三维脑白质纤维束示踪成像

目的使用磁共振弥散张量成像数据三维示踪大脑白质纤维束。方法对18名健康自愿者使用弥散加权-回波平面成像(DW-EPI)序列进行头部DTI检查。输出DICOM格式的DTI图像数据并根据已知的脑白质纤维束的解剖学知识,选取起始区、目标区、回避区,使用Diffusion Tensor VisualizerⅡ软件进行脑白质纤维束示踪三维重建。结果大脑的连合系、联络系和投射系的各种脑白质纤维束的结构和其在三维空间的走行可在每例实验对象的三维示踪结果显示,与解剖学所描述相对比基本一致。结论使用三维脑白质纤维束示踪成像可以在活体立体直观地显示大脑的各种脑白质纤维束。不仅可以用于解剖学教学,还对临床神经系统疾病的辅助诊断和科学研究有潜在的应用价值。     

脑白质高信号与阿尔茨海默病的相关性

脑白质高信号(white matter hyperintensity,WMH)为磁共振成像(magnetic resonance imaging,MRI)中T2加权像(T2 weighted imaging,T2WI)或T2液体衰减反转恢复序列(fluid attenuation inversion recovery,...     

基于弥散张量白质网络的阿尔茨海默病研究

【摘 要】 目的:利用弥散张量成像（DTI）技术构建大脑白质结构网络,通过网络拓扑参数研究阿尔茨海默病（AD）患者大脑微观结构的异常。 方法:重建19例正常人和20例AD患者的结构脑网络,采用双样本t检验,从全脑和特定脑区两个水平对AD患者与正常对照组的网络拓扑参数进行差异性分析。 结果:在全脑水平上,AD患者的加权特征路径长度（[Lp]）值上升,全局效率（[Eg]）、网络强度（[Sp]）、局部效率（[Elocal]）值下降,并且进一步研究发现:AD患者左半球[Lp]、加权簇系数（[Cp]）值上升,[Eg]值下降比右半球明显。在特定脑区水平上,选取楔前叶为感兴趣脑区,发现两侧楔前叶脑区的[Lp]值上升、[Eg]值下降,而[Cp]、[Elocal]值并没有明显差异。 结论:网络拓扑参数可以作为评估AD患者微观结构异常的指标,对早期诊断AD具有重要的指向作用。     

脑白质病变的影像学研究进展

<正>脑白质病变(White Matter Lesions,WML)由加拿大神经病学家Hachinski等[1]于1987年首次提出,指脑室周围或皮质下区脑白质的弥漫性斑点影像或斑片状影像。WML早期常无症状,晚期可出现认知障碍、双下肢无力、尿失禁、抑郁等表现而显著影响患者的生活质量[2-5]。因此,WML的早期诊断、及时治疗对于提高WML患者的生活质量意义重大。神经影像学检查在WML早期     

阿尔茨海默病与血管性痴呆患者认知功能的比较研究

目的 :评价阿尔茨海默病 (AD)和血管性痴呆 (VD)患者认知功能障碍的异同 ;方法 :用简易智力状态检查表 (MMSE)、韦氏记忆量表 (WMS)、日常生活能力量表 (ADL)对 34例AD患者和 4 9例VD患者的认知功能进行测查 ;结果 :(1)MMSE结果表明AD组在短程记忆得分低于VD组 (P <0 .0 1) ,在语言复述得分高于VD组 (P <0 .0 5 ) ;(2 )WMS结果表明AD组在经历 (P <0 .0 5 )、图形再认 (P <0 .0 5 )、理解记忆 (P <0 .0 5 ) ,定向 (P <0 .0 1)得分显著低于VD组 ;(3)ADL结果显示AD组与VD组无显著差异。结论 :AD组和VD组均有记忆障碍 ,AD组受损更为严重并以记忆注意受损为突出 ,VD组相对较轻并以语言复述受损为突出     

弥散张量磁共振成像的新进展

弥散张量磁共振成像技术是近年来出现的一项新技术，由于其对脑白质纤维具有高度敏感性以致在临床上的应用日益广泛，并为人体中枢神经系统的深人研究提供了有效的工具。     

阿尔茨海默病与脑血管病痴呆患者的诱发电位比较研究

目的：观察阿尔茨海默病痴呆（AD）和脑血管病痴呆（VD）视觉及听觉诱发电位的特点。方法：收集25例AD组、24例VD及22名正常老年人（NC），完成听觉诱发电位（AEP）和视觉诱发电位（VEP）检查，并进行简易智力状态检查（MMSE）评分比较。结果：与NC组相比，AD组AEP的N1、P2，VEP的P1潜伏期延迟，AEP的P2、P2，VEP的P2、P3波幅降低；VD组VEP的P2潜伏期延迟，P2和P3波幅降低。AD组和VD组相比，AD组AEP的N1、P2潜伏期延迟于VD组。AD组VEP的P2波的潜伏期，VD组AEP的P3波幅及VEP的N1潜伏期改变与其MMSE评分有关联。结论：AD组和VD组的诱发电位有类似变化，两组的VEP和AEP变化与MMSE相关。     

