Preliminary Study Of ~1H-MRS,DWI And Language FMRI In Temporal Lobe Epilepsy

BackgroundEpilepsy is the second serious illness of the nervous system after cerebrovascular disease,it has a serious impact on the quality of life of patients. In drug refractory epilepsy, the temporal lobe epilepsy(TLE) has become the focus of the study because of the high incidence of clinical and good surgical outcome. It's evaluation of preoperative imaging studies remains one of the hot spots. With the increase of magnetic resonance field strength, signal to noise ratio ,spatial resolution and the application of advanced acquisition technology, the non-invasive evaluation of brain function playing an increasingly important role in preoperative assessment and follow-up study in epilepsy. 1H-magnetic resonance spectroscopy(1H-MRS), diffusion weighted imaging(DWI) and functional magnetic resonance imaging(fMRI) are generalized functional magnetic resonance imaging technology. 1H-MRS, DWI and fMRI were performed in a 3.0 T MR scanner. The metabolism, movement of water molecules changes of the hippocampus in patients with TLE were observed for clinical preoperative evaluation and lesion location; activation of language fMRI was analyzed to explore the impact of TLE, and provide imaging evidence for the study of plasticity and reorganization of language function. Objective1. To study the interictal 1H-MRS and DWI changes of hippocampus in patients with TLE and hippocampal sclerosis(HS), investigate the correlation between 1H-MRS and DWI, discuss the value of 1H-MRS and DWI when they reflect the changes of pathological structures of hippocampal sclerosis.2. To investigate the activation areas of the brain by fMRI study using two language tasks in normal adult subjects whose native language were Chinese and provide normal control for investigation of localizing language cortex.3. To study the difference of lateralization index and activation in bilateral inferior frontal gyrus areas(IFG) between patients with TLE and HS and normal adult subjects when they performed two language tasks, discuss the language plasticity and reorganisation in adult epileptic patients.Methods1. Twelve normal controls and twelve cases of interictal TLE patients with unilateral HS underwent both 1H-MRS and DWI study using a 3.0 T MR scanner. The NAA/(Cr+Cho) ratios, Cho/Cr ratios and ADC values in each hippocampus were compared between patients and normal controls. The correlation between NAA/(Cr+Cho) ratios,ADC value and duration of epilepsy were analyzed.2. Twelve right-handed TLE patients and normal volunteers whose native language were Chinese participated in the study. They underwent fMRI scanning inside a 3.0 T MR scanner when performing the word generation and the verb generation task respectively. The SPM5 software was used to analyze the functional data and generate the activated brain areas of each task. The lateralization indexes(LIs) were calculated from the number of activated voxels in three regions of interest (ROI): the right and left inferior frontal gyrus(IFG), the anterior two-thirds of the hemispheres and the whole hemispheres. The number of activated voxels and the average T value of activated voxels of bilateral IFG activation between two groups were compared.Results1. When compared with controls and the contralateral side, the NAA/(Cr+Cho) ratios of hippocampus in patients with HS were significant decreased; the interictal ADC values were significant increased. A negative correlation was observed between the NAA/(Cr+Cho) ratios and ADC values in the sclerised hippocampus(r=-0.79,P=0.002),but not between the Cho/Cr ratios and ADC values. In TLE patients, ipsilateral hippocampal NAA/(Cr+Cho) ratios was negatively correlated with the duration of epilepsy (r =-0.58, P = 0.048). there was a significant correlation between ADC values and duration (r = 0.72, P = 0.007).2. The bilateral inferior frontal gyrus, anterior cingulate, supplementary motor area, left middle frontal gyrus, precentral gyrus, basal ganglia, bilateral insula, occipital lobe and cerebellum were strongly activated in both the word generation and the verb generation process. The activation brain map and lateralization indexes indicated a significant left lateralized activation.3. When performing the two language tasks, different patterns of activation were proven within both hemispheres between the patients and the controls. Significant differences were found in the values of the language LIs between the investigated groups in each ROI. Compared with the controls, the number of activated voxels in left inferior frontal gyrus(LIFG) of patients were decreased, the average T value of activated voxels in LIFG were lower. And compared with the controls, the number of activated voxels in right inferior frontal gyrus(RIFG) of patients were increased, the average T value of activated voxels in RIFG were higher.Conclusion1. These data suggest that NAA / (Cr+Cho) ratios decreased and ADC values increased in the sclerised hippocampus in interictal period, there was a significant negatively correlation between the NAA/(Cr+Cho) ratios and ADC values. And they were both correlated with duration of epilepsy. 1H-MRS and DWI capture partially complementary aspects of hippocampal pathology and the course development noninvasively in vivo.2. Left hemisphere was dominant activated in the processing of word generation and verb generation in Chinese. The Broca's area was effectively highlighted by both of the two tasks above-mentioned. These data suggest that fMRI can be one of feasible methods for investigation of localizing language cortex preoperatively.3. The values of the language LIs were significantly decreased in TLE patients. The activation was reduced in LIFG and increased in RIFG. Our results support the hypothesis of a significant interhemispheric functional reorganization of language-related neuronal networks in left TLE, the right inferior frontal gyrus may play a compensatory role in the reorganization of language function.4. 1H-MRS, DWI, fMRI technology may provide useful information for non-invasive assessment changes of pathology or cognitive function in TLE patients in vivo.