采用基于纤维束示踪的空间统计分析方法观察先天性耳聋患者的脑白质改变

目的 应用基于纤维束示踪的空间统计分析(TBSS)方法,观察先天性感音神经性耳聋患者听觉中枢及相关中枢的脑白质改变.方法 对15例先天性耳聋患者和28名正常志愿者的听觉中枢及相关中枢进行扩散张量成像(DTI)及三维快速扰相梯度回波数据采集.应用TBSS对先天性耳聋患者和正常志愿者的DTI数据进行分析,获取部分各向异性(FA)值具有显著性差异的脑区.结果 与正常志愿者相比,先天性耳聋患者的双侧额下回、颞横回、颞上回、颞中回中后部内侧的脑白质以及双侧内囊前肢、外囊、视辐射FA值显著下降(P<0.05),左侧颞中回中后部内侧脑白质及视辐射FA值下降的范围大于右侧.结论 先天性耳聋患者听觉中枢及相关中枢脑白质FA值显著下降,提示出入听觉中枢及相关中枢的脑白质纤维髓鞘形成不良和(或)白质纤维数量减少.     

Diffusion tensor imaging with tract-based spatial statistics reveals local white matter abnormalities in preterm infants

Infants born preterm have a high incidence of neurodevelopmental impairment in later childhood, often associated with poorly defined cerebral white matter abnormalities. Diffusion tensor imaging quantifies the diffusion of water within tissues and can assess microstructural abnormalities in the developing preterm brain. Tract-based spatial statistics (TBSS) is an automated observer-independent method of aligning fractional anisotropy (FA) images from multiple subjects to allow groupwise comparisons of diffusion tensor imaging data. We applied TBSS to test the hypothesis that preterm infants have reduced fractional anisotropy in specific regions of white matter compared to term-born controls. We studied 26 preterm infants with no evidence of focal lesions on conventional magnetic resonance imaging (MRI) at term equivalent age and 6 healthy term-born control infants. We found that the centrum semiovale, frontal white matter and the genu of the corpus callosum showed significantly lower FA in the preterm group. Infants born at less than or equal to 28 weeks gestational age (n=11) displayed additional reductions in FA in the external capsule, the posterior aspect of the posterior limb of the internal capsule and the isthmus and middle portion of the body of the corpus callosum. This study demonstrates that TBSS provides an observer-independent method of identifying white matter abnormalities in the preterm brain at term equivalent age in the absence of focal lesions.     

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。     

应用基于纤维束的空间统计分析技术研究2型糖尿病脑白质异常

应用弥散张量成像技术(DTI)对2型糖尿病(T2DM)导致的白质损害进行研究是近年来的研究热点。基于纤维束的空间统计分析技术(TBSS)技术是目前应为十分广泛的DTI数据分析技术,2014年以来逐渐被用于T2DM相关白质损害的研究。我们回顾总结了2014年以来发表的相关文献,发现虽然研究结论有一致性,但也存不可忽视的差异。我们对共同的结论进行了总结,也从不同的方面分析了存在差异的原因以及后续研究的努力方向。     

Brain white matter tracts degeneration in Friedreich ataxia. An in vivo MRI study using tract-based spatial statistics and voxel-based morphometry

BACKGROUND AND PURPOSE: Neuropathological examination in Friedreich ataxia (FRDA) reveals neuronal loss in the gray matter (GM) nuclei and degeneration of the white matter (WM) tracts in the spinal cord, brainstem and cerebellum, while the cerebral hemispheres are substantially spared. Tract-based spatial statistics (TBSS) enables an unbiased whole-brain quantitative analysis of the fractional anisotropy (FA) and mean diffusivity (MD) of the brain WM tracts in vivo. PATIENTS AND METHODS: We assessed with TBSS 14 patients with genetically confirmed FRDA and 14 age- and sex-matched healthy controls who were also examined with voxel-based morphometry (VBM) to assess regional atrophy of the GM and WM. RESULTS: TBSS revealed decreased FA in the inferior and superior cerebellar peduncles and the corticospinal tracts in the medullary pyramis, in WM tracts of the right cerebellar hemisphere and in the right occipito-frontal and inferior longitudinal fasciculi. Increased MD was observed in the superior cerebellar peduncles, deep cerebellar WM, posterior limbs of the internal capsule and retrolenticular area, bilaterally, and in the WM underlying the left central sulcus. Decreased FA in the left superior cerebellar peduncle correlated with clinical severity. VBM showed small symmetric areas of loss of bulk of the peridentate WM which also correlated with clinical severity. CONCLUSIONS: TBSS enables in vivo demonstration of degeneration of the brainstem and cerebellar WM tracts which neuropathological examination indicates to be specifically affected in FRDA. TBSS complements VBM and might be a more sensitive tool to detect WM structural changes in degenerative diseases of the CNS.     