基于弥散张量成像的原发性失眠患者大脑白质变化

使用基于纤维束示踪的空间统计学方法对原发性失眠患者的弥散张量成像影数据进行分析,探讨其大脑白质变化。结果显示相较于健康对照组,原发性失眠患者的白质连接发生改变,主要表现为前放射冠、胼胝体膝部的各向异性分数降低。进一步的相关分析结果表明胼胝体膝部区域各向异性分数值降低与患者睡眠状况自评量表分数显著负相关。     

磁共振弥散张量成像的脑白质纤维优化重建

磁共振弥散张量成像(DTI)可对大脑白质纤维束的三维几何结构进行无创研究,其主要方法为DTI纤维追踪成像.研究打破现有DTI纤维追踪成像从初始种子区域逐步追踪增长的框架,提出脑白质的纤维优化重建方法,从全局角度描述追踪纤维,通过其对弥散倾向和几何结构的优化估计,重构最优纤维路径.结果表明,该方法可提供连接两个感兴趣区域(ROI)的有效和对称连接,同时通过全局优化手段消除累积噪声及局部随机噪声,提高长距离成像的可靠性;在人工合成数据集和真实人体数据集中均能较好成像,较之现有纤维追踪成像具有更高的可靠性和可重复性.     

基于DTI技术的健康成人胼胝体、扣带回、中脑白质纤维束密度随年龄变化关系的研究

目的:应用磁共振弥散张量成像(diffusion tensor imaging,DTI)技术定量探讨健康成人胼胝体、扣带回、中脑纤维束密度随年龄变化的关系。方法:将125例健康志愿者按年龄分成五组(第一组16~30岁,20例;第二组31~45岁,34例;第三组46~60岁,24例;第四组61~75岁,22例;第五组76~90岁,25例),行3T磁共振(magnetic resonance imaging,MRI)扫描,获取脑T1和DTI图像。所有DTI数据经DTI Studio软件预处理并追踪得到脑白质纤维束,手工设置三个感兴趣区,即胼胝体、扣带回和中脑,统计各区的纤维束密度(fiber tract density,FD),将所有数据输入SPSS软件进行统计学分析。结果:得到了三个感兴趣区的纤维束走行,其中胼胝体区纤维束成辐射状分布,走行有向前、后、左、右方向;扣带回区纤维束走行大致为前、后方向;中脑区纤维束走行大致为上、下方向,追踪结果分别与它们各自的解剖学结构相一致。对三个区的纤维束密度的统计学分析结果为:(1)胼胝体区,各年龄组的FD均存在显著差异(P0.05),且随着年龄的增长,胼胝体区纤维束密度逐渐降低。(2)扣带回区,各年龄组的FD均存在显著差异(P0.05),第一组的左、右侧扣带回FD存在显著性差异(P0.05),在其左、右区,各年龄组的FD相互比较均具有显著性差异(P0.05);进一步分析得到,左侧扣带回区FD随年龄增长的下降趋势大于右侧。(3)中脑区,各年龄组的FD无显著性差异(P0.05),在其左、右区,各年龄组的FD无显著性差异(P0.05)。结论:随着年龄增长,胼胝体、扣带回区内FD明显降低。磁共振弥散张量成像技术的量化指标FD可以用来了解脑白质纤维束的变化。     

Voxel-based assessment of gray and white matter volumes in Alzheimer's disease

Using the study-specific templates and optimized voxel-based morphometry (VBM), this study investigated abnormalities in gray and white matter to provide depiction of the concurrent structural changes in 13 patients with Alzheimer's disease (AD) compared with 14 age- and sex-matched normal controls. Consistent with previous studies, patients with AD exhibited significant gray matter volume reductions mainly in the hippocampus, parahippocampal gyrus, insula, superior/middle temporal gyrus, thalamus, cingulate gyrus, and superior/inferior parietal lobule. In addition, white matter volume reductions were found predominately in the temporal lobe, corpus callosum, and inferior longitudinal fasciculus. Furthermore, a number of additional white matter regions such as precentral gyrus, cingulate fasciculus, superior and inferior frontal gyrus, and sub-gyral in parietal lobe were also affected. The pattern of gray and white matter volume reductions helps us understand the underlying pathologic mechanisms in AD and potentially can be used as an imaging marker for the studies of AD in the future.     

