正常人颞叶质子磁共振波谱研究

目的 运用质子磁共振波谱（^1H—MRS）研究年龄对正常人颞叶脑组织代谢物浓度的影响。方法 将80例健康人分为4个不同年龄组并对双侧颞叶进行^1H—MRS检测，对比分析不同年龄组的颞叶N-乙酰基天门冬氨酸（NAA）／肌酸复合物（Cr）和含胆碱化合物（Cho）／Cr比值的变化。结果 随着年龄的增长，在≤50岁年龄段颞叶的NAA／Cr和Cho／Cr比值无明显改变（P〉0．05），但在〉50岁年龄段颞叶的NAA／Cr比值逐渐降低（P〈0．05）、Cho／Cr比值逐渐增高（P〈0．05）。结论 ^1H-MRS是一种可以为正常人颞叶与年龄相关的代谢物浓度改变提供有价值信息的无创技术。     

Chemical Pathology in Brain White Matter of Recently Detoxified Alcoholics: A 1H Magnetic Resonance Spectroscopy Investigation of Alcohol-Associated Frontal Lobe Injury

BACKGROUND: Investigations have suggested that frontal lobe abnormalities are a prominent feature of the alcoholic brain, indicated by impaired neuropsychological performance on tests of frontal lobe function and by reduced frontal lobe volume in neuroimaging and neuropathological examinations. White matter compartment volume loss may underlie observed brain shrinkage and cognitive deficits associated with the frontal lobes, although the nature of this change has not been well-characterized. METHOD: To investigate the susceptibility of frontal lobe white matter to alcohol-associated metabolic change and to understand the nature of alcohol-related white matter injury, 1H magnetic resonance spectroscopy (MRS) was used to measure concentrations of metabolites in frontal white matter (FWM) and parietal white matter (PWM) of recently detoxified alcoholics (RDA) and nonalcoholic controls (CON). Concentrations of N-acetylaspartate (NAA), choline-containing compounds (Cho), myo-inositol (Ins), and creatine plus phosphocreatine (Cr) were measured in 37 RDA (mean age, 40.4 years; mean length of abstinence, 27.9 days) and 15 CON (mean age, 38.0 years). RESULTS: Analysis of variance (ANOVA) revealed a group by region of interest interaction for concentrations of NAA. Simple effects analysis revealed a significant 14.7% reduction in FWM NAA, while NAA levels in PWM were similar in RDA and CON. In addition, RDA had an 11.8% increase (averaged across both regions of interest) in brain white matter Ins relative to CON. Reductions in FWM NAA were associated with a longer drinking history in the RDA group, but this result was not found when both age and drinking history were used to predict the level of FWM NAA. CONCLUSIONS: Alcohol-associated reductions in FWM NAA may be the result of neuronal loss or dysfunction in the metabolism of NAA. While alcohol-induced oxidative stress may cause global brain impairments in the metabolism and subsequent reduction of NAA, the frontal lobes are particularly rich in excitatory amino acid pathways, and axonal damage or destruction secondary to glutamate-mediated excitotoxicity during alcohol withdrawal may cause frontal lobe-specific reductions in NAA. Elevations in brain white matter Ins may reflect astrocyte proliferation as well as an osmotic response to cell shrinkage.     

1H MR Spectroscopy of the Brain in HIV-1-Seropositive Subjects: Evidence for Diffuse Metabolic Abnormalities

PURPOSE: To analyze brain metabolite changes in HIV-1-seropositive subjects in order to define whether the neuronal impairment is a localized or more diffuse process.MATERIALS and METHODS: 15 patients and 18 volunteers underwent multivoxel proton magnetic resonance (MR) spectroscopy at 1.5T. Nine patients were classified as being neuropsychiatrically unimpaired and six as having HIV-1-associated dementia on the basis of a full neuropsychological examination. Spectra were analysed from multiple voxels located in the fronto-parietal cortex and white matter at the level of centrum semiovale.RESULTS: A significant reduction in mean peak area ratios of NAA/Cr (p<0.005 in the grey matter, p<0.01 in the white matter) and an elevation in mean Cho/Cr (p<0.005 in both grey matter and white matter) were observed in patients with HIV-1-associated dementia when compared to healthy volunteers. No significant metabolite abnormalities were detected in the neuropsychiatrically unimpaired group, although there was a similar trend in the metabolite ratios. The changes in metabolite ratios were of the same order of magnitude in the cortical grey matter and subcortical white matter as in the deeper white matter in all patients. There were also no significant regional variations in mean metabolite ratios between right and left hemispheres or anterior and posterior voxels at the level of the brain studied. There were no abnormalities in Glx/Cr in any spectra analysed from either patient group.CONCLUSION: The absence of significant regional variation in metabolite ratios at the level of the centrum semiovale provides some evidence that abnormalities of cerebral metabolites in HIV-infected patients may be part of a diffuse process.     

