基于纤维束空间统计学分析视神经脊髓炎谱系疾病脑白质微结构改变

目的 采用DTI基于纤维骨架空间统计方法（TBSS）分析视神经脊髓炎谱系疾病（NMOSD）患者脑白质纤维束微结构的改变。方法 对20例NMOSD患者（NMOSD组）和20名健康志愿者（正常对照组）行全脑常规MR和DTI扫描,使用FSL软件包中TBSS步骤对DTI数据行全脑非参数统计分析,并对NMOSD组有统计学差异的纤维束FA值与临床扩展残疾状态量表（EDSS）评分进行相关性分析。结果 与正常对照组比较,NMOSD组大脑及小脑白质区纤维束如胼胝体、穹隆、皮质脊髓束、钩束、小脑脚等广泛FA值减低（P<0.05,FEW校正）,其中扣带束、胼胝体、穹隆等AD值减低、RD值增高,穹隆和左侧内囊豆核后部MD值升高（P<0.05,FEW校正）。NMOSD患者左侧钩束、右侧外囊、左侧小脑下脚及双侧内囊前肢、内侧丘系FA值与EDSS评分呈负相关（P均<0.05）。结论 TBSS显示NMOSD患者大脑及小脑存在广泛脑白质损伤,可解释NMOSD部分临床症状,与残疾症状无关的脑区纤维束微结构改变提示NMOSD患者这些区域病变可能存在更复杂的病理机制。     

首发和慢性精神分裂症幻听患者的扩散张量成像研究

目的:探索首发和慢性精神分裂症幻听患者是否存在听觉、语言及记忆/边缘系统网络的相关白质纤维异常。方法:纳入21例首发和12例慢性精神分裂症幻听患者及人口学参量匹配的26例健康对照。收集所有研究对象的DTI数据,采用基于纤维束的空间统计分析方法比较两组患者和对照组间的白质纤维差异。结果:与对照组相比,首发精神分裂症幻听患者在胼胝体、上纵束、下额枕束、钩束、扣带束、外囊及内囊前肢区域部分各向异性(FA)显著降低,径向扩散张量(RD)显著升高。慢性精神分裂症幻听患者表现出比首发患者更广泛的白质损害,且除FA和RD的改变外,部分脑区还表现出轴向扩散张量(AD)的升高。结论:精神分裂症幻听患者存在连接语言、听觉和记忆/边缘系统网络的多种白质纤维异常。慢性精神分裂症幻听患者与首发患者相比可能表现出更严重的神经退行性改变。     

White matter hemisphere asymmetries in healthy subjects and in schizophrenia: a diffusion tensor MRI study

Hemisphere asymmetry was explored in normal healthy subjects and in patients with schizophrenia using a novel voxel-based tensor analysis applied to fractional anisotropy (FA) of the diffusion tensor. Our voxel-based approach, which requires precise spatial normalization to remove the misalignment of fiber tracts, includes generating a symmetrical group average template of the diffusion tensor by applying nonlinear elastic warping of the demons algorithm. We then normalized all 32 diffusion tensor MRIs from healthy subjects and 23 from schizophrenic subjects to the symmetrical average template. For each brain, six channels of tensor component images and one T2-weighted image were used for registration to match tensor orientation and shape between images. A statistical evaluation of white matter asymmetry was then conducted on the normalized FA images and their flipped images. In controls, we found left-higher-than-right anisotropic asymmetry in the anterior part of the corpus callosum, cingulum bundle, the optic radiation, and the superior cerebellar peduncle, and right-higher-than-left anisotropic asymmetry in the anterior limb of the internal capsule and the anterior limb's prefrontal regions, in the uncinate fasciculus, and in the superior longitudinal fasciculus. In patients, the asymmetry was lower, although still present, in the cingulum bundle and the anterior corpus callosum, and not found in the anterior limb of the internal capsule, the uncinate fasciculus, and the superior cerebellar peduncle compared to healthy subjects. These findings of anisotropic asymmetry pattern differences between healthy controls and patients with schizophrenia are likely related to neurodevelopmental abnormalities in schizophrenia.     