Lymphomatosis cerebri as a cause of white matter dementia

Primary central nervous system lymphoma most often presents as a solitary, isolated lesion in immunocompetent patients. Rarely, the disease presents as a diffuse, infiltrating condition without formation of a cohesive mass, a pattern called lymphomatosis cerebri. We present 3 immunocompetent individuals who developed rapidly progressive dementia. Magnetic resonance imaging features mimicked other disorders of white matter and prompted preoperative diagnoses of Binswanger's disease (subcortical ischemic vascular dementia), unknown leukoencephalopathy, viral infection, or infiltrating glioma. Neuropathologic examination at biopsy (Poon T, Matoso I, Tchertkoff V, Weitzner I Jr, Gade M. CT features of primary cerebral lymphoma in AIDS and non-AIDS patients. J Comput Assist Tomogr . 1989;13:6-9) and autopsy (Schwaighofer BW, Hesselink JR, Press GA, Wolf RL, Healy ME, Berthoty DP. Primary intracranial CNS lymphoma: MR manifestations. Am J Neuroradiol . 1993;10:725-9) demonstrated nonnecrotic, diffusely infiltrating, large-cell B-cell lymphoma of white matter, with relative sparing of gray matter, and without significant leptomeningeal involvement or bulky periventricular disease at autopsy. Microglial and astrocytic reactions, but only subtle myelin pallor, were evident as individual tumor cells permeated the entire brain and spinal cord, albeit with considerable variation in cell density. Individual tumor cells could be identified from the optic nerve to spinal cord, documenting the "whole-brain" nature of the disease. CD20 immunostaining was necessary to fully appreciate the extent of individual lymphoma cell percolation through the white matter. The neurobehavioral deficits manifested by these patients demonstrate that lymphomatosis cerebri is an additional neoplastic cause of white matter dementia and can be added to the growing list of disorders responsible for this syndrome.     

基于计算机软件病灶自动检测技术对不同类型痴呆患者脑白质高信号体积的定量研究

目的 定量测量不同类型痴呆患者不同部位的脑白质高信号(WMH)体积,并分析WMH体积与认知功能的相关性.方法 收集广州医科大学附属广州市第一人民医院神经内科2008至2012年收治的阿尔茨海默病(AD,n=17)、混合型痴呆(MD,n=12)及血管性痴呆(VD,n=15)住院患者的临床资料及磁共振成像(MRI)资料,采用计算机自动检测技术对3组患者的FLAIR序列图像进行分析,分别测量侧脑室体旁、侧脑室体上、侧脑室体下3个层面的脑WMH体积.进行组间及组内不同部位WMH体积及总体积比较,分析各组患者不同部位WMH体积、WMH总体积与简易智能精神状态检查量表(MMSE)评分的相关性.结果 3组患者MMSE评分组间比较差异有统计学意义(F=9.715,P=0.000),其中MD组患者MMSE评分较VD组明显降低(16.4±7.1比19.3±4.3,P＜0.05).3组患者的侧脑室体旁WMH体积均大于侧脑室体下WMH体积(均P＜0.05),而VD组患者侧脑室体旁WMH体积大于侧脑室体上WMH体积,且侧脑室体上WMH体积大于侧脑室体下WMH体积(均P＜0.05).3组患者WMH总体积比较差异无统计学意义(F=0.838,P＞0.05).MD组患者侧脑室体下WMH体积大于AD组(P＜0.05).AD组患者WMH总体积与MMSE评分呈负相关(r=-0.360,P=0.004).结论 使用WMH自动检测技术可以成功获得患者脑部不同部位的WMH体积数据,不同部位WMH在不同痴呆患者中分布不同.     

Gray matter density and white matter integrity in pianists' brain: a combined structural and diffusion tensor MRI study

The current study combined structural magnetic resonance imaging (sMRI) and diffusion tensor MRI (DT-MRI) to investigate both gray matter density (GMD) and white matter integrity (WMI) in 18 pianists and 21 age-matched non-musicians. The pianists began their piano training at a mean age of 12. Voxel-based morphometry of the sMRI data showed that the pianists had higher GMD in the left primary sensorimotor cortex and right cerebellum. Voxel-based analysis of the DT-MRI data showed that pianists had higher fractional anisotropy (FA) (indicating higher WMI) in the right posterior limb of the internal capsule. The sMRI and DT-MRI results indicate that both the GMD and WMI of pianists may exhibit movement-related increases during adolescence or even early adulthood compared with non-musicians.     

A meta-analysis of diffusion tensor imaging in mild cognitive impairment and Alzheimer's disease

We reviewed case-control studies of diffusion tensor imaging (DTI) in patients with Alzheimer's dementia (AD) and mild cognitive impairment (MCI), in order to establish the relative severity and location of white matter microstructural changes. EMBASE and MEDLINE were searched using the keywords, ([“diffusion tensor”] and [“Alzheimer*” or “mild cognitive impairment”]), as were reference lists of relevant papers. Forty-one diffusion tensor imaging studies contained data that were suitable for inclusion. Group means and standard deviations for fractional anisotropy and mean diffusivity, or p values from 2-sample tests, were extracted and pooled, using standard methods of meta-analysis and metaregression. Fractional anisotropy was decreased in AD in all regions except parietal white matter and internal capsule, while patients with MCI had lower values in all white matter regions except parietally and occipitally. Mean diffusivity was increased in AD in all regions, and in MCI in all but occipital and frontal regions.     

