Structural And Functional Evaluation Of Motor Network In Relaping Remitting Multiple Sclerosis: A Functional Connectivity MRI And Diffusion Tensorimaging-fiber Tractography Study

Objective:To find the characteristic of funcitional connectivity and structure in resting-statemotor network,and to analyze the correlation between them, meanwhile investigatingthe probable mechanism combined with clinical assessment parameters, by means ofthe functional connectivity magnetic resonance imaging and diffusion tensor imagingfiber tractography.Methods:1.25patients been clinically diagnosed as relaping remitting multiple sclerosisin our hospital were called the RRMS group,gived EDSS score,25healthy volunteerswere recruited as the control group. All the subjects were given the the resting-statefunctional magnetic resonance imaging and diffusion tensor imaging scans.2.The maps of seed-based functional connectivity,the functional connectivitycoefficients value(Fc) and diffusion tensor patameters value that were meandiffusivity(MD) and fractional anisotropy(FA)were recieved, with the functionalconnectivity. Analysis of two-sample t-test was used for the statistical analyses aboutfunctional connectivity and diffusion tensor patameters.Combined with Clinicallyrelevant parameters,Pearson-test was used for correlation statistical analyses aboutcorresponding variables.Results:1.The positive activated brain areas in the one sample t test map of functionalconnectivity were mainly distributed in bilateral precental and postcentalgyrus,bilateral supplementary motor area,either based the left primary motor cortex(M1) seed or the the left primary motor cortex(M1) seed,which were almostly sameas typical of motor cortical area (P<0.001).The result were homologous in thecontrol group and MS group.2.Compared with the control group,the enhancement areas of functionalconnectivity based the left M1seed in RRMS group were the occipital lobe, superior frontal lobe and the right supramarginal gyrus, the weakened areas were the cingulate,bilateral parahippocampal gyrus,and right cerebellar posterior lobe(P<0.05);Theenhancement areas of functional connectivity based the right M1seed in RRMSgroup were temporal lobe,the left inferior frontal gyrus and the left supramarginalgyrus,the weakened areas were mainly distributed in the right superior frontal gyrus(P<0.05).3.The LPM-RSPL connection coefficient has statistics difference between thecontrol group and RRMS group in the resting-state motor network(P=0.012),theremaining connection coefficients had no statistical significance.4.Compared with the control group. RRMS group had the statistically significantdecreased FA value of motor network tracer fiber in the LSMA(P=0.001),RPreCG(P=0.016),RSMA(P=0.003),RSPL(P=0.009),and LSMA-RSMA(P=0.008)area,whilestatistically significant increased MD value of motor network tracer fiber in theLSMA(P=0.002), RPreCG(P=0.013),RSPL(P=0.046).5.The functional connectivity and MD value, and FA value of LSMA-RSMAtracer fiber showed no statistically significant correlation(r=-0.031,P=0.838;r=0.062,P=0.683); The functional connectivity of RRMS group motor network hubs andEDSS, and lesion count showed no statistical significance(r=0.046,P=0.227;r=0.069,P=0.066);The MD value of motor network modestly correlated with EDSS(r=0.302,P<0.001),it showed no statistically significant correlation with lesion counts(r=0.061,P=0.477);The FA value of motor network modestly correlated with EDSS (r=-0.211,P=0.013),showed modest correlation with lesion count (r=-0.21,P=0.014).Conclusion:1、There was true active motor network in the resting state brain.Theresting-state motor network areas were mostly same as the anatomic areas of themotor cortex.2、RRMS group showed abnormal functional connectivity in some conductionpathways areas of the brain,mainly including the cingulate gyrus and parahip-pocampal gyrus.The reinforced functional connectivity of scattered cerebrum areassuggested the compensation function of the brain.3、The statistically significant differences between the control group’s functional connectivity coefficients among the motor network hubs and the RRMSgroup’s were minimal,suggesting the functional connectivity of RRMS group’sresting-state motor network was not almostly changed.The cause may be the braincompensatory function of RRMS group that was in disease remission state mostly.4、RRMS showed widespread abnormalities in the microstructure of motornetwork tracer fiber,suggesting extensive demyelination and axonal loss in pathology.5、The structure parameters value of motor network tracer fiber modestlycorrelated with EDSS,presumably suggested the changes of the microstructure maycause the abnormalities in motor conduction pathway and then affect the motorfunction;The FA value of motor network tracer fiber modestly correlated withEDSS,suggesting the myelin integrity motor network tracer fiber can be affected bylesion count.