Investigate Brain Network Topological Property Changes In The Early Stage Of Mild Traumatic Brain Injury,a Study Based On MRI

Objective:To explore the changes of topological properties of the brain networks based on DTI and BOLD data from patients with mild traumatic brain injury(mTBI)in early stage.Materials and methods:A prospective case-control study admitted by the medicine ethics committee of medical college of Xiamen university.It began in November 2014 in the southeast hospital affiliated of xiamen university,and ended in August 2015.Inclusion criteria:clinical diagnosis of mTBI(GCS score 13-15 points);Right-handed;Cooperate with a check.Exclusion criteria:All the patients performed DTI scan and BOLD scan.within 1 week after injury.Meanwhile,subjects who matched in age and gender of the mTBI group were choosen as healthy control group.Two groups were scaned the same sequences with the same parameters.DTI data analysis were processed by PANDA software.The cerebral white matter fiber network was constructed by the fractional anisotropy matrix.BOLD data analysis were processed by DPARSF software.The functional network was constructed by the correlation between time series.we finally analyzed brain structural and functional network topology characteristics based on the graph theory.Two sample t-test was used to compare the differences of brain network characteristic parameters,such asy,?,?,Cp(clustering coefficient),Lp(short path length),Eloc(local efficiency),Eg(global efficiency),module value Q(modularity),Be(betweenness),node degree and node efficiency.Results:We collected 22 mTBI patients including 16 male and 6 female.Average age was 40.68± 12.50 years;14 cases were in the control group,including 9 male and 5 female.The average age was 41.57±15.42 years.mTBI group and the control group both showed small-world network topological characteristics,accordingto the basic characteristics of small world network:?>>1,??1,?>>1.There was no statistical difference(p>0.05)between ?,???,Cp,Be;Ki and Qof the two groups.Eg,Eloc and Lp had significant difference(p<0.05)in mTBI group compared with normal control group.Eg decreased in sparse degree threshold between 0.05?0.4.Eloc decreased in sparse degree threshold between 0.1 to 0.4.and Lp increases(sparse degree:0.05?0.4).Within the scope of the preset sparse degree,the module value had no statistical significance between the two groups.Local effect of structure nodes between two groups was also different.Node degree in mTBI group decreased in left inferior frontal opercularisgyrus,left medial frontal gyrus,left rectusgyri,left caudate nucleus and right heschl's gyri(p<0.05).There was decreased node efficiency(p<0.05)in right frontal dorsolateral gyrus,left orbital frontal gyrus,bilateral inferior frontal opercularis gyrus,right supplementary motor area,bilateral medial frontal gyrus,left orbital frontal gyrus,leftrectusgyri,left hippocampus,left surrounding cortex of calcarine sulcus,left superior parietal lobule,left caudate nucleus,right thalamus,right heschl's gyri and left inferior temporal gyrus.As for the functional network constructed by BOLD data,in the preset threshold range 0.05?0.15,mTBI group and the control group both show small world network topological characteristics,which according to the basic characteristics of small world network.? and ? had no statistical difference between two groups(p>0.05);? had statistical significant differece between threshold range 0.05?0.07(p<0.05).In the preset threshold range 0.05?0.15,Eg and Cp decreased,but there were no statistical significance(p>0.05).In the the threshold range 0.31?0.40,Eloc declined and Lp increased(0.05<p<0.1).Within thethreshold range 0.05?0.15,Q and Be had no statistically significant difference(p>0.05).Functional nodal effect between the two groups were also different.Compared with normal control group,the obital part of right inferior frontal gyrus,left medial frontal gyrus,left medial orbital frontal gyrus,left anterior cingulateand paracingulate gyri,left angular gyrus,left precuneus,right superior temporal gyrus,bilateral middle temporal gyrus and right superior temporal gyrus had changes in node degree,node efficiency and betweenness(p<0.05).Among them,the left orbital part of inferior frontal gyrus and left medial frontal gyrus had decreased node degree,low efficiency and betweenness(p<0.05).In the left medial orbital frontal gyrus,node degree,node efficiency and betweenness increased(p<0.05).In the left insula,right precuneus,left caudate nucleus,left putamen,bilateral pallidus and bilateral temporal pole:superior temporal gyrus,these brain regions had changes in node degree and node efficiency(p<0.05).Conclusion:1.The brain networks of mTBI patients constructed by DTI and BOLD data were proved to both have small world properties.2.Eloc and Eg of the structural network in mTBI group decreased than the control group,while there was no statitical difference in the functional network.It suggested a compensate for structural injuries to keep the brain processing information in a normal level.3.In mTBI Patients,some brain regions which had structural and functional changed nodal effect mainly distribute in the frontal lobe,temporal lobe and basal ganglia region.These structural and functional changes may be related with PCS,PTA and post-traumatic mental state...