原发性颞叶内侧癫痫伽玛刀治疗后放射性坏死的MRI诊断

目的：探讨原发性颞叶内侧癫痫伽玛刀治疗后出现放射性坏死的磁共振表现。方法：搜集2002年～2009年经伽玛刀治疗原发性颞叶内侧癫痫后MRI复查出现放射性坏死患者共13例,评价其磁共振表现。结果：放射性坏死出现时间9～67个月,平均时间为26.2个月。放射性坏死的MRI表现：照射侧颞叶内部大片状长T1长T2信号,静脉注射Gd-DTPA病灶中心不规则花环状强化,周围大片水肿,占位效应明显,强化灶大于照射野,治疗后病灶可缩小。结论：原发性颞叶内侧癫痫伽玛刀治疗后放射性坏死的出现时间及其磁共振表现具有特征性,磁共振检查有助于放射性坏死的早期诊断并指导临床治疗。     

Uncinate fasciculus fiber tracking in mesial temporal lobe epilepsy. Initial findings

In temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS), ictal discharge spread to the frontal and insulo-perisylvian cortex is commonly observed. The implication of white matter pathways in this propagation has not been investigated. We compared diffusion tensor imaging (DTI) measurements along the uncinate fasciculus (UF), a major tract connecting the frontal and temporal lobes, in patients and controls. Ten right-handed patients referred for intractable TLE due to a right HS were investigated on a 1.5-T MR scanner including a DTI sequence. All patients had interictal fluorodeoxyglucose PET showing an ipsilateral temporal hypometabolism associated with insular and frontal or perisylvian hypometabolism. The controls consisted of ten right-handed healthy subjects. UF fiber tracking was performed, and its fractional anisotropy (FA) values were compared between patients and controls, separately for the right and left UF. The left-minus-right FA UF asymmetry index was computed to test for intergroup differences. Asymmetries were found in the control group with right-greater-than-left FA. This asymmetrical pattern was lost in the patient group. Right FA values were lower in patients with right HS versus controls. Although preliminary, these findings may be related to the preferential pathway of seizure spread from the mesial temporal lobe to frontal and insulo-perisylvian areas.     

MRI of the fornix and mamillary body in temporal lobe epilepsy

We performed MRI on 27 patients with clinically proven temporal lobe epilepsy (TLE), all with prior EEG lateralisation, and 10 volunteers, studied to evaluate disparity in size arising from biological variation (group 1). Three-dimensional spoiled GRASS (3DSPGR) sequences provided 2-mm contiguous sections of the limbic system, enabling assessment of the hippocampus (HC), fornix (FN) and mamillary body (MB). Measurements of FN and MB width were made from a workstation. Any percentage difference in size was computed. In 19 cases there was unilateral abnormality in the HC (group 2); in 18 and 19 cases respectively there was a smaller FN and MB on the same side as the abnormal HC. This percentage difference in size was significantly greater than that in group 1 in the FN and MB in 17 and 17 cases respectively. Comparison of percentage difference computations for FN and MB between groups 1 and 2 showed high statistical significance (P < 0.0002). In 5 patients with clinical TLE the HC was normal on MRI (group 3). Unequal FN and MB sizes were found in 4, significant in 2. Comparison of percentage difference computations for FN and MB showed statistical significance (P < 0.0005 and P < 0.0003 respectively). There was no case of discordance between the sides of hippocampal abnormality and the smaller FN or MB or between the sides of smaller FN and MB. The strong concordance between the changes in the HC and those in the FN and MB suggests that this combination will play an important role in the assessment of TLE and limbic system abnormality. Received: 12 March 1996 Accepted: 12 August 1996     

1H MR spectroscopy in histopathological subgroups of mesial temporal lobe epilepsy

The aim of the study was to analyze the lateralizing value of proton magnetic resonance spectroscopy (¹H MRS) in histopathologically different subgroups of mesial temporal lobe epilepsies (MTLE) and to correlate results with clinical, MRI and seizure outcome data. A group of 35 patients who underwent resective epilepsy surgery was retrospectively studied. Hippocampal ¹H MR spectra were evaluated. Metabolite concentrations were obtained using LCModel and NAA/Cr, NAA/Cho, NAA/(Cr+Cho), Cho/Cr ratios and coefficients of asymmetry were calculated. MRI correctly lateralized 89% of subjects and ¹H MRS 83%. MRI together with ¹H MRS correctly lateralized 100% of patients. Nineteen subjects had “classical” hippocampal sclerosis (HS), whereas the remaining 16 patients had “mild” HS. Nineteen patients had histopathologically proven malformation of cortical development (MCD) in the temporal pole; 16 subjects had only HS. No difference in ¹H MRS findings was found between patients in different histopathological subgroups of MTLE. Our results support the hypothesis that ¹H MRS abnormalities do not directly reflect histopathological changes in MTLE patients. Subjects with non-lateralized ¹H MRS abnormalities did not have a worse postoperative seizure outcome. We found no significant impact of contralateral ¹H MRS abnormality on post-surgical seizure outcome.     

