基于纤维骨架的空间统计的精神分裂幻听患者的全脑白质各向异性分数研究

目的 研究精神分裂幻听患者的全脑白质细微结构的改变情况.方法 应用西门子3.0T MR对A组32例精神分裂幻听患者及B组32例正常对照者进行扩散张量成像(DTI)扫描,采用基于纤维骨架的空间统计(TBSS)方法分析2组全脑DTI的各向异性分数(FA)图,并使用基于非参数的随机排列检验(RPT)对2组FA数据进行统计学比较.结果 与正常对照组相比,精神分裂幻听组左侧钩束、下额-枕束及左侧丘脑前辐射区的左侧额叶白质、左侧内囊前肢及左侧外囊FA值明显降低,差异有统计学意义(P＜0.05,TFCE-corrected).结论 本研究结果表明,左侧钩束、下枕-枕束及左侧丘脑前辐射区的白质纤维损伤,提示左侧额叶与左侧丘脑、左枕颞区的白质纤维连接异常导致了精神分裂幻听的发生.     

首发精神分裂症静息态脑白质功能活动研究

目的 探究首发精神分裂症(SZ)脑白质的功能活动改变及其与临床特点的关系.方法 将44例首发SZ患者(SZ组)和44例健康对照(HC组)纳入本研究,采集了高分辨T1 WI和静息态功能磁共振成像(rs-fMRI)图像,根据JHU ICBM-DTI-81白质模板的48个感兴趣区(ROI),计算脑白质的功能连接(FC)并比较...     

扩散张量成像在精神分裂症患者脑部结构的临床应用

目的：用扩散张量成像（DTI）的磁共振技术探讨研究精神分裂症患者可能的脑部结构的病理改变。方法：对15例成年男性精神分裂症患者和15例成年男性健康对照者行DTI磁共振检查,比较患者组和健康对照组的部分各向异性（FA）差异性。结果：精神分裂症患者右侧额中回、额下回、右侧颞上回、左侧颞下回、左侧颞中回、左侧扣带回、左侧中央前回的各项分数异性（FA）值较健康对照组低（P〈0.05）。未发现患者组白质FA值有明显增高的脑区。结论：额叶区域白质结构的异常可能是精神分裂症患者额叶的执行功能损害的病理生理学机制之一。     

治疗前男性精神分裂症内囊前肢的DTI研究

目的：应用磁共振扩散张量成像（DTI）探讨男性精神分裂症患者治疗前两侧内囊前肢神经纤维束的微观结构改变。方法：对13例治疗前（病程〈5年）的男性精神分裂症患者（病例组）和11例年龄相匹配的男性健康志愿者（对照组）行DTI检查,在12个方向施加扩散梯度磁场,采用小兴趣区（ROI）法测量并比较两组受试者内囊前肢各向异性分数（FA）值和表观扩散系数（ADC）值的差异。结果：病例组左、右侧内囊前肢的FA值分别为0.587±0.034和0.620±0.042,ADC值分别为（7.349±0.414）和（7.359±0.340）×10-4mm2/s,对照组左、右侧内囊前肢的FA值分别为0.627±0.032和0.639±0.045,ADC值分别为（7.186±0.302）和（7.243±0.389）×10-4mm2/s。病例组左侧内囊前肢FA值低于对照组,差异有显著性意义（t=2.297,P〈0.05）,两组右侧内囊前肢FA值和双侧内囊前肢ADC值的差异均无显著性意义（P〉0.05）。结论：治疗前男性精神分裂症患者白质微观结构发生改变,提示左侧丘脑与前额叶、扣带回前部相互联系的白质功能障碍,可以解释男性精神分裂症的一些临床症状和认知缺陷。     

首发抑郁症患者脑白质微结构异常的扩散张量成像研究

目的 应用磁共振扩散张量成像(DTI)技术研究首次发作抑郁症(MDD)患者脑白质微结构改变.资料与方法 对22例首次发作MDD患者和30例性别、年龄和受教育程度相匹配的正常对照者进行全脑DTI扫描.应用基于体素的形态学分析法比较两组受检者的各向异性分数(FA),并分析MDD患者脑白质微结构改变与MDD病程及严重程度的相...     