Effects of heavy drinking, binge drinking, and family history of alcoholism on regional brain metabolites

BACKGROUND: The main goals are to investigate the effects of chronic active heavy drinking on N-acetylaspartate (NAA) and other metabolites throughout the brain and to determine whether they are affected by family history (FH) of alcoholism and long-term drinking pattern. METHODS: Forty-six chronic heavy drinkers (HD) and 52 light drinkers (LD) were recruited from the community and compared on measures of regional brain structure using magnetic resonance imaging and measures of common brain metabolites in gray matter (GM) and white matter (WM) of the major lobes, subcortical nuclei, brainstem, and cerebellum using short-echo time magnetic resonance spectroscopic imaging. Regional atrophy-corrected levels of NAA, myoinositol (mI), creatine, and choline-containing metabolites were compared as a function of group, FH of alcoholism, and bingeing. RESULTS: Frontal WM NAA was lower in FH-negative HD than FH-positive HD and tended to be lower in women than men. Creatine-containing metabolites in parietal GM were higher in HD than LD. FH-negative compared with FH-positive HD also had more mI in the brainstem and tended to have lower NAA and more mI in frontal GM. Although parietal GM NAA was not significantly lower in HD than LD, it was lower in non-binge drinkers than bingers. Frontal WM NAA was lower in HD than LD, with the difference driven by a small number of women, FH-negative HD, and older age. Lower frontal WM NAA in HD was associated with lower executive and working memory functions and with lower P3b amplitudes at frontal electrodes. CONCLUSIONS: Community-dwelling HD who are not in alcoholism treatment have brain metabolite changes that are associated with lower brain function and are likely of behavioral significance. Age, FH, and binge drinking modulate brain metabolite abnormalities. Metabolite changes in active HD are less pronounced and present with a different spatial and metabolite pattern than reported in abstinent alcoholics.     

Coronary heart disease is associated with regional grey matter volume loss: implications for cognitive function and behaviour

Coronary heart disease (CHD) has been associated with impaired cognition, but the mechanisms underlying these changes remain unclear. We designed this study to determine whether adults with CHD show regional brain losses of grey matter volume relative to controls. We used statistical parametric mapping (SPM5) to determine regional changes in grey matter volume of T₁-weighted magnetic resonance images of 11 adults with prior history of myocardial infarction relative to seven healthy controls. All analyses were adjusted for total grey and white matter volume, age, sex and handedness. CHD participants showed a loss of grey matter volume in the left medial frontal lobe (including the cingulate), precentral and postcentral cortex, right temporal lobe and left middle temporal gyrus, and left precuneus and posterior cingulate. CHD is associated with loss of grey matter in various brain regions, including some that play a significant role in cognitive function and behaviour. The underlying causes of these regional brain changes remain to be determined.     

皮层下缺血患者认知功能评估及功能磁共振研究

目的 利用磁共振弥散张量成像(DTI)和磁共振质子波谱分析(MRS)技术探讨皮层下缺血(SIVD)导致认知功能障碍患者的影像学特征.方法 52例皮层下缺血性脑血管病患者经认知量表评分后32例有认知障碍归入血管性认知功能障碍(VCI)组,20例无认知障碍作为对照组,完成DTI和MRS检查.计算双侧额叶、颞叶、顶叶、枕叶和半卵圆区的表观弥散系数(ADC)和各向异性(FA)平均值.测定右侧额叶和左侧颞叶N-乙酰基天门冬氨酸(NAA)、肌酸复合物、含胆碱化合物(Cho)、肌醇的峰值.结果 VCI组与对照组相比,在额叶、颞叶、顶叶和半卵圆区FA值降低,ADC值升高(P＜0.05).FA值的降低以额叶、半卵圆区最明显.ADC值升高以颢叶最明显.波谱分析结果,在额叶VCI组与对照组相比NAA/肌酸复合物比值明显降低(1.43±0.08比1.53±0.92),在颢叶VCI组肌醇/肌酸复合物比值升高(0.51±0.06比0.46±0.07),P＜0.05.结论 VCI患者在额叶、半卵圆区FA值明显降低,额叶白质区NAA值明显降低,DTI和MRS可为早期诊断与评估VCI提供有用的指标.

