弥散张量成像和18F-AV1451 PET tau蛋白脑显像对MCI诊断及鉴别诊断的初步研究

目的 研究磁共振扩散张量成像(diffusion tensor imaging,DTI)与18F-AV1451 tau蛋白脑显像对于轻度认知障碍(mild cognitive impairment,MCI)的诊断价值,为今后临床早期发现诊断MCI患者并进行早期干预治疗提供帮助.材料与方法 本前瞻性研究分别选取13名临床...     

多模态MRI在阿尔茨海默病早期诊断中的研究进展

阿尔茨海默病(Alzheimer's disease,AD)是发生于中老年人中最常见的中枢神经系统退行性疾病,以进行性认知障碍和行为非认知功能能力的减低为主要症状。近年来,随着磁共振成像(magnetic resonance imaging,MRI)多种序列的逐渐成熟,多模态MRI诊断在AD早期诊断中占有越来越重要的角色;作者就磁共振成像中结构性磁共振(structural magnetic resonance imaging,s MRI)、磁共振波谱成像(magnetic resonance spectroscopy,MRS)、磁共振弥散张量成像(diffusion tensor imaging,DTI)和磁共振扩散峰度成像(diffusion kurtosis imaging,DKI)、磁敏感加权成像(susceptibility weighted imaging,SWI)和定量磁敏感成像(quantitative susceptibility mapping,QSM)及静息态功能磁共振(functional MRI,f MRI)在AD早期诊断中的应用进行综述。     

磁共振成像在前列腺癌诊断中的研究进展

因MRI具有良好的软组织分辨率、多方位成像、多参数功能成像等优点,逐渐成为运用影像学诊断前列腺癌的重要检查方法。随着MRI成像技术的不断成熟,多种成像方法如磁共振灌注成像(perfusion weighted imaging,PWI)、扩散加权成像(diffusionweightedimaging,DWI)、体素内不相干运动(intravoxel incoherent motion,IVIM)扩散成像、磁共振波谱成像(magnetic resonance spectroscopy,MRS)、扩散张量成像(diffusion tensor imaging,DTI)、扩散峰度成像(diffusion kurtosis imaging,DKI)、T2 mapping技术、磁敏感加权成像(susceptibility weighted imaging,SWI)在前列腺癌的诊断中有着重要的作用,随着这些技术的发展,前列腺癌诊断的准确性明显提高,现将近年来磁共振成像技术在前列腺癌诊断中的作用展开综述。     

扩散张量成像在急性脊髓损伤中的研究进展

脊髓是中枢神经系统的重要组成部分,不同时期、不同程度的脊髓损伤造成的后果及预后也不同,急性脊髓损伤病情发展迅速且较为严重。常规磁共振成像(magnetic resonance imaging,MRI)上的信号变化对于临床评估具有一定的局限性,磁共振扩散加权成像(diffusion weighted imaging,DWI)和磁共振扩散张量成像(diffusion tensor imaging,DTI)通过测量水分子的扩散运动,从微观上反映脊髓的损伤情况,不仅能早期及时地判断出急性脊髓损伤,而且能定量分析白质纤维束损伤的严重程度,为临床对这类患者的干预提供一定的价值信息。本文简要介绍了磁共振扩散加权成像和磁共振扩散张量成像技术在急性脊髓损伤中的应用情况及研究进展。     

MR扩散加权成像在软组织肿瘤中的应用进展

磁共振扩散加权成像是反映水分子扩散特性、检测组织微观结构变化的功能成像技术,包括单指数扩散加权成像(diffusion weighted imaging,DWI)、体素内不相干运动(intravoxel incoherent motion,IVIM)模型、扩散张量成像(diffusion tensor imaging,DTI)和扩散峰度成像(diffusion kurtosis imaging,DKI),目前已用于软组织肿瘤临床评估.本文就上述四种技术类型做简要介绍,并就其在软组织肿瘤的良恶性鉴别诊断、组织学分级预测、浸润评估、术后复发监测以及放化疗疗效评价或预测中的应用进展进行综述.     

磁共振扩散峰度成像在乳腺癌诊断中的研究进展

磁共振扩散峰度成像(diffusion kurtosis imaging,DKI)能够表征生物体内组织水分子的扩散受限程度及扩散的不均质性,它是基于磁共振扩散张量技术(diffusion tensor imaging,DTI)发展的一种新兴成像技术。作为一种非侵入性磁共振成像技术,扩散峰度成像由于其优异的软组织对比度和非高斯特性而越来越多地应用于乳腺病灶的诊断。近年来,乳腺癌发病率持续上升,已成为我国女性恶性肿瘤之首,而扩散峰度成像能够有效反映乳腺病灶微观结构的复杂性,在乳腺良恶性肿瘤的鉴别及乳腺癌预后评估中具有一定的价值,为临床诊疗提供信息。文章综述了DKI在乳腺良、恶性病变的鉴别诊断、乳腺癌组织学分级及与生物预后因子的关系等方面的研究进展。     