MR单体素波谱和化学位移成像在颞叶癫痫中的研究

目的　应用MR氢质子波谱 (1HMRS)不同成像方法 ,包括单体素波谱 (SVS)、化学位移成像 (CSI) ,探讨1HMRS对颞叶癫痫 (TLE)的诊断价值。方法　设对照组 4 0例、颞叶癫痫组 (TLE) 2 0例。应用1HMRS分别进行海马结构 (HF)的SVS和CSI,应用SVS比较TLE患侧组、对侧组及对照组各代谢物比值 ,并行致痫灶定侧诊断。应用CSI分析TLE患侧组、对侧组及对照组HF从前到后各体素氮 乙酰天门冬氨酸 / (胆碱 肌酸复合物 ) [NAA/ (Cho Cr) ]的变化规律 ,并进行三组间、各体素间两两比较。结果　SVS示TLE组患侧组HF的NAA/ (Cho Cr) (0 4 8± 0 10 )、NAA/Cr(1 2 0± 0 19)下降 ,与对照组、对侧组 (分别为 0 71± 0 0 7、1 4 8± 0 16 ;0 6 1± 0 12、1 4 4± 0 2 3)差异有显著性意义 (F值分别为 4 1 95 8、15 5 75 ,P值 <0 0 0 0 1)。SVS对TLE定侧敏感度为 85 % ,特异度为 93%。CSI示对照组、TLE患侧、对侧组HF的NAA/ (Cho Cr)与HF部位间呈直线相关关系 ,后部较前部大 ;与正常组比较 ,患侧组前部NAA/ (Cho Cr)的降低程度较后部大。结论　SVS可帮助TLE致痫灶定侧。CSI显示HF从前到后存在NAA/ (Cho Cr)渐变现象 ,TLE患侧头部代谢改变较尾部大。在比较代谢改变时 ,保证定位于HF的相同部位很重要。     

不同MRI序列在显示颞叶内侧硬化的对照研究

目的比较各序列在颞叶内侧硬化病人显示海马信号强度增加的作用。材料与方法对３０例临床及脑电图或脑地形图诊断为颞叶癫痫的病人采用双回波常规自旋回波（ＳＥ）序列、快速自旋回波（ＦＳＥ）序列和液体衰减反转恢复（ＦＬＡＩＲ）序列进行ＭＲＩ检查，并通过目测观察和信号强度测量等方法对图像进行处理。结果ＳＥ序列质子密度加权像判别海马信号强度增加的准确度最差（４３．３％）；ＦＳＥ序列次之（６２．２％）；ＳＥ序列Ｔ２加权像和ＦＬＡＩＲ序列判别海马信号强度增加的准确度很高，且ＦＬＡＩＲ序列（８８．９％）较ＳＥ序列Ｔ２加权像（７７．８％）更为准确。结论在诊断颞叶内侧硬化方面ＦＬＡＩＲ序列有可能成为常规ＳＥ序列的替代者     

Voxel- and ROI-based statistical analyses of PET parameters for guidance in the surgical treatment of intractable mesial temporal lobe epilepsy