Abstract：

Objective To evaluate the imaging features of patients with vascular cognitive impairment (VCI) induced by Subcortical Ischemic Vascular Disease (SIVD), through magnetic resonance diffusion tensor imaging ( DTI ) and proton spectroscopy ( MRS ) technology. Methods A total of 52 patients with SIVD were enrolled. After analysis of scale score, 32 patients with cognitive impairment were assigned to VCI group and 20 patients with no cognitive impairment were assigned to control group. Both group received DTI and MRS examination. The mean values of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of the bilateral temporal, frontal, parietal and occipital white matter regions as well as in the bilateral centrum semiovale were calculated. The peak value of MRS of N-acetyl aspartate (NAA) , choline ( Cho), creatine (Cr) and phaseomannite ( mI ) were calculated. Results Compared with control group, FA decreased in the region of temporal, frontal, parietal as well as in the centrum semiovale , and ADC increased in VC[group ( P ＜ 0.05 ) . In the frontal regions and centrum semiovale,the VCI patients had a significant FA decrease. The ADC value increased obviously in the temperal lobe.Spectrum analysis results showed, NAA/Cr was lower than control group in VCI group in the frontal lobe (1.43 ±0.08 vs 1.53 ± 0. 92), while mI/Cr was higher than control group in the temporal lobe(0. 51 ±0. 06 vs 0. 46 ± 0. 07 ) ( P ＜ 0. 05 ). Conclusion FA in the temporal and centrum semiovale regions of VCI group and NAA in the temporal white matter regions decreased obviously. DTI and MRS could provide a reference value for early diagnosis and assessment of VCI.     

Body mass index is associated with brain metabolite levels in alcohol dependence--a multimodal magnetic resonance study

Background: Recent studies demonstrated that alcohol dependence and excessive alcohol consumption are associated with increased rates of obesity. In healthy light‐drinkers, we and others have observed associations between elevated body mass index (BMI) and reductions in brain volumes, lower concentrations of N‐acetyl‐aspartate (NAA, marker of neuronal viability) and choline‐containing compounds (Cho, involved in membrane turnover), and lower glucose utilization, particularly in frontal lobe—a brain region that is particularly vulnerable to the effects of alcohol dependence. Here, we evaluated whether BMI in alcohol‐dependent individuals was independently associated with regional measures of brain structure, metabolite concentrations, and neocortical blood flow. Methods: As part of a study on the effects of alcohol dependence on neurobiology, we analyzed retrospectively data from 54 alcohol‐dependent males, abstinent from alcohol for about 1 month and with BMI between 20 and 37 kg/m² by structural MRI, perfusion MRI (blood flow), and proton magnetic resonance spectroscopic imaging. Results: After correction for age, smoking status, and various measures of alcohol consumption, higher BMI was associated with lower concentrations of NAA, Cho, creatine and phosphocreatine (Cr, involved in high energy metabolism), and myo‐inositol (m‐Ino, a putative marker of astrocytes) primarily in the frontal lobe, in subcortical nuclei, and cerebellar vermis (p < 0.004). Regional brain volumes and perfusion were not significantly related to BMI. Furthermore, comorbid conditions, clinical laboratory measures, and nutritional assessments were not significant predictors of these MR‐based measures. Conclusions: The results suggest that BMI, independent of age, alcohol consumption, and common comorbidities, is related to regional NAA, Cho, Cr, and m‐Ino concentrations in this cohort of alcohol‐dependent individuals. Additionally, as some common comorbid conditions in alcohol dependence such as cigarette smoking are associated with BMI, their associations with regional brain metabolite levels in alcohol‐dependent individuals may also be influenced by BMI.     

Longitudinal brain metabolic characterization of chronic alcoholics with proton magnetic resonance spectroscopy

