Identification of abnormal neuronal metabolism outside the seizure focus in temporal lobe epilepsy

PURPOSE: The aim of this study was to identify metabolically abnormal extrahippocampal brain regions in patients with temporal lobe epilepsy with (TLE-MTS) and without (TLE-no) magnetic resonance imaging (MRI) evidence for mesial-temporal sclerosis (MTS) and to assess their value for focus lateralization by using multislice 1H magnetic resonance spectroscopic imaging (MRSI). METHODS: MRSI in combination with tissue segmentation was performed on 14 TLE-MTS and seven TLE-no and 12 age-matched controls. In controls, N-acetylaspartate/(creatine + choline) [NAA/(Cr+Cho)] of all voxels of a given lobe was expressed as a function of white matter content to determine the 95% prediction interval for any additional voxel of a given tissue composition. Voxels with NAA/(Cr+Cho) below the lower limit of the 95% prediction interval were defined as "pathological" in patients and controls. Z-scores were used to identify regions with a higher percentage of pathological voxels than those in controls. Results: Reduced NAA/(Cr+Cho) was found in ipsilateral temporal and parietal lobes and bilaterally in insula and frontal lobes. Temporal abnormalities identified the epileptogenic focus in 70% in TLE-MTS and 83% of TLE-no. Extratemporal abnormalities identified the epileptogenic focus in 78% of TLE-MTS but in only 17% of TLE-no. Conclusions: TLE is associated with extrahippocampal reductions of NAA/(Cr+Cho) in several lobes consistent with those brain areas involved in seizure spread. Temporal and extratemporal NAA/(Cr+Cho) reductions might be helpful for focus lateralization.     

Metabolic characteristics of cortical malformations causing epilepsy

Purpose Cortical malformations (CMs) are increasingly recognized as the epileptogenic substrate in patients with medically refractory neocortical epilepsy (NE). The aim of this study was to test the hypotheses that: 1. CMs are metabolically heterogeneous. 2. The structurally normal appearing perilesional zone is characterized by similar metabolic abnormalities as the CM. Methods Magnetic resonance spectroscopic imaging (MRSI) in combination with tissue segmentation was performed on eight patients with NE and CMs and 19 agematched controls. In controls, NAA, Cr, Cho,NAA/Cr and NAA/Cho of all voxels of a given lobe were expressed as a function of white matter content and thresholds for pathological values determined by calculating the 95% prediction intervals. These thresholds were used to identify metabolically abnormal voxels within the CM and in the perilesional zone. Results 30% of all voxels in the CMs were abnormal, most frequently because of decreases of NAA or increases of Cho. Abnormal voxels tended to form metabolically heterogeneous clusters interspersed in metabolically normal regions. Furthermore, 15% of all voxels in the perilesional zone were abnormal, the most frequent being decreases of NAA and Cr. Conclusion In CMs metabolically normal regions are interspersed with metabolically heterogeneous abnormal regions. Metabolic abnormalities in the perilesional zone share several characteristics of CMs and might therefore represent areas with microscopic malformations and/or intrinsic epileptogenicity.     

Proton spectroscopic imaging shows abnormalities in glial and neuronal cell pools in frontal lobe epilepsy

PURPOSE: Proton magnetic resonance spectroscopic imaging (1H MRSI) can lateralize the epileptogenic frontal lobe by detecting metabolic ratio abnormalities in frontal lobe epilepsy (FLE). We used 1H MRS to lateralize and localize the epileptogenic focus, and we also sought to characterize further the metabolic abnormality in FLE. METHODS: We measured signals from N-acetyl aspartate (NAA), choline-containing compounds (Cho), and creatine + phosphocreatine (Cr) in the supraventricular brain of 14 patients with frontal or frontoparietal epilepsy and their matched controls. The supratentorial brain also was segmented into gray matter, white matter, and cerebrospinal fluid classes. Regional metabolite alterations were compared with localizing and lateralizing results from other examination modalities and with histology from three patients. RESULTS: Spectroscopy lateralized the epileptogenic focus in 10 patients in agreement with video-EEG and functional imaging. In four patients, spectroscopy showed bilateral, focal metabolic abnormality, whereas video-EEG suggested unilateral or midline abnormality. In the epileptogenic focus, Cho and Cr were increased by 23% and 14%, respectively, and NAA was decreased by 11%, suggesting metabolic disturbances both in the glial and in the neuronal cell pools. Two Taylor dysplasia lesions confirmed by histology and one with radiologic diagnosis showed high Cho and low or normal NAA, whereas two dysembryoplastic neurogenic tumors had normal Cho and low NAA. Contralateral hemisphere NAA/(Cho + Cr) was decreased in FLE, indicating diffusely altered brain metabolism. Segmentation of brain tissue did not reveal atrophic changes in FLE. CONCLUSIONS: Spectroscopy is useful in lateralizing frontoparietal epilepsy and shows promise as a "noninvasive biopsy" in epileptogenic lesions.     

