Methods: In this retrospective study,all included patients underwent 3D pseudo-continuous arterial spin labeling with post-labeling delays(PLDs)of 1.5s and 2.5s.The total CSVD burden was assessed by four separate features: white matter hyperintensity,perivascular space(PVS),lacunes and cerebral microbleed.Total CSVD burden(t SVD score)was calculated.Cerebral blood flow(CBF)of middle cerebral artery territory was calculated.Collateral perfusion was defined as(CBF 2.5s-CBF 1.5s)at lesion side minus(CBF 2.5s-CBF 1.5s)at normal side as the quantitative value of collateral circulation and antegrade flow.Results: From 2015.10 to 2019.12,a total of 809 patients with cerebrovascular disease were admitted into our institution.Ninety-one patients with symptomatic anterior circulation severe stenosis or occlusion met the inclusion criteria and included into analysis.Compared with patients with no CSVD burden(N = 24),those with any CSVD(N = 67)were older(t =-2.56,p = 0.01),and showed higher incidence of diabetes mellitus(χ2 = 10.71,p = 0.001).Furthermore,the mean CBF at PLDs 1.5s and 2.5s in patients with any CSVD was lower than those without CSVD(t = 2.05,p = 0.04;t = 3.19,p = 0.002).Collateral perfusion was significantly correlated with t SVD score in univariate linear regression(b =-1.19,p = 0.04).However,the correlation disappeared in multivariate model(b =-0.61,p = 0.36).As to the four separate features,collateral perfusion was significantly different among PVS grades(F = 3.76,p = 0.03).Conclusion: Our results suggested that collateral perfusion was not related with total CSVD burden in anterior circulation stenosis.However,PVS may affect the collateral perfusion after a relatively long time from symptom onset,which might present as a potential biomarker and possible therapeutic target.Part 3: Ivy sign in Moyamoya disease reflecting leptomeningeal collaterals: a comparative study of the FLAIR vascular hyperintensity sign against contrast-enhanced MRIObjective: The ability of the ivy sign on contrast-enhanced T1-weighted MR(CEMR)and fluid-attenuated inversion recovery(FLAIR)to reflect cerebral perfusion in Moyamoya disease(MMD)remained largely unknown.This,we aimed to compare the capabilities of these two modalities for reflecting leptomeningeal collaterals.Methods: From 2018.9-2019.2,forty-four MMD patients(79 hemispheres)were included in this study.The ivy sign was scored separately on CEMR and FLAIR(FLAIR vascular hyperintensity,FVH)using the Alberta Stroke Program Early CT Score.The status of leptomeningeal collaterals was scored on digital subtraction angiography(DSA).Mean cerebral blood flow(CBF)of the middle cerebral artery territory was calculated automatically.Results: Correlation analyses revealed that DSA score was more consistent with the CEMR-based ivy sign score(r = 0.25,p = 0.03)than with FVH(r = 0.05,p = 0.65).The CEMR-based ivy sign score was significantly correlated with CBF in late-Suzuki stage MMD(t =-2.64,p = 0.02).Conclusion: In this study,CEMR outperformed FLAIR in capturing ivy sign in MMD.In addition,the CEMR-based ivy sign score provided adequate information on hemodynamic status.The current study suggested that CEMR could be considered as an alternative to FLAIR in future studies investigating leptomeningeal collaterals in MMD.Part 4: The relationship between Ivy sign at baseline and post-EDAS neoangiogenesis in Moyamoya diseaseObjective: The ability of ivy sign on fluid attenuated inversion recovery(FLAIR)and contrast-enhanced T1-weighted MR(CEMR)to predict postoperative neoangiogenesis after encephalo-duro-arterio-synangiosis(EDAS)in Moyamoya disease(MMD)is still unknown.Methods: From 2018.9 to 2019.5,twenty-eight patients(40 hemispheres)were consecutively enrolled in this study.The ivy sign was scored on both FLAIR(FLAIR vascular hyperintensity,FVH)and CEMR according to the Alberta Stroke Program Early CT Score.The leptomeningeal collaterals was assessed and scored on digital subtraction angiography(DSA).All patients underwent EDAS after examination.The postoperative Matsushima grades was evaluated at least 3 months after surgical revascularization.Results: There was significant difference of symptom onset(ischemic/hemorrhagic onset)between good postoperative neoangiogenesis and poor neoangiogenesis groups(χ2 = 7.36,p = 0.03).Correlation analysis showed significant relationship between FVH/CEMR-based ivy sign score at baseline and postoperative Matsushima grades(ρ = 0.34,p = 0.03;ρ = 0.33,p = 0.04).Logistic regression showed that the CEMR-based ivy sign score at baseline was significantly related with neoangiogenesis after surgical revascularization(OR,1.48;95% CI,1.05-2.09,p = 0.03).Conclusion: This study found that the FVH and CEMR-based ivy sign score significantly correlated with postoperative Matsushima grades.Furthermore,the CEMR-based ivy sign score could be considered as one potential predictive factor for neoangiogenesis.The current results could contribute to the evaluation of patients before surgery,patient selection for surgery and prediction of postoperative effect.