Focal And Universal Remodeling Of The Middle Cerebral Artery

Background:Arterial Remodeling is a common phenomenon during the process of atherosclerosis in coronary arteries and peripheral arteries.The previous studies showed that there was focal expansive or constrictive remodeling in the stenotic intracranial atherosclerotic arteries.Diffuse lumen dilation was also observed in patients with cerebral small vessel diseases.3 Dimensional High Resolution Magnetic Resonance Imaging(3D HRMRI)showed advantages both in covering the whole intracranial vessels and displaying less obliqueness artifact.Objective:To explore the subtypes of arterial remodeling and its distribution along MCA within intracranial atherosclerotic disease and white matter lesions disease by 3D HRMRI.Methods:We retrospectively reviewed patients from PUMCH during 2013-2016,respectively with stenotic MCA,white matter lesions(WMLs),and control adults.Each stenotic MCA was classified as culprit artery(upstream from the cerebrovascular event)or non-culprit artery(no cerebrovascular event within its vascular territory).MCA outer wall area(OWA)was measured in the most stenotic site and reference site to calculate the remodeling ratio.Each artery of the anterior circulation was measured bilaterally by 3D HRMRI.3 points of outer wall areas were measured every other 3mm on MCA.The symmetry of anterior circulation was evaluated in control group and patients with WMLs.Vessel symmetric index(VSI)was obtained in each group by averaging the measured MCA OWA of one side over the contralateral side(VSI=meanOWAsideA/meanOWAsideB).We identified whether the stenotic MCA is diffusely expansive or constrictive compared to the contralateral non-stenotic artery by VSI.Diffuse arterial remodeling of WMLs group was studied by comparing the mean MCA OWA with control group.Results:78 study subjects were enrolled in this study,including 17 patients with WMLs(Fazekas scale 2-3),35 patients with stenotic MCA and 26 control subjects.The OWA of anterior circulation(MCA,ACA and ICA)were symmetric bilaterally within control group and WMLs group(P>0.05).The OWA of M1 segment was tapering from proximal to distal(P<0.05).Compared with the control group,patients with WMLs have a larger OWA and wall area(P<0.05).Among the stenotic MCA group,more focal expansive remodeling,larger remodeling ratio and larger OWA were associated with the culprit arteries(P<0.05).Focal constrictive remodeling was more frequent in the non-culprit arteries(P<0.05).The VSI of stenotic MCA group(0.87±0.22)was smaller than the VSI of control group(1.00±0.16)(P<0.05),which was interpreted as asymmetric constrictive pattern,meaning that the stenotic MCA tended to be diffusely more constrictive than the contralateral non-stenotic artery.Among the stenotic MCA subgroups,there was no difference of the VSI between patients with focal expansive remodeling or constrictive remodeling(P>0.05).Conclusions:1)In vivo study,the anterior circulation(AC A?MCA?IC A)was symmetric in terms of the OWA among the control group and WMLs group.The OWA of M1 segment was tapering from proximal to distal.2)Two types of arterial remodeling of intracranial arteries were observed:Diffuse expansive remodeling of MCA in patients was observed in patients with WMLs.More focal expansive remodeling was associated with the culprit arteries,whereas focal constrictive remodeling was more frequent in the non-culprit arteries(P<0.05);No matter the focal remodeling is expansive or constrictive at the stenotic site,the stenotic MCA tended to be more constrictive than the contralateral non-stenotic MCA.We speculate that hemodynamics of intracranial arteries contributes to the heterogeneities of arterial remodeling.