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.     

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.     

质子磁共振波谱评价颈内和大脑中动脉狭窄与闭塞的脑代谢研究

目的探讨质子磁共振波谱(1H-MRS)在单侧颈内动脉(ICA)和大脑中动脉(MCA)重度狭窄与闭塞中的应用价值。方法32例单侧ICA或MCA重度狭窄或闭塞患者(ICA18例,MCA14例)行1H-MRS检查,测量患侧和对侧大脑半球半卵圆中心N-乙酰天门冬氨酸(NAA)、胆碱(Cho)和肌酸(Cr)的波峰下面积,比较患侧和对侧各代谢物峰下面积比值NAA/Cho、NAA/Cr和Cho/Cr的差异,并观察有无乳酸(Lac)峰出现。结果1H-MRS显示患侧半卵圆中心的NAA/Cho、NAA/Cr低于对侧,差异有显著性意义(P<0.01),Cho/Cr高于对侧,差异有显著性意义(P<0.01),5例患者于患侧检测到Lac峰。结论1H-MRS能够早期发现ICA或MCA重度狭窄或闭塞患者缺血脑组织的代谢异常,从代谢产物角度评价脑缺血程度,对于早期治疗和判断预后具有重要价值。     

The metabolic alterations within the normal appearing brain in patients with Hashimoto’s thyroiditis are correlated with hormonal changes

Hashimoto’s thyroiditis (HT) is the most common autoimmune disease in humans usually associated with subsequent hypothyroidism. The purpose of the study was to assess metabolic alterations within the normal appearing brain in subjects with HT using MR spectroscopy (MRS) and to correlate MRS measurements with hormonal concentrations. Fifty-five HT patients (mean age 43.5 yrs) and 30 healthy controls (mean age 42.5 yrs) were examined with the use of a 1.5 T MR scanner. There were no signs of central nervous system involvement in the studied group. The MRS examinations were performed using the single voxel method. The voxels were placed in the left parietal white matter (PWM) and the posterior cingulate gyrus (PCG). The NAA/Cr, Cho/Cr, and mI/Cr ratios were calculated. The correlations between metabolite ratios and hormonal concentrations (TSH, fT3, fT4) as well as anti-TG and anti-TPO levels were also assessed. We found significantly (p?<?0.05) decreased NAA/Cr ratios in PCG and PWM in HT subjects compared to the control group. There were no other significant differences in metabolite ratios. We observed significant positive correlations between the NAA/Cr ratio in PCG as well as the PWM and fT3 level. There was also a significant negative correlation between the Cho/Cr ratio in the PCG and fT4 level. MRS could be a sensitive biomarker capable of depicting early cerebral metabolic disturbances associated with HT. Our findings may indicate the reduction of neuronal activity within the normal appearing brain in patients with HT as well as suggesting that there is a possible biological association between thyroid dysfunction and cerebral metabolic changes.

     

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.     

Advanced magnetic resonance imaging of the brain in patients treated with TNF-alpha blocking agents

OBJECTIVE: Neurological symptoms have been reported in patients treated with anti-TNF-alpha. In a pilot study we evaluated the effect of anti-TNF-alpha on cerebral parenchyma using advanced Magnetic Resonance (MR) techniques. METHODS: Seven patients with a systemic inflammatory disease (5 rheumatoid arthritis, 2 psoriatic arthritis) had Magnetization Transfer Imaging, Diffusion Weighted Imaging (DWI) and Magnetic Resonance Spectroscopy (MRS) of the brain before and after administration of anti-TNF-alpha. Four patients were neuropsychologically evaluated. RESULTS: After treatment with TNF-alpha blocking agents the Magnetization Transfer Ratio histogram Peak-heights (MTR-Pht) of the white and gray matter decreased (p < 0.01 and p < 0.05 respectively). The Apparent Diffusion Coefficient for the white and gray matter and the metabolite ratios in the centrum semiovale did not significantly change after therapy. Neuropsychological assessment showed no difference before and after anti-TNF-alpha. CONCLUSION: The decrease of the MTR-Pht after anti-TNF-alpha therapy suggests loss of parenchyma integrity; however, these changes could not be attributed to inflammation or demyelination based on our complementary DWI and MRS data. The decrease of the MTR-Pht did not result in decreased cognitive function.     