Spectroscopic evidence of hippocampal abnormalities in neocortical epilepsy

Lesional neocortical epilepsy (NE) can be associated with hippocampal sclerosis or hippocampal spectroscopic abnormalities without atrophy (dual pathology). In this study, magnetic resonance spectroscopic imaging (MRSI) was used to determine the frequency of hippocampal damage/dysfunction in NE with and without structural lesion. Sixteen patients with NE [seven temporal NE (NE-T), nine extratemporal (NE-ET)] and 16 controls were studied with a 2D MRSI sequence (Repetition time/echo time (TR/TE) = 1800/135 ms) covering both hippocampi. Seven NE patients had MR visible lesions (NE-Les), nine had normal MRI (NE-no). In each hippocampus, 12 voxels were uniformly selected. In controls, mean (+/- SD) NAA/(Cr + Cho) values for each voxel were calculated and voxels with NAA/(Cr + Cho) < or = (mean in controls--2SD in controls) were defined as 'pathological' in patients. Eight of 16 NE patients had at least two 'pathological' voxel (mean 2.5, range 2-5) in one hippocampus. Four were NE-Les and four NE-no. Three (43%) NE-T patients, had evidence for hippocampal damage/dysfunction and five (56%) had NE-ET. The ipsilateral hippocampus was affected in six of eight NE patients. Evidence for unilateral hippocampal damage/dysfunction was demonstrated in 50% of the NE patients. The type of NE, i.e. NE-Les or NE-no, NE-T or NE-ET, had no influence on the occurrence of hippocampal damage/dysfunction.     

Spectroscopic metabolic abnormalities in mTLE with and without MRI evidence for mesial temporal sclerosis using hippocampal short-TE MRSI

PURPOSE: Long echo time (TE) spectroscopy reliably identifies the epileptogenic hippocampus in mesial temporal lobe epilepsy. Short-TE spectroscopy gives additional metabolic information but may have more artifacts. The aim of this study was to test (a) lateralization of the seizure focus by short-TE spectroscopy, and (b) value of myoinositol (MI) in the identification of the epileptogenic hippocampus. METHODS: Twenty-four patients with temporal lobe epilepsy: 16 with mesial temporal sclerosis (TLE-MTS), eight patients with normal magnetic resonance imaging (MRI; TLE-No), and 16 controls were studied with hippocampal 2D short-TE magnetic resonance spectroscopic imaging (MRSI). RESULTS: In TLE-MTS, the ipsilateral N-acetylaspartate (NAA) was decreased compared with contralateral (p = 0.03) or controls (p = 0.007). Additionally, the ipsilateral MI was decreased compared with controls (p = 0.012). TLE-No values showed no side differences and were not different from controls. Abnormalities in the anterior hippocampus correctly lateralized the epileptogenic hippocampus in 相似文献   

Measures of hippocampal volumes, diffusion and 1H MRS metabolic abnormalities in temporal lobe epilepsy provide partially complementary information