BACKGROUND: Proton magnetic resonance spectroscopy may elucidate the molecular underpinnings of alcoholism-associated brain shrinkage and the progression of alcohol dependence. METHODS: Using proton magnetic resonance spectroscopy, we determined absolute concentrations of -acetylaspartate (NAA), creatine/phosphocreatine (Cr), and choline (Cho)-containing compounds and -inositol (mI) in the anterior superior cerebellar vermis and frontal lobe white matter in 31 alcoholics and 12 normal controls. All patients were examined within 3 to 5 days of their last drink. Patients who did not relapse were again studied after 3 weeks and 3 months of abstinence by using an on-line repositioning technique that allows reliable localization of volumes of interest (VOIs). RESULTS: At 3 to 5 days after the last drink, frontal white matter metabolite concentrations were not significantly different from those of normal controls, whereas brain tissue in the VOI was reduced. Cerebellar [NAA] and [Cho] and brain and cerebellar volumes were decreased, but [Cr], [mI], and VOI brain tissue volume were not significantly different. Eight patients relapsed before 3 weeks (ER), 12 relapsed between 3 weeks and 3 months (LR), and 11 did not relapse (NR) during 3 months. Cerebellar [NAA] was reduced only in ER patients, despite the fact that ER patients drank for significantly fewer years and earlier in life than LR or NR patients. After 3 months, in the 11 continuously abstinent patients, cerebellar [NAA] and brain and cerebellar volumes increased; cerebellar [Cho], [Cr], and [mI] and VOI brain tissue did not change significantly. CONCLUSIONS: Decreased [NAA] and [Cho] in cerebellar vermis indicate a unique sensitivity to alcohol-induced brain injury. Cerebellar [NAA] increased with abstinence, but reduced [Cho] persisted beyond 3 months. Further studies are needed to determine whether low cerebellar [NAA] is a risk factor for, or consequence of, malignant, early-onset alcoholism.     

Brain metabolic alterations in adolescents and young adults with fetal alcohol spectrum disorders

BACKGROUND: Prenatal alcohol exposure affects brain structure and function. This study examined brain metabolism using magnetic resonance spectroscopy (MRS) and searched for regions of specific vulnerability in adolescents and young adults prenatally exposed to alcohol. METHODS: Ten adolescents and young adults with confirmed heavy prenatal alcohol exposure and a diagnosis within the fetal alcohol spectrum disorders (FASD) were included. Three of them had fetal alcohol syndrome (FAS), 3 had partial FAS (PFAS), and 4 had alcohol-related neurobehavioral disorder (ARND). The control group consisted of 10 adolescents matched for age, sex, head circumference, handedness, and body mass. Exclusionary criteria were learning disorders and prenatal alcohol exposure. Three-dimensional (1)H magnetic resonance spectroscopic imaging ((1)H MRSI) was performed in the cerebrum and cerebellum. Metabolite ratios N-acetylaspartate/choline (NAA/Cho), NAA/creatine (Cr) and Cho/Cr, and absolute metabolite intensities were calculated for several anatomic regions. RESULTS: In patients with FASD, lower NAA/Cho and/or NAA/Cr compared with controls were found in parietal and frontal cortices, frontal white matter, corpus callosum, thalamus, and cerebellar dentate nucleus. There was an increase in the absolute intensity of the glial markers Cho and Cr but no change in the neuronal marker NAA. CONCLUSIONS: Our results suggest that prenatal alcohol exposure alters brain metabolism in a long-standing or permanent manner in multiple brain areas. These changes are in accordance with previous findings from structural and functional studies. Metabolic alterations represent changes in the glial cell pool rather than in the neurons.     

老年人放射性脑损伤的动态磁共振波谱研究

目的 探讨老年人放射性脑损伤的代谢特点.方法 对15例接受放射治疗(放疗)老年鼻咽癌患者(老年组)在治疗前和接受放射线剂量为20 Gy、40 Gy、60 Gy时分别进行磁共振波谱检查,观察不同剂量时双侧颞叶主要代谢物比值的变化趋势;选择23例同期接受放疗的青年鼻咽癌患者为对照组.结果 放疗前,老年组N-乙酰天门冬氨酸(NAA)与肌酐(Cr)的比值(NAA/Cr)为1.86±0.17,胆碱(Cho)与Cr的比值(Cho/Cr)为1.84±0.23,分别高于和低于对照组(2.15±0.22、1.62±0.31,P＞0.05);放疗过程中,两组均表现为NAA峰和Cho峰降低,放射线剂量达20 Gy前NAA/Cr、Cho/Cr和NAA和Cho比值(NAA/Cho)降幅较小,放射线剂量20～60 Gy阶段降幅加快;放疗结束时,老年组Cho/Cr降低幅度小于对照组(P＜0.05),NAA/Cr降低的幅度大于对照组,差异有统计学意义(P＜0.01).结论 接受边缘放射线辐射条件下,老年人放射性脑损伤发生较早,神经元损伤程度大于青年人,而对胶质细胞损伤程度相对较小.