Voxel-based analysis derived from fractional anisotropy images of white matter volume changes with aging

Although age-related effects on brain volume have been extensively investigated post mortem and in vivo using magnetic resonance imaging (MRI), regional and temporal patterns of white matter (WM) volume changes with aging are not defined yet. The aim of this study was to assess the topographical distribution of age-related WM volume changes using a recently developed voxel-based method to obtain estimates of WM fiber bundle volumes using diffusion tensor (DT) MRI. Brain conventional and DT MRI were obtained from 84 healthy subjects (mean age=44 years, range=13-70). Linear and non-linear relationships between age and WM fiber bundle volume changes were tested. A negative linear correlation was found between age and WM volume decline in the corona radiata, anterior cingulum, body and crus of the fornix and left superior cerebellar peduncle. A positive linear correlation was found between age and volume increase of the right deep temporal association fibers. The non-linear regression analysis also showed age-related changes of the genu of the corpus callosum and fitted better the volume changes of the right deep temporal association fibers. WM volume decline with age is unevenly distributed across brain regions. Our approach holds promise to gain additional information on the pathological changes associated to neurological disorders of the elderly.     

应用弥散张量磁共振成像定量分析正常成人大脑白质纤维各向异性特征

目的定量分析正常成人大脑不同部位白质纤维各向异性所存在的差异.方法测量52名正常志愿者大脑白质纤维不同部位的FA值和ADC值,测量的部位有:外囊、内囊前肢、内囊后肢、胼胝体膝部和胼胝体压部.结果 FA值以胼胝体压部为最高是0.893±0.0645.统计分析大脑白质各部位间FA值的差别均有统计学意义(P＜0.01).结论 FA值可定量分析大脑不同部位的白质纤维的各向异性程度.     

Fractional anisotropy of cerebral white matter and thickness of cortical gray matter across the lifespan

We examined age trajectories of fractional anisotropy (FA) of cerebral white matter (WM) and thickness of cortical gray matter (GM) in 1031 healthy human subjects (aged 11-90 years). Whole-brain FA and GM thickness values followed quadratic trajectories with age but the relationship between them was linear, indicating that a putative biological mechanism may explain the non-linearity of their age trajectories. Inclusion of the FA values into the quadratic model of the whole-brain and regional GM thickness changes with age made the effect of the age(2) term no longer significant for the whole-brain GM thickness and greatly reduced its significance for regional GM thickness measurements. The phylogenetic order of cerebral myelination helped to further explain the intersubject variability in GM thickness. FA values for the early maturing WM were significantly better (p=10(-6)) at explaining variability in GM thickness in maturing (aged 11-20) subjects than FA values for the late maturing WM. The opposite trend was observed for aging subjects (aged 40-90) where FA values for the late maturing WM were better (p=10(-16)) at explaining the variability in GM thickness. We concluded that the non-linearity of the age trajectory for GM thickness, measured from T1-weighted MRI, was partially explained by the heterogeneity and the heterochronicity of the age-related changes in the microintegrity of cerebral WM. We consider these findings as the evidence that the measurements of age-related changes in GM thickness and FA are driven, in part, by a common biological mechanism, presumed to be related to changes in cerebral myelination.     

Microstructural white matter changes in normal aging: A diffusion tensor imaging study with higher-order polynomial regression models

Diffusion tensor imaging (DTI) has already proven to be a valuable tool when investigating both global and regional microstructural white matter (WM) brain changes in the human aging process. Although subject to many criticisms, voxel-based analysis is currently one of the most common and preferred approaches in such DTI aging studies. In this context, voxel-based DTI analyses have assumed a ‘linear’ correlation when finding the significant brain regions that relate age with a particular diffusion measure of interest. Recent literature, however, has clearly demonstrated ‘non-linear’ relationships between age and diffusion metrics by using region-of-interest and tractography-based approaches. In this work, we incorporated polynomial regression models in the voxel-based DTI analysis framework to assess age-related changes in WM diffusion properties (fractional anisotropy and axial, transverse, and mean diffusivity) in a large cohort of 346 subjects (25 to 81 years old). Our novel approach clearly demonstrates that voxel-based DTI analyses can greatly benefit from incorporating higher-order regression models when investigating potential relationships between aging and diffusion properties.     

