Analysis of brain volume asymmetry and clinical application in patients with temporal lobe epilepsy with hippocampal sclerosis based on automatic brain segmentation

Abstract

Objective: To analyze whole brain structural volume asymmetry in temporal lobe epilepsy with hippocampal sclerosis (TLE-HS) using automated brain segmentation technology, and to investigate the application value of this technology in the diagnosis of TLE-HS and the performance in determining the location the lateralization of epileptogenic focus. Methods: Twenty-eight patients with TLE-HS were enrolled in the First Affiliated Hospital of Zhengzhou University from April 2019 to October 2020, including 13 females and 15 males, aged ranged from 18 to 63 (30±12) years, and these patients were divided two group according to the epilepsy lateralization, left TLE-HS(LTLE-HS) group (n=11), right TLE-HS(RTLE-HS) group (n=17) and 28 normal controls [aged ranged from 18 to 49 (29±10) years]. All of these subjects underwent three-dimensional T1 weighted image (3D T1WI). The differences of brain structure and volumes in LTLE-HS, RTLE-HS and normal controls group were retrospectively analyzed, and Pearson's correlation coefficient was used to evaluate the left and right volume correlations, and effect size was used for evaluating the differences in left and right volume averages. The asymmetry index (AI) of the left and right lateral volumes in each group was also calculated and compared among the three groups. Results: Standard volumes of all structures within the brain were asymmetric in the normal controls, LTLE-HS, and RTLE-HS groups, with smaller volumes of ipsilateral hippocampus than contralateral hippocampus in both the LTLE-HS and RTLE-HS groups(0.20%±0.03% vs 0.24%±0.02%,0.21%±0.03% vs 0.25%±0.02% respectively;both P<0.001), and smaller volumes of gray and white matter of the ipsilateral temporal lobe than contralateral in the LTLE-HS group(4.41%±0.38% vs 5.01%±0.43%,1.83%±0.22 % vs 2.22%±0.14%;both P<0.001). There was a moderate to strong linear correlation (0.553<r<0. 964,all P<0.05) between left and right lateral volumes in the normal controls, LTLE-HS, and RTLE-HS groups. All three groups showed the largest effect sizes in the cingulate gyrus (The effect sizes were 3.07, 4.85 and 4.22 in control, LTLE-HS and RTLE-HS, respectively.). The AI values of the hippocampus, temporal lobe gray matter, and temporal lobe white matter were statistically different among the three groups (-1.48±8.64 vs 15.91±10.15 vs -17.59±10.00, 7.46±2.67 vs 12.67±6.67 vs 3.67±6.15, 6.53±3.71 vs 19.91±9.85 vs 1.57±8.38;all P<0.001). Conclusion: Volumetric measurements by automated brain segmentation techniques can play an important role in preoperative assessment of TLE, and the asymmetry of brain volume may be of value in determining the localization and extent of the epileptogenic focus.