OBJECTIVE: Positron emission tomography (PET) can be used to locate epileptic foci in patients with mesial temporal lobe epilepsy (MTLE) by measuring multiple parameters of the brain. We investigated a series of patients with MTLE using PET measurements of three parameters: the cerebral blood flow measured with [15 O] H2O, the uptake of [18F] fluorodeoxyglucose (FDG), an index of the cerebral metabolism rate of glucose, and the distribution volume (DV) of [11C] flumazenil (FMZ), an index of the binding potential of central benzodiazepine receptor. We compared predictive values obtained from two methods: a voxel-based statistical analysis using statistical parametric mapping (SPM) and an asymmetry index obtained by placing regions of interest (ROIs) on PET images. METHODS: Preoperative PET data of 11 patients with surgically confirmed MTLE were retrospectively examined. In the voxel-based analysis, the PET data were analyzed using SPM99 by statistically comparing the voxel values of PET parameters between individual patients and the mean values of 12 normal volunteers. Voxels with values significantly lower than the normal control values were mapped on a standard brain atlas. In the ROI-based analysis, the asymmetry index was calculated to depict ROIs with abnormally decreased values when compared with the contralateral side. RESULTS: (1) Statistical parametric mapping and ROI analyses of the FDG uptake correctly determined epileptic temporal lobe in 73% and 82%, respectively. (2) The decreased DV of FMZ depicted by SPM revealed the mesial temporal pathology in 91%. CONCLUSIONS: Positron emission tomography measurement of FDG uptake was most sensitive in detecting the side of the epileptic focus. On the other hand, SPM analysis of the DV of FMZ was the most sensitive method for delineating the actual epileptic focus.     

大鼠Li-Pilocarpine癫痫模型的MRI与海马体积测量动态研究

目的 :观察Li Pilocarpine大鼠癫痫模型在慢性期出现反复自发性癫痫发作过程中MRI与海马体积的进行性变化 ,探索癫痫发生的病理生理机制。方法 :分别在成功诱发癫痫持续状态大鼠的 3小时～ 8周的不同时间点分别行MRI成像与海马体积测量 ,并与正常对照组相比较 ,观察急性期至慢性期过程中的动态变化。结果 :在急性期最早累及杏仁核、内嗅皮层和梨状皮层 ,进而出现海马的水肿。两周后出现海马的进行性萎缩 ,海马体积在慢性期萎缩至正常的 1/2左右。结论 :癫痫持续状态后的脑损伤包括多个受累部位 ,既累及海马 ,也累及其它边缘系统 ,如杏仁核和邻近的梨状皮层、内嗅皮层、丘脑及大脑皮层感觉运动区。包括海马在内的边缘系统的改变更为复杂。     

海马测量对颞叶癫痫的研究

目的 :探讨MRI海马测量对颞叶癫痫的诊断价值。方法 :正常成人对照组 2 0例 ,测量海马体积 ;脑电图检查发现颞叶有癫痫波的患者 2 8例 ,用 1.5T超导磁共振仪检查 ,作垂直于海马长轴的倾斜冠状位 ,同时测量双侧海马。结果 :正常成人海马体积 ,右侧下限为 2 .60cm3 ,左侧下限为 2 .42cm3 。 2 8例患者中 15例未见海马萎缩 ,但其中有 5例颞叶病变 ,10例未发现异常病变 ;13例有海马萎缩 ,其中 9例单纯海马萎缩 (2例为双侧萎缩 ) ,2例为胶质瘤 ,其它 2例分别为海绵状血管瘤与囊肿。结论 :海马的萎缩是颞叶癫痫的重要原因 ,萎缩以单侧多见 ;T2 WI信号的升高反映了海马的硬化程度 ;MR的海马成像是脑外科开展癫痫外科手术治疗的不可缺少的部分。     

Bilateral cingulum fiber reductions in temporal lobe epilepsy with unilateral hippocampal sclerosis

PurposeTo evaluate whether white matter tracts within the Papez circuit are altered in patients with unilateral hippocampal sclerosis (HS).MethodsTwenty patients with histologically proven unilateral HS and 20 age-matched controls were studied with a 3 T Epilepsy-dedicated MRI protocol including a MPRAGE sequence for hippocampus volumetry and a diffusion tensor imaging (DTI) sequence (61 diffusion-encoding directions, 2 × 2 × 2 mm³ voxels) for diffusion tensor tractography (DTT). An energy-based global tracking algorithm was used to calculate streamline counts (SC) and fractional anisotropy (FA) of cingulate, fornix, and mammillo-thalamic tracts, respectively.ResultsSclerotic hippocampi were significantly smaller compared to the contralateral side and to age-matched controls. Cingulum SC but not FA were reduced on the hippocampal sclerosis (258 + 81.0) and contralateral side (271 + 85.6) compared to age-matched controls (447 + 138).ConclusionFocusing on white matter tracts of the Papez circuit we showed that in patients with intractable temporal lobe epilepsy unilateral hippocampal sclerosis is associated with a bilateral reduction of cingulum association fibers projecting from the cingulate gyrus to the parahippocampal gyrus.     