抑郁症患者脑白质纤维的各向异性变化

目的：探讨MRI DWI上抑郁症患者脑白质纤维的各向异性特征。方法：对9例抑郁症患者以及与患者组年龄、性别相匹配的10例志愿者（对照组）行MR扩散张量成像（DTI）。记录额叶、颞叶、枕叶和胼胝体白质的各向异性分值（FA值）。结果：抑郁症患者左右额叶上中下部、左右颞叶、胼胝体压部的脑白质FA值均低于对照组,差异有显著性意义（P〈0.05）。结论：抑郁症患者的额叶和颞叶的白质纤维束FA值比正常人低,而且左右侧不对称。     

基于格兰杰因果分析对精神分裂症幻听患者的脑有效连接研究

目的 基于静息态功能磁共振成像(rs-fMRI)的格兰杰因果分析,探索精神分裂症幻听相关的脑有效连接改变.方法 18例精神分裂症幻听患者和18例匹配的非幻听患者均接受rs-fMRI扫描,以双侧颞上回(STG)、Broca区、Wernicke区作为感兴趣区(ROI),计算任意2个ROI的净因果值并比较2组间的差异,计算净...     

首发精神分裂症患者大脑左侧额叶 CT 值变化分析

目的：分析首发精神分裂症(FES)患者大脑左侧额叶的 CT 值变化。方法回顾性分析100例经临床确诊的 FES 患者的脑部 CT 图像,所有患者均符合 ICD10诊断标准、首次发病、首次经抗精神药物治疗且病程≤2年,并和对照组(n=100)的脑部CT 图像进行对照研究。对研究对象大脑左侧额叶同一部位进行 CT 值的测量,所测值经过统计学处理后,分析 FES 患者大脑左侧额叶的 CT 值变化。结果大脑左侧额叶 CT 值：FES 患者为(33.55±2.08)HU,对照组为(37.17±3.16)HU,FES 患者大脑左侧额叶 CT 值较对照组减小。结论FES 患者大脑左侧额叶的 CT 值减低,为精神分裂症病因学研究提供重要的影像学依据。     

创伤性脑白质损伤的扩散张量成像研究

目的:评价扩散张量成像(DTI)在创伤性脑白质损伤(WMI)中的应用价值。方法:16例创伤性脑外伤后经临床诊断有WMI的患者通过Philips 1.5TIntera Achieva MR扫描仪行常规MRI和DTI。后处理获得部分各向异性指数(FA)、表观弥散系数(ADC)和纤维示踪成像三维图。根据T2WI及T2快速场回波图像,分别于WMI区域、同侧同名或对侧同名纤维束正常区域取感兴趣区,测量FA值和ADC值并进行比较。结果:脑外伤患者损伤脑白质中挫伤和出血、仅挫伤和仅出血区域三者之间的FA值(F=0.68,P>0.05)和ADC值(F=0.53,P>0.05)均未见明显不同。除仅出血区域的ADC值与对照区域相比差异无统计学意义(t=1.36,P>0.05),挫伤和出血(t=9.72,P<0.05)、仅挫伤(t=8.28,P<0.05)和仅出血(t=5.44,P<0.05)区域的FA值较正常对照区域明显降低,挫伤和出血(t=4.71,P<0.05)、仅挫伤(t=4.81,P<0.05)的ADC值较正常对照明显增高,纤维示踪成像显示损伤区域脑白质较正常区域稀疏、分离、缺失。结论:DTI技术能够显示患者WMI区域的异常改变,但ADC值对出血的判断有局限性。     

