Similar 1H magnetic resonance spectroscopic metabolic pattern in the medial temporal lobes of patients with mild cognitive impairment and Alzheimer disease

Structures of the medial temporal lobes are recognized to play a central role in memory processing and to be the primary sites of deterioration in Alzheimer disease (AD). Mild cognitive impairment (MCI) represents potentially an intermediate state between normal aging and AD. Proton magnetic resonance spectroscopy (MRS) was used to examine brain metabolic changes in patients with AD and MCI in the medial temporal lobes (MTLs), parietotemporal cortices (PTCs) and prefrontal cortices (PFCs). Fourteen patients with MCI, 14 patients with mild AD and 14 age- and sex-matched control subjects were studied. Patients with AD and MCI demonstrated significant reductions of NAA/H(2)O and Cho/H(2)O in the left MTL relative to control subjects. Patients with AD showed mI/H(2)O increases relative to patients with MCI and control subjects in all six regions investigated, and a statistically significant mI/H(2)O increase was measured in the right PTC. Patients with AD and MCI demonstrated the same metabolic pattern in the left MTL, suggesting a similar pathological process underlying memory impairment. Increased mI signal appears to be a neurochemical abnormality associated mostly with AD and the dementia process. Some interhemispheric metabolite asymmetries were increased in AD patients.     

Regional metabolic patterns in mild cognitive impairment and Alzheimer's disease: A 1H MRS study

BACKGROUND: Mild cognitive impairment (MCI) is a recently described transitional clinical state between normal aging and AD. Assuming that amnestic MCI patients had pathologic changes corresponding to an early phase and probable AD patients to a later phase of the disease progression, the authors could approximate the temporal course of proton MR spectroscopic (1H MRS) alterations in AD with a cross-sectional sampling scheme. METHODS: The authors compared 1H MRS findings in the superior temporal lobe, posterior cingulate gyri, and medial occipital lobe in 21 patients with MCI, 21 patients with probable AD, and 63 elderly controls. These areas are known to be involved at different neurofibrillary pathologic stages of AD. RESULTS: The N-acetylaspartate (NAA)/creatine (Cr) ratios were significantly lower in AD patients compared to both MCI and normal control subjects in the left superior temporal and the posterior cingulate volumes of interest (VOI) and there were no between-group differences in the medial occipital VOI. Myoinositol (MI)/Cr ratios measured from the posterior cingulate VOI were significantly higher in both MCI and AD patients than controls. The choline (Cho)/Cr ratios measured from the posterior cingulate VOI were higher in AD patients compared to both MCI and control subjects. CONCLUSION: These findings suggest that the initial 1H MRS change in the pathologic progression of AD is an increase in MI/Cr. A decrease in NAA/Cr and an increase in Cho/Cr develop later in the disease course.     

急性脑梗死后血管性认知障碍的磁共振波谱研究

目的应用质子磁共振波谱(1 H-MRS)技术,探讨急性脑梗死后血管性认知障碍(VCI)患者的颅内物质代谢变化与认知损害的关系。方法对86例脑梗死患者(脑梗死组)及21名健康对照者(对照组)进行简易精神状态检查量表(MMSE)和蒙特利尔认知评分量表(MoCA)评分,并计算其视空间及执行功能评分。根据认知评分结果,将脑梗死组分为脑梗死后认知功能正常组(NCI)、脑梗死后VCI非痴呆组(VCIND)、脑梗死后痴呆组。对脑梗死组及健康对照进行1 H-MRS检查,测定右额叶、左颞叶、左丘脑及顶枕叶交界处N-乙酰天冬氨酸(NAA)/肌酸(Cr)、肌醇(mI)/Cr及胆碱复合物(Cho)/Cr比值,并分析脑梗死组物质代谢比值与认知评分(MoCA评分、视空间及执行功能)间的相关性。结果 (1)与对照组(左颞叶及左丘脑NAA/Cr 1.53±0.08、1.52±0.10)相比,VCIND组左颞叶及左丘脑NAA/Cr(1.46±0.07、1.47±0.07)降低(P=0.001、P=0.006);与VCIND组右额叶1.46±0.10比较,梗死后痴呆组右额叶、左颞叶及左丘脑NAA/Cr(1.38±0.14、1.39±0.06、1.42±0.09)降低(分别P<0.001、P<0.001、P=0.003)。对照组及NCI组间的各区域物质代谢比值无统计学差异(均P>0.05)。(2)所有脑梗死患者中,除右额叶Cho/Cr外,余各感兴趣区物质代谢比值与MoCA评分间均相关,其中以左颞叶、左丘脑NAA/Cr值与MoCA评分的相关性为著(分别r=0.566,P<0.001;r=0.485,P<0.001);除右额叶、丘脑及顶枕叶交界处Cho/Cr外,余各物质代谢比值与视空间及执行功能评分间相关,其中亦以左颞叶及左丘脑NAA/Cr值的相关性为著(分别NAA/Cr为r=0.591,P<0.001;r=0.491,P<0.001)。结论左丘脑及左颞叶代谢异常可能为VCI患者认知损害的早期关键环节之一,随着VCI病变进展可能整个皮质及皮质下环路区域都将出现代谢异常。     