Head size may modify the impact of white matter lesions on dementia

We aimed to examine whether total intracranial volume (TICV), a marker of premorbid brain size, modified the impact of the apolipoprotein E (apoE) e4 phenotype and ischemic white matter lesions (WMLs) on odds for dementia. The study comprised a population-based sample of 104 demented and 135 nondemented 85-year-olds, and included physical and neuropsychiatric examinations, and head computerized tomography (CT). Dementia disorders were defined according to standard criteria. TICV and WMLs were rated on computerized tomography. Using the highest group as reference, the risk for dementia, Alzheimer's disease (AD), and vascular dementia (VaD) was increased in those with the smallest half, tertile, and quartile of TICV. Smaller TICV increased the odds of dementia, Alzheimer's disease, and vascular dementia in participants with WMLs. WMLs were not associated with increased odds of dementia in those with the largest TICV. The interaction term WMLs*TICV was also significant. TICV did not modify the odds of dementia in those with the apolipoprotein e4 phenotype. Our results suggest that the impact of brain pathology on the risk of dementia is modified by premorbid brain size.     

Aging in deep gray matter and white matter revealed by diffusional kurtosis imaging

Diffusion tensor imaging has already been extensively used to probe microstructural alterations in white matter tracts, and scarcely, in deep gray matter. However, results in literature regarding age-related degenerative mechanisms in white matter tracts and parametric changes in the putamen are inconsistent. Diffusional kurtosis imaging is a mathematical extension of diffusion tensor imaging, which could more comprehensively mirror microstructure, particularly in isotropic tissues such as gray matter. In this study, we used the diffusional kurtosis imaging method and a white-matter model that provided metrics of explicit neurobiological interpretations in healthy participants (58 in total, aged from 25 to 84 years). Tract-based whole-brain analyses and regions-of-interest (anterior and posterior limbs of the internal capsule, cerebral peduncle, fornix, genu and splenium of corpus callosum, globus pallidus, substantia nigra, red nucleus, putamen, caudate nucleus, and thalamus) analyses were performed to examine parametric differences across regions and correlations with age. In white matter tracts, evidence was found supportive for anterior–posterior gradient and not completely supportive for retrogenesis theory. Age-related degenerations appeared to be broadly driven by axonal loss. Demyelination may also be a major driving mechanism, although confined to the anterior brain. In terms of deep gray matter, higher mean kurtosis and fractional anisotropy in the globus pallidus, substantia nigra, and red nucleus reflected higher microstructural complexity and directionality compared with the putamen, caudate nucleus, and thalamus. In particular, the unique age-related positive correlations for fractional anisotropy, mean kurtosis, and radial kurtosis in the putamen opposite to those in other regions call for further investigation of exact underlying mechanisms. In summary, the results suggested that diffusional kurtosis can provide measurements in a new dimension that were complementary to diffusivity metrics. Kurtosis together with diffusivity can more comprehensively characterize microstructural compositions and age-related changes than diffusivity alone. Combined with proper model, it may also assist in providing neurobiological interpretations of the identified alterations.     

应用DTI技术对人脑白质纤维束的初步研究

目的建立扩散张量纤维束成像对人脑白质纤维的显示方法,并应用中国数字化可视人体数据进行对照观察,验证扩散张量成像(DTI)方法的可靠性。方法选择5名健康志愿者进行DTI成像,采用DtiStudio软件进行分析处理,重建出部分各向异性(FA)图、容积比(VR)图、相对各向异性(RA)图、表面扩散系数(ADC)图以及二维彩色张量图。应用中国数字化可视人体数据集断面图像、FA图及彩色FA图进行对照观察,利用fibertracking纤维跟踪软件及3DMRI软件进行三维重建显示脑内主要白质纤维束,辨认脑内白质纤维束的位置、形态。结果应用DTI纤维束成像可以清晰准确地描绘脑白质内主要神经纤维束的解剖图谱,包括联络纤维如弓形纤维、钩束、扣带束、上纵束和下纵束,连合纤维如胼胝体、前连合和穹隆,投射纤维如锥体束、视放射、内侧丘系等。DTI纤维束成像结果与已知解剖知识、中国可视化人体断面图像具有很好的一致性。结论应用DTI纤维束成像可以清晰准确地描绘脑白质内主要神经纤维束的解剖图谱,其结果与中国可视化人体断面图像、已知解剖知识是一致的,应用DTI纤维束成像研究脑内纤维连通性是可靠的。