脑白质束扩散张量与阿尔茨海默病患者的神经心理学量表评分的多元线性回归分析

目的应用线性回归方法,通过对阿尔茨海默病(AD)的相关脑白质束扩散张量分析,找出与AD患者神经心理学评分的相关关系并建立回归方程。资料与方法对20例轻度AD患者、30例中重度AD患者以及25名年龄相匹配的正常老年自愿者进行扩散张量成像(DTI)扫描。DTI采用单次激励平面回波成像(EPI)序列,扩散敏感梯度施加在25个不同方向,生成平均扩散系数(MD)、部分各向异性(FA)参数图,结合彩色向量图及纤维追踪图分别测定各白质束的参数值,包括双侧扣带束、上纵束、下纵束、下额枕束、钩束、穹窿体、胼胝体膝部及压部。利用多元线性回归分析,建立各DTI参数与简易智能量表(MMSE)评分的回归模型。结果对照组与轻度AD组比较仅穹窿体和左侧扣带束的FA值存在明显差异;轻度AD组与中重度AD组比较穹窿体、双侧钩束、扣带束、下纵束、胼胝体膝部及压部及右侧下额枕束的FA值均存在统计学差异。对照组与轻度AD组的MD值在穹窿体区存在统计学差异,而轻度AD组与中重度AD组在穹窿体、双侧钩束、下额枕束、左侧扣带束、右侧上、下纵束、胼胝体膝部及压部均存在MD值的显著差异。回归模型提示穹窿体和左侧扣带束的FA值与MMSE评分存在正线性相关关系,...     

轻型创伤性脑损伤脑白质纤维束扩散张量成像研究

目的：使用3.0T 磁共振扩散张量成像(DTI)技术观察轻型创伤性脑损伤(mTBI)患者脑白质纤维束的改变,探讨 DTI对 mTBI 的临床诊断价值。方法选取30例 mTBI 患者及30例健康对照者分别进行常规 CT、MRI 及 DTI 检查,分别测量 mTBI患者(急性期、亚急性期、伤后5周~3个月)和对照者的胼胝体膝部、压部、双侧内囊前后肢、扣带束、上纵束、下纵束的各向异性(FA)值、表观扩散系数(ADC)值,观察各测量值的变化规律。结果mTBI 患者部分脑白质纤维束区的 FA 值在急性期、亚急性期减低(P 均<0.05),伤后5周~3个月时仍低于对照者(P 均<0.05),但胼胝体膝部及压部的 FA 值在急性期不减低反而升高(P 均>0.05),此后呈逐渐减低趋势,并在外伤5周~3个月时略低于正常对照组,但差异无统计学意义(P 均>0.05)。急性期、亚急性期 mTBI 患者的 ADC 值低于正常对照组,并在外伤5周~3个月时接近或略高于对照组,但差异无统计学意义(P 均>0.05)。结论DTI 对 mTBI 敏感性较高,能够准确显示白质纤维束的损伤情况并使其可视化,DTI 对 mTBI 的诊断具有重要的临床价值。     

Dynamic corticospinal white matter connectivity changes during stroke recovery: A diffusion tensor probabilistic tractography study

Purpose

To investigate corticospinal tract connectivity changes at the cortical surface using diffusion tensor imaging (DTI) tractography during recovery from stroke.

Materials and Methods

Using data from 10 stroke patients (four subcortical) and six elderly controls, we developed an automated method to quantify altered motor connectivity that involves the use of a simplified cortical surface model as a seed mask with target regions defined within the corticospinal tracts to initiate a probabilistic tractography algorithm.

Results

We found no change in volume overlap of the generated corticospinal tracts in the stroke patients compared to controls, but significant connectivity changes at the boundary of the simplified cortical surface mask, especially within the ipsilesional hemisphere of stroke patients over time. Using the cortical regions with significantly enhanced connectivity as a seed mask on the patient data, tracts that are directly associated with stroke recovery can be delineated. Measures of uncertainty in fiber orientation within these fiber tracts significantly correlated with functional outcome.

Conclusion

The novel findings from this study highlight the usefulness of this methodology to study white matter repair/reorganization during stroke recovery. J. Magn. Reson. Imaging 2009;29:529–536. © 2009 Wiley‐Liss, Inc.     