Mapping radiation dose distribution on the fractional anisotropy map: applications in the assessment of treatment-induced white matter injury

We describe a method to map whole brain radiation dose distribution on to diffusion tensor MR (DT-MR) fractional anisotropy (FA) images and illustrate its applications for studying dose-effect relationships and regional susceptibility in two childhood medulloblastoma survivors. To determine the FA changes voxel-by-voxel in white matter, the post-treatment follow-up FA maps were coregistered to baseline pre-treatment FA maps and automatic segmentation for white matter was carried out. DeltaFA maps representing relative FA change in white matter were hence generated for visual inspection and quantitative analysis. The radiation dose distribution, calculated from radiotherapy plan and exported as images, was coregistered to baseline FA images. DT-MR imaging and processing noise was small with root mean square value of 1.49% for mean DeltaFA. We evaluated the mean DeltaFA changes of regions-of-interest according to radiation dose regions to provide an estimate of the dose-response and found increasing reduction in mean DeltaFA with increasing radiation dose up to 45 Gy after which there was a reversal in the mean FA trend and mean FA approached baseline value. We also found more severe mean FA reduction in the frontal lobes compared to the parietal lobes despite the same radiation dose, suggesting regional susceptibility in the frontal lobe, and mean FA increase in the brainstem after radiation in both patients. We conclude that the method described may be useful in estimating dose-effect relationships and studying regional susceptibility of the brain to radiation in medulloblastoma survivors.     

Brain regions associated with Brunnstrom and functional independence measure scores in patients after a stroke: a tract-based spatial statistics study

[Purpose] We aimed to assess diffusion tensor fractional anisotropy to outline the brain regions associated with the long-term motor and cognitive functional outcomes of patients with stroke. [Participants and Methods] Eighty patients from our previous study were enrolled. Fractional anisotropy maps were acquired on days 14–21 after stroke onset, and tract-based spatial statistics were applied. Outcomes were scored using the Brunnstrom recovery stage and Functional Independence Measure motor and cognition components. Fractional anisotropy images were assessed in relation to outcome scores using the general linear model. [Results] For both the right (n=37) and left (n=43) hemisphere lesion groups, the corticospinal tract and the anterior thalamic radiation were most strongly associated with the Brunnstrom recovery stage. In contrast, the cognition component involved large regions encompassing the anterior thalamic radiation, superior longitudinal fasciculus, inferior longitudinal fasciculus, uncinate fasciculus, cingulum bundle, forceps major, and forceps minor. The results for the motor component were intermediate between those for the Brunnstrom recovery stage and those for the cognition component. [Conclusion] Motor-related outcomes were associated with fractional anisotropy decreases in the corticospinal tract, whereas cognitive outcomes were related to broad regions of association and commissural fibers. This knowledge will help scheduling appropriate rehabilitative treatments.     

Corpus callosum damage in heavy marijuana use: preliminary evidence from diffusion tensor tractography and tract-based spatial statistics

Heavy marijuana use has well established long term consequences for cognition and mental health, but the effect on brain structure is less well understood. We used an MRI technique that is sensitive to the structural integrity of brain tissue combined with a white matter mapping tractography technique to investigate structural changes in the corpus callosum (CC). Diffusion tensor imaging (DTI) was obtained in eleven heavy marijuana users who started using marijuana in early adolescence and eleven age matched controls. Mean diffusivity (MD) and fractional anisotropy (FA) (which measure structural integrity and tract coherence, respectively) were analysed within the corpus callosum which was spatially defined using tractography and tract-based spatial statistics (TBSS). MD was significantly increased in marijuana users relative to controls in the region of the CC where white matter passes between the prefrontal lobes. This observation suggests impaired structural integrity affecting the fibre tracts of the CC and is in keeping with previous reports of altered and diversified activation patterns in marijuana users. There was a trend towards a positive correlation between MD and length of use suggesting the possibility of a cumulative effect of marijuana over time and that a younger age at onset of use may predispose individuals to structural white matter damage. Structural abnormalities revealed in the CC may underlie cognitive and behavioural consequences of long term heavy marijuana use.     