难治性颞叶癫痫海马和同侧前颞叶MRI特征及其与临床相关性

目的：探讨难治性颞叶癫痫海马硬化（HS）与同侧前颞叶 MRI特征及其与临床的相关性。方法：搜集经影像学或病理诊断为难治性颞叶癫痫 HS的34例患者的临床和影像资料,其中25例行手术治疗。34例中女15例,男19例,平均年龄（22．4±8．2）岁。观察海马及同侧前颞叶 MRI征象,根据海马及前颞叶 MRI 征象将34例分为同侧前颞叶正常组与前颞叶异常组,后者再分为同时出现灰白质分界模糊和颞叶萎缩组与仅出现一种征象组两亚组,比较各组间临床特征的差异。结果：34例中,22例（64．7％）出现 HS及同侧前颞叶异常,12例同侧颞叶正常。前颞叶异常组首次癫痫发作年龄低于前颞叶正常组（t＝－3．438,P＝0．002）,病程时间比前颞叶正常组长（t＝2．453,P＝0．020）。前颞叶同时出现灰白质分界模糊和颞叶萎缩组与仅存在一种征象组间临床特征无统计学差异。结论：难治性颞叶癫痫伴有前颞叶异常的颞叶癫痫多数首次发病年龄小,病程长,MRI特征与临床病情具有紧密的相关性,对于手术侧别选择意义重大。     

Thalamic changes with mesial temporal sclerosis: MRI

We reviewed the preoperative images of 28 patients with pathologically proven mesial temporal sclerosis, to assess thalamic asymmetry and signal change. A further 25 nonsurgical patients with temporal lobe epilepsy and unequivocal, unilateral changes of mesial temporal sclerosis, and 20 controls, were also reviewed. None of the control group had unequivocal asymmetry of the thalamus. There was an ipsilateral asymmetrically small thalamus in five (18 %) of the surgical group and in three (12 %) of the nonsurgical patients. In four cases there was thalamic signal change. In three patients with thalamic volume loss there was ipsilateral hemiatrophy. All patients with an asymmetrically small thalamus had an asymmetrically small fornix and all but one a small ipsilateral mamillary body. Received 18 October 1998/Accepted: 6 November 1999     

颞叶癫痫患者前额叶背外侧的定量质子磁共振波谱研究

目的:利用氢质子磁共振波谱(1H-MRS)研究颞叶癫痫(TLE)患者前额叶背外侧区(DLPFC)的生化改变,探讨额叶在TLE发病代谢机制中的作用.方法:纳入TLE患者(TLE组)及健康志愿者(健康对照组)各20例.根据24h视频脑电图(VEEG)所提示致痫灶所在部位将TLE组分为左侧TLE亚组及右侧TLE亚组.利用单体素1 H-MRS点分辨波谱序列(PRESS)进行扫描,并采用LCModel软件进行后处理,获取所有被试者双侧DLPFC区氮乙酰天门冬氨酸(NAA)、肌酸(Cr)、胆碱(Cho)、肌醇(Ins)及谷氨酸/谷氨酰胺复合物(Glx)的绝对浓度.然后分别对比健康对照组及TLE患者左侧DLPFC区与右侧DLPFC区、健康对照组与TLE患者同侧DLPFC区之间各代谢物浓度的差异.结果:健康对照组左右侧DLPFC区NAA浓度分别为(7.24±0.57) mmol/L、(6.76±0.87) mmol/L,左侧NAA浓度显著高于右侧(P=0.024);而TLE患者上述NAA不对称性消失,左右侧NAA浓度分别为(6.58±0.56) mmol/L、(6.31±0.62)mmol/L(P=0.092).与健康对照相比,TLE患者左侧DLPFC区NAA、Cr及Ins浓度显著降低(P=0.000、0.014、0.025),右侧DLPFC区仅Ins浓度显著降低(P=0.013),而Cho、Glx浓度在左右侧DLPFC区均无显著改变.分层分析进一步揭示左侧TLE亚组的左侧DLPFC区NAA、Cr及Ins浓度较对照组显著降低(P=0.001、0.047、0.007),右侧DLPFC区Ins浓度较对照组显著降低(P=0.002);而右侧TLE组仅有左侧DLPFC区NAA浓度显著降低(P=0.037).结论:颞叶癫痫患者的额叶也存在生化代谢异常,且以左侧额叶改变为主,说明额叶在TLE发病的代谢机制中可能起着重要作用.     