Abstract：

Objective To study the metabolic characteristics of temporal lobe injury during the radiotherapy in the elderly with nasopharyngeal carcinoma through 1H- magnetic resonance spectroscopy (MRS). Methods The 15 aged and 23 young cases among 80 cases with nasopharyngeal carcinoma confirmed clinically and receiving radiotherapy for the first time were involved in the same period of July 2006 to May 2009. Conventional MRI scanning and bilateral temporal MRS were performed before and during radiotherapy at radiation dosages of 20 Gy, 40 Gy, and 60 Gy respectively. The spectroscopy morphology and the ratios of the three main metabolites were compared and analyzed. Results The values of N-acetylasparate (NAA)/creatine (Cr) was lower and choline-containing compound (Cho)/Cr ratio was higher in aged group than in young group before radiotherapy (P＞0.05). The spectroscopy morphology stepped down, NAA, Cho, NAA/Cr, Cho/Cr and NAA/Cho decreased to some extent along with the adding of radiation dosages in the course of radiotherapy. At the end of radiotherapy, the decreased amplitude of NAA/Cr value was larger in aged group than in control group (P＜0.01), and the amplitude of Cho/Cr value was lower than other group. Conclusions The neurons of aged patients with nasopharyngeal carcinoma have a weak tolerance to the radiation, brain injury occurs earlier and heavier in aged patients than in young patients. It is necessary to prevent neuron injury early.     

Brain metabolite concentrations and neurocognition during short-term recovery from alcohol dependence: Preliminary evidence of the effects of concurrent chronic cigarette smoking

BACKGROUND: Longitudinal studies of brain tissue metabolite recovery in short-term abstinent alcoholics have primarily investigated the frontal lobes and cerebellum with variable results. Preliminary proton magnetic resonance spectroscopic imaging (1H MRSI) suggested that chronic cigarette smoking exacerbates alcohol-induced brain injury in 1-week abstinent alcoholics. However, the potential effects of chronic cigarette smoking on the recovery of alcohol-induced brain injury have not been studied. METHODS: Multislice short-echo time 1H MRSI was used to measure longitudinal changes in common brain metabolites in 25 recovering alcohol-dependent individuals (RA), retrospectively assigned to smoking (n = 14) and nonsmoking (n = 11) subgroups. Recovering alcohol-dependent individuals in longitudinal analyses were studied after approximately 7 and 34 days of abstinence from alcohol. In cross-sectional analyses, 36 RA (19 smokers, 17 nonsmokers) with approximately 34 days of sobriety were compared with 29 light drinkers (LD). Relationships between neurocognition and metabolite concentrations in abstinent RA were also examined. RESULTS: Over 1 month of abstinence from alcohol, RA, as a group, showed significant increases of regional N-acetylaspartate (NAA; marker of neuronal viability) and choline-containing compounds (Cho; marker of cell membrane synthesis/turnover) primarily in frontal and parietal lobes. These increases appeared to be driven by nonsmoking RA. Cross-sectional results indicate that metabolite levels in RA at 35 days of sobriety are not significantly different from those in LD in most regions, except for lower NAA and Cho in parietal WM and subcortical structures. However, metabolite levels at that time appear to be strongly modulated by smoking status. The patterns of metabolite-neurocognition relationships were different for nonsmoking and smoking RA. CONCLUSIONS: Within the first weeks of sobriety, regional brain NAA and Cho levels increased, but metabolite levels did not normalize in all brain regions after 35 days of sobriety. Neurobiologic recovery in RA appeared to be adversely affected by chronic smoking. Greater consideration of the effects of continued cigarette smoking on the neurobiologic and neurocognitive recovery of alcohol-dependent individuals is warranted.     

Evaluation of in vivo cerebral metabolism on proton magnetic resonance spectroscopy in patients with impaired glucose tolerance and type 2 diabetes mellitus

The aim of this study was to investigate possible metabolic alterations in cerebral tissues on magnetic resonance spectroscopy (MRS) in patients with impaired glucose tolerance (IGT) and with type 2 diabetes mellitus (T2-DM). Twenty-five patients with T2-DM, 13 patients with IGT, and 14 healthy volunteers were included. Single-voxel spectroscopy (TR: 2000 ms, TE: 31 ms) was performed in all subjects. Voxels were placed in the frontal cortex, thalamus, and parietal white matter. N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, and myo-inositol (MI)/Cr ratios were calculated. Frontal cortical Cho/Cr ratios were increased in patients with IGT compared to control subjects. Parietal white matter Cho/Cr ratios were significantly higher in patients with IGT when compared to patients with T2-DM. In the diabetic group, frontal cortical MI/Cr ratios were increased, and parietal white matter Cho/Cr ratios were decreased when compared to the control group. Frontal cortical NAA/Cr and Cho/Cr ratios and parietal white matter Cho/Cr ratios were decreased in diabetic patients with poor glycemic control (A1C>10%). A1C levels were inversely correlated with frontal cortical NAA/Cr and Cho/Cr ratios and with parietal white matter Cho/Cr ratios. T2-DM and IGT may cause subtle cerebral metabolic changes, and these changes may be shown with MRS. Increased Cho/Cr ratios may suggest dynamic change in membrane turnover in patients with IGT. Diabetic patients with poor glycemic control may be associated with neuronal dysfunction/damage in brain in accordance with A1C levels and, in some, extend with insulin resistance.     

