轻度认知功能障碍与脑白质弥散张量成像的相关性研究

目的通过磁共振弥散张量成像研究不同区域脑白质损害与轻度认知功能(MCI)的关系。方法纳入2015年7月至2016年2月我院的住院患者56例为研究对象,其中MCI组34例,认知功能正常组22例。所有研究对象进行一般情况检查,完成神经心理学量表检测。通过头颅磁共振弥散张量成像(DTI)检查对不同脑区白质纤维进行部分各向异性(FA)值测量。结果 MCI组患者与认知功能正常组相比,右侧额叶FA值(0.335±0.068)、左侧颞叶白质FA值(0.391±0.032)及胼胝体膝部FA值(0.658±0.053)降低,差异具有统计学意义(P0.05)。将上述FA值和MMSE、Mo CA量表中各认知域进行典型相关分析,结果显示右侧额叶白质FA值与注意与计算力呈正相关,左侧颞叶白质和胼胝体膝部FA值与记忆力呈正相关(P0.05)。结论 MCI患者注意与计算力的障碍可能与右侧额叶白质损害有关,而左侧颞叶白质及胼胝体膝部白质的损害可能导致早期的记忆障碍。DTI可能成为超早期识别与诊断MCI的新方法。     

弥散张量成像与老年人认知功能的相关性

目的：研究老年人认知功能与MRI弥散张量成像（DTI）参数的相关性。方法：年龄〉60岁的老年人43例,按其认知功能量表评分[简易智能状态量表（MMSE）、临床痴呆量表（CDR）、总体衰退量表（GDS）和日常生活活动能力量表（ADL）]分为认知功能正常组、轻度认知功能障碍组和阿尔茨海默病3组,比较各组间头颅MRI部分各向异性（FA）和表观弥散系数（ADC）值是否具有差异,寻找与认知功能相关的颅内结构。结果：左侧颞叶、胼胝体膝部、压部的FA和ADC值,以及右侧额叶、双侧半卵圆中心的ADC值组间差异有统计学意义（P〈0.05）。FA值随认知功能减退而降低;而ADC值随认知功能减退而增高。额叶、颞叶、半卵圆中心和胼胝体等部位的DTI参数与常用的MMSE、CDR、GDS、ADL评分显著相关（P〈0.05）。结论：MRIDTI参数与老年人认知功能水平显著相关。     

轻度脑外伤患者弥散张量成像与认知功能

目的探讨轻度脑外伤(mild traumatic brain injury,m TBI)患者脑白质弥散张量成像(diffusion tensor imaging,DTI)的特点及其与认知功能的关系。方法对36例m TBI患者(患者组)36例健康受试者(对照组)进行全脑DTI扫描和认知功能测查,采用基于体素的全脑分析法比较患者组和对照组全脑白质各向异性(fractional anisotropy,FA)图像;采用t检验比较两组FA值的差异;提取患者组差异脑区FA值,与P300波幅、潜伏期,蒙特利尔认知评估量表(Montreal cognitive assessment,Mo CA)评分,汉密顿抑郁量表(Hamilton depression scale,HDRS)评分,汉密顿焦虑量表(Hamilton anxiey scale,HAMA)评分,年龄及受教育程度进行相关分析。结果与对照组比较,患者组FA降低的脑区分布在右额内侧回,双侧中央后回、左楔前叶,左后扣带回和右颞上回(P<0.01,FDR校正);未发现有FA增高的脑区。Pearson相关分析未发现各异常脑区FA值与患者各临床特征因子存在相关(P>0.05)。结论 m TBI患者存在认知功能损害和多个脑区白质微细结构的损害。     

阿尔茨海默病与轻度认知障碍弥散张量成像研究

目的:应用磁共振弥散张量成像技术(DTI)研究阿尔茨海默病(AD)与轻度认知障碍患者(MCI)脑白质损伤情况。方法:对21例AD患者、15例MCI患者和20名健康志愿者进行脑部DTI扫描后,测量双脑区感兴趣区的各向异性分数值(FA)且进行比较。结果:AD患者额叶、顶叶、颞叶和胼胝体的FA值与MCI组和对照组均存在显著性差异,MCI患者仅颞叶和胼胝体的FA值与对照组均存在显著性差异。结论:AD患者与MCI患者存在脑白质结构的差异,DTI技术能够在一定程度上提供MCI的早期诊断指标。     