1H-MRS evaluation of metabolism in Alzheimer's disease and vascular dementia

Proton magnetic resonance spectroscopy (1H-MRS) allows major metabolites to be measured noninvasively in defined regions of the living brain, and can detect biochemical abnormalities where conventional structural imaging appears normal. MRS can be performed in 10 min as part of a clinical MRI examination. Biochemical abnormalities in Alzheimer's Disease (AD), vascular dementia (VaD) and other primary degenerative dementias have been investigated using MRS. Characteristic and consistent abnormalities in AD are decreased N-acetyl aspartate (NAA) and elevated myo-inositol (mI) in the mesial temporal and parieto-occipital cortex. These are thought to represent neuronal loss/dysfunction and gliosis, in anatomic distributions which reflect early pathological involvement and atrophy patterns in AD. Less consistent disturbances of glutamine and glutamate (Glx) and choline-containing compounds (Cho) have also been reported. Similar changes are seen in VaD; mostly in white matter, whereas in AD they predominate in cortical grey matter. The regional distribution of grey matter involvement may differ between AD and other degenerative dementias. Hence, both the nature and anatomic distribution of metabolite abnormalities contribute to diagnostic discrimination with MRS. NAA/mI ratios from short echo time spectra of the posterior cingulate region cortex discriminate reliably between AD subjects, normal individuals and those with VaD, and provides a useful clinical test, as an adjunct to structural imaging. Elevated mI is detected in mild cognitive impairment (MCI) and quantitative metabolite measures correlate with degrees of cognitive impairment in AD; these suggest a possible role for MRS in early diagnosis and for surrogate biochemical markers for monitoring disease progression and therapeutic response.     

轻度认知障碍和轻度Alzeimer病的磁共振波谱分析

目的探讨氢质子磁共振波谱（1H—MRs）在轻度认知障碍（MCI）、轻度Alzheimer病（AD）诊断与鉴别诊断中的作用。方法对20例MCI患者、20例AD患者、20例正常对照者行。H—MRS检查,采用点分辨自旋回波波谱序列（PRESS）,测定双侧内侧颞叶的N-乙酰天门冬氨酸（NAA）、胆碱（Cho）和肌醇（mI）与肌酸（Cr）的比值,并比较各组闻NAA／Cr、mI／Cr、Cho／Cr比值的差别。结果轻度AD组及MCI组与正常对照组间双侧NAA／Cr有显著性差异（P〈0．05）,MCI组、轻度AD组、正常对照组三组间双侧mI／Cr有显著性差异（P〈0．05）,三组间Cho／Cr比值差异无统计学意义。结论1H—MRs能无创性提供MCI、AD患者脑部的代谢情况,NAA／Cr降低和mI／Cr升高有助于MCI、轻度AD的早期诊断。     