Magnetic resonance imaging and proton spectroscopic alterations correlate with parkinsonian signs in patients with cirrhosis

BACKGROUND & AIMS: The relationship between abnormalities found by magnetic resonance imaging (MRI) and proton spectroscopy (MRS) and the clinical signs of hepatic encephalopathy is not well characterized. Motor disturbances have been described, suggesting that basal ganglia (BG) are altered. METHODS: We evaluated 19 unselected consecutive patients with biopsy-proven cirrhosis evaluated for liver transplantation for the presence of parkinsonian signs using the Unified Parkinson's Disease Rating Scale (UPDRS) and Purdue Pegboard test, and correlated these neurologic abnormalities with MRI and MRS studies. Brain MRI intensities were expressed as signal-to-noise ratios. MRS findings obtained from one voxel in the BG and one in the occipital white matter (WM) were expressed as metabolite ratios. Six healthy subjects had normal values. RESULTS: Compared with healthy subjects, patients with subclinical or grade 1 hepatic encephalopathy had hyperintensity in occipital WM and all BG tissues except thalamus and reduced Ino/Cr and Cho/Cr ratios in both voxels. In the BG, MRI intensity was correlated with the UPDRS (P < 0.05, r = 0.56). The Cho/Cr ratio also correlated with both UPDRS (P < 0.02, r = -0.59) and Pegboard scores (P < 0.02, r = 0.61). CONCLUSIONS: In cirrhosis, parkinsonian signs correlate with BG alterations detected by MRI and MRS.     

1H-MRS in autism spectrum disorders: a systematic meta-analysis

We conducted a systematic review and meta-analysis of proton magnetic resonance spectroscopy (1H-MRS) studies comparing autism spectrum disorder (ASD) patients with healthy controls, with the aim of profiling ASD-associated changes in the metabolites N-acetyl-aspartate (NAA) and Creatine (Cr). Meta-regression models of NAA and Cr levels were employed, using data from 20 eligible studies (N = 852), to investigate age-dependent differences in both global brain and region-specific metabolite levels, while controlling for measurement method (Cr-ratio versus absolute concentrations). Decreased NAA concentrations that were specific to children were found for whole-brain grey and white matter. In addition, a significant decrease in NAA was evident across age categories in the parietal cortex, the cerebellum, and the anterior cingulate cortex. Higher levels of Cr were observed for ASD adults than children in global grey matter, with specific increases for adults in the temporal lobe and decreased Cr in the occipital lobe in children. No differences were found for either NAA or Cr in the frontal lobes. These data provide some evidence that ASD is characterized by age-dependent fluctuations in metabolite levels across the whole brain and at the level of specific regions thought to underlie ASD-associated behavioural and affective deficits. Differences in Cr as a function of age and brain region suggests caution in the interpretation of Cr-based ratio measures of metabolites. Despite efforts to control for sources of heterogeneity, considerable variability in metabolite levels was observed in frontal and temporal regions, warranting further investigation.     

脑白质小血管缺血性病变的MRS、DTI研究

目的应用磁共振波谱（MRS）与磁共振弥散张量成像（DTI）,分析脑白质小血管缺血性病变的微观改变。方法选取发生在半卵圆中心、放射冠区的脑白质小血管缺血性病变患者作为研究对象,其中急性腔隙性梗死组（腔梗组）病灶12例,缺血性脑白质疏松组（疏松组）病灶20例,并设置15例正常志愿者作为对照组,行半卵圆中心、放射冠区T1WI、T2WI、T2FLAIR、DWI、MRS、DTI扫描。测量N-乙酰天门冬氨酸（NAA）、胆碱（Cho）、肌酸（Cr）值,测量平均弥散系数（MD）值,各向异性分数（FA）值。比较各组间的差异。结果与对照组比较,腔梗组与疏松组NAA、FA值均显著降低（P〈0.01）,腔梗组与疏松组之间,NAA、FA值没有明显差异（P〉0.05）。结论在脑白质小血管缺血性病变中,NAA、FA值显著降低,共同反映了神经轴突髓鞘结构和功能的损伤、破坏;联合应用MRS、DTI分析评价脑白质小血管缺血性病变,将有助于全面认识其发病机制及病理改变。     

