Application Of Multimodal Magnetic Resonance Imaging In The Diagnosis And Treatment Of Refractory Mesial Temporal Lobe Epilepsy

Part 1Study of hippocampal internal architecture in medial temporal lobe epilepsy using high field(3T)and ultra high field(7T)MRIObjective:To compare the HIA between high field(3T)and ultra high field(7T)MRI in patients with mTLE,to investigate the utility of HIA and hippocampal volume asymmetry in epilepsy lateralization,and to explore the relationship between asymmetry of HIA and hippocampal volume,and surgical outcomes.Materials and methods:Thirty-nine mTLE patients(mean age 27 ±8 years;19 females,20 males)were recruited with 3T and 7T MRI scans and a semi-quantitative assessment of the HIA was performed.Kruskal-Wallis H test was used to compare the difference of HIA scores between 3T and 7T MRI.HIA and hippocampal volume asymmetry scores were also calculated and compared.The utility of HIA and hippocampal volume asymmetry scores in epilepsy lateralization by using binary logistic regression test,and the predictive value between these two indicators were compared.In 25 patients with amygdalohippocampectomy and one-year follow-up,Kruskal-Wallis H test was used to compare the HIA asymmetry scores and hippocampal volume asymmetry scores between groups with different postoperative outcomes.Results:HIA scores of hippocampi in the ipsilateral side of epileptogenic focus were lower than those of contra-lateral ones at 3T and 7T MRI.Higher HIA scores were observed at 7T MRI on both ipsilateral and contra-lateral hippocampi compared with those at 3T MRI.The HIA asymmetry and hippocampal volume asymmetry were both strong predictors in the diagnosis of epilepsy lateralization and did not show difference in predictive value.25 patients underwent amygdalohippocampectomy and one-year follow-up.No statistical differences in HIA and hippocampal volime asymmetry were observed between seizure-free patients(ILAE 1)and patients with seizures(ILAE 2?5).Conclusions:Visualization of HIA may be improved at 7T MRI.HIA asymmetry is a significant independent predictor of laterality of seizure onset in mTLE patients and has similar predictive value as hippocampal volume asymmetry.However,HIA asymmetry at 7T does not have extra value in determining epilepsy lateralization and neither does predict surgical outcomes under the similar imaging parameters with 3T MRI.Part 2Study of brain volume and perfusion asymmetry in medial temporal lobe epilepsyObjectives:To compare the features of brain inter-ictal perfusion and volume asymmetry patents between mTLE patients with and without HS,and to explore the correlation between hippocampal perfusion and volume asymmetry,and surgical outcomes.Materials and methods:The total of 86 patients(61 with HS and 25 without HS)were recruited.Forty healthy controls were also included(mean age 27.0±6.7 years;20 female/20 male).The differences of perfusion and volume in ipsilateral and contralateral hippocampi between mTLE-HS+and mTLE-HS-groups were compared by paired Wilcoxon rank test.Kruskal-Wallis H test was used to compare the differences of perfusion and volume asymmetry index among mTLE-HS+,mTLE-HS-and HC groups.Mann-Whitney U test compared the difference of volume and perfusion asymmetry indexes in whole brain between patients with different surgical outcomes.Results:Significant differences in perfusion were found between the ipsilateral and contralateral hippocampi in mTLE-HS+and mTLE-HS-.mTLE-HS+and mTLE-HS-had higher hippocampal perfusion asymmetry index than HC.mTLE-HS+had higher hippocampal volume asymmetry index than mTLE-HS-and HC.mTLE-HS-and HC had similar hippocampal volume asymmetry index.There was no significant correlation between the asymmetry index of hippocampal perfusion and volume.mTLE-HS+presented more extensive whole-brain perfusion and volume asymmetry than mTLE-HS-.There were differences of asymmetry index in putamen volume and perfusion of inferior occipital gyrus in mTLE-HS+patients with different surgical outcomes.The perfusion asymmetry index of cuneus,precuneus,caudate nucleus and putamen showed differences in mTLE-HS-patients with different surgical outcomes.No difference in volume asymmetry index was found in mTLE-HS-with different surgical outcomes.Conclusion:mTLE-HS+and mTLE-HS-have different patterns of whole-brain perfusion and volume asymmetry.Hippocampal perfusion asymmetry is revealed in both mTLE-HS+and mTLE-HS-patients.The asymmetry of hippocampal volume and perfusion has no predictive value in the prognosis of surgical outcomes based on the cohort of our study.In mTLE-HS-group,the perfusion asymmetry of extrahippocampal is more extensive in patients with poor prognosis.Part 3Study of microstructure of brain white matter in medial temporal lobe epilepsy based on Diffusion Tensor ImagingObjectives:To explore the asymmetry features of DTI parameters in left and right mTLE(with or without HS),and the differences of preoperative WM asymmetry between patients with different surgical outcomes.The DTI parameters(FA,MD,AD,RD)were longitudinally compared before and after surgery to explore the correlation between the dynamic changes of WM fibers and surgical outcome.Materials and methods:Fift-eight mTLE patients(40 with HS and 18 without HS)were enrolled.Preoperative MRI images were collected.15 cases had MRI images 3?6 months after surgery.Forty controls(mean age 27.0±6.7years;20 female/20 male)were enrolled.The DTI parameters of 20 paried WM fibers were extracted using JHU WM tractography atlas by PANDA.Paired t-test was used to compare the bilateral standardized DTI parameters and the longitudinal changes of DTI parameters of specific fiber before and after surgery.The differences of DTI parameter asymmetry index of paired fibers were compared between different surgical outcome groups using independent sample t-testResults:The number of asymmetrical WM fibers in mTLE-HS-was fewer compared to mTLE-HS+group.The WM asymmetry patterns of left and right mTLE were different.mTLE-HS-and right mTLE-HS+groups with different surgical outcomes had similar preoperative DTI parameter asymmetry index.Differnces of asymmetry index in the FA of IFO(P=0.023)and ILF(P=0.009)in left mTLE-HS+patients were found between different surgical outcome groups.All mTLE patients had longitudinally decreased FA values in ipalateral CGH and UNC,increased MD values in ipalateral ILF,IFO and UNC,and increased RD values in ipalateral CGH,IFO and UNC.The MD values in ipalateral CGH were longitudinally increased,the RD values in ipalateral ILF,and the AD values in ipalateral ILF and UNC were longitudinally decreased in ILAE 1 patients.The FA values in ipalateral CGC and AD values in ipalateral IFO were longitudinally increased in ILAE 2?5 patients.Conclusion:The WM tracts asymmetry is more extensive in mTLE-HS+.The preoperative asymmetry index of WM fibers can predict the surgical prognosis of left mTLE-HS+patients,but not for right mTLE-HS+and mTLE-HS-patients.The longitudinal changes of WM fibers may provide clues for predicting the surgical results.