Evaluation of functional MRI markers in mild cognitive impairment

We aimed to investigate the use of advanced functional MRI (fMRI) techniques such as proton magnetic resonance spectroscopy (¹H-MRS) and the apparent diffusion coefficient (ADC) value in diffusion weighted imaging (DWI), in the diagnosis of mild cognitive impairment (MCI). Multiple indicators were combined in order to improve the early diagnostic value of MRS and ADC. We administered MRS and DWI-ADC to 13 patients with Alzheimer’s disease (AD), 9 patients with MCI, and 13 control patients. Changes in N-acetylaspartate/creatine and phosphocreatine (NAA/Cr), myoinositol/creatine (mI/Cr), and the ADC values in the hippocampus and the temporoparietal region were compared among groups. The sensitivity and specificity of different markers were analyzed individually and combined with others. All participants were evaluated by the mini mental state examination (MMSE), and the correlation between NAA/Cr, MI/Cr, ADC and the score of MMSE were analyzed separately. The NAA/Cr, mI/Cr and ADC values in the hippocampus among AD, MCI patients, and controls were significantly different (p < 0.05). At a fixed specificity of 84.6%, the high sensitivity of 100% and 92.9% in differentiating AD and MCI from normal controls were obtained by combining the three indicators. The receiver operating characteristic plots illustrated that the area under the multimarker curve was the biggest among the all four curves, and the sensitivity of the multimarkers was highest. The best correlation was obtained between ADC and MMSE, rather than between NAA or mI and MMSE. Thus, we found that changes in NAA/Cr, mI/Cr and ADC in the hippocampus and the temporoparietal regions were helpful in the clinical diagnosis of MCI. Furthermore, these changes showed potential in predicting the progression of MCI to AD if the multimarkers were combined.     

壳聚糖、磷脂酰胆碱对轻度认知功能障碍患者脑组织氢质子磁共振波谱成像的影响

目的观察壳聚糖、磷脂酰胆碱对轻度认知功能障碍(MCI)患者海马氢质子磁共振波谱成像(1H-MRSI)的影响。方法对15例MCI患者(MCI组)和15名正常老年人(正常对照组)进行海马1H-MRSI检查。给予MCI组患者壳聚糖、磷脂酰胆碱治疗2个月后对其进行复查,比较N-乙酰天门冬氨酸(NAA)/肌酸(Cr)、胆碱(Cho)/Cr、肌醇(mI)/Cr的比值。结果与正常对照组相比,MCI组服药前、后NAA/Cr比值显著降低,mI/Cr比值显著升高(均P<0.05),Cho/Cr的差异无统计学意义。MCI组治疗后的NAA/Cr比值较治疗前明显升高(P<0.05),mI/Cr比值明显降低(P<0.05),Cho/Cr比值治疗前后的差异无统计学意义。结论1H-MRSI显示,壳聚糖和磷脂酰胆碱能改善脑组织的代谢,可能对MCI有一定的治疗作用。     

Longitudinal metabolic and cognitive changes in mild cognitive impairment patients

Advancements in clinical therapies have identified the need for biomarkers of early Alzheimer disease that distinguish the earliest stages of pathology and target those patients who are likely to gain the most benefit. The aim of this study was to characterize the longitudinal metabolic changes measured by 1H magnetic resonance spectroscopy in correlation to neuropsychologic indices of episodic memory, attention and mental processing speed, language facility, and executive function in subjects with mild cognitive impairment (MCI). Quantitative 1H magnetic resonance spectroscopy of the posterior cingulate gyrus was performed and repeated at 11.56+/-4.3 months. N-acetyl aspartate (NAA), total choline (Cho), total creatine (Cr), myo-inositol (mI), and glutamate/glutamine (Glx) metabolite levels were measured, corrected for cerebrospinal fluid dilution, and ratios calculated in MCI and cognitively normal subjects. In the first study, MCI subjects showed lower NAA levels, NAA/Cho, and NAA/mI ratios and increased Cho/Cr and mI/Cr compared with controls. In the follow-up study, 36% of the MCI subjects [atypical MCI (atMCI)] showed interval increases in NAA, Cr, and Glx levels compared with 64% of MCI subjects (typical MCI) who showed an interval decrease in NAA, Cr, and Glx. Both MCI subgroups had higher Clinical Dementia Rating scores and lower scores on episodic memory, phonemic, and semantic word fluency tasks, compared with controls. The annualized rate of change in metabolic and cognitive status did not differ between normal aging and MCI subjects. atMCI subjects showed significant negative correlations between metabolite levels and executive function task scores, with NAA/mI showing a significant positive correlation with phonemic and semantic word fluency. There were no significant correlations between metabolite levels and cognitive performance in tMCI subjects; however, NAA/mI and mI/Cr were negatively correlated with executive function tasks. These results indicate 2 distinct evolving metabolite profiles that correlate with changes in executive function and can be used to differentiate MCI from normal aging.     