难治性颞叶癫痫的分子影像学研究与病理对照

目的:对照难治性颞叶癫痫(TLE)手术病理资料,探讨联合单光子发射计算机断层(SPECT)和质子磁共振波谱(1 H-MRS)两种分子影像学技术对TLE定位的临床价值。方法:选择29例经手术病理证实的单侧TLE。所有患者术前均行SPECT发作间期脑血流(CBF)灌注显像、常规磁共振(MRI)扫描和1 H-MRS成像。将两种分子影像学技术,发作间期CBF灌注显像和1 H-MRS,对TLE的定位表现与病理结果进行对比分析。结果:病理改变最常见的是海马硬化和皮质发育不良,共27例(93.10%),此两种改变伴随出现于16例中(55.17%)。对于双重病理TLE,MRI、SPECT定位阳性率均为100%(16/16),MRS为87.50%(14/16)。对于单纯性海马硬化,MRI为阴性,SPECT仅为14.29%(1/7),而MRS高达57.14%(4/7)。对于单纯性皮质发育不全,MRS为阴性,MRI为50.00%(2/4),而SPECT高达75.00%(3/4)。联合应用SPECT和MRS对TLE定位率高达86.20%(25/29),尤其是对MRI阴性的患者,两种技术联合能发现54.55%(6/11)TLE的致痫灶。结论:联合SPECT发作间期脑血流灌注显像和1 H-MRS两种分子影像学技术能为难治性TLE提供更为全面和准确的定位诊断信息,可进一步提高定位MRI阴性TLE患者致痫灶的比例。     

难治性颞叶癫痫定位诊断的SPECT与质子MR波谱对照研究

目的：探讨单光子发射计算机断层（SPECT）和质子磁共振波谱（1H-MRS）两种分子影像学技术对难治性颞叶癫痫定位诊断的临床价值。方法：选择经手术病理证实的单侧TLE患者29例。所有患者术前均行发作间期SPECT脑血流灌注显像、常规MRI扫描和1H-MRS成像。将两种分子影像学检查技术,发作间期脑血流灌注显像和1H-MRS,对颞叶癫痫致痫灶的定位诊断结果进行对比分析。结果：29例单侧TLE患者,常规MRI发现异常18例,其中海马硬化16例,定位率62.07%。SPECT异常21例,定位率72.41%,其中,MRI阴性病例中27.27%（3/11）的患者SPECT为阳性1。H-MRS发现异常18例,定位率62.07%,但MRI阴性病例中36.36%（4/11）的患者MRS为阳性。结论：SPECT对TLE功能异常脑区敏感,尤其是颞叶新皮质的异常1。H-MRS对早期海马硬化比MRI敏感。此两种分子影像学技术都能有效定位颞叶致痫灶,相互不可替代。     

磁共振波谱与颞叶癫痫痫样放电的相关性研究

目的：探讨颞叶癫痫（TLE）患者氢质子磁共振波谱（1H-MRS）与癫痫发作之间的关系。方法：对45例手术证实为单侧TLE患者的单体素1H-MRS及视频脑电图（VEEG）进行回顾性分析,计算代谢产物氮-乙酰天门冬氨酸（NAA）、肌酸（Cr）、胆碱复合物（Cho）的值,分析代谢产物变化与临床癫痫发作程度的相关性。癫痫发作程度以24h内VEEG所记录的痫样放电的次数及程度来描述。结果：病变侧和对侧NAA、Cr和Cho均值分别为（52.31±12.78）ppm和（42.78±8.06）ppm、（43.36±10.43）ppm和（58.04±13.25）ppm、（40.49±10.02）ppm和（42.42±10.68）ppm,NAA值和发作间期痫样放电频率呈明显负相关（r=-0.67,P〈0.05）,而Cr水平与癫痫发作症状呈明显正相关（r=0.86,P〈0.05）。结论：1H-MRS分析能够反映TLE的严重程度,是TLE患者术前评价的一种有价值的辅助检查方法。     

颞叶癫痫的功能MRI研究进展

颞叶癫■（TLE）是癫■中最常见的难治性类型,临床上对于药物难以控制的癫■,手术切除致■灶具有良好的治疗效果。随着MRI技术的迅速发展,功能磁共振成像（fMRI）在癫■研究中的优势越来越显著,尤其在癫■灶的定侧、定位方面明显优于常规MRI,具有更好的临床应用价值。fMRI对TLE脑网络、认知功能的研究,及在TLE病因、病理生理机制、治疗预后等方面的应用取得了诸多进展。     