氢质子核磁波谱对儿童热性惊厥脑异常检出和预后评估的价值分析

目的探讨氢质子核磁波谱（H1-MRS）检查对儿童热性惊厥（FS）的脑实质异常的检测效率,及其用于预测临床预后的价值。 方法选择中山市人民医院普通儿科自2017年3月至2018年5月收治的38例FS患儿作为研究对象,所有患儿均进行颅脑MRI及H1-MRS检查,比较MRI和H1-MRS检查对FS患儿颅内异常检出效率差异。根据H1-MRS结果计算代谢物质氮-乙酰天门冬氨酸（NAA）/[肌酸（Cr）+磷酸肌酸（Cho）]、NAA/Cr、NAA/Cho值,然后根据患儿出现临床不良预后情况分为有不良临床预后组和无不良临床预后组,比较2组患儿间NAA/（Cr+Cho）、NAA/Cr、NAA/Cho值差异,并分析其对预后的评估价值。 结果38例FS患儿中,MRI检出颅脑异常情况有23例,H1-MRS检出颅脑异常情况有32例,异常情况检出率比较差异具有统计学意义（χ²=5.330,P=0.021）。13例FS患儿出现不良临床预后,有不良临床预后组患儿中表现为复杂型的比率高于无不良临床预后组,差异有统计学意义（P<0.05）。有不良临床预后组患儿的NAA/（Cr+Cho）、NAA/Cr、NAA/Cho值均小于无不良临床预后组,差异有统计学意义（P<0.05）。绘制NAA/（Cr+Cho）、NAA/Cr、NAA/Cho值对预测不良临床预后ROC曲线,其相应的曲线下面积分别为0.848、0.774、0.797。 结论H1-MRS检查对FS患儿脑实质异常的检出率高于MRI检查,且H1-MRS结果计算所得的NAA/（Cr+Cho）、NAA/Cr、NAA/Cho值在FS患儿中显著降低,其中,NAA/（Cr+Cho）值对患儿的预后具有较好的预测价值。     

Evaluation of metabolite changes in visual cortex in diabetic retinopathy by MR-spectroscopy

PurposeTo evaluate metabolite changes in the visual cortex of diabetic patients with nonproliferative or proliferative diabetic retinopathy by Magnetic Resonance Spectroscopy (MRS).Materials and Methods15 normal subjects (group 1), 15 patients with diabetes who did not have diabetic retinopathy (group 2), 15 patients with nonproliferative diabetic retinopathy (NPDR) (group 3), and 15 patients with proliferative diabetic retinopathy (PDR) (group 4) were included in the study. Furthermore, diabetic patients were divided into two groups according to HbA1c levels (Group A: 20 patients, HbA1c < 8%; Group B: 20 patients, HbA1c > 8%). In all cases' left visual cortex, amounts of N-acetyl-aspartate (NAA), choline (Cho), and creatine (Cr) were measured by MRS. NAA/Cr, Cho/Cr, and NAA/Cho ratios were calculated. Furthermore, all cases' complete blood count (CBC) and biochemical parameters were evaluated.ResultsThere was no statistically significant difference for NAA/Cr, Cho/Cr, and NAA/Cho ratios between groups 1, 2, 3, and 4 (P > 0.05). However there was a statistically significant difference for NAA/Cr and NAA/Cho ratios between groups A and B (P < 0.05). There was no statistically significant difference for Cho/Cr ratio between groups A and B (P > 0.05).ConclusionAlthough NAA/Cr and NAA/Cho ratios decrease in the visual cortex while diabetic retinopathy progresses, these decreases are not statistically significant. While HbA1c levels increase, the NAA concentration decreases in the visual cortex which indicates neuronal loss. The metabolite changes in the visual cortex are associated with acute events rather than chronic.     