扩散张量纤维束成像技术对Broca失语症语言功能区及纤维结构的活体分析

背景:磁共振扩散张量成像和纤维素成像技术是惟一能在活体上进行白质纤维结构分析的方法.目的:通过扩散张量纤维束成像技术观察Broca失语症时语言功能区及其纤维结构的变化.设计、时间和地点:对比观察临床实验,于2003-11/2005-02在昆明医学院第一附属医院和首都医科大学北京天坛医院完成.对象:选择不同程度Broca失语症患者30例,女9例,男21例,年龄17～63岁.经北京医科大学附属一院神经心理研究室汉语失语成套测验确诊失语症,以不同亚项测试作出失语症分类诊断.方法:应用3T超高场强磁共振扫描仪及工作站对患者完成全脑的数据采集和处理.选定Brodmann 45、44区和22区、39区及右侧半球相应脑区为语言功能区,脑内与语言功能区密切相关的主要联合、连合纤维束为纤维追踪的兴趣区,分别进行神经纤维束的追踪显示.主要观察指标:观察从语言功能区发出的神经纤维束的走行、分布及其与其它脑区间的联系和病理情况下的改变,并与文献资料中的正常人进行对比.结果:30例Broca失语症患者全部进入结果分析.①Broca失语症患者的左侧45区和44区纤维束及其平均各向异性阈值少于正常人,差异有显著性意义(t=-2.683 65,-5.300 55,P＜0.05).②Broca区向下穿行的纤维束中断或移位,与弓状纤维束前部的联系松散或分离,到中央前回及额叶内侧面的纤维减少.③Broca失语症的弓状纤维束的改变主要是前端的纤维束完整性破坏和纤维束移位所致Broca区与弓状纤维束的分离,左侧弓状束的纤维束数量和平均各向异性阈值也均少于正常人,差异有显著性意义(P＜0.05).结论:脑Broca区皮质及其纤维环路结构的损伤均可导致Broca失语症的发生.     

White matter fiber tracts of the human brain: three-dimensional mapping at microscopic resolution, topography and intersubject variability

The position and extent of individual fiber tracts within the white matter of human brains can be identified in vivo using diffusion tensor imaging (DTI) and fiber tracking methods. Previous to this study, however, the lack of three-dimensional (3-D) probability maps precluded comparing the anatomical precision of MRI studies with microscopically defined fiber tracts in human postmortem brains. The present study provides 3-D registered maps of the topography, course and intersubject variability of major fiber tracts, which were identified at microscopic resolution. The analyzed tracts include the corticospinal tract, optic and acoustic radiations, fornix, cingulum, corpus callosum, superior longitudinal, superior and inferior occipito-frontal and uncinate fascicles; sources and targets of fiber tracts include the lateral and medial geniculate nuclei and mamillary bodies. Tracts and nuclei were identified in serial myelin-stained histological sections of ten postmortem brains. The sections were 3-D reconstructed and registered to a standardized stereotaxic space of an in vivo MR reference brain by means of linear and non-linear, elastic transformations. The individual fiber tracts and nuclei were superimposed in the reference space, and probability maps were generated as a quantitative measure of intersubject variability for each voxel of the stereotaxic space. This study presents the first stereotaxic atlas of the course, location and extent of fiber tracts and related nuclei based on microscopically defined localization and topographic data taken at multiple levels on each of the three orthogonal planes. The maps are useful for evaluating and identifying fiber bundles in DTI, for localizing subcortical lesions visible in anatomical MR images and for studying neuronal connectivity.     

A comprehensive reliability assessment of quantitative diffusion tensor tractography

Diffusion tensor tractography is increasingly used to examine structural connectivity in the brain in various conditions, but its test-retest reliability is understudied. The main purposes of this study were to evaluate 1) the reliability of quantitative measurements of diffusion tensor tractography and 2) the effect on reliability of the number of gradient sampling directions and scan repetition. Images were acquired from ten healthy participants. Ten fiber regions of nine major fiber tracts were reconstructed and quantified using six fiber variables. Intra- and inter-session reliabilities were estimated using intraclass correlation coefficient (ICC) and coefficient of variation (CV), and were compared to pinpoint major error sources. Additional pairwise comparisons were made between the reliability of images with 30 directions and NEX 2 (DTI30-2), 30 directions and NEX 1 (DTI30-1), and 15 directions and NEX 2 (DTI15-2) to determine whether increasing gradient directions and scan repetition improved reliability. Of the 60 tractography measurements, 43 showed intersession CV ≤ 10%, ICC ≥ .70, or both for DTI30-2, 40 measurements for DTI30-1, and 37 for DTI15-2. Most of the reliable measurements were associated with the tracts corpus callosum, cingulum, cerebral peduncular fibers, uncinate fasciculus, and arcuate fasciculus. These reliable measurements included factional anisotropy (FA) and mean diffusivity of all 10 fiber regions. Intersession reliability was significantly worse than intra-session reliability for FA, mean length, and tract volume measurements from DTI15-2, indicating that the combination of MRI signal variation and physiological noise/change over time was the major error source for this sequence. Increasing the number of gradient directions from 15 to 30 while controlling the scan time, significantly affected values for all six variables and reduced intersession variability for mean length and tract volume measurements. Additionally, while increasing scan repetition from 1 to 2 had no significant effect on the reliability for DTI with 30 directions, this significantly reduced the upward bias in FA values from all 10 fiber regions and fiber count, mean length, and tract volume measurements from 5 to 7 fiber regions. In conclusion, diffusion tensor tractography provided many measurements with high test-retest reliability across different fiber variables and various fiber tracts even for images with 15 directions (NEX 2). Increasing the number of gradient directions from 15 to 30 with equivalent scan time reduced variability whereas increasing repetition from 1 to 2 for 30-direction DTI improved the accuracy of tractography measurements.     