In vivo proton magnetic resonance spectroscopy of the temporal lobe in Alzheimer's disease

PURPOSE: Prior proton magnetic resonance spectroscopy (MRS) studies have consistently reported decreased brain n-acetyl aspartate (NAA) levels and increased myo-inositol (mI) levels in subjects with Alzheimer's disease (AD) relative to healthy comparison subjects. These studies have usually been conducted in small and homogeneous populations of patients with established Alzheimer's disease. Few studies have tested the usefulness of this finding in a general population seeking evaluation for memory loss and other cognitive declines. We designed a study to evaluate the significance of single-voxel proton MRS findings in these patients with memory loss and other cognitive declines. GENERAL METHOD: Thirty-five subjects with a primary complaint of memory loss and other cognitive declines were consecutively referred over a period of 13 months to a specialty clinic. Patients with a diagnosis of mild to moderate probable Alzheimer's disease (N = 22), non-Alzheimer's dementia (depression, multiinfarct dementia, Parkinson's Disease, Korsakoff's Psychosis, and bipolar disorder; N = 13), and healthy comparison subjects (N = 18) were examined with respect to possible differences in metabolites using proton MRS in a 3.4-ml anterior temporal lobe voxel. FINDINGS: The Alzheimer's disease group had 10.7% lower NAA/creatine (Cr) ratios relative to the healthy comparison group and 9.4% lower NAA/creatine relative to the non-Alzheimer's dementia group (15.0% lower NAA/creatine relative to the depression subgroup of the non-Alzheimer's dementia group). There were no significant differences in choline (Cho) or myo-inositol ratios among the groups. There were significant correlations between NAA/creatine ratios and mini-mental status exam (MMSE) scores in subjects with Alzheimer's disease (t = 2.41, p = 0.032) but not in subjects with non-Alzheimer's dementia or in its depression subgroup. CONCLUSIONS: This study found a reduction in the neuronal marker NAA in the anterior temporal lobe of patients diagnosed with probable Alzheimer's disease, using a short add-on proton MRS exam. This change was not observed in patients whose memory loss and other cognitive declines were not attributed to Alzheimer's disease, suggesting that it may aid in the diagnosis or detection of Alzheimer's disease.     

A decrease in N-acetylaspartate and an increase in myoinositol in the anterior cingulate gyrus are associated with behavioral and psychological symptoms in Alzheimer's disease

BACKGROUND AND PURPOSE: The cognitive decline in Alzheimer's disease (AD) patients has been reported to involve alterations in the medial temporal lobe and the posterior cingulate gyrus. On the other hand, the neurochemical pathologies of the behavioral and psychological symptoms of dementia (BPSD) have not been sufficiently discussed. The aim of this study was to clarify the pathologies of BPSD in AD patients. METHODS: Thirty patients with probable AD were included and underwent the following assessments: Mini Mental State Examination (MMSE), Clock Drawing Test (CDT), Story Recall Test (SRT), Behavioral pathology in Alzheimer's disease (BEHAVE-AD) and proton MRS ((1)H-MRS). None of them had been medicated for BPSD. RESULTS: The MRS study revealed that MMSE, CDT, and SRT scores were positively related to N-acetyl-aspartate (NAA)/creatine(Cr) and negatively related to myoinositol (mI)/Cr in the posterior cingulate gyrus, but not in the anterior cingulate gyrus. On the other hand, the scores obtained in two categories of BEHAVE-AD (delusional thought/ activity disturbances) were negatively related with NAA/Cr and positively related with mI/Cr in the anterior cingulate gyrus, but not in the posterior cingulate gyrus. CONCLUSION: We conclude that BPSD and the decline in cognitive function in AD might have separate pathologies.     

Metabolic changes in 37 newly diagnosed Wilson's disease patients assessed by magnetic resonance spectroscopy

Wilson's Disease (WD) is a rare autosomal recessive disorder. The literature about proton MR spectroscopy (MRS) in WD is based mostly on data derived from patients undergoing treatment. The aim of this study was to identify brain metabolic changes in newly diagnosed WD patients using MRS to elucidate the pathomechanism of the cerebral pathology of WD. The globus pallidus and thalamus of 37 patients with WD were examined bilaterally with MRS. The calculations were performed for: myoinositol (mI), choline (Cho), creatine (Cr), N-acetyl-aspartate (NAA), lipid (Lip), glutamine, and glutamate (Glx). In all WD patients a significantly decreased mI/Cr and NAA/Cr ratio levels and an increased Lip/Cr ratio in the pallidum were observed. Analysis revealed a significantly increased Glx/Cr and Lip/Cr ratio in the thalamus. In the pallidum of neurologically impaired patients, Cho/Cr, Glx/Cr and Lip/Cr ratios were higher than in control subjects, and the NAA/Cr was significantly lower. In hepatic patients, the mI/Cr, Cho/Cr and NAA/Cr ratio levels were lower than in controls. The Cho/Cr and Lip/Cr ratios were higher in the thalami of neurologically impaired patients, and Lip/Cr ratios were higher than controls' in hepatic patients. Both findings were statistically significant. Compared to the thalamus, the basal ganglia are more sensitive to ongoing degenerative changes and portal-systemic encephalopathy in WD. The NAA/Cr reduction in hepatic and neurologically impaired patients could indicate that neurodegeneration is associated with all presentations of WD. In hepatic patients a mI and Cho decrease and in neurological Glx increase can be caused by porto-systemic shunting.     

