Hippocampal Metabolic Heterogeneity In Healthy Volunteers And Patients With Temporal Lobe Epilepsy:proton Magnetic Resonance Spectroscopy -Initial Findings

Objective:To explore the differences of metabolic ratios in hippocampus along its an- teroposterior axis in healthy youths,elders and paitents respectively.And to study the differences of metabolitic ratios between groups of healthy youths and elders, health- y youths and patients using the proton magnetic resonance spectroscopy.Materials and methods: 38 healthy volunteers(20 youths,18 elders) and 16 patient with surgical pathology comfirmed unilateral temporal lobe epilepsy(the surgical side of temporal lobe was defined as ipsilateral,the symmetric side was defined as contralateral) were performed multi-voxel magnetic resonance spectroscopy. The hippocampus was divided into 4 parts in average along its anteroposterior axis. The ratios of NAA/(Cho+Cr),NAA/Cho,NAA/Cr in each part of all subjects were calculated. Then, the results were compared between young group and elder group, young group and contralateral group, young group and ipsilateral group, contralateral group and ipsilateral group. Finally, correlation analysis was conducted in each group to study the position-related of the ratios of NAA/(Cho+Cr),NAA/Cho,NAA/Cr along anteroposterior axis of hippocampus.Results: The ratios of NAA/(Cho+Cr),NAA/Cr,NAA/Cr in healthy volunteers of hippocampus showed no significant gender-related differences and no significant bilateral differences(P>0.05). In young group,mean value and standard deviation of NAA/(Cho+Cr ) ,NAA/Cho,NAA/Cr ratios of hippocampal forefront part were 0.60±0.07,1.20±0.15,1.22±0.15,respectively,that of hippocampal last part were 0.75±0.04,1.44±0.09,1.56±0.08,respectively;In older group,mean value and standard deviation of NAA/(Cho+Cr),NAA/Cho,NAA/Cr ratios of hippocampal forefront part were 0.54±0.11,1.02±0.29,1.23±0.41,respectively,that of hippocampal last part were 0.68±0.07,1.28±0.11,1.53±0.43, respectively;In contralateral group,mean value and standard deviation of NAA/(Cho+Cr),NAA/Cho,NAA/Cr ratios of hippocampal forefront part were 0.57±0.03,1.12±0.09,1.20±0.09,respectively,that of hippocampal last part were 0.72±0.02,1.43±0.08,1.47±0.11,respectively;In ipsilateral group, mean value and standard deviation of NAA/(Cho+Cr ) ,NAA/Cho,NAA/Cr ratios of hippocampal forefront part were 0.43±0.09,0.78±0.22,1.03±0.23,respectively,that of hippocampal last part were 0.65±0.06,1.22±0.11,1.31±0.37,respectively.The ratios of NAA/(Cho+Cr)and NAA/Cho in young group were higher than elder group(P<0.05).The ratios of NAA/(Cho+Cr),NAA/Cho and NAA/Cr in young and contralateral group showed no significant difference(P>0.05).The ratios of NAA/(Cho+Cr),NAA/Cho and NAA/Cr in young group were higher than ipsilateral group(P<0.05).The ratios of NAA/(Cho+Cr)and NAA/Cho in contralateral group were higher than ipsilateral group(P<0.05).The ratios of NAA/(Cho+Cr),NAA/Cho and NAA/Cr in four groups were positively correlated with the position of hippocampus(P<0.05).The ratios of NAA/(Cho+Cr),NAA/Cho and NAA/Cr of the forefront part in each group were higher than that of last part of hippocampus(P<0.05).Conclusion: 1H-MRS could reflect varieties of anteroposterior hippocampal meatabo- lites in normal adults from different ages and patients with temporal lobe epilepsy no- ninvasively ,provide objective basis for early diagnosis of some hippocampal lesions.