We assessed whether interictal measures of hippocampal volume, hippocampal diffusion and metabolic abnormalities yield correlated or complementary information about hippocampal pathology in patients with temporal lobe epilepsy (TLE). Volumes, apparent diffusion coefficients (ADC) and ratios of N-acetyl-aspartate (NAA) to Creatine/Phosphocreatine (Cr) and Choline (Cho) were measured from each hippocampus during one magnetic resonance imaging (MRI) session in patients with TLE. Structural MRI showed unilateral hippocampal sclerosis (HS) in 13 patients and was normal in the remaining nine patients. Pearson's correlation (two-tailed) between ADC values and NAA/(Cr + Cho) ratios was significant (P = 0.04, r = -0.45) for the hippocampus ipsilateral to the epileptogenic zone as determined on the basis of interictal and ictal scalp EEG recordings. This finding was driven by a very high correlation between the two measures in the presence of HS (P < 0.001, r = -0.96). Furthermore, ipsilateral ADC values but not NAA/(Cr + Cho) ratios were correlated with disease duration (P = 0.001, r = 0.67). Hippocampal volumes did not correlate with either ADC values, NAA/(Cr + Cho) ratios or disease duration. These data suggest that hippocampal volumes, NAA/(Cr + Cho) ratios and ADC values capture partially complementary aspects of hippocampal pathology.     

Spatial extent of neuronal metabolic dysfunction measured by proton MR spectroscopic imaging in patients with localization-related epilepsy

SUMMARY: PURPOSE: To assess the spatial extent of the decrease in the neuronal marker N-acetyl-aspartate (NAA) relative to creatine (Cr) in patients with localization-related epilepsy, and to assess clinical differences between patients with and without widespread NAA/Cr reduction. METHODS: We studied 51 patients with localization-related epilepsy. Patients were divided into three groups according to the EEG investigation: (a) temporal lobe epilepsy (TLE, n = 21), (b) extratemporal lobe epilepsy (extra-TLE, n = 20), and (c) multilobar epilepsy (patients with a wider epileptogenic zone, n = 10). We acquired proton magnetic resonance (MR) spectrocopic imaging (1H-MRSI) of temporal and frontocentroparietal regions in separate examinations for both patients and controls. NAA/Cr values 2 standard deviations below the mean of normal controls were considered abnormal. RESULTS: Twenty-three (45%) patients including 12 with TLE had normal MR imaging including volumetric studies of the hippocampus. Forty-nine (96%) patients had low NAA/Cr, indicating neuronal dysfunction in either temporal and/or extratemporal 1H-MRSIs; 38% of patients with TLE and 50% of patients with extra-TLE also had NAA/Cr reduction outside the clinical and EEG-defined primary epileptogenic area. The NAA/Cr reduction was more often widespread in the multilobar group [six (60%) of 10] than in temporal or extratemporal groups [five (31%) of 16]. Nonparametric tests of (a) seizure duration, (b) seizure frequency, and (c) lifetime estimated seizures showed no statistically significant difference (p > 0.05) for TLE and extra-TLE patients with or without NAA/Cr reduction outside the seizure focus. CONCLUSIONS: Of patients with localization-related epilepsy, 40-50% have neuronal metabolic dysfunction that extends beyond the epileptogenic zone defined by clinical-EEG and/or the structural abnormality defined by MRI.     

颞叶癫(癎)与磁共振质子波谱及利物浦(癎)性发作严重程度量表的研究

目的 评价磁共振质子波谱扫描与利物浦癎性发作严重程度量表对颞叶癫癎的诊断价值。方法 采用磁共振成像和质子波谱对15例颞叶癫癎患者及15例健康志愿者进行检测，并用量表对患者做进一步评估。结果 癫癎组病侧NAA/（Cr＋Cho）比值明显低于对侧以及正常组（P〈0.01），后二者比较差异无显著性（P〉0.05）；病侧NAA/（Cr＋Cho）比值与LSSS2.0评分分数呈显著正相关（r=0.969，P〈0.05）。结论 磁共振质子波谱较磁共振成像更能早期、准确地反映癫癎的脑损伤，LSSS2.0评分与NAA/（Cr＋Cho）比值能一致反映脑损伤的严重程度。     

Seizure frequency and bilateral temporal abnormalities: a proton magnetic resonance spectroscopy of temporal lobe epilepsy.