氢质子磁共振波谱对Alzheimer病神经生化改变的分析

目的研究Alzheimer病(Alzheimerdisease,AD)的氢质子磁共振波谱分析改变,并与认知正常的老年志愿者(normalcognition,NC)进行比较。方法对AD组21例及NC组20名被观察者行磁共振波谱分析,测定双侧海马、颞顶叶联合区的N乙酰天门冬氨酸(N acetylaspartate,NAA)、胆碱(choline,Cho)和肌醇(myo inositol,mI)与肌酸(creatine,Cr)的比值。采用SPSS11.5软件进行统计分析。结果AD组和NC组双侧海马和颞顶联合区的NAA/Cr差异有显著性(P<0.05),双侧海马和左侧颞顶叶联合区的mI/Cr差异有显著性(P<0.05),双侧海马和颞顶叶联合区的Cho/Cr差异无显著性(P<0.05)。只有左侧海马的NAA/Cr水平下降与AD的严重程度呈正相关(r=0.470,P<0.05)。结论磁共振波谱分析可发现AD海马及颞顶联合区的NAA/Cr、mI/Cr改变,左侧海马NAA/Cr的减低可帮助评价AD的严重程度。     

Evidence for cortical dysfunction in clinically non-demented patients with Parkinson's disease: a proton MR spectroscopy study

OBJECTIVES: To investigate whether proton magnetic resonance spectroscopy (1H MRS) can detect cortical dysfunction in non-demented patients with Parkinson's disease, and to correlate changes with cognitive function on formal neuropsychological testing. METHODS: Multivoxel 1H MRS was performed in 17 patients with levodopa treated idiopathic Parkinson's disease with out clinical dementia, and 10 age match ed control subjects. Measurements of N-acetylaspartate (NAA)/choline (Cho), NAA/creatine+phosphocreatine (Cr), and Cho/Cr were obtained from right and left temporoparietal cortex and occipital cortex. Fourteen patients with Parkinson's disease underwent a full battery of neuropsychological testing including performance and verbal subtests of the WAIS-R, Boston naming test, FAS test, and California verbal learning test. RESULTS: There were significant temporoparietal cortex reductions in NAA/Cr ratios in right and left averaged spectra of the patients with Parkinson's disease (p=0.012 after Bonferroni correction) and in spectra contralateral to the worst clinically affected limbs of the patients with Parkinson's disease compared with controls (p = 0.003 after Bonferroni correction). There was a significant correlation between reduction in NAA/Cr ratios and measures of global cognitive decline, occurring independently of motor impairment (p=0.019). CONCLUSIONS: This study suggests that 1H MRS can detect temporoparietal cortical dysfunction in non-demented patients with Parkinson's disease. Further longitudinal studies are needed to investigate whether these 1H MRS changes are predictive of future cognitive impairment in the subset of patients with Parkinson's disease who go on to develop dementia, or occur as part of the normal Parkinson's disease process.     

Comparative diagnostic utility of different MR modalities in mild cognitive impairment and Alzheimer's disease