轻度认知障碍磁共振扩散张量成像研究的Meta分析

目的用Meta分析法评价磁共振扩散张量成像对轻度认知障碍(mild cognitive impairment,MCI)的诊断价值。材料与方法使用计算机检索数据库Pubmed、CNKI、万方、维普等,收集有关磁共振扩散张量成像对MCI研究的文献,检索时限均为自建库至2015年1月31日。从文献中提取轻度认知障碍组与正常对照组(NC)所使用的定量指标各向异性(fractional anisotrophy,FA)值对不同脑区(额叶、顶叶、颞叶、枕叶、后扣带束、海马、海马旁回、内囊后肢、上、下纵束、穹窿、胼胝体膝部及压部、钩束)的测量数据,用Meta分析软件(Review manager 5.3)对最终符合标准的文献进行汇总分析,获得汇总加权均数差(weighted mean difference,WMD)及95%可信区间(95%CI)。结果共纳入47篇文献(30篇英文、17篇中文),MCI组的FA值低于NC组,汇总WMD及95%CI为–0.05[–0.05,0.04],上述脑区除枕叶外差异均具有统计学意义。结论 MCI患者存在脑白质微细结构的损害,弥散张量成像(diffusion tensor imaging,DTI)技术能够提供MCI的早期诊断指标。     

磁共振神经突方向离散度和密度成像在阿尔茨海默症中的研究进展

神经突方向离散度和密度成像(neurite orientation dispersion and density imaging,NODDI)是一种新型的磁共振扩散成像技术,可用于量化神经树突和轴突微观结构的复杂性,从而获取神经纤维的形态学信息.与目前广泛应用于临床的扩散张量成像(diffusion tensor imaging,DTI)相比,此类神经突指标对脑组织微观结构的评估更具有特异性和敏感性.阿尔茨海默症(Alzheimer's disease,AD)是以进行性认知功能障碍和记忆力减退为特征的中枢神经系统退行性疾病,通过NODDI技术可以评估AD患者神经系统微观结构的复杂性.现就NODDI技术的基本原理和在AD中的研究进展进行综述.     

常见精神障碍性疾病的扩散峰度成像研究进展

精神障碍性疾病目前诊断主要依赖于临床表现,至今为止尚未发现明确的生物学指标。扩散峰度成像(diffusion kurtosis imaging,DKI)是扩散磁共振成像中的一种,反映组织内水分子非高斯扩散特性,能够更真实、更细微地反映微观结构变化的信息,可以不依赖组织的空间位置、同时导出标准的扩散张量成像(diffusion tensor imaging,DTI)参数及DKI参数。DKI技术在精神障碍性疾病(精神分裂症、抑郁症)的研究中发现了脑灰质、白质微结构的改变,有助于对其神经病理生理机制的研究。作者就DKI的成像原理及其在常见精神障碍性疾病中的应用进行综述。     

磁共振扩散峰度成像在脑肿瘤的研究进展

磁共振扩散峰度成像(diffusion kurtosis imaging,DKI)是扩散张量成像(diffusion tensorimaging,DTI)技术的延伸,该技术的主要优势是可以量化组织内水分子非高斯扩散的特性,对人体组织微观结构的复杂状态比其他技术更敏感,进而能够提供更多的结构变化信息并反映疾病的病理生理改变,有利于在疾病早期进行定性诊断并尽早指导临床决策。目前,DKI技术在临床多种疾病和科研中都有较多的应用,作者对DKI在脑肿瘤中的国内外研究进展进行综述。     

轻度认知功能障碍脑结构与功能MRI研究进展

轻度认知功能障碍（MCI）患者被认为是阿尔茨海默病的高危人群，并且在MCI阶段进行干预治疗，有利于延缓病情进展甚至逆转认知功能破坏，故对于MCI的研究，具有重要的临床意义。MRI技术包含多个序列成像，可从不同角度发现MCI的大脑结构和功能异常，有利于早期诊断、预测病情进展情况和揭示病理机制，促进MCI和阿尔茨海默病的防治。本文主要对于近些年来结构磁共振成像、功能磁共振成像、扩散张量成像、动脉自旋标记和质子磁共振波谱分析在MCI的诊断、分类、预测病情方面的研究现状进行了论述，希望为今后的临床诊疗及科研提供借鉴。      

Identification of MCI individuals using structural and functional connectivity networks