Proton magnetic resonance spectroscopy ((1)H-MRS) was performed in seven healthy volunteers and 17 patients with temporal lobe epilepsy (TLE) to clarify the correlation of the severity of epilepsy with bilateral temporal changes in N-acetylaspartate (NAA), choline-containing compounds (Cho) and creatine + phosphocreatine (Cr). Despite unilateral EEG focus, bilateral temporal reduction in NAA /(Cho + Cr) was revealed in patients with intractable seizures. The potential for seizure generation correlated with the NAA /(Cho + Cr) reduction not only on the ipsilateral side but also on the contralateral side. Proton MRS proved to be a useful measurement for obtaining important information about the neuronal changes as well as the lateralization of the epileptogenic focus in TLE patients.     

精神分裂症患者前额叶和丘脑的质子磁共振波谱研究

Objective To identify the metabolite levels in prefrontal lobe and thalamus in patients with schizophrenia by proton magnetic resonance spectroscopy (1H-MRS). Methods Thirty-eighty schizophrenics and 38 normal controls were involved in this study. A multi-voxel 1H-MRS was given to all the subjects on prefrontal lobe and thalamus within 24 hours they got in hospital. The N-acetylaspartate (NAA), choline-congtaining compounds (Cho), and creatine compounds (Cr) were measured and the ratios of NAA/Cr, Cho/Cr and NAA/( Cho + Cr) were determined Results In left prefrontal lobe and bilateral thalamus, the NAA/Cr ratio in patients demonstrated lower than that in normal controls ( all P <0. 05). In left prefrontal lobe, the NAA/(Cho + Cr) ratio in patients showed lower than that in normal controls (0. 64 ±0. 13 vs. 0. 74±0. 22,t =2. 26, P<0. 05). Both in patients and in normal controls, there were no significant differences in NAA/Cr, Cho/Cr and NAA/(Cho + Cr) between the two sides (all P >0. 05). Conclusious Abnormalities in neuronal function and/or integrity are present in schizophrenics.There is no significantly lateralized asymmetry for metabolite levels such as NAA, Cho and Cr in either the schizophrenics or the controls.     

颞叶癫痫患者磁共振质子波谱与脑电图的关系

目的 探讨颞叶癫痫患者的磁共振质子波谱(1H-MRS)与动态脑电图和MRI之间的关系.方法 对入组的38例颞叶癫痫患者均行1H-MRS、常规MRI和动态脑电图检测,以16例健康儿童作为对照.根据MRI结果进行分组:单、双侧海马硬化组及非海马硬化组,计算各组病灶侧和病灶对侧的NAA/(Cr+Cho)、NAA/Cr和NAA/Cho并进行比较,同时分析脑电图中癫痫样放电情况.结果 38例患者中有14例MRI发现海马硬化(比例 为36.8%),31例1H-MRS异常(比例为81.6%),双侧、单侧海马硬化组病灶侧和病灶对侧及非海马硬化组病灶侧的上述3个指标均高于正常对照组(P＜0.05);38例患者中有27例动态脑电图异常,27例动态脑电图异常中有17例与1H-MRS的定位一致,二者的符合率为62.9%.结论 1H-MRS较MRI诊断海马硬化及对癫痫灶定侧的敏感性高;1H-MRS和动态脑电图在癫痫灶的定位中具有一致性.     