This study compares the diagnostic accuracy of magnetic resonance (MR)-based hippocampal volumetry, single voxel (1)H MR spectroscopy ((1)H MRS) and MR diffusion-weighted imaging (DWI) measurements in discriminating patients with amnestic mild cognitive impairment (MCI), Alzheimer's disease (AD) and normally aging elderly. Sixty-one normally aging elderly, 24 MCI and 22 AD patients underwent MR-based hippocampal volumetry, (1)H MRS and DWI. (1)H MRS voxels were placed over both of the posterior cingulate gyri, and N-acetyl aspartate (NAA)/creatine (Cr), myoinositol (MI)/Cr and NAA/MI ratios were obtained. Apparent diffusion coefficient (ADC) maps were derived from DWI, and hippocampal borders were traced to measure hippocampal ADC. At 80% specificity, the most sensitive single measurement to discriminate MCI (79%) and AD (86%) from controls was hippocampal volumes. The most sensitive single measurement to discriminate AD from MCI was posterior cingulate gyrus NAA/Cr (67%). At high specificity (>85-90%), combinations of MR measures had superior diagnostic sensitivity compared with any single MR measurement for the AD vs. control and control vs. MCI comparisons. The MR measures that best discriminate more from less affected individuals along the cognitive continuum from normal to AD vary with disease severity. Selection of imaging measures used for clinical assessment or monitoring efficiency of therapeutic intervention should be tailored to the clinical stage of the disease.     

Multimodal imaging in diagnosis of Alzheimer's disease and amnestic mild cognitive impairment: value of magnetic resonance spectroscopy, perfusion, and diffusion tensor imaging of the posterior cingulate region

The purpose of this study was to assess metabolic, perfusion, and microstructural changes within the posterior cingulate area in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) using advanced MR techniques such as: spectroscopy (MRS), perfusion weighted imaging (PWI), and diffusion tensor imaging (DTI). Thirty patients with AD (mean age 71.5 y, MMSE 18), 23 with aMCI (mean age 66 y, MMSE 27.4), and 15 age-matched normal controls (mean age 69 y, MMSE 29.5) underwent conventional MRI followed by MRS, PWI, and DTI on 1.5 Tesla MR unit. Several metabolite ratios (N-acetylaspartate [NAA]/creatine [Cr], choline [Ch]/Cr, myoinositol [mI]/Cr, mI/NAA, mI/Cho) as well as parameters of cerebral blood volume relative to cerebellum and fractional anisotropy were obtained in the posterior cingulate region. The above parameters were correlated with the results of neuropsychological tests. AD patients showed significant abnormalities in all evaluated parameters while subjects with aMCI showed only perfusion and diffusion changes in the posterior cingulate area. Only PWI and DTI measurements revealed significant differences among the three evaluated subject groups. DTI, PWI, and MRS results showed significant correlations with neuropsychological tests. DTI changes correlated with both PWI and MRS abnormalities. Of neuroimaging methods, DTI revealed the highest accuracy in diagnosis of AD and aMCI (0.95, 0.79) followed by PWI (0.87, 0.67) and MRS (0.82, 0.47), respectively. In conclusion, AD is a complex pathology regarding both grey and white matter. DTI seems to be the most useful imaging modality to distinguish between AD, aMCI, and control group, followed by PWI and MRS.     

Proton spectroscopy in Alzheimer's disease and cognitive impairment not dementia: a community study

OBJECTIVE: To describe the proton magnetic resonance spectroscopy (1H-ERM) data in Alzheimer's disease (AD) and Cognitive Impairment Not Dementia (CIND) in a community sample. METHOD: We investigated subjects with AD (n=6), CIND (n=7) and normal control (n=7). 1H-ERM was performed with single voxel (8 cm3) placed in temporal, parietal and occipital regions and studied metabolites were: N-acetylaspartate (NAA), creatine (Cr), choline (Cho) and myo-inositol (mI). RESULTS: NAA concentration was higher in control subjects than AD and intermediated in CIND patients. Cho parietal plus occipital and Cr parietal plus Cho occipital classified correctly 92.3% of subjects Control vs AD. Temporal mI classified 78.6% of subjects between Control vs CIND. CONCLUSION: Spectroscopy can be used in the diagnosis and follow-up of individuals with cognitive impairment; evaluation of community subjects may show different patterns of brain metabolites distribution.     

非痴呆型血管性认知障碍的磁共振波谱成像研究进展

血管性认知障碍（VCI）目前已成为老年人认知障碍的主要病因，其中，非痴呆型血管性认知障碍（VCIND）是VCI的初期阶段，具有可逆性。近年来，磁共振波谱（MRS）以其高分辨率、无创的特点，越来越广泛地应用于临床，成为了研究的热点。目前研究表明，VCIND患者的认知损害包括执行功能、视空间、感知功能、记忆力等几乎所有的主要认知域。MRS与认知量表的联合应用可提高VCIND的临床诊断的准确率。VCIND患者额叶、颞叶NAA/Cr降低较为明确，而丘脑仍需进一步研究。Cho在VCIND患者脑组织中的变化研究结果不甚一致。另外，MRS在M-aMCI与VCIND的鉴别中可起到重要的作用。关于VCIND的研究尚存在诸多问题，且结果差异较大，尚需进一步研究。     

1H magnetic resonance spectroscopy, cognitive function, and apolipoprotein E genotype in normal aging, mild cognitive impairment and Alzheimer's disease.