Reversible Alterations in Brain Metabolites During Therapy for Disseminated Nocardiosis Using Proton Magnetic Resonance Spectroscopy

We report reversible abnormalities in magnetic resonance spectra acquired from a patient with AIDS undergoing antibiotic and corticosteroid therapy for disseminated nocardiosis, a rare opportunistic infection of immunosuppressed patients which can cause cerebral abscess formation. There was no clinical, CT or MRI evidence of HIV-1 encephalitis. MR spectra were acquired before and after treatment using a two-dimensional chemical shift imaging technique (TR 1500ms, TE 130ms). Prior to treatment, a rise in the choline to creatine ratio and a reduction in the N-acetylaspartate to creatine ratio were observed in MR spectra localized to areas of the left anteromedial centrum semiovale that appeared normal on MR imaging. After 16 weeks, the patient had recovered with complete resolution of the cerebral abscesses on MRI. The MR spectral abnormalities also returned to normal. Two months later, the patient had a relapse with focal neurological signs and further abscesses were demonstrated on MRI of the brain. The patient subsequently died and histopathological and microbiological findings at autopsy confirmed the clinical picture of a recurrence of cerebral nocardiosis with no evidence of HIV-1 encephalitis. This case illustrates reversible MR-measurable metabolite changes in the brain of an HIV-seropositive patient without HIV-1 encephalitis who underwent treatment for cerebral nocardiosis.     

Clinical significance of cerebral white matter lesions in older Asians with suspected dementia

BACKGROUND: cerebral white matter lesions are commonly seen on neuroimaging in older people and have been associated with clinical features such as gait abnormalities, urinary incontinence and depression. The significance of cerebral white matter lesions in older people with dementia remains uncertain. OBJECTIVES: to study the association between cerebral white matter lesions and the presence or absence of dementia in a group of elderly Asian patients; and to determine the clinical significance of cerebral white matter lesions in patients who are diagnosed to have dementia in terms of associated clinical features and the impact of cerebral white matter lesions on cognitive status. METHODS: for the first objective, the records of 141 older people of Asian ethnicity presenting to a memory clinic for the evaluation of suspected dementia were reviewed to compare the prevalence of cerebral white matter lesions in patients who did not fulfil the criteria for dementia, patients diagnosed to have Alzheimer's disease and patients diagnosed to have vascular dementia. For the second objective, 115 of these patients who were diagnosed to have dementia were studied to determine if demented patients with cerebral white matter lesions were more likely to have urinary incontinence, Parkinsonism, depression and greater severity of dementia. In addition, a comparison was made between demented patients with cerebral white matter lesions and those without cerebral white matter lesions in terms of psychometric assessment scores. RESULTS: cerebral white matter lesions were more common in Asian patients with vascular dementia. Demented patients with cerebral white matter lesions were also found to have more severe dementia and greater functional disability. CONCLUSION: cerebral white matter lesions are common, and are associated with greater functional disability in elderly Asian patients with dementia.     

脑白质疏松

脑白质疏松是多种原因造成的,CT表现为脑室周围或皮质下区(半卵圆中心)弥漫性低密度带,在MRI T2加权像上为弥漫性高信号。小动脉病变导致的白质纤维脱髓鞘是发生白质疏松的主要原因之一。文章对脑白质疏松的临床表现、影像学、病理学特点及其发病机制进行了综述。     

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.     

Brain imaging correlates of mild cognitive impairment and early dementia in patients with type 2 diabetes mellitus

Background and aims

The risk of mild cognitive impairment and dementia is increased in type 2 diabetes mellitus (T2DM). We aimed to identify the neuroanatomical correlates of mild cognitive impairment (MCI) and early dementia in patients with T2DM, using advanced multimodal MRI.