弥散张量成像与认知功能

弥散张量成像是tNRI中常见的一种,本文综述其在测量认知功能中的应用,并指出其可能存在的问题。     

弥散张量成像技术预测遗忘型轻度认知障碍患者向老年性痴呆转化的随访研究

目的:探讨弥散张量成像技术(diffusion tensor imaging,DTI)对遗忘型轻度认知功能障碍(aMCI)向老年性痴呆(AD)转化的预测作用。方法:41例aMCI患者(aMCI组)常规予核磁共振(MRI)和DTI扫描,测定感兴趣区的各向异性分数(fractional anisotropy,FA)和表观扩散系数(apparent diffusion coefficient,ADC),以20名老年健康志愿者作为对照(正常对照组)并随访1~3年。结果:与正常对照组比较,aMCI组41例患者中有22例扣带束FA基线值偏低(P0.05),随访1~3年后,其中有19例转化为AD;另外19例扣带束FA值正常的aMCI患者只有2例转化为AD。与非转化AD者比较,AD转化者前额叶、颞叶、海马、下额枕束、胼胝体膝部和扣带束等部位FA值降低(P均0.01),颞叶、海马等部位ADC值升高(P均0.05)。结论:DTI技术具有预测aMCI向AD转化的作用,aMCI患者扣带束FA值低可能是aMCI向AD转化的敏感指标。     

弥散张量成像在认知功能中的研究现状

近年来磁共振弥散张量在认知功能的临床研究中正逐步地开展。它能检测出联系大脑功能分区间的纤维变化,从而反映正常人脑白质随年龄改变的情况。此外对于多发性硬化、缺血性脑白质病、阿尔茨海默病、精神分裂症患者的认知功能的研究也有一定意义。     

磁共振弥散张量成像对阿尔茨海默病脑白质损害的评估及鉴别价值

目的：应用MR弥散张量成像（DTI）观察阿尔茨海默病（AD）患者脑白质纤维束完整性。方法：健康老年志愿者为对照组（NC）组、遗忘型轻度认知障碍（aMCI）组、AD组和皮质下缺血性血管性痴呆（SIVD）组各20例,行常规MRI和DTI扫描后,测定相同感兴趣区（ROI）的各向异性分数（FA）值和表观扩散系数（ADC）值进行比较。结果：与NC组比较, AD组前额叶、颞叶、海马等部位FA值降低,颞叶、海马等部位ADC值升高（P〈0.05）;aMCI组仅扣带束FA值降低,与AD组比差异有统计学意义（P〈0.05）;SIVD组下额枕束等部位FA值下降,ADC值升高,与AD组比较差异有统计学意义（P〈0.05）。结论：DTI可以用来评估白质纤维束完整性,AD组白质损害甚于aMCI患者;扣带束FA值可以作为aMCI患者筛查的指标;根据受累部位不同可对SIVD与AD进行鉴别。     