The aim of this study was to examine the associations of apolipoprotein E (APOE) genotype, metabolic changes in the posterior cingulate detected by 1H magnetic resonance spectroscopy (MRS), and neuropsychologic measures of memory and cognition both in normally aging elderly, and in patients with mild cognitive impairment (MCI) and AD. We studied 67 controls, 18 MCI and 33 AD patients. We used the Dementia Rating Scale total score (DRSTOT) as a measure of general cognitive function and the total learning from the Auditory Verbal Learning Test (AVTOT) as a measure of memory performance. No differences were noted on 1H-MRS metabolite ratios or cognitive measures across APOE genotype within control and patient groups. In controls, age was a significant predictor of both cognitive test scores, and NAA/Cr was a univariate associate of DRSTOT. All 3 1H-MRS metabolite ratios, N-acetylaspartate (NAA)/creatine (Cr), myoinositol (MI)/Cr, and NAA/MI, were univariate associates of AVTOT and DRSTOT scores in the combined MCI and AD group. In stepwise regression analyses in the combined patient group only NAA/MI entered the models. These data suggest NAA/Cr could be a modest predictor of general cognitive function in both healthy elderly and impaired patients, while MI/Cr is a more specific marker for neuropsychologic dysfunction associated with neurodegenerative disease. Among 1H-MRS measurements, the NAA/MI ratio maybe the most efficient predictor of memory and cognitive function in patients with MCI and AD.     

1H-MRS asymmetry changes in the anterior and posterior cingulate gyrus in patients with mild cognitive impairment and mild Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia worldwide. Amnestic mild cognitive impairment (aMCI) is often the prodromal stage to AD. Most patients with aMCI harbor the pathologic changes of AD and demonstrate transition to AD at a rate of 10%–15% per year. Patients with AD and aMCI experience progressive brain metabolite changes. Accumulating evidence indicates that the asymmetry changes of left and right brain happen in the early stage of AD. However, the features of asymmetry changes in both anterior cingulate gyrus (ACG) and posterior cingulate gyrus (PCG) are still unclear. Here, we examine the left–right asymmetry changes of metabolites in ACG and PCG. Fifteen cases of mild AD patients meeting criteria for probable AD of NINDS-ADRDA, thirteen cases of aMCI according to the Mayo Clinic Alzheimer's Disease Research Center criteria, and sixteen cases of age-matched normal controls (NC) received Proton magnetic resonance spectroscopy (¹H-MRS) for measurement of NAA/mI, NAA/Cr, Cho/Cr, and mI/Cr ratios in the PCG and ACG bilaterally. We analyzed ¹H-MRS data by paired t-test to validate the left–right asymmetry of ¹H-MRS data in the PCG and ACG. In AD, there was a significant difference in mI/Cr between the left and right ACG (P < 0.001) and the left and right PCG (P = 0.007). In aMCI, there was a significant difference in mI/Cr between the left and right ACG (P < 0.001). In NC, there were no differences in the ratio value of metabolites NAA/mI, NAA/Cr, Cho/Cr, and mI/Cr between the left and right ACG and PCG. Thus, the left–right asymmetry of mI/Cr in the ACG and PCG may be an important biological indicator of mild AD.     

质子磁共振波谱用于帕金森病黑质代谢研究价值的探讨

目的探讨质子磁共振波谱（^1H MRS）技术在帕金森病（PD）黑质代谢变化研究中的价值。方法PD患者56例和正常对照30例行^1H MRS检查，测定双侧黑质的N-乙酰天门冬氨酸／肌酸（NAA／Cr）、N-乙酰天门冬氨酸／胆碱复合物（NAA／Cho）和胆碱复合物／肌酸（Cho／Cr）比值。结果PD患者和对照组黑质的NAA／Cr、Cho／Cr和NAA／Cho比值无显著性差异。PD患者的^1H MRS结果与UPDRS评分、H＆Y分级和病程均不存在显著相关性。结论目前的^1H MRS技术尚不能精准地反应PD患者黑质的代谢变化。