Functional And Structural Changes In Putamen Of Relapsing-remitting Multiple Sclerosis: A MRI Study

Objective:Using resting-state functional MRI (rs-fMRI) and diffusion tensor imaging (DTI)to evaluate the resting functional connectivity（FC）and structural change of thebilateral putamen in patients with relapsing remitting multiple sclerosis (RRMS),investigating the probable mechanism combined with clinical assessment parameters.Methods:1.20patients been clinically diagnosed as relaping remitting multiple sclerosisin our hospital were called the RRMS group，gived EDSS score and PASAT score，20healthy volunteers were recruited as the control group, gived EDSS score andPASAT score as well．All the subjects were given the the resting state functionalmagnetic resonance imaging and diffusion tensor imaging scans．2. Using data processing assistant for resting state fMRI(DPARSF2.1) tool toprocess the fMRI data, based on matrix laboratory (MATLAB7.8.0) platform.Choosed left/right putamen as regions of interest(ROIs) respectively, done seed-base the correlation analysis(SCA) between ROIs with the whole brain, got the valuesof functional connectivity(FC) by doing pearson correlation analysis and built thefunction connectivity diagram.3. To preprocess and compute the data of DTI, quantitative parameters of DTI[including feature vectors, the fractional anisotropy(FA) and the diffusion parameters]by using Diffusion Toolkit0.6.2and TrackVis0.5.2. Extracted fiber track throughthe bilateral putamen, obtained the value of track density,mean diffusivity(MD),fractional anisotropy(FA) and the vector-values of dispersion ellipsoid which presentthe characteristics of different directions of diffusion, includingλ1、λ2，λ3.4. 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 about the functional, structural changes and clinical parameters in patients with RRMS.Results:1. Compared with HCs group, FC in the RRMS group between left putamenand the left middle frontal gyrus, the right inferior frontal gyrus, the left inferiorparietal lobule increased; FC between left putamen with the bilateral limbic lobes, theleft parahippocampal gyrus, the left middle temporal gyrus decreased; FC betweenright putamen with the left superior frontal gyrus, the left inferior temporal gyrus, theleft limbic lobe decreased.2. Compared with healthy controls, MD values of bilateral putamen withRRMS rised significantly (t=4.896, P <0.001, t=4.671, P <0.001); FA valuesdecreased significantly (t=3.012, P=0.004; t=2.822, P=0.007). λ3values risedsignificantly (t=4.024, P <0.001, t=3.869, P <0.001); λ2value of the left putamenrised significantly (t=4.174, P <0.001), the track density（t=-1.307，P=0.197；t=0.111，P=0.912），λ1values(t=0.238, P=0.813; t=0.174, P=0.863) of bilateralputamen and λ2value of the right putamen (t=1.861, P=1.861) had no statisticaldifference.3. The FC of the left putamen-left middle frontal gyrus with RRMS had asignificantly positive correlation with the course of the disease（r=0.628, P=0.628）;the decreased FC of the right putamen-left inferior temporal gyrus with RRMS had asignificantly negative correlation with the MD value of the left putamen（r=0.46, P=0.46）. The correlation of the FA value and λ2value in right putamen and the numberof lesions was significant statistically(p=0.039; p=0.001).There were no correlationsbetween the the rest brain regions having abnormal FC,the related parameter value ofDTI, the course of the disease, the number of Lesions, the EDSS score and thePASAT score (all P>0.05).Conclusion:1. There were abnormal FC between bilateral putamen with the whole brain,the change of functional connectivity in RRMS patients may be related to motor andcognitive dysfunction. 2. The MD values and FA values of bilateral putamen with RRMS rised anddecreased significantly, separately, the vector-values of dispersion ellipsoid such asλ2,λ3was changed as well.This pointed out that there might be pathological changesof microscopic structure in bilateral putamen of RRMS.3. The correlation of the FA value and λ2value in the right putamen with thenumber of lesions was significant statistically,it might owing to having damage inafferent and efferent pathway caused by the development of white matter lesions.4. The abnormal FC(FC value)of the left putamen had significant correlationwith the course,implayed that the different period of MS had different FC pattern, theabnormal FC(FC value)of the right putamen had significant correlation with the MDvalue of the left putamen, prompted the structural abnormality is the basis of theabnormal functional connectivity.