基于纤维束骨架的空间统计方法研究维持性透析终末期肾病患者脑白质结构变化

目的 探讨基于纤维束骨架的空间统计方法研究维持性透析终末期肾病（ESRD）患者脑白质微结构变化。方法 采用3.0T MR仪对32例行维持性血透的ESRD患者和30名健康对照行DTI扫描,应用基于纤维束骨架的空间统计（TBSS）方法分析DTI多参数图,获得部分各向异性分数（FA）、平均弥散度（MD）、轴向弥散度（AD）及径向弥散度（RD）有显著差异的脑区。将ESRD患者差异脑区FA值与简易精神状态测试（MMSE）评分进行偏相关分析。结果 与健康对照比较,ESRD患者双侧额叶白质、双侧前辐射冠、胼胝体体部及膝部、左侧颞叶白质及多条联络纤维FA值显著减低;MD值呈广泛且对称性显著升高;右侧上纵束、左侧上辐射冠AD值显著升高,左侧丘脑前辐射AD值显著降低;双侧额叶、胼胝体及双侧上纵束等白质区RD值显著升高（P均<0.05）。右侧额叶白质（r=0.404,P=0.022）及左侧上纵束（r=0.475,P=0.006）FA值与MMSE评分呈正相关。结论 ESRD患者脑区白质微结构受损,可能导致其认知障碍。     

脑白质病变与老年首次短暂性脑缺血/轻型卒中患者认知功能障碍的研究

目的探讨老年首次短暂性脑缺血/轻型卒中患者认知功能障碍与脑白质高信号（WMHs）的关系。 方法选取2015年1月至2018年12月无锡市锡山人民医院神经内科收治的,符合标准的105例老年首次短暂性脑缺血/轻型卒中患者,均行头颅MRI等检查,患者认知障碍根据蒙特利尔认知评估量表（MoCA）评分结果分为无认知障碍组、暂时性认知障碍组和持续性认知障碍组。采用单因素方差分析比较3组间年龄、美国国立卫生院卒中量表评分、MoCA评分的差异,组间差异两两比较应用q检验;采用χ²检验比较组间性别（男性）、高血压、糖尿病、高脂血症、MRI影像改变及梗死部位的差异;采用多因素Logistic回归分析老年首次短暂性脑缺血/轻型卒中患者发生认知功能障碍的危险因素。 结果持续性认知障碍组患者的年龄、男性比例和WMHs比例高于无认知障碍组,差异均具有统计学意义（P<0.05）;而在高血压、糖尿病、高脂血症、脑微出血、血管间隙扩大、腔隙性缺血灶、磁共振弥散加权成像（DWI）阳性病变及DWI显示脑梗死病变部位比较差异均无统计学意义（P均>0.05）。WMHs病变程度越严重,发生认知障碍的比例越高,差异具有统计学意义（P<0.05）。经校正年龄、性别、高血压、糖尿病等因素后,年龄和中-重度WMHs病变为老年首次短暂性脑缺血/轻型卒中后持续性认知功能障碍发生的独立危险因素（OR：1.08,95%CI：1.01~1.15,P=0.021;OR：1.66,95%CI：0.79~2.89,P=0.042）。 结论年龄和WMHs中-重度病变为老年首次短暂性脑缺血/轻型卒中患者第90天后发生持续性认知障碍的危险因素。     

儿童先天性感音神经性耳聋与脑白质病变的关系

目的 探讨儿童感音神经性耳聋（SNHL）与脑白质病变（WML）的关系。方法 收集SNHL患儿436例,其中有WML者196例（A组）,对患儿进行MR检查。收集同期无SNHL因他病接受颅脑MR检查的患儿720例,选取其中仅有WML者118例作为对照（B组）。依据改良Scheltens量表对脑室旁白质区（枕叶、额叶和侧脑室）和深部白质区（颞叶、额叶、顶叶、枕叶）各部位WML进行评分,并进行统计学分析。结果 A组WML患儿占所有SNHL患儿的44.95%（196/436）,B组WML患儿占无SNHL者的16.39%（118/720）。A组平均年龄小于B组（P＝0.009）。A组侧脑室带状高信号灶评分高于B组（P<0.05）。额叶帽状高信号灶和枕叶帽状高信号灶评分差异均无统计学意义（P均>0.05）。A组深部白质区颞叶、额叶、顶叶WML评分均高于B组（P均<0.01）,两组枕叶WML评分差异无统计学意义（P>0.05）。A组与B组脑室旁白质区与深部白质区各部位WML评分总和差异有统计学意义（P<0.05）。结论 SNHL患儿WML发生率高、发病年龄较小,WML较严重。     

