A Research On Patients With Temporal Lobe Epilepsy From Diffusion Tensor Imaging

Temporal lobe epilepsy(TLE)in patients with abnormal white matter microstructure abnormalities in the brain area and abnormal changes in white matter network is to clarify the law of the abnormal changes in brain structure,the key to cognitive dysfunction,and it is also an important basis for accurate clinical diagnosis and effective treatment.In this paper,brain diffuse tensor imaging(DTI)was collected from 22 TLE patients and 28 healthy controls(NC).The fractional anisotropy(FA),mean diffusivity(MD),axial diffusivity(AD),radial diffusivity(RD)were calculated,and the tract-based spatial statistics(TBSS)were used to analyze the brain differences between TLE and NC.Then,the two-sample t-test and recursive feature elimination(RFE)were used to select the important features,and the patients with temporal lobe epilepsy and healthy subjects were classified by the linear support vector(SVM).Finally,the distribution of important brain regions was analyzed and discussed.The results showed that compared with NC group,the FA measures of the TLE group decreased significantly in the corpus callosum,superior longitudinal fasciculus,corona radiata,external capsule,internal capsule,inferior fronto-occipital fasciculus,fasciculus uncinatus and sagittal stratum,which were nearly bilaterally distributed,while the MD and RD increased significantly in most of these brain regions of the TLE group.Although the AD also increased,the differences were not statistically significant.The SVM-TBSS classifier obtained accuracies of 82%,76% and 76% using the FA,MD and RD for classification,respectively,and 80% using combined measures.However,the SVM-RFE could acquire accuracies of 90%,90% and 92% using the FA,MD and RD in discrimination,while the highest accuracy was 100% using combined measures.It demonstrated that the SVM-RFE outperformed the SVM-TBSS.According to the number of selection and weight ranking of important brain regions acquired by the SVM-RFE.The characteristics of the forefront were located on the left superior fronto-occipital fasciculus,fornix,right cingulum(hippocampus),right superior cerebellar peduncle,right posterior corona radiate,bilateral retrolenticular part of internal capsule,right superior longitudinal fasciculus,right anterior limb of internal capsule,right superior corona radiate.In addition,the network of white matter structure was constructed by deterministic fiber tracing technique.The connectivity and topological properties of brain tissue white matter network between TLE group and NC group were analyzed.The results showed that compared with NC group,node connectivity of FA white matter network is abnormal in the pontine crossing tract,splenium of corpus callosum,left cerebral peduncle,right corticospinal tract,bilateral anterior limb of internal capsule,right sagittal stratum,right retrolenticular part of internal capsule.The genu of corpus callosum,body of corpus callosum,left medial lemniscus,left cerebral peduncle,right anterior limb of internal capsule,bilateral retrolenticular part of internal capsule,bilateral anterior corona radiata,left posterior thalamic radiation,left external capsule,left cingulum(cingulate gyrus)and left sagittal stratum in the MD white matter network connectivity is abnormal;RD white matter network node connectivity abnormal brain area is locate in the body of corpus callosum,splenium of corpus callosum,left medial lemniscus,left cerebral peduncle left anterior limb of internal capsule,left posterior limb of internal capsule,right retrolenticular part of internal capsule,bilateral anterior corona radiata,left posterior thalamic radiation,bilateral sagittal stratum,left cingulum(cingulate gyrus)and so on.The global efficiency and small world properties of the white matter network of the TLE group was lower than the NC group,and the shortest path length is higher.Compared with NC group,there is no significant difference in the clustering coefficient of FA white matter network,the clustering coefficients of the MD and RD white matter networks were increased.It is no significant difference in the clustering coefficient of MD white matter network,and the local efficiency of FA and RD white matter networks were not increased.In this paper,we used tract-based spatial statistics,support vector machine and deterministic fiber tracing to study the changes of microstructure of white matter in patients with temporal lobe epilepsy.The results showed that temporal lobe epilepsy in the corpus callosum,the superior longitudinal fasciculus,corona radiata,internal capsule,middle cerebellar peduncle,sagittal stratum and other brain area anatomical abnormalities,and the brain area of white matter network connectivity abnormalities is also basically distributed in these brain areas,mainly in the associative fiber and commissural fiber.The results of this study not only confirmed the temporal lobe epilepsy of white matter damage exists in a wide range of brain structure,but also confirmed that TLE is a functional and structural damage to the network disease.The results of the brain area can help to study the development of TLE network,more in-depth understanding the pathophysiology,lesion positioning and automatic diagnosis of TLE mechanism.