Abnormalities Of Anatomy And Function In Patients With Ischemic Cerebrovascular Diseases:A Multi-modal MRI Study

Ischemic Cerebrovascular Disease(ICVD)has become one of the major diseases that cause death or disability in our country.Multi-modal MR images allow researchers to explore the abnormal brain mechanisms from different perspectives.The purpose of this thesis is to explore the abnormalities of brain anatomy and function in patients with ICVD by multi-modal MRI.It contains two studies,which separately explore two common ICVD clinical types: ischemic stroke(IS)and transient ischemic attack(TIA).Ischemic stroke can cause permanent brain damage,various serious complications,and even death.Most of the previous researches split the structure and function of the brain.The studies exploring structural abnormalities did not continue to explore the related function damages.The researches exploring functional abnormalities was based on the pre-selected function networks rather than the real structural damage.The main purpose of study 1 is to combine the exploration of brain structural and functional abnormalities in patients with ischemic stroke through multi-modal MRI,to explore the effects of IS on patients more comprehensively.This study enrolled a total of 14 ischemic stroke patients with basal ganglia infarction and 15 genderand age-matched healthy controls.The group difference of gray matter volume(GMV)between two groups was obtained by voxel-based morphometry(VBM),which were then chosen as seed for functional connectivity(FC)analysis.Compared with healthy subjects,IS patients showed significant GMV reduction in bilateral thalamus,and significant decreased FC between right orbital-frontal cortex and thalamus.Those structural and functional abnormalities in the brain of IS may lead to post-stroke depression.It also indicates that ischemic stroke not only causes structural damage,but also the related functional impairments which may not be detected by conventional MRI.Transient ischemic attack is a high-risk factor of stroke.However,in clinical practice,the majority of TIA patients with cerebral nerve damage lack the appropriate imaging to confirm,especially the very little research on structural MRI,which is not enough to understand the abnormal brain structure changes in TIA patients objectively and comprehensively.Therefore,study 2 aimed to analyze various morphological indicators with voxel-and surface-based morphometry(SBM)using structural MRI,which could complete a comprehensive and systematic exploration of the brain structural abnormalities in TIA patients.In this study,a total of 51 TIA patients and 40 ages-and gender-matched healthy controls were recruited.The gray matter volume in two groups was obtained by VBM.The cortical thickness,sulcal depth,Gyrification index(GI)and fractal dimension(FD)in two group were obtained by SBM.The results showed that compared with healthy subjects,TIA patients showed significant GMV reduction in the right middle frontal gyrus,right superior frontal gyrus,right orbitofrontal and left superior temporal gyrus.They also showed FD increase in bilateral postcentral and left orbital-frontal cortex and GI increase in left superior middle frontal gyrus.These findings suggested that the brain structure of TIA patients has changed,even the clinical symptoms last only a few minutes or hours,and these changes may strongly be linked to the clinical symptoms of TIA.