Different imaging modalities provide essential complementary information that can be used to enhance our understanding of brain disorders. This study focuses on integrating multiple imaging modalities to identify individuals at risk for mild cognitive impairment (MCI). MCI, often an early stage of Alzheimer's disease (AD), is difficult to diagnose due to its very mild or insignificant symptoms of cognitive impairment. Recent emergence of brain network analysis has made characterization of neurological disorders at a whole-brain connectivity level possible, thus providing new avenues for brain diseases classification. Employing multiple-kernel Support Vector Machines (SVMs), we attempt to integrate information from diffusion tensor imaging (DTI) and resting-state functional magnetic resonance imaging (rs-fMRI) for improving classification performance. Our results indicate that the multimodality classification approach yields statistically significant improvement in accuracy over using each modality independently. The classification accuracy obtained by the proposed method is 96.3%, which is an increase of at least 7.4% from the single modality-based methods and the direct data fusion method. A cross-validation estimation of the generalization performance gives an area of 0.953 under the receiver operating characteristic (ROC) curve, indicating excellent diagnostic power. The multimodality classification approach hence allows more accurate early detection of brain abnormalities with greater sensitivity.     

Altered spontaneous activity in Alzheimer's disease and mild cognitive impairment revealed by Regional Homogeneity

Alzheimer's disease (AD), the most prevalent cause of dementia in the elderly, is characterized by progressive cognitive and intellectual deficits. Most patients with mild cognitive impairment (MCI) are thought to be in a very early stage of AD. Resting-state functional magnetic resonance imaging reflects spontaneous brain activities and/or the endogenous/background neurophysiological process of the human brain. Regional Homogeneity (ReHo) can provide a fast method for mapping regional activity across the whole brain. Little has been previously published about where or how spontaneous activity differs between MCI and AD, although many previous fMRI studies have shown that the activity pattern is altered in MCI/AD. In the present study, we first used the ReHo method to explore differences in regional spontaneous activities throughout the whole brain between normal controls (NC) and people with MCI and with AD. A one-way ANOVA was performed to determine the regions in which the ReHo differs between the three groups, and then a post hoc analysis was performed to evaluate differences in the pattern among the three groups. Finally a correlation analysis was done between the ReHo index of these regions and clinical variables in order to evaluate the relationship between ReHo and cognitive measures in the AD and MCI groups. An exploratory classification analysis also demonstrated that ReHo measures were able to correctly separate subjects in 71.4% of the cases. Altered brain spontaneous activations were found in the medial prefrontal cortex, the bilateral posterior cingulate gyrus/precuneus and the left inferior parietal lobule (IPL) in both MCI and AD. In MCI, the ReHo index in the left IPL was higher than that of the NC, which could indicate the presence of a compensatory mechanism in MCI. More obviously, the correlation analysis indicated that the lower the memory and other cognitive abilities, the lower the ReHo in patients with MCI and AD. Combining our findings with the results in earlier studies, we propose that the spontaneous activity pattern in the resting state could potentially be used as a clinical marker for MCI/AD.     

动脉自旋标记成像用于轻度认知障碍研究进展

轻度认知障碍（MCI）是阿尔茨海默病（AD）的前驱期，对其发病机制尚不明确。脑血流量是衡量脑功能的重要指标，各种原因致局部脑血流量（rCBF）减低而损伤大脑。动脉自旋标记（ASL）MRI是通过磁化标记动脉血中氢质子作为内源性示踪剂测量rCBF的成像技术。本研究针对ASL成像在早期诊断MCI、监测疾病进展及评估疗效中的研究进展进行综述。     

A whole brain MR spectroscopy study from patients with Alzheimer's disease and mild cognitive impairment

Brain damage in Alzheimer's disease (AD) and mild cognitive impairment (MCI) is widespread with involvement of large portions of the neocortex and the subcortical white matter. A quantitative measure of neuronal damage of the entire brain might be valuable in the context of large-scale, longitudinal studies of these patients. This study investigated the extent of neuroaxonal injury of patients with AD and MCI using a novel unlocalized proton magnetic resonance spectroscopy ((1)H-MRS) technique, which allows quantification of the concentration of N-acetylaspartate from the whole of the brain tissue (WBNAA). Conventional brain MRI and WBNAA were obtained from 28 AD patients, 27 MCI patients and 25 age-matched controls. Normalized brain volume (NBV) was also measured using an automated segmentation technique. WBNAA and NBV showed a significant heterogeneity between groups (P < 0.001). WBNAA concentration was different between controls and MCI patients (P = 0.003), but not between MCI and AD patients (P = 0.33). NBV differed both between controls and MCI patients (P = 0.02) and between MCI and AD patients (P = 0.03). A multivariate regression model retained WBNAA as the best MRI predictor of the Mini Mental State Examination score (P = 0.001). Significant neuronal damage, which is related to the extent of cognitive decline, can be quantified in the whole brain tissue of patients with AD, using a novel (1)H-MRS approach. The demonstration in patients with MCI of MR structural and metabolic findings, intermediate between those of healthy volunteers and those of AD patients, indicates that neuronal damage is already evident and widespread in individuals with MCI before they are clinically demented.     