弥散张量成像在非痴呆帕金森病认知障碍患者中的应用

目的探讨帕金森病的轻度认知障碍(PD-MCI)与各脑白质分区微结构改变的关系。方法选择40例帕金森病(PD)患者作为研究对象,其中认知正常组(PD-CogNL)和轻度认知障碍组(PD-MCI组)各20例,另选20例健康志愿者作为对照组,行蒙特利尔认知评估量表(MoCA)评估其认知功能;DTI检查测定脑部50个脑白质分区的微观结构改变。对三组研究对象的MoCA量表得分及其中7个认知阈检查分别进行方差分析,测定50个的分数各向异性(fFA)值,三组之间FA值行方差分析。最后,将PD-MCI组的MoCA量表评分与选定的23个脑区的FA值进行Pearson相关性分析。结果(1)在认知阈检查发现视空间与执行功能、注意力两项差异有统计学意义(P0.05);(2)在FA值统计中结果为除穹窿、右皮质脊髓束、左皮质脊髓束、左上放射冠差异无统计学意义(P0.05),其他脑白质分区差异均有统计学意义(P0.05);(3)将具有统计学意义的脑白质分区,在PD-CogNL组和PD-MCI组间进行统计学分析。结果得出23个脑白质分区具有统计学意义(P0.05);在PD-MCI组内将上述脑区的FA值和MoCA进行Pearson相关分析,胼胝体体部、胼胝体压部、左扣带(海马)、左穹窿/终纹、右上额枕束、左下额枕束、左钩束和MoCA得分具有相关性且r为正数,P0.05。结论PD患者轻度认知障碍程度与患者胝体体部、胼胝体压部、左扣带(海马)、左穹窿/终纹、右上额枕束、左下额枕束、左钩束病变严重程度呈正相关,提示这些部位改变可能与PD-MCI患者的认知改变相关,且为进一步研究PD-MCI的病理基础及临床早期诊断提供依据。     

弥散张量成像在弥漫性轴索损伤临床诊疗中的应用

弥漫性轴索损伤(DAI)是脑外伤(TBI)中一种常见且危重的类型,此类型疾病从发现、命名至今,通过大量尸检病理学检查,其病理学改变特征已经较为明确。但从影像学角度对于此类疾病诊断及治疗标准的认识尚处于模糊状态,从而导致DAI在临床诊疗过程中被低估。通过查阅近几年的相关文献,本文将介绍弥散张量成像(DTI)技术以及其在DAI临床诊疗过程中的应用,以期待为临床医务人员对DAI的诊疗提供新思路。     

Executive dysfunction and periventricular diffusion tensor changes in amnesic mild cognitive impairment and early Alzheimer's disease

Our aim in this study was to explore the neural substrates of executive function in frontal and nonfrontal white matter using diffusion tensor imaging (DTI). We studied the relationship between executive dysfunction and DTI measurements on 13 subjects with amnesic mild cognitive impairment (aMCI), 11 subjects with early Alzheimer's disease (AD), and 16 control subjects. All participants underwent an examination of their intelligence, memory, and executive function and were subjected to DTI. Both aMCI and early AD subjects showed executive function impairment with differential performance in frontal‐related behaviors. Both aMCI and early AD subjects showed increased mean diffusivity in the genu of the corpus callosum and left frontal periventricular white matter (PVWM), whereas subjects with early AD showed an additional decrease in the fractional anisotropy of bilateral frontal PVWM and in the genu of the corpus callosum. The frontal PVWM was associated with performance on the Verbal Fluency Test, the Wisconsin Card Sorting Test (WCST), and Part B of the Trail Making Test. The parietal PVWM was associated with perseverative errors on the WCST and Part A of the Trail Making Test. In summary, executive function was impaired in subjects with aMCI and early AD and was associated with frontal and parietal PVWM changes. These changes may be due to early AD degeneration of the lateral cholinergic projections or to early change of the superior longitudinal fasciculus. Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.     

Diffusion tensor imaging in Alzheimer disease and mild cognitive impairment

A wide range of imaging studies provides growing support for the potential role of diffusion tensor imaging (DTI) in evaluating microstructural white matter integrity in Alzheimer disease (AD) and mild cognitive impairment (MCI). Our review aims to present DTI principles, post-processing and analysis frameworks and to report the results of particular studies.The distribution of AD-related white matter abnormalities is widely discussed in the light of deteriorated connectivity within certain tracts due to secondary white matter degeneration; primary alterations are also assumed to contribute to the pattern. The question whether it is more effective to assess the whole-brain diffusion or to directly concentrate on specific regions remains an interesting issue. Assessing white matter microstructure alterations, as evaluated by group-level differences of tensor-derived parameters, may be a promising neuroimaging tool for differential diagnosis between AD, MCI and other cognitive disorders, as well as being particularly helpful in the interpretation of underlying pathological processes.     