Quantitative proton MR spectroscopic imaging of the mesial temporal lobe

PURPOSE: To evaluate variations in regional metabolite concentrations in the anterior mesial temporal lobe (ATL), and compare metabolite concentrations between the allocortex and neocortex using quantitative proton MR spectroscopic imaging (MRSI). MATERIALS AND METHODS: Metabolite concentrations and ratios were measured in 20 healthy young subjects with the use of a multislice spin-echo (SE) sequence (TR/TE=2300/280 msec). Quantitation of MRSI data was performed by means of the phantom replacement methodology. RESULTS: The highest choline (Cho) concentration (4.1 +/- 1.1 mM) was found in the ATL (P=0.0015 compared to the middle mesial temporal lobe (MTL), and P=0.0008 compared to the posterior mesial temporal lobe (PTL)). The ATL also had a higher Cho/creatine (Cr) ratio and a lower N-acetyl aspartate (NAA)/Cho ratio compared to other examined regions (P <0.0001 and P < or = 0.052, respectively). In the allocortical regions, the average Cho concentration (3.5 +/- 0.8 mM) was 68% higher, and the NAA concentration (9.5 +/- 1.8 mM) was 13% lower than in the neocortex (P <10(-6) and P <0.008, respectively). Cho/Cr was 64% higher, NAA/Cr 14% lower, and NAA/Cho 47% lower in the allocortex than in the neocortex (P <10(-6), P=0.013, and P <10(-6), respectively). CONCLUSION: The mesial temporal lobe shows high levels of Cho, which presumably reflect a difference in cellular composition between the allocortex and neocortex. Regional metabolite variations must be considered when pathological conditions involving the mesial temporal lobe are evaluated.     

Temporal lobe epilepsy with varying severity: MRI study of 222 patients

MRI was performed in 222 consecutive adult patients with temporal lobe epilepsy of varying severity from January 1991 to May 1993. The diagnosis of hippocampal sclerosis was established visually by three independent observers. The accuracy of visual assessment of hippocampal asymmetry was compared with volumetric measurements. Neuropathological correlations were obtained in 63 patients with refractory seizures. Temporal lobe abnormalities were observed in 180 patients (81 %) as follows: hippocampal sclerosis in 122 (55 %); developmental abnormalities in 16 (7.2 %); tumours in 15 (6.8 %); scars in 11 (5 %); cavernous angiomas in 10 (4.5 %); miscellaneous lesions in 6. MRI was normal or showed unrelated changes in 42 patients (19 %). Visual assessment correctly lateralised hippocampal sclerosis in 79 of the 84 patients measured (94 %). Temporal lobectomy confirmed the MRI data (side and aetiology) in all 63 operated patients. Patients with normal MRI had an older age of seizure onset and were more often drug-responsive than patients with hippocampal sclerosis. MRI showed temporal lobe abnormalities in 81 % of epileptic patients with varying severity with good neuropathological correlation. Patients with normal MRI had a less severe form of the disease. Received: 19 August 1996 Accepted: 13 November 1996     

A multicenter reproducibility study of single-voxel 1H-MRS of the medial temporal lobe

Proton magnetic resonance spectroscopy (¹H-MRS) has provided evidence for a reduction of N-acetyl-aspartate (NAA) in the medial temporal lobe (MTL) in cerebral disorders such as Alzheimer’s Disease. Within the ¹H-MRS study of the German Research Network on Dementia, we determined the multicenter reproducibility of single-voxel ¹H-MRS of the MTL. At five sites with 1.5T MR systems, single-voxel ¹H spectra from the MTL of an identical healthy subject were measured. The same subject was also examined at one of the sites five times to assess intracenter stability. The protocol included water-suppressed spectra with TE 272 ms and TE 30 ms and unsuppressed spectra for absolute quantification of metabolite concentrations. The intracenter reproducibility of absolute NAA concentration, expressed as coefficient of variation (CV), was 1.8%. CV for the concentrations of creatine (Cr), choline (Cho), and myoinositol (MI) and for the ratios NAA/Cr, NAA/Cho, and MI/NAA varied by 11–16%. Intercenter CV was 3.9% for NAA and were below 10% for all other metabolites and metabolic ratios. Our study demonstrates that quantitative assessment of NAA with single-voxel MRS can be performed with high intercenter reproducibility. This is the basis for applying ¹H-MRS in large-scale early recognition and treatment studies in MTL affecting disorders. The study is part of the German Research Network on Dementia and was funded by the German Federal Ministry for Education and Research (grant O1GI 0102)