Age-related cognitive decline, mild cognitive impairment or preclinical Alzheimer's disease?

With the promising development of effective treatment, significant improvement in the very early diagnosis of Alzheimer's disease (AD) is required. There is vast agreement that a decline in memory, especially in verbal episodic memory, is the earliest and perhaps the most sensitive sign of incipient AD at the preclinical stage. However, this review offers evidence that impairment in episodic memory can be observed in normal elderly people as well as in aged subjects with mild cognitive impairment (MCI), a large proportion of whom will, however, not convert to dementia. Quantitative measurement of atrophy and brain activation in the hippocampal-parahippocampal formation by using structural and functional magnetic resonance imaging may help to distinguish the MCI decliners from the nondecliners. Cerebrospinal fluid levels of tau protein and Abet1-42 peptide, together with the presence of an apolipoprotein (apo)E epsilon4 allele may also increase our confidence in the early positive diagnosis of AD. This review concludes, however, that while adequate for constituting groups of patients in a research perspective, the extensive diagnostic procedure based on specific cognitive testing, neuroimaging and biological investigations is still out of reach for the practitioner.     

轻度认知障碍患者计算能力的fMRI研究

目的 探讨早期诊断A1zheimer病的方法，以及轻度认知障碍(MCI)患者计算能力损害的脑功能定位。方法 对8例MCI患者和9例正常对照使用神经心理测定和功能磁共振(fMRI)检查相结合的方法，比较两组反应时间、正确率和fMRI的脑激活图。结果 患者的反应时间比对照组延长(退位减法P＞0．05，非退值减法P＜0．05一0．01)，正确率降低(P＜0．01-0．001)。脑激活图显示：患者在左侧前额叶外下部，颞叶外侧和顶叶激活减弱(P＜0．05)，而右侧前额叶外下部激活代偿性增强(P＜0．05)。结论MCI患者的计算功能已有损害。计算功能的fMRI与认知神经心理学的联合研究能为早期诊断AD提供有力的参考依据。     

阿尔茨海默病及轻度认知损伤患者PET与MRI分析

目的 探讨PET葡萄糖代谢成像与MR结构成像诊断阿尔茨海默病（AD）与轻度认知损伤（MCI）的临床价值。方法 收集AD患者18例（AD组）、MCI患者6例（MCI组）,其中AD患者包括11例中重度AD） 中重度AD组）及7例轻度AD） 轻度AD组）,另招募10名健康志愿者（对照组）,同期进行PET与MR结构成像,通过视觉评价与定量分析法观察脑内放射性分布及海马萎缩情况。结果 所有AD患者（18/18,100%）均可见脑内特定区域葡萄糖代谢减低,其中11例中重度AD患者均同时伴有海马萎缩,7例轻度AD患者中3例可见海马萎缩;MCI患者中,5例（5/6,83.33%）未见海马萎缩,但其中2例可见葡萄糖代谢减低。对照组（10/10,100%）均未见海马萎缩,其中2例可见轻度脑萎缩,FDG分布对称性轻度减低。结论 PET及MRI均可用于诊断AD与MCI,但各有侧重,二者联合应用有利于进一步提高对AD的诊断能力。     

Examining the gateway to the limbic system with diffusion tensor imaging: the perforant pathway in dementia

Current treatments for Alzheimer's disease (AD) are only able to slow the progression of mental deterioration, making early and reliable diagnosis an essential part of any promising therapeutic strategy. In the initial stages of AD, the first neuropathological alterations occur in the perforant pathway (PP), a large neuronal fiber tract located at the entrance to the limbic system. However, to date, there is no sensitive diagnostic tool for performing in vivo assessments of this structure. In the present bimodal magnetic resonance imaging (MRI) study, we examined 10 elderly controls, 10 subjects suffering from mild cognitive impairment (MCI), and 10 AD patients in order to evaluate the sensitivity of diffusion tensor imaging (DTI), a new MRI technique, for detecting changes in the PP. Furthermore, the diagnostic explanatory power of DTI data of the PP should be compared to high-resolution MRI volumetry and intervoxel coherences (COH) of the hippocampus and the entorhinal cortex, two limbic regions also involved in the pathophysiology of early AD. DTI revealed a marked decrease in COH values in the PP region of MCI (right side: 26%, left side: 29%, as compared to controls) and AD patients (right side: 37%, left side: 43%, as compared to controls). Reductions in COH values of the PP region were significantly correlated with cognitive impairment. DTI data of the PP zone were the only parameter differing significantly between control subjects and MCI patients, while the volumetric measures and the COH values of the hippocampus and the entorhinal cortex did not. DTI of medial temporal brain regions is a promising non-invasive tool for the in vivo diagnosis of the early/preclinical stages of AD.