基于DTI的三叉神经痛脑白质结构异常及其与临床特征的相关性

目的 采用基于纤维束的空间统计方法（TBSS）探讨原发性三叉神经痛（PTN）患者脑白质微结构异常。方法 对38例PTN患者（PTN组）和38名年龄、性别匹配的健康志愿者（对照组）行全脑DTI扫描,并用FSL软件进行分析,寻找FA值、平均扩散系数（MD）、径向扩散系数（RD）和轴向扩散系数（AD）存在组间统计学差异的脑区,并与视觉模拟评分（VAS）进行相关分析。结果 与对照组相比,PTN组胼胝体、放射冠、左侧上纵束、左侧下纵束及下额枕束FA值降低;且PTN组双侧丘脑后辐射、双侧内囊、双侧外囊、穹窿、右侧上纵束同时存在MD值和RD值升高,而AD升高脑区仅局限于双侧内囊前支、左侧内囊后支、双侧上放射冠和双侧上纵束。PTN患者左侧上纵束FA值与VAS呈负相关（r=-0.502,P=0.001）,左侧上纵束MD值与VAS评分呈正相关（r=0.437,P=0.006）。结论 丘脑、内囊MD值和RD值同向升高而不伴FA值降低可能是PTN的相对特征性DTI表现;左侧上纵束FA值和MD值对评估PTN患者疼痛水平有参考价值。     

针刺阳陵泉对脑梗死患者白质结构的影响

目的研究针刺阳陵泉穴后脑卒中患者白质结构的变化。方法6 例脑卒中恢复期左侧偏瘫的患者,以假穴为对照,在针刺左侧阳陵泉前后对患者进行弥散张量成像(DTI)检查,采用西门子1.5 T磁共振仪采集数据,应用FSL软件包中的基于传导束的空间统计(TBSS)方法对针刺前后的数据进行比较。结果针刺阳陵泉穴对脑白质各向异性(FA)的影响强于假穴的区域包括左侧中央前、后回,颞中、下回,辅助运动区,额下回,内囊,穹窿和双侧顶下回。这些区域中走行的纤维束有锥体束、弓状束、胼胝体纤维和皮层间联络纤维,涉及运动代偿、体感、语言和记忆等多个功能网络。结论与假穴相比,针刺阳陵泉可使脑梗死患者的白质超微结构出现变化,主要的变化区域出现在健侧半球,与多个脑功能网络相关。     

纤维束示踪成像评价复发缓解型多发性硬化患者边缘系统纤维通路损伤

目的 利用扩散张量纤维束示踪成像评估多发性硬化（MS）边缘系统纤维通路损害。方法 对20例复发缓解型MS患者（MS组）和20名健康志愿者（对照组）进行纤维束示踪成像。追踪扣带束、穹窿、钩束,获得相应纤维条数、FA值、MD值。并进行统计学分析。结果 与对照组比较,MS组扣带束、穹窿、钩束FA值均减低（P均<0.01）,MD值均升高（P均<0.05）。MS组穹窿纤维条数较对照组减少（P<0.001）。MS组中左侧与右侧钩束纤维条数、对照组中左侧与右侧钩束FA值、纤维条数差异均有统计学意义（P均<0.05）。MS组扣带束、钩束FA值与EDSS评分呈负相关（r=-0.572、-0.665,P均<0.05）,MD值与EDSS评分呈正相关（r=0.627、0.603,P均<0.05）。结论 纤维束示踪成像对评估MS边缘系统纤维通路损害及监测临床进程有重要应用价值。     

DTI量化评估旋律语调疗法治疗Broca失语症后脑细微结构变化的研究

目的通过扩散张量成像(diffusion tensor imaging,DTI)提供语言功能相关的纤维结构信息,探讨旋律语调疗法(melody intonation therapy,MIT)治疗Broca失语症脑纤维结构改变的特征。材料与方法收集新疆医科大学第一附属医院2019年1月至2020年6月卒中后Broca失语症37例患者,随机分为两组,对照组19例,采取常规语言疗法,实验组18例,在常规语言疗法基础上再行旋律语调疗法治疗,两组患者均在治疗前及治疗2月后行DTI扫描,分别测量并比较实验组治疗前后双侧Broca区及弓状纤维束的各向异性分数(fractional anisotropy,FA),以及比较实验组与对照组治疗前后双侧Broca区及弓状纤维束的FA值。结果实验组治疗前后对比显示,双侧Broca区、弓状纤维束FA值差异均有统计学意义(双侧弓状纤维束区及左侧Broca区P<0.001,右侧Broca区P=0.008);治疗前实验组与对照组双侧Broca区及弓状纤维束区FA值无统计学差异(右侧Broca区P=0.154,左侧Broca区P=0.228,右侧弓状纤维束区P=0.361,左侧弓状纤维束区P=0.135),治疗后实验组与对照组右侧弓状纤维束FA值差异有统计学意义(P=0.008),左侧弓状纤维束及双侧Broca区FA值差异无统计学意义(右侧Broca区P=0.138,左侧Broca区P=0.093,左侧弓状纤维束P=0.259)。结论旋律语调疗法对Broca失语患者的强化康复治疗后,右侧弓状纤维束区FA值增加,提示MIT的治疗机制与右侧弓状纤维的结构变化相关。