Regional variations in cerebral proton spectroscopy in patients with chronic hepatic encephalopathy

Regional variations in proton magnetic resonance spectroscopy (MRS) were assessed in 26 patients and 14 healthy volunteers using a two dimensional chemical shift imaging technique. Patients were classified as being neuropsychiatrically unimpaired, or as having subclinical or overt chronic hepatic encephalopathy (CHE). Peak area ratios of choline (Cho), glutamine and glutamate (Glx) and N-acetylaspartate (NAA) relative to creatine (Cr) were measured. Significant reductions in mean Cho/Cr and elevations in mean Glx/Cr were observed in the patient population, which correlated with the severity of CHE. There were significant regional variations in these metabolite ratios with the mean Cho/Cr lowest in the occipital cortex and the mean Glx/Cr highest in the basal ganglia. NAA/Cr remained relatively constant in all areas of the brain analysed. The regional variation in the metabolite ratios suggests that spectral information from more than one voxel may be useful in the assessment of patients with CHE.     

Neurochemical alterations of the entorhinal cortex in amnestic mild cognitive impairment (aMCI): a three-year follow-up study

The neurochemical alterations in the entorhinal cortex have not yet been measured, even though the entorhinal cortex is the earliest involved brain region in aMCI. In this study, we investigated whether brain regions including the entorhinal cortex would show early involvement of neurochemical abnormalities in aMCI, and whether magnetic resonance spectroscopy (MRS) abnormalities might be a predictive marker of conversion of aMCI to Alzheimer's disease (AD). MRS was performed on 13 aMCI patients and 11 patients with no cognitive impairment (NCI). Localizing voxels were placed within the entorhinal cortex, hippocampus, posterior cingulate gyrus, and occipital white matter in the dominant hemisphere. N-acetyl aspartate/creatinine (NAA/Cr) ratios in the entorhinal cortex were significantly lower in aMCI patients than in NCI subjects. After a three-year follow-up, seven aMCI patients converted to AD and six remained stable. Baseline NAA/Cr ratios of entorhinal cortex were decreased in converters, compared to NCI. Our study suggested the entorhinal cortex is the earliest site that is subject to neurochemical alteration in aMCI patients, and baseline MRS metabolite ratios in the entorhinal cortex can be a marker for predicting conversion of aMCI to AD.     

Underconnectivity between voice-selective cortex and reward circuitry in children with autism

Individuals with autism spectrum disorders (ASDs) often show insensitivity to the human voice, a deficit that is thought to play a key role in communication deficits in this population. The social motivation theory of ASD predicts that impaired function of reward and emotional systems impedes children with ASD from actively engaging with speech. Here we explore this theory by investigating distributed brain systems underlying human voice perception in children with ASD. Using resting-state functional MRI data acquired from 20 children with ASD and 19 age- and intelligence quotient-matched typically developing children, we examined intrinsic functional connectivity of voice-selective bilateral posterior superior temporal sulcus (pSTS). Children with ASD showed a striking pattern of underconnectivity between left-hemisphere pSTS and distributed nodes of the dopaminergic reward pathway, including bilateral ventral tegmental areas and nucleus accumbens, left-hemisphere insula, orbitofrontal cortex, and ventromedial prefrontal cortex. Children with ASD also showed underconnectivity between right-hemisphere pSTS, a region known for processing speech prosody, and the orbitofrontal cortex and amygdala, brain regions critical for emotion-related associative learning. The degree of underconnectivity between voice-selective cortex and reward pathways predicted symptom severity for communication deficits in children with ASD. Our results suggest that weak connectivity of voice-selective cortex and brain structures involved in reward and emotion may impair the ability of children with ASD to experience speech as a pleasurable stimulus, thereby impacting language and social skill development in this population. Our study provides support for the social motivation theory of ASD.     

Cigarette smoking exacerbates chronic alcohol-induced brain damage: a preliminary metabolite imaging study