Quantitative 1H MR spectroscopic imaging in early Rett syndrome

OBJECTIVE: To determine cerebral regional concentrations of N-acetyl aspartate (NAA), total choline (Cho), and total creatine (Cr) in Rett syndrome (RS) using 1H magnetic resonance spectroscopic imaging (MRSI). BACKGROUND: The biochemical defect underlying RS is unknown. Because in vivo MRSI can detect important cerebral metabolites, MRSI has a potential to reveal impairment of regional cerebral metabolism in RS noninvasively. METHODS: High-resolution, multislice 1H MRSI was carried out in 17 girls with RS. The control group consisted of nine healthy children. RESULTS: In patients with RS, average Cho concentration was 12% higher (p < 0.005) and average NAA concentration 11% lower (p < 0.0001) compared with the control group. Regional metabolic differences included significantly lower NAA concentration in the frontal gray and white matter, insula, and hippocampus in RS; no difference in regional Cho and Cr concentrations were found. A 20 to 38% higher Cho:NAA ratio in frontal and parietal gray and white matter, insular gray matter, and hippocampus (p < 0.05) and a 14 to 47% lower NAA:Cr ratio in frontal cortical gray matter, parietal and temporal white matter, insula, and putamen (p < 0.05) were found in subjects with RS compared with controls. Patients with seizures had higher average concentrations of Cho, Cr, and NAA compared with those without seizures (8-19%, p < 0.05). CONCLUSION: Metabolic impairment in RS involves both gray and white matter and particularly involves frontal and parietal lobes and the insular cortex. Loss of NAA most likely reflects reduced neuronal and dendritic tree size; increased Cho concentration may result from gliosis.     

Choline is increased in pre-lesional normal appearing white matter in multiple sclerosis

OBJECTIVE: Our aim was to determine if the resonance intensity of choline-containing compounds (Cho) measured using proton magnetic resonance spectroscopy (MRS) was increased in pre-lesional normal appearing white matter (NAWM) in patients with multiple sclerosis (MS) relative to NAWM that remained stable in subsequent scans. BACKGROUND: The Cho peak in MR spectra is associated with membrane phospholipids and increases in acute MS plaques, possibly even before the appearance of MRI-visible MS lesions. METHODS: Three combined proton MRI and MRS imaging examinations of the corpus callosum and adjacent periventricular white matter were performed on 12 MS patients at intervals of 6 months. Proton density (PD) images were visually matched across 3 time points and the lesion volume in each voxel of the volume of interest was determined. The voxels were subdivided into four groups based on the presence or absence of lesion at baseline and change or no change in lesion volume on the subsequent scan. RESULTS: We found a significantly higher baseline Cho/Creatine (Cr) ratio in NAWM voxels that displayed MRI visible lesions 6 months later than NAWM voxels that remained unchanged (1.57 +/- 0.30 and 1.37 +/- 0.33, respectively, p < 0.001). The 12-month interval data revealed similar pre-lesional elevated Cho/Cr, (1.51 +/- 0.29 versus 1.39 +/- 0.32, p = 0.009). Voxels that contained lesion at baseline and increased in lesion volume at 6 months also showed a significantly higher Cho/Cr ratio than those whose lesion volume did not change (1.60 +/- 0.32 and 1.49 +/- 0.36, respectively, p = 0.043). CONCLUSIONS: The results of this study are consistent with focal pre-lesional myelin membrane pathology in the NAWM at least 12 months before lesions become visible on conventional MRI. This could reflect altered myelin chemistry or the presence of inflammation as seen in experimental allergic encephalomyelitis.     

Combined MR measurements of magnetization transfer,tissue diffusion and proton spectroscopy. A feasibility study with neurological cases

Magnetic resonance imaging (MRI) of diffusion and magnetization transfer was combined with 1H-spectroscopic imaging (CSI) to evaluate the clinical potential of in-vivo profiles of various brain pathologies. Ten patients (multiple sclerosis, cerebrovascular disease, leukodystrophy, Alzheimer dementia) and five healthy volunteers were investigated with diffusion-weighted MRI, magnetization transfer imaging, and CSI. Proton spectra were analyzed as ratios of NAA/Cr and Cho/Cr calculated from the peak areas of N-acetylaspartate (NAA), (phospho)-creatine (Cr) and choline (Cho). The apparent diffusion coefficient (ADC) and the magnetization transfer ratio (MTR) were determined in identical voxels to ensure identical partial volume effects compared to CSI. Compared to MTR and ADC assessments, the lower spatial resolution of CSI clearly indicates a hindrance at 1.5 T. In most demyelinating lesions, NAA/Cr reduction paralleled attenuated MTRs and elevated ADCs. By contrast, in acute stroke and some acute MS lesions the ADC was reduced, while MTR and NAA/Cr were also decreased. In Alzheimer's dementia, ADC was increased, MTR unchanged and Cho/Cr increased. In a case of leukodystrophy, ADC was pronouncedly increased, MTR and NAA/Cr both reduced, and Cho/Cr normal. Combined measurements of ADC, MTR and CSI are feasible and provide differential in-vivo information on various brain pathologies.     

