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The purpose of this study was to estimate the gamma-aminobutyric acid (GABA) and glutamate plus glutamine (Glx) concentrations in the cortical tubers of patients with tuberous sclerosis complex (TSC) using the MEGA-editing J-difference method and a stimulated echo-acquisition mode with a short echo time, and to determine which abnormality was more dominant between GABA and Glx in patients with TSC with epilepsy. This study included six patients with TSC (mean age, 4.3 years) and seven control subjects (mean age, 4.8 years). Measurements were obtained with a three-Tesla apparatus and postprocessing was conducted with an LCModel. The GABA level in the cortical gray matter (cgGABA) was calculated as a result of segmentation in voxels and from the literature values for gray and white matter ratios for GABA. Increased GABA and myo-inositol (mI) concentrations and a decreased N-acetyl aspartate (NAA) concentration were observed in the cortical tubers. The cgGABA level, and cgGABA/NAA and cgGABA/Glx ratios were also higher in patients with TSC than in control subjects. No significant difference was found in Glx concentration between patients with TSC and control subjects. Although the number of patients with TSC in this study was small, the increase in GABA and no significant change in Glx were consistent with previous neurochemical studies and support the hypothesis that brain GABA plays a key role in the pathophysiology of epilepsy during the process of neuronal development.

We report 2 patients of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and consider the pathophysiology of stroke-like lesions, using magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI) on MRI, perfusion imaging on MRI, and 1H magnetic resonance spectroscopy (1H-MRS). In Patient 1, T2-weighted imaging (T2-WI) on MRI at onset and even at 44 days after onset of the stroke-like episode showed high intensity in left parietal, temporal, and occipital lobe lesions. In the temporal lobe lesion, the apparent diffusion coefficient (ADC) at 44 days after onset was higher (average: 1.219x10(-3)mm2/s) than that in a normal region (average: 0.796x10(-3)mm2/s). (1)H-MRS of the left parietal lobe lesion at the same day showed a decrease in N-acetylaspartate/(creatine+phosphocreatine) (NAA/Cr) (0.43) and a peak in lactate. 1H-MRS of the contralateral side at the same day showed NAA/Cr (1.57) and no peak in lactate. Thereafter, ADC gradually decreased and NAA/Cr gradually increased, and the peak in lactate disappeared in the lesion. In Patient 2, T2-WI at onset showed high intensity in bilateral occipital lobe lesions. In the left occipital lobe lesion, ADC at the same day was higher (1.082x10(-3)mm2/s) than that in a normal region (average: 0.841x10(-3)mm2/s). (1)H-MRS of the left occipital lobe lesion at the same day showed a decrease of NAA (3.0mM) and a peak in lactate (13.1mM) (measured by LCModel). In 1H-MRS of the normal left parietooccipital lobe at 4 months before onset, NAA was 7.6mM and there was no peak in lactate (0mM). Perfusion imaging at onset showed high intensity in bilateral occipital lobes, which indicated hyperperfusion in stroke-like lesions. Thereafter, ADC gradually decreased and the peak in lactate partially decreased, and the low concentration of NAA persisted (regardless of the partial recovery) in the lesion. These results suggest that the stroke-like episodes is related to vasogenic edema, hyperperfusion, and neuronal damage. Acute oxidative phosphorylation defect may have a crucial role in the pathophysiology of stroke-like episodes.

Objective: There has been reports on the usefulness of diffusion tensor imaging (DTI) about age-or disease-related degradation. DTI is generally evaluated by the region of interest (ROI) methodology. In this study, we applied a statistical way using Statistical Parametric Mapping (SPM) to assess normal aging by DTI and compared results of these two methods.Methods: Ten young and ten senior normal volunteers were examined. On SPM, tensor images were changed into normalized tensor images. They were compared between the two groups by t-test.Results: In the senior group, fractional anisotropy (FA) values were higher on the basal ganglia, cingulated gyrus and other cortical gray matter, lower in the corona radiata, internal capsule, centrum semiovale and corpus callosum by using SPM. In the ROI method, the results were almost compatible except in the brain periphery.Conclusions: Aging changes on water diffusion anisotropy was clearly shown by SPM method which would be useful to evaluate change of water diffusion anisotropy without operator bias even in clinical setting instead of ROI measurement. J. Med. Invest. 52: 186-190, August, 2005