缺血再灌注模型大鼠脑白质扩散张量成像研究

目的:利用MR弥散张量成像(DTI)技术对脑缺血再灌注大鼠的大脑行动态观察,研究其扩散变化规律。方法:将24只成年雄性SD大鼠随机分为假手术组和模型组各12只,假手术组只分离血管,模型组根据线栓法制备缺血2h再灌注模型。术后24h、7d、14d用改良神经功能缺损评分(mNSS)评价大鼠神经功能缺损情况;行T2加权成像(T2WI)、DTI扫描,观察脑梗死体积与相关脑区平均弥散率(MD)和各向异性分数(FA)。结果:模型组较假手术组大鼠缺血再灌注后24h、7d和14d的mNSS评分均升高(均P<0.01),且缺血再灌注后7d的mNSS评分低于上一时间点(P<0.05)。T2WI成像显示,模型组大鼠梗死部位呈异常高信号,随时间推移高信号区域面积减少。DTI结果显示,缺血后24h,模型组较假手术组患侧所有脑区MD值均显著下降(P<0.01,0.05),7d后呈假正常化,14d均高于假手术组(P<0.01,0.05);缺血后24h,患侧胼胝体、海马及纹状体的FA值均显著下降(均P<0.05),7d时均持续下降(P<0.01,0.05),除了胼胝体,其他脑区在14d达到最低水平(P<0.01,0.05)。缺血后24h,除了感觉皮层,健侧脑区MD和FA值均高于假手术组(P<0.01,0.05);缺血后7d,除了胼胝体和海马,其他脑区MD值均低于假手术组(P<0.01,0.05)。结论:DTI能够反映不同时期缺血再灌注后脑白质损伤的变化特点,患侧白质随着时间的推移演变为不可转逆的结构破坏,健侧白质功能变化可能与交互性半球间抑制作用有关。     

The relationship between fMRI activation and cerebral atrophy: comparison of normal aging and alzheimer disease

Functional MRI has recently been used to examine activation associated with aging and dementia, yet little is known regarding the effect of cerebral atrophy on fMRI signal. The purpose of this study was to examine the relationship between measures of global and regionally specific atrophy and fMRI activation in normal aging and in Alzheimer disease (AD). Two groups of subjects were studied with echoplanar imaging and quantitative structural volumetry: healthy controls spanning a broad age and atrophy range (n = 16) and patients with mild AD (n = 8). Results from a semantic task previously found to activate left inferior frontal (LIFG) and left superior temporal (LSTG) gyri were analyzed. The correlations between clusters of activation in the LIFG and LSTG and measures of local atrophy in the LIFG and LSTG regions were evaluated. For control subjects, there was no significant correlation between activation and regional or total brain atrophy (for LIFG r = -0.03, NS; for LSTG r = 0.20, NS). In contrast, for AD patients, there was a significant positive correlation between atrophy and activation in LIFG (r = 0.70, P = 0.05) but not LSTG (r = 0.00, NS). These results suggest that activation of language regions and atrophy within those regions may be independent among healthy adults spanning a broad age and atrophy range. However, in AD, a relationship exists in the LIFG that may reflect compensatory recruitment of cortical units or disease-specific changes in the hemodynamic response.     

伴右向左分流脑梗死患者脑血管反应性和脑白质病变的相关性研究

目的 观察伴右向左分流脑梗死患者脑血管反应性和脑白质病变的相关性。方法 回顾性纳入2020年8月至2021年8月青岛大学附属医院收治的79例急性脑梗死患者,按照脑梗死致病原因不同将其分为伴右向左分流脑梗死(观察组,n=35)和房颤所致脑梗死(对照组,n=34)。对比两组患者的埃森卒中风险评分量表(ESRS)评分、超敏C反应蛋白和同型半胱氨酸水平、美国国立卫生研究院卒中量表(NIHSS)评分,以及磁共振检测、屏气试验和二氧化碳吸入试验结果。结果 观察组患者的ESRS评分、NIHSS评分、超敏C反应蛋、同型半胱氨酸水平为(4.61±1.12)分、(7.31±2.16)分、(8.36±2.81) mg/L、(18.33±5.52)μmol/L,明显高于对照组[(3.64±1.43)分、(2.01±0.36)分、(6.14±2.11) mg/L、(15.13±4.92)μmol/L],差异均有统计学意义(P <0.05)。磁共振成像检查中,观察组患者多发梗死的患者比率(17.1%)明显低于对照组(42.9%),后循环梗死病例的比率(25.7%)明显高于对照组(8.8%),差异均有统计学意...     

静脉系统与脑小血管病白质高信号相关性研究

脑白质高信号是脑小血管病主要影像学标记物之一,普遍存在于老年人群中。目前其发病机制尚不清楚,以往的研究大多集中在动脉系统上,但静脉系统在脑白质高信号中的作用也越来越受到关注,小静脉胶原增生、下游颅内静脉扩张以及颈内静脉的返流或许都参与脑白质高信号的形成与发展。