The Study Of Functional Connectivity Of Hippocampus In Epilepsy Using Resting-state FMRI

Objective: To observe the changes of functional connectivity in the hippocampus of patients with epilepsy using resting-state functional magnetic resonance imaging(rsf MRI),and to summarize the pathological significance of these changes,provide more reliable imaging basis for diagnosis and treatment of epilepsy.Objects and methods: The patients with epilepsy in our hospital from 2014 to 2016 were collected.According to the clinical manifestation and the discharge characteristics of scalp EEG,the epilepsy patients were divided into two groups,17 patients with mesial temporal lobe epilepsy(m TLE)and 12 patients with benign epilepsy with centrotemporal spikes(BECT).Using the Siemens Trio Tim 3.0T magnetic resonance scanning equipment and 32 channel head coil,the structural MRI and functional MRI were collected.FMRI data preprocessing in MATLAB platform with SPM8 software to complete.The region of interest(ROI)was selected in the head of bilateral hippocampal,draw a small ball in the ROI,the central of the coordinate is ±27,-12,-17,rmm=5mm.Using the REST1.8 software to analyze the data of functional connectivity,get all the functional connectivity diagrams.The m TLE group,BECT group and normal control group were analyzed by REST1.8 software.(1)The three groups were tested in each group using one sample t-test,and observed the difference of functional connectivity intensity in each group;(2)to observe the changes of the functional connectivity between the hippocampus and the whole brain using two independent sample t-test in each two groups of the m TLE group,the BECT group and the normal control group;(3)twelve regions of interest(ROI)were selected outside the hippocampus: bilateral middle frontal gyrus,bilateral precentral gyrus,bilateral postcentral gyrus,bilateral superior occipital gyrus,bilateral caudatum and bilateral thalamus,then the correlation coefficient between the head of hippocampus and the ROIs in the three groups were calculated.The changes of functional connectivity were compared between each two groups using two independent sample t-test.It was concluded that P<0.05 was statistically significant.The statistical results of(1)and(2)are shown in the REST1.8 as the overlay template,and the statistical results are superimposed on the base map of the standard T1 structure.The statistical results are corrected by Alpha Sim,and P<0.05 has statistical significance.Results: 1.The analysis results of m TLE group,BECT group and normal control group showed that the hippocampus was positively correlated with amygdala and parahippocampal gyrus and had the highest correlation,and the other positive correlation functional connectivity brain areas were the extratemporal cortex,insula,thalamus and basal ganglia and other brain regions,the three groups were basically consistent.The hippocampus was negative correlated with the frontal lobe,parietal lobe,occipital lobe and other cortical regions.The negative activation area of the m TLE group and the BECT group was more narrowly than the normal control group,and the m TLE group was more obvious.2.Compared with the normal control group,the hippocampus and whole brain functional connectivity in m TLE group were decreased.The reduced areas of the brain included the right hippocampus,the right parahippocampus gyus,the right superior temporal gyrus,the right middle temporal gyrus,the right temporal pole,the right lenticular nucleus,the right rolandic operculum,the bilateral precuneus and the right insula.3.Compared with the normal control group,the functional connectivity between hippocampus and the whole brain of BECT was increased.The areas included bilateral supramarginal gyus,left postcentral gyrus,left central gyrus,left temporal pole-superior temporal gyrus,left lingual gyrus,right cuneus,left superior occipital gyrus,left middle cingulum gyrus and bilateral supplementary motor area.4.The m TLE group compared with BECT group,the the functional connectivity between hippocampus and whole brain was decreased.The reduced brain areas were bilateral hippocampal,bilateral parahippocampal gyrus,left postcentral gyrus,left superior temporal gyrus,bilateral rolandic poerculum gyrus,bilateral temporal pole,bilateral calcarine,right cerebellum,right insula and right middle cingulum gyrus.5.The functional connectivity between the hippocampus and the twelve ROIs: The m TLE group compared with the normal control group showed that the functional connectivity between the hippocampus and bilateral frontal lobe was decreased.The BECT group compared with the normal control group showed the functional connectivity increased between the hippocampus with the left postcentral gyrus and the left caudatum.The m TLE group compared with the BECT group showed that the functional connectivity changed in the left middle frontal gyrus,the right postcentral gyrus,the left postcentral gyrus and the left caudatum.Conclusion: 1.The hippocampus in patients with epilepsy were negative correlated with the cortex,and the area of activation was significantly narrowly than that of normal controls,and the changes of m TLE were more obvious than those of BECT.2.The changes of functional connectivity between hippocampus with the whole brain of m TLE group and BECT group were completely different.The m TLE was mainly manifested the functional connectivity decreased in the default mode network,while the BECT was showed the enhancement of brain functional activities.Compared with the BECT,the damage of m TLE showed more obviously in the default mode network and the limbic system,it may be a reason for the severity of the illness and more cognitive impairment in m TLE.3.The analysis of the functional connectivity between the hippocampus and the ROIs showed that the frontal lobe lesion of m TLE patients was more significant,and it may be associated with the cognitive impairment in patients with mTLE.