Sensitivity of quantitative (1)H magnetic resonance spectroscopy of the brain in detecting early neuronal damage in systemic lupus erythematosus

OBJECTIVE: To quantify N-acetylaspartate (NAA), total creatines (tCr), total cholines (tCho), and myo-inositol (mI) levels in normal and abnormal appearing white matter of patients with neuropsychiatric systemic lupus erythematosus (NPSLE) in order to determine the specific changes in metabolite concentrations. METHODS: Axial proton density and T(2) weighted magnetic resonance images, and short echo time (TE 30 ms) (1)H spectra were acquired with a GE SIGNA 1.5 T magnetic resonance system. Concentrations of NAA, tCr, tCho, and mI were determined, using brain tissue water as a reference, from nine patients (seven female, mean age 40.3 years, range 16-65) with NPSLE and eight healthy women (mean age 43 years, range 31-65). RESULTS: A significant rise of tCho (12.4%, p<0.05) and mI (31.4%, p<0.005) and a significant reduction in NAA (-12%, p<0.05) was found in normal appearing white matter compared with controls. Analysis according to severity of the clinical NPSLE features (subgrouped as major or minor) showed that SLE major had reduced NAA compared with SLE minor (-18.4%, p<0.05) and controls (-20%, p<0.005). The SLE major group showed a significant rise of mI (32%, p<0.01) and the SLE minor group a significant increase in tCho (18.6%, p<0.05) compared with controls. Longitudinal analysis of brain metabolites in normal appearing white matter showed consistent abnormalities in NAA, tCho, and mI in a patient with stable clinical features and a constant rise of tCho, but transient rise of mI was seen during a flare of disease in another patient. CONCLUSION: Quantitative (1)H magnetic resonance spectroscopy (MRS) suggests a particular course of neurometabolite changes that precedes irreversible reductions in NAA and permanent neuronal loss. Initially, in patients with SLE minor, there is a significant rise in tCho and a trend (reversible) for mI also to be raised. In patients with SLE major the NAA is significantly and permanently reduced and mI is significantly raised, whereas the tCho levels are near normal. Further investigations are needed to determine how specific MRS is as a clinical marker for brain disturbance in SLE.     

老年人脑白质结构的扩散张量成像研究

目的应用扩散张量成像（diffusion tensor imaging，DTI）阐明老年人脑白质结构平均弥散系数（ADCavg）和部分各向异性（FA）的变化。方法老年组及非老年组各30例。所有受检者均进行神经科查体和简易智能精神状态量表（MMSE）测试，无影响神经系统的疾病。所有受检者均行DTI检查，选择额叶白质、顶叶白质、半卵圆中心、胼胝体膝部、胼胝体压部为兴趣区，定量测量ADCavg与FA值。结果ADCavg、FA值男、女性别差异无统计学意义（P〉0．05），左右半球无明显改变。随着年龄增长，ADCavg值与年龄呈正相关，FA值与年龄呈负相关。在额叶白质（ADCavg：r=0．449，P〈0．05；FA：r=0．350，P〈0．05）、半卵圆中心（ADCavg：r=0．347，P〈0．05；FA：r=0．409，P〈0．05）、胼胝体膝部（ADCavg：r=0．452，P〈0．01；FA：r=0．556，P〈0．01）、压部（ADCavg：r=0．296，P〉0．05；FA：r=0．289，P〉0．05）、顶叶白质（ADCavg：r=0．367，P〈0．05；FA：r=0．287，P〉0．05）。老年组额叶白质、胼胝体膝部、半卵圆中心的ADCavg、FA值与简易智能精神状态量表（MMSE）相关，尤其是额叶白质的FA值相关更显著（r=0．466，P〈0．01）。结论与年龄相关的定量DTI分析，可有助于评价与年龄相关的变化。并且可建立一个与神经变性疾病比较对照的标准。DTI功能与结构的结合，表明老年人认知功能的衰退与白质微结构密切相关。     

高血压与脑小血管病患者磁共振弥散张量成像的相关性研究

目的探讨高血压与脑小血管病(SVD)患者磁共振弥散张量成像(DTI)的关系。方法选择55例SVD患者分为血压正常组19例和高血压组36例。行MRI和DTI检查,观察感兴趣区部分各向异性(FA)及表观扩散系数(ADC)的变化,分析其与血压的相关性。结果与血压正常组比较,高血压组左、右侧半卵圆中心和左侧额叶FA值显著降低(P<0.01);左侧半卵圆中心ADC值显著升高(P<0.05)。Pearson相关分析显示,高血压组左、右侧半卵圆中心FA值与收缩压呈负相关(r=-0.338,P=0.044;r=-0.334,P=0.046);左侧半卵圆中心和左侧额叶FA值与舒张压呈负相关(r=-0.419,P=0.011;r=-0.355,P=0.034);右侧半卵圆中心ADC值与舒张压呈正相关(r=0.336,P=0.045)。结论 DTI能够更敏感地显示高血压对SVD患者脑微观结构的损害,为评价高血压性脑损伤提供研究工具。     