Diffusion anisotropy in subcortical white matter and cortical gray matter: changes with aging and the role of CSF-suppression

PURPOSE: To determine the relevance of cerebrospinal fluid (CSF)-suppression for the measurement of diffusion anisotropy in well-localized areas of the brain, particularly the subcortical white matter (WM) within the gyri and cortical gray matter (GM), in young and elderly subjects, and to assess the changes of water diffusivity in the brain with normal aging. MATERIALS AND METHODS: Quantitative measures of anisotropy in 26 regions, including subcortical WM (i.e., in the gyri), cortical GM, major deep WM, and deep GM regions of young (21-25 years, N = 8) and elderly (61-74 years, N = 10) normal volunteers, were assessed with CSF-suppressed diffusion tensor imaging (DTI) relative to standard DTI. RESULTS: CSF-suppressed DTI demonstrated significant increases in fractional anisotropy (FA) of 3-12% in the young and 2-14% in the elderly groups with the largest changes being in the subcortical WM of the gyri. Furthermore, FA decreased by 10-19% in the subcortical WM of the gyri of the elderly subjects relative to the young, primarily due to increases in the perpendicular diffusivity, lambda(3), with age. CONCLUSION: CSF-suppressed DTI yields more accurate measures of quantitative anisotropy in cortical and subcortical brain regions. Reductions of anisotropy with aging were predominantly observed in subcortical WM of the gyri.     

遗忘型轻度认知障碍的脑白质纤维束成像研究

目的：应用纤维束成像术研究遗忘型轻度认知功能障碍(aMCI)患者脑白质细微结构的改变。方法对30例经临床诊断的 aMCI 患者和31例正常对照(NC)组行扩散张量成像,用 dTV II 软件重建出扣带束、胼胝体、钩状束及下枕额束,并沿着白质束测量部分各向异性(FA)值。对比分析 aMCI 组与 NC 组各白质束的 FA 值,并将 aMCI 组的 FA 值与简易智能精神状态检查量表(MMSE)评分进行相关性分析。结果①aMCI 组的两侧扣带束、两侧钩状束及胼胝体 FA 值明显低于 NC 组,差异有统计学意义;左侧下枕额束 FA 值低于 NC 组,但差异无统计学意义。②右侧扣带束的 FA 值与 MMSE 评分呈正相关。结论aMCI 患者扣带束、钩状束及胼胝体 FA 值的异常改变,提示在阿尔茨海默病(AD)的前驱阶段存在与记忆相关的脑白质束的微损害,纤维束成像(tractography)技术对脑白质的早期损害具有很高的敏感性。     

Directional correlation in white matter tracks of the human brain

PURPOSE: To describe a technique for the detection of distinct brain fibers in sets of magnetic resonance (MR) diffusion tensor imaging (DTI) data. MATERIALS AND METHODS: MR-DTI can be used for a tractography of brain fibers presuming a data set of high spatial resolution and high signal to noise. A less demanding technique for the visualization of discrete brain fiber bundles involves segmentation. By using a region-growing algorithm, those voxels that have a direction similar to that of the major eigenvector in neighboring voxels of a data set can be marked. It has been shown recently by Mori et al (1) that this technique can be successfully applied to data from a single slice of a mouse brain. In this study, the segmentation technique was applied with modifications to multislice DTI data from the human brain. RESULTS: A distinct segmentation of various brain fiber bundles could be achieved by the use of a two-step algorithm. In the first step, voxels within large fiber tracts-such as corticofugal tracts (e.g., corticospinal tract) and the optic radiation-were segmented by starting the region-growing algorithm in the corpus callosum (CC) and erasing this major structure from the data set. In the second step, remaining voxels were segmented by the same algorithm; this revealed a good assignment of the similarly oriented fibers derived by segmentation to the anatomically given brain lobes. This two-step procedure was successfully applied to DTI data of six healthy volunteers. CONCLUSION: The segmentation technique for DTI data proposed by Mori et al (1) for data from mouse brains can be applied to multislice data from the human brain by using a two-step algorithm including a masking of the major fiber tracts.     