Neuropsychological characteristics of mild cognitive impairment subgroups

OBJECTIVE: To describe the neuropsychological characteristics of mild cognitive impairment (MCI) subgroups identified in the Cardiovascular Health Study (CHS) cognition study. METHODS: MCI was classified as MCI-amnestic type (MCI-AT): patients with documented memory deficits but otherwise normal cognitive function; and MCI-multiple cognitive deficits type (MCI-MCDT): impairment of at least one cognitive domain (not including memory), or one abnormal test in at least two other domains, but who had not crossed the dementia threshold. The MCI subjects did not have systemic, neurological, or psychiatric disorders likely to affect cognition. RESULTS: MCI-AT (n = 10) had worse verbal and non-verbal memory performance than MCI-MCDT (n = 28) or normal controls (n = 374). By contrast, MCI-MCDT had worse language, psychomotor speed, fine motor control, and visuoconstructional function than MCI-AT or normal controls. MCI-MCDT subjects had memory deficits, though they were less pronounced than in MCI-AT. Of the MCI-MCDT cases, 22 (78.5%) had memory deficits, and 6 (21.5%) did not. MCI-MCDT with memory disorders had more language deficits than MCI-MCDT without memory disorders. By contrast, MCI-MCDT without memory deficits had more fine motor control deficits than MCI-MCDT with memory deficits. CONCLUSIONS: The most frequent form of MCI was the MCI-MCDT with memory deficits. However, the identification of memory impaired MCI groups did not reflect the true prevalence of MCI in a population, as 16% of all MCI cases and 21.5% of the MCI-MCDT cases did not have memory impairment. Study of idiopathic amnestic and non-amnestic forms of MCI is essential for an understanding of the aetiology of MCI.     

Brain imaging of mild cognitive impairment and Alzheimer’s disease

The rapidly increasing prevalence of cognitive impairment and Alzheimer’s disease has the potential to create a major worldwide healthcare crisis. Structural MRI studies in patients with Alzheimer’s disease and mild cognitive impairment are currently attracting considerable interest. It is extremely important to study early structural and metabolic changes, such as those in the hippocampus, entorhinal cortex, and gray matter structures in the medial temporal lobe, to allow the early detection of mild cognitive impairment and Alzheimer’s disease. The microstructural integrity of white matter can be studied with diffusion tensor imaging. Increased mean diffusivity and decreased fractional anisotropy are found in subjects with white matter damage. Functional imaging studies with positron emission tomography tracer compounds enable detection of amyloid plaques in the living brain in patients with Alzheimer’s disease. In this review, we will focus on key findings from brain imaging studies in mild cognitive impairment and Alzheimer’s disease, including structural brain changes studied with MRI and white matter changes seen with diffusion tensor imaging, and other specific imaging methodologies will also be discussed.     

Diffusion tensor imaging based white matter changes and antioxidant enzymes status for early identification of mild cognitive impairment

Mild cognitive impairment (MCI) is an early stage of dementia. The changes in white matter integrity and antioxidant enzymes levels are crucial in onset and progression to Alzheimer’s disease (AD). To elucidate the changes in cognitive performance, white matter integrity, oxidative stress marker, for early detection of prodromal state of AD. Fifty cases of MCI and controls (55-75 years) were subjected to Mini Mental State Examination (MMSE), diffusion tensor imaging (DTI) followed by estimation of superoxide dismutase, glutathione peroxidase and lipid peroxidation in serum of MCI and control population. The MMSE scores of MCI subjects were (28±2 - 22.6±1) as compared with controls (28±1- 29±1). DTI metrics fractional anisotropy (FA) values in right and left frontal lobe, fornix, corpus callosum, while apparent diffusion coefficient (ADC) values in right temporal lobe, hippocampus head, corpus callosum right, and forcep major were significantly altered in MCI as compared with controls. Superoxide dismutase, glutathione peroxidase level were lower while lipid peroxidation marker malondialdehyde (MDA) was increased in patients with MCI as compared with controls. The study emphasized that changes in neuro-psychological performance, white matter integrity and antioxidant enzymes level provide early signature for diagnosis of MCI.