Multi-delay PCASL-based Leptomeningeal Collateral Perfusion Analysis In Patients With Middle Cerebral Artery Stenosis Or Occlusion

Background and purposeThe high incidence of ischemic stroke(63%in low-and middle-income countries)and mortality(57%in low-and middle-income countries)is a global health problem.Intracranial atherosclerotic stenosis or occlusion is an important cause of ischemic stroke.The incidence of middle cerebral artery stenosis in stroke patients is 7.0%～17.7%.According to reports,the recurrence rate of patients with symptomatic cerebrovascular stenosis(>70%stenosis)after treatment is 23%.The hemodynamics of patients with middle cerebral artery atherosclerosis stenosis or occlusion is extremely complex,and accurate and quantitative assessment of cerebral blood perfusion information and collateral circulation in the stenosis area has important guiding significance for early clinical diagnosis,disease progression,treatment decision,and prognosis evaluation。Arterial spin labeling(ASL)is a newer magnetic resonance perfusion imaging technology that uses water molecules in arterial blood as an endogenous tracer for labeling imaging,which has the advantages of safety,non-invasiveness,no need for external contrast agents,high repeatability and so on.patients with intracranial atherosclerotic stenosis have slowing down of blood flow and the establishment of collateral circulation,their arterial transit time(ATT)is relatively prolonged,ASL with single post-labeling delay(PLD)or inversion time(TI)is not sensitive to ATT,so it will underestimate cerebral blood flow(CBF).Multi-delay ASL using multiple PLDs or Tls can quantify ATT and improve the accuracy of hemodynamic quantification,and several studies had indicated that the CBF is more consistent with DSC-PWI,which is better than the ASL with single PLD or TI.In this study,Multi-delay pCASL was used to obtain CBF,ATT,CBV by setting 5 PLDs to evaluate leptomeningeal collateral perfusion in patients with MCA stenosis or occlusion and patients with stenting.The relationship between degrees of MCA stenosis and leptomeningeal collateral perfusion was analyzed,and the leptomeningeal collateral perfusion before and after a stent in patients with MCA stenosis was evaluated.Materials and MethodsThe study recruited 112 patients with MCA stenosis or occlusion who attended the Department of Neurology and Neurointervention of the First Affiliated Hospital of Zhengzhou University from 2018.10 to 2020.06.All patients underwent a head scan,TOF-MRA,Multi-delay pCASL,and 2D high-resolution MRI(HRMRI)examinations.The degree of MCA stenosis was measured on TOF-MRA and 2D HRMRI according to warfarin-aspirin symptomatic intracranial disease(WASID).Using 2D HRMRI as a reference,according to the North American Symptomatic Carotid Endarterectomy(NASCET),they are divided into groups:mild stenosis group(0～49%stenosis,n=30),moderate stenosis group(50%～69%stenosis,n=27),severe stenosis group(70%～99%stenosis,n=29),occlusion group(100%stenosis,n=26);23 patients with MCA stenosis had a stent,and they were divided into pre-and post-operative.The Multi-delay pCASL data is transmitted to the Beijing Animage Brain Cloud Computing(ABCC)through the Siemens syngo workstation for post-processing to obtain CBF,ATT,and CBV.Statistical analysis was performed using SPSS 17.0.Continuous variables are expressed as mean±standard deviation.Shapiro-Wilk was used to test for normal distribution of continuous variables,and paired data were analyzed by paired t-test.P<0.05 considered the difference to be statistically significant.Results1.The CBF values of the main blood supply areas and ASPECTS of the patients with MCA stenosis or occlusion were lower than those of the healthy side.There were statistically significant in the CBF values between the main blood supply areas(Lepto AC A、MCA Perf、Lepto PCA、Lepto MCA)and the ASPECTS(Caudate、M1)in the severe stenosis and occlusion groups.2.The ATT values of the main blood supply areas and ASPECTS of the patients with MCA stenosis or occlusion were higher than those of the healthy side.The difference in ATT values between the main blood supply areas(MCA Perf、Lepto MCA)and the ASPECTS(Caudate、M1、M2)in the mild-to-moderate stenosis group was statistically significant;and between the main blood supply areas(Lepto ACA、MCA Perf、Lepto PCA、Lepto MCA)and the ASPECTS(Caudate、Internal capsule、M1、M2、M3)in the severe stenosis and occlusion groups were statistically significant.3.The CBV values of the main blood supply areas and ASPECTS of the patients with MCA stenosis or occlusion were higher than those of the healthy side.The difference in CBV values between the main blood supply areas(MCA Perf、Lepto MCA)and the ASPECTS(Caudate、M1、M2)in the mild-to-moderate stenosis group was statistically significant;and between the main blood supply areas(Lepto ACA、MC A Perf、Lepto PC A、Lepto MCA)and the ASPECTS(Caudate、M1、M2)in the severe stenosis and occlusion groups were statistically significant.4.For pre-operative,the CBF values of the main blood supply areas and the ASPECTS of the affected side were lower than those of the healthy side,and the CBV and ATT values were higher than those of the healthy side,there were statistically significant in the CBF,ATT and CBV values of the affected side of the main blood supply areas(Lepto ACA、MCA Perf、Lepto PC A、Lepto MCA)and the ASPECTS(Caudate、Internal capsule、M1、M2、M3);For post-operative,only the CBF,ATT and CBV values of the ASPECTS(M1)had statistically significant.5.For post-operative,the CBF and CBV values of the main blood supply areas and ASPECTS of the affected side were higher than those of pre-operative,and the ATT values were lower than those of pre-operative.There are statistically significant differences in the CBF,ATT and CBV values of the main blood supply areas(Lepto AC A、MCA Perf、Lepto PCA、Lepto MCA)and ASPECTS(Caudate、M1、M2).Conclusions1.In patients with MCA stenosis or occlusion,leptomeningeal collateral perfusion in the main blood supply areas and ASPECTS is proportional to the degree of stenosis.2.Time-based ATT is more sensitive to cerebral hemodynamic changes in patients with MCA stenosis or occlusion than CBF and CBV.3.Multi-delay pCASL can identify leptomeningeal collateral perfusion pre-and post-operative in patients with MCA stenosis.