BACKGROUND: Cigarette smoking is common among alcohol-dependent individuals. Nevertheless, previous research has typically not accounted for the potential independent or compounding effects of cigarette smoking on alcohol-induced brain injury and neurocognition. METHODS: Twenty-four 1-week-abstinent recovering alcoholics (RAs; 14 smokers and 10 nonsmokers) in treatment and 26 light-drinking controls (7 smokers and 19 nonsmokers) were compared on measures of common brain metabolites in gray matter and white matter of the major lobes, basal ganglia, midbrain, and cerebellar vermis, obtained via multislice short-echo time proton magnetic resonance spectroscopic imaging. Smoking and nonsmoking RAs were also contrasted on measures of neurocognitive functioning, as well as laboratory markers of drinking severity and nutritional status. RESULTS: Chronic alcohol dependence, independent of smoking, was associated with lower concentrations of frontal N-acetylaspartate (NAA) and frontal choline-containing compounds, as well as lower parietal and thalamic choline. Smoking RAs had lower NAA concentrations in frontal white matter and midbrain and lower midbrain choline than nonsmoking RAs. A four-group analysis of covariance also demonstrated that chronic cigarette smoking was associated with lower midbrain NAA and choline and with lower vermian choline. In smoking RAs, heavier drinking was associated with heavier smoking, which correlated with numerous subcortical metabolite abnormalities. The 1-week-abstinent smoking and nonsmoking RAs did not differ significantly on a brief neurocognitive battery. In smoking RAs, lower cerebellar vermis NAA was associated with poorer visuomotor scanning speed and incidental learning, and in nonsmoking RAs lower vermis NAA was related to poorer visuospatial learning and memory. CONCLUSIONS: These human in vivo proton magnetic resonance spectroscopic imaging findings indicate that chronic cigarette smoking exacerbates chronic alcohol-induced neuronal injury and cell membrane damage in the frontal lobes of RAs and has independent adverse effects on neuronal viability and cell membranes in the midbrain and on cell membranes of the cerebellar vermis. Higher smoking levels are associated with metabolite concentrations in select subcortical structures. Greater consideration of the potential effects of comorbid cigarette smoking on alcohol-induced brain damage and other diseases affecting the central nervous system is warranted.     

不同认知水平的广泛性脑萎缩患者磁共振波谱分析

目的 观察不同认知水平的广泛性脑萎缩患者脑内生化物质含量的差异. 方法 按照美国精神障碍诊断与统计手册第4版(DSM-Ⅳ)和认知功能障碍的诊断标准将33名广泛性脑萎缩患者分为阿尔茨海默病(AD)组14例、遗忘型轻度认知功能损害(aMCI)组9例和认知功能正常组10例.所有研究对象接受神经心理量表检测,然后采用1.5-T MR系统对左侧额叶皮质和左侧海马进行氢质子磁共振波谱(1H-MRS)检测分析. 结果 广泛性脑萎缩AD组的左侧海马和左侧额叶皮层的N-乙酰天门冬氨酸(NAA)/肌酸(Cr)值较认知正常组分别降低10.2%和5.3%.胆碱复合物(Cho)/Cr值分别升高17.5%和16.7%,肌醇(MI)/Cr值分别升高39.5%和19.2%.与aMCI组比较,广泛性脑萎缩AD组的左侧海马NAA/Cr值降低6.4%,左侧海马和左侧额叶皮层的Cho/Cr值分别升高9.3%和12.3%,左侧海马和左侧额叶皮层的MI/Cr值分别升高30%和17%,而左侧额叶皮层的NAA/Cr值在两者间差异无统计学意义.广泛性脑萎缩aMCI组的左侧海马NAA/Cr值比正常组降低4.1%、Cho/Cr值比认知正常组升高7.5%,但是左侧额叶皮层的生化改变在两组间差异均无统计学意义. 结论 不同认知水平的广泛性脑萎缩患者存在脑内神经生化物质的变化.左侧海马NAA/Cr值的降低、左侧海马和左侧额叶皮质Cho/Cr和MI/Cr值的升高有助于预测aMCI进展为AD;左侧海马NAA/Cr降低和Cho/Cr升高有助于鉴别广泛性脑萎缩伴aMCI患者与广泛性脑萎缩认知功能正常的患者.     

Correlation between each task of the Mini-Mental State Examination and regional glucose hypometabolism in at-rest Alzheimer's disease patients

We investigated the relationship between each task of the Mini-Mental State Examination (MMSE) and regional glucose hypometabolism in patients with Alzheimer's disease (AD). We studied 38 patients with probable AD using 2-¹⁸F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET). The images were corrected for differences in FDG uptake by cerebellar normalization, and were spatially normalized into a standard stereotactic anatomical space using statistical parametric mapping (SPM). There was a positive correlation between FDG uptake and the MMSE subscores for temporal orientation in the bilateral temporal and frontal cortex, and cingulate gyrus; for spatial orientation in the left parietal cortex, bilateral frontal and temporal cortex, and cingulate gyrus; for attention and calculation in the left temporal and frontal cortex; for writing in the left temporal cortex; and for copying and drawing, the correlation was positive in the bilateral parietal and occipital cortex. The total MMSE score was positively correlated with FDG uptake in the left temporal and frontal lobe. Our study demonstrated that, in AD patients, the distribution of hypometabolism in the resting state was related to clinical symptoms and that MMSE scores reflected brain dysfunction in the left hemisphere. Correlation analysis using SPM and FDG PET is useful for the objective evaluation of cognitive tests and diagnostic scoring.