1H MRSI predicts surgical outcome in MRI-negative temporal lobe epilepsy

1H MRS imaging (MRSI) was performed on 15 patients with MRI-negative temporal lobe epilepsy (TLE) who underwent seizure surgery. The non-seizure-free patients (NSF) ipsilateral hippocampal N-acetylaspartate (NAA)/(Cr+Cho) z scores were lower than the contralateral scores (p = 0.04), and the NSF ipsilateral z scores were lower than the seizure-free patients' (SF) ipsilateral z scores (p = 0.0049). Similarly, NSF contralateral scores were lower than contralateral SF (p = 0.02). These findings suggest NAA predicts the surgical outcome in patients with TLE without evidence of mesial temporal sclerosis on MRI.     

Proton Magnetic Resonance Spectroscopic Imaging in Patients with Extratemporal Epilepsy

Summary: Purpose: Reduced levels of N-acetylaspartate (NAA) in temporal lobes responsible for temporal lobe epilepsy have been observed consistently in proton magnetic resonance spectroscopy (MRS) studies.
Methods: We investigated the potential of proton MRS to detect low NAA outside of the temporal lobes in patients with non-lesional partial extratemporal epilepsy. Proton MR spectroscopic imaging (MRSI) data of both frontal lobes and central/postcentral regions were obtained in 20 such patients and 16 normal control subjects. The epileptogenic region was determined by an extensive clinical-EEG investigation, including the recording of habitual seizures in each patient, and intracranial EEG recordings in 10 patients.
Results: The relative NAA resonance intensities (i.e., NAN/phosphocreatine plus creatine (CR_t), NAN/choline-containing metabolites (Cho_t) and NAA/Cr_t+ Cho_t), were all significantly reduced throughout the spectroscopic image as compared with that of the controls. Furthermore, reduction of the NAA ratios was greater in the epileptogenic region as compared with the nonepileptogenic regions, on EEG investigation.
Conclusions: In vivo proton MRSI of patients with nonlesional partial extratemporal epilepsy detected evidence of widespread neuronal damage or dysfunction that was greatest in the region of seizure focus.     

颞叶癫痫的磁共振波谱学定侧研究

目的　探讨磁共振波谱学 (magneticResonanceSpectroscopy ,MRS)在颞叶癫痫术前定位中的作用。方法　取 18例接受手术治疗的顽固性颞叶癫痫患者为研究对象 ,其术前已接受EEG、MRI和PET等检查获得定位。接受双侧颞叶内侧的MRS检查 ,测定其N -乙酰天门冬氨酸 (NAA)、肌酐 (Cr)和胆碱 (Cho)含量 ,并计算NAA/(Cr Cho)的比值 ;以NAA/(Cr Cho) <0 .6 8和双侧NAA/(Cr Cho)比值的差别 >7%为标准。结果　在18例病例中 16例患侧颞叶MRS检查结果异常 ,其中 9例为患侧MRS异常 ,7例为双侧MRS异常 ,以患侧为重 ,2例患者的比值正常 ;MRS的敏感性高于MR(15 /18) ,与MR结合 ,可对 17例患者进行术前定侧。结论　MRS对颞叶癫痫的定侧诊断有较高的准确性 ,为颞叶癫痫的定位诊断提供新的手段 ;与MRI、PET等手段结合使用 ,可进一步提高对颞叶癫痫诊断的敏感性和准确性     

Combined MR measurements of magnetization transfer,tissue diffusion and proton spectroscopy. A feasibility study with neurological cases

