Application Of Resting State FMRI To Brain Dysfunctions In Patients With Transient Ischemic Attack

Transient ischemic attack(TIA)is an acute episode of reversible temporary neurologic dysfunction caused by transient ischemia of the cerebral artery or retina.Despite the transient episodes of clinical symptoms,patients with TIA may exhibit different degrees of cognitive impairment.Moreover,TIA is an important risk factor for eventual stroke or silent stroke.Therefore,detection of brain abnormality resulted from TIA is important for early diagnosis and intervention of stroke.However,the ischemia affect the brain functional mechanisms in TIA is still unclear.Resting-state functional magnetic resonance imaging(rs-fMRI)is a commonly used brain imaging method to investigate the changes in human brain.In recent years,it has been increasingly used in the study of various brain diseases.In the current study,we employed rs-fMRI to explore the brain functional abnormalities in patients with TIA.In this study,we aim to explore the functional abnormality of the brain in patients with TIA.In study 1,we performed functional connectivity(FC)to explore the functional abnormalities within DMN in patients with TIA.Specially,we sought to determine whether and how TIA disrupts the FC within DMN and whether associations exist between these FC alterations and clinical characteristics of the TIA patients.Further,we examined whether these FC abnormalities could predict future ischemic attacks in the patients in a year.Our findings showed that the decreased FC were observed between mPFC and left MTG/AG,PCC/Pcu and left MTG/AG,mPFC and right Pcu,mPFC and left PCC,right Pcu and left PCC.The FC alterations between mPFC and left PCC was predictive to future ischemic attacks in TIA patients.Moreover,no significant correlation was found between these alterations and clinical/physiological/biochemical characteristics in TIA patients.In study 2,we adopted three voxel based rs-fMRI analysis metrics(amplitude of low frequency fluctuation(ALFF),regional homogeneity(ReHo)and degree centrality(DC))to research brain functional alterations in TIA,and to research the relationship between these abnormalities(if observed)and clinical/physiological/biochemical characteristics scores.Further,we examined whether these abnormalities could predict future ischemic attacks in the patients in a year.The results exhibited disrupted brain function in TIA patients that ALFF in left MTG/AG and DC in TP-RIF were significantly lower than healthy controls.There was a significant group difference in ALFF on left MTG/AG between TIA patients with and without future ischemic attacks in 1 year.No significant correlation was found between these alterations and clinical/physiological/biochemical characteristics in TIA patients.Collectively,these findings highlight the emergence of brain functional alterations in TIA with resting state FC and voxel based rs-fMRI analysis metrics,which may aid in guiding diagnostic and therapeutic decisions for stroke.