DTI对HIV感染者脑白质细微结构病变的诊断研究

目的 探讨扩散张量成像(DTI)技术对人类免疫缺陷病毒(HIV)感染者脑白质细微病变的诊断和临床应用价值.方法选取80例HIV阳性者(阳性组)和83例HIV阴性者(对照组),均行MRI常规序列及DTI扫描.测定双侧内囊前支、内囊后支、内囊膝、胼胝体膝部、压部及双侧胼胝体干脑白质感兴趣区(ROI)的各向异性分数(FA)值和表观扩散系数(ADC)值,利用独立样本t检验比较2组间FA值及ADC值的差异.结果与正常对照组相比,阳性组双侧内囊前支及内囊膝、胼胝体膝部及双侧胼胝体干FA值均低于对照组,差异有统计学意义(P<0.05);阳性组双侧内囊前支、后支、膝部及双侧胼胝体干ADC值均高于对照组,差异亦有统计学意义(P<0.05).结论DTI通过FA值和ADC值的异常改变而发现HIV阳性患者内囊及胼胝体区脑白质结构的细微病变,为临床早期诊断和治疗干预提供参考依据.     

Gray and white matter changes in Alzheimer's disease: a diffusion tensor imaging study

PURPOSE: To investigate microstructural changes in cortical and white matter pathways in patients with Alzheimer's disease using diffusion tensor imaging (DTI). MATERIALS AND METHODS: Measures of mean diffusivity (MD) and fractional anisotropy (FA) were compared in the brains of 13 Alzheimer's disease (AD) patients and a group of 13 aged-matched control participants employing an optimized DTI technique involving a fully automated, voxel-based morphometric (VBM) analysis. RESULTS: After rigorous control for anatomical variation and confounding partial volume effects, we found significantly elevated MD measures within the hippocampus, amygdala, and medial temporal, parietal, and frontal lobe gray matter regions in the AD participants. The largest number of pixels with increased MD was localized bilaterally, within the posterior cingulate gyrus. The FA was significantly reduced within the thalamus, parietal white matter, and posterior limbs of the internal capsule, indicating significant involvement of corticothalamic and thalamocortical radiations. CONCLUSION: This study demonstrates that rigorous VBM analysis of DTI data can be used to investigate microstructural changes in cortical, subcortical, and white matter regions in AD.     

Whole brain white matter changes revealed by multiple diffusion metrics in multiple sclerosis: a TBSS study

Objective

To investigate whole brain white matter changes in multiple sclerosis (MS) by multiple diffusion indices, we examined patients with diffusion tensor imaging and utilized tract-based spatial statistics (TBSS) method to analyze the data.

Methods

Forty-one relapsing-remitting multiple sclerosis (RRMS) patients and 41 age- and gender-matched normal controls were included in this study. Diffusion weighted images were acquired by employing a single-shot echo planar imaging sequence on a 1.5 T MR scanner. Voxel-wise analyses of multiple diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) were performed with TBSS.

Results

The MS patients had significantly decreased FA (9.11%), increased MD (8.26%), AD (3.48%) and RD (13.17%) in their white matter skeletons compared with the controls. Through TBSS analyses, we found abnormal diffusion changes in widespread white matter regions in MS patients. Specifically, decreased FA, increased MD and increased RD were involved in whole-brain white matter, while several regions exhibited increased AD. Furthermore, white matter regions with significant correlations between the diffusion metrics and the clinical variables (the EDSS scores, disease durations and white matter lesion loads) in MS patients were identified.

Conclusion

Widespread white matter abnormalities were observed in MS patients revealed by multiple diffusion metrics. The diffusion changes and correlations with clinical variables were mainly attributed to increased RD, implying the predominant role of RD in reflecting the subtle pathological changes in MS.