Abstract

Magnetic resonance imaging (MRI) of diffusion and magnetization transfer was combined with 1Hspectroscopic imaging (CSI) to evaluate the clinical potential of in-vivo profiles of various brain pathologies. Ten patients (multiple sclerosis, cerebrovascular disease, leukodystrophy, Alzheimer dementia) and five healthy volunteers were investigated with diffusion-weighted MRI, magnetization transfer imaging, and CSI. Proton spectra were analyzed as ratios of NAA/Cr and Cho/Cr calculated from the peak areas of N-acetyl-aspartate (NAA), (phospho)-creatine (Cr) and choline (Cho). The apparent diffusion coefficient (ADC) and the magnetization transfer ratio (MTR) were determined in identical voxels to ensure identical partial volume effects compared to CSI. Compared to MTR and ADC assessments, the lower spatial resolution of CSI clearly indicates a hindrance at 1.5 T. In most demyelinating lesions, NAA/Cr reduction paralleled attenuated MTRs and elevated ADCs. By contrast, in acute stroke and some acute MS lesions the ADC was reduced, while MTR and NAA/Cr were also decreased. In Alzheimer's dementia, ADC was increased, MTR unchanged and Cho/Cr increased. In a case of leukodystrophy, ADC was pronouncedly increased, MTR and NAA/Cr both reduced, and Cho/Cr normal. Combined measurements of ADC, MTR and CSI are feasible and provide differential in-vivo information on various brain pathologies.     

In vivo measurements of glutamine + glutamate (Glx) and N-acetyl aspartate (NAA) levels in human partial epilepsy

OBJECTIVE: To investigate whether cerebral levels of N-acetyl aspartate (NAA), and glutamine + glutamate (Glx), are interictally altered in the epileptogenic regions of patients with partial seizures. MATERIAL AND METHODS: NAA, Glx, creatine (Cr), choline (Cho) and myo-inositol (mI) was measured in 28 patients with partial epilepsy and 10 healthy controls using localized 1H magnetic resonance spectroscopy. According to the multimethodological consensus, the epileptogenic region was mesial temporal in 18 and neocortical in 10 patients. RESULTS: The Glx/NAA and Glx/Cr ratios in epileptogenic regions were higher, and the NAA/Cr ratios lower than in the homologous regions (P=0.013, P=0.002 and P<0.0001). Applying the 95% confidence interval of controls, 17 of the 20 mesial temporal epileptogenic regions were correctly identified by an increased Glx/NAA and 15 of 20 by a decreased NAA/Cr ratio. Among patients with neocortical epilepsy the Glx/NAA ratio was increased in 8 of the 10 epileptogenic regions, whereas the NAA/Cr ratio was decreased in three. CONCLUSION: Both Glx and NAA are useful to identify the epileptogenic zone. The Glx/NAA ratios may be particularly useful to indentify neocortical epileptogenic regions.     

Early detection and longitudinal changes in amyotrophic lateral sclerosis by (1)H MRSI

OBJECTIVE: To determine 1) the reproducibility of metabolite measurements by (1)H MRS in the motor cortex; 2) the extent to which (1)H MRS imaging (MRSI) detects abnormal concentrations of N-acetylaspartate (NAA)-, choline (Cho)-, and creatine (Cre)-containing compounds in early stages of ALS; and 3) the metabolite changes over time in ALS. METHODS: Sixteen patients with definite or probable ALS, 12 with possible or suspected ALS, and 12 healthy controls underwent structural MRI and multislice (1)H MRSI. (1)H MRSI data were coregistered with tissue-segmented MRI data to obtain concentrations of NAA, Cre, and Cho in the left and right motor cortex and in gray matter and white matter of nonmotor regions in the brain. RESULTS: The interclass correlation coefficient of NAA was 0.53 in the motor cortex tissue and 0.83 in nonmotor cortex tissue. When cross-sectional data for patients were compared with those for controls, the NAA/(Cre + Cho) ratio in the motor cortex region was significantly reduced, primarily due to increases in Cre and Cho and a decrease in NAA concentrations. A similar, although not significant, trend of increased Cho and Cre and reduced NAA levels was also observed for patients with possible or suspected ALS. Furthermore, in longitudinal studies, decreases in NAA, Cre, and Cho concentrations were detected in motor cortex but not in nonmotor regions in ALS. CONCLUSION: Metabolite changes measured by (1)H MRSI may provide a surrogate marker of ALS that can aid detection of early disease and monitor progression and treatment response.