In vivo detection and functional correlates of white matter microstructural disruption in chronic alcoholism

BACKGROUND: Postmortem studies report degradation of brain white matter microstructure in chronic alcoholism, but until recently, in vivo neuroimaging could provide measurement only at a macrostructural level. The development of magnetic resonance diffusion tensor imaging (DTI) for clinical use offers a method for depicting and quantifying the diffusion properties of white matter expressed as intravoxel and intervoxel coherence of tracts and fibers. METHODS: This study used DTI to examine the intravoxel coherence measured as fractional anisotropy (FA) and intervoxel coherence (C) of white matter tracts of the genu and splenium of the corpus callosum and of the centrum semiovale in 15 detoxified alcoholic men and 31 nonalcoholic control subjects. Exploratory correlational analyses examined the relationships between regional DTI measures and tests of attention and working memory in the alcoholic patients. RESULTS: The alcoholic group had lower regional FA than the control group. C was lower in the alcoholics than controls in the splenium only. Working memory correlated positively with splenium FA, whereas attention correlated positively with genu C. CONCLUSIONS: These results provide in vivo evidence for disruption of white matter microstructure in alcoholism and suggest that interruption of white matter fiber coherence contributes to disturbance in attention and working memory in chronic alcoholism.     

1H-MRS对碘异常引起脑损伤的诊断价值

目的 探讨氢质子磁共振波谱分析（^1H-MRS）在碘异常引起脑损伤病变中的应用价值。方法 收集临床诊断碘异常引起脑损伤的病例28例，其中低碘组16例，高碘组12例。使用西门子1．5TMPd，多体素相位矩阵扫描。检测低碘组和高碘组病人海马区与正常参照区域的代谢物浓度，利用SPSS12．0分析各种代谢物的变化。结果 ^1H-MRS示低碘组胆碱降低、γ-氨基丁酸、N-乙酰天门冬氨酸减少；高碘组胆碱增加、谷氨酸升高，γ-氨基丁酸、N-乙酰天门冬氨酸减少。结论 ^1H-MRS在碘异常引起脑损伤病变定性诊断中有重要的临床价值。     

Disruption of smooth pursuit eye movements in cirrhosis: relationship to hepatic encephalopathy and its treatment

Smooth pursuit eye movements (SPEM) are the conjugate movements used to track the smooth trajectory of small dots. Jerky or 'saccadic' ocular pursuit has been reported in patients with cirrhosis, but no formal assessment of SPEM has ever been undertaken. The aim of this study was to evaluate SPEM in patients with cirrhosis and varying degrees of hepatic encephalopathy. The patient population comprised 56 individuals (31 men, 25 women) of mean age 51.1 (range, 25-70) years, with biopsy-proven cirrhosis, classified, using clinical, electroencephalographic, and psychometric variables, as either neuropsychiatrically unimpaired or as having minimal or overt hepatic encephalopathy; patients were further categorized in relation to their treatment status. The reference population comprised 28 healthy volunteers (12 men, 16 women) of mean age 47.3 (range, 26-65) years. SPEM was assessed using an electro-oculographic technique. Visual inspection of the SPEM recordings showed clear disruption of smooth pursuit in the patients with minimal hepatic encephalopathy, and more pronounced disruption, if not complete loss, of smooth pursuit in patients with overt hepatic encephalopathy. The differences observed in quantifiable SPEM indices between the healthy volunteers/unimpaired patients and those with overt hepatic encephalopathy were significant (P < .05). In conclusion, SPEM performance is impaired in patients with hepatic encephalopathy in parallel with the degree of neuropsychiatric disturbance: the pathophysiology of these changes is unknown, but retinal, extrapyramidal, and attentional abnormalities are likely to play a role. Treatment status confounds the classification of neuropsychiatric status and should be taken into account when categorizing these patients.