基于大脑结构网络特征的遗忘型轻度认知障碍诊断模型

选取与认知表现分数相关性高的结构网络拓扑特征,利用这些特征建立分类模型,实现对正常老化者及遗忘型轻度认知障碍(aMCI)患者的分类.本研究包含两组扩散张量影像(DTI)数据,一组为52例正常老化受试者,一组为39例aMCI患者.分别对两组数据进行结构网络构建,采用图论分析法提取结构网络的特征,将所有特征与简单智能状态检查量表(MMSE)分数进行相关性分析,选取与认知表现分数高度相关的特征,基于这些特征建立5种分类模型,并对模型的分类效果进行评估.对于正常老化数据,选出18个与认知能力显著相关的结构网络特征,集中于解剖自动贴标(AAL)图谱中的9个脑区;对于aMCI数据,也选出18个与认知能力显著相关的结构网络特征,集中于AAL图谱中的9个脑区;二者选出的特征及分布的脑区是不同的.通过对分类模型的评估,得出支持向量机序列最小优化算法建立的模型分类效果最佳,特异性达到88.46％,敏感性达到83.05％,准确性达到85.71％.所提取的与认知表现相关性高的结构网络特征,可以作为生物标记指针,来建立分类模型,对正常老化者及aMCI患者进行分类,也可提供相应脑区间连接变化的信息.     

基于功能连接的大脑年龄预测的影响因素

目的 探索基于静息态功能连接进行大脑生理年龄预测的可行性及相关影响因素.方法 选取来自阿尔茨海默病神经影像学计划(Alzheimer disease neuroimaging initiative,ADNI)数据库的41例满足条件的健康受试者.首先对静息态功能磁共振成像(resting-state functional MRI,rs-fMRI)数据进行预处理并提取功能连接特征,利用基于Bootstrap的特征筛选方法进行特征降维;然后使用支持向量回归建立正常人大脑年龄的预测模型,最后用留一法进行交叉验证,并比较不同大脑模板、全脑信号回归及性别因素对年龄预测的影响.结果 基于AAL-90、AAL-1024、Shen-268、Fan-246脑图谱得到的预测值与真实年龄之间的相关系数r分别为0.23、0.29、0.17、0.38.使用全局信号回归,基于Fan-246脑图谱得到年龄预测模型的相关系数r显著提升为0.66.利用性别分组建模,基于Fan-246脑图谱预测模型的相关系数r提升为0.46.结论 根据静息态功能磁共振的功能连接特征可以较好地估计健康大脑的生理年龄,且大脑模板、全局信号回归对年龄估计模型的性能有较大影响.本研究可加深对大脑老化过程的认识,对阿尔兹海默病的早期诊断和预防有着重要的指导价值.     

静息态功能磁共振成像功能连接特异性指数模型在评估健康老年人认知分数中的应用

与传统量表法和任务态功能磁共振成像(fMRI)相比,静息态功能磁共振(rfMRI)在认知功能检测上有很大优势(特别是针对老年人),但脑老化功能影像学标记尚在探索中。提出功能连接特异性指数模型,试图与健康壮年人对照,分析健康老年人脑功能特异性,寻求区分认知分数的功能影像学指标,探索其分类认知分数优差的可能性,为替代提供研究基础。实验数据来自98名健康老年人和90名健康壮年人,前者来源于葡萄牙健康老年人认知功能的队列研究,在rfMRI扫描前,在认知量表测试分数最优和最差中,分别选出55名和43名作为实验组;后者数据来自哈佛医学院GSP影像组学,年龄在18～35岁之间,在rfMRI扫描前的认知功能评价分数居中,作为对照组。首先,对rfMRI预处理后,计算每人全脑功能连接,构建以脑区为单位的功能连接特异性指数模型,分析老年人脑功能连接与壮年人的偏移程度,统计、对比获得对优、差分数敏感的标志性脑区;然后,以其特异性指数值形成特征向量;最后,应用概率神经网络(PNN)模型对优、差分数组进行分类和N折交叉验证以检验所建指数模型的分类能力。健康老年人脑功能连接特异性指数模型可定位于健康老年人认知分数敏感的标志性脑区,分别处于额叶、颞叶、顶叶中的5个脑区;以这些脑区的指数为特征向量,可有效地区分优、差认知分数,准确度可达81.7%。通过对评价指数的建模并联合机器学习方法,可为rfMRI评估健康老年人认知分数提供有效的评价指标和新方法。     

用18F-FDG PET预测正常老年人的认知减弱

据de Leon MJ等[Proc Natl Acad Sci USA,2001,98(19):10966-10971]报道,用PET研究老年人大脑皮质的糖代谢,预测认知缺损. 有轻度认知缺损(MCI)和Alzheimer's病的患者的典型神经病理病变位于内嗅皮质(EC)、海马(Hip)、颞新皮质.活体显像可对认知缺损预测痴呆.虽然正常认知个体可有EC灶性损伤,但将这一解剖现象做为认知缺损和大脑改变的预测因素则尚乏研究.对正常老年人用MRI导引18F-FDG做大脑PET扫描,研究EC糖代谢减少是否预测认知缺损,Hip和颞新皮质是为本研究的目的.对48例正常健康老年人进行3年的研究,其中12例(平均年龄72岁)证明有认知缺损(11例为MCI,1例为Alzheimer's病).无认知缺损对照组中基因型载脂蛋白E、年龄、教育和性别均与研究前相匹配.在基线时EC代谢降低能准确预测由正常转向MCI.认知降低者中基线EC预测了纵向记忆和颞新皮质代谢降低.随诊中认知降低者表现记忆受损和颞叶新皮质及Hip代谢低下,其中载脂蛋白EE4携带者有显著的颞新皮质减少. 总之,这些数据说明可检测正常老年人中大脑EC预测认知的发展和脑代谢降低.与E4相关的低代谢进展可预测痴呆的易感性增加.仍需进一步评价个体在认知正常时发生痴呆的危险性以确定检测METglu改变的生理基础.     

基于N-back认知任务的正常脑老化事件相关电位分析

本文旨在研究不同N-back认知任务下正常脑老化的全脑事件相关电位P300的变化趋势。通过对15个正常年轻人和10个正常老年人进行N-back认知任务下全脑的事件相关电位P300的测定,将所得结果进行分析。结果表明,在执行相同负荷的认知任务时,老年人的P300潜伏期较年轻人在全脑范围内增长;峰值较年轻人在前额-中央区增加,其中在前额区增加的差异具有统计学意义;在认知任务负荷增加时,老年人峰值在全脑范围内增大,以额-中央区为主,但老年人在两种负荷认知任务下的峰值差异不具有统计学意义;而潜伏期在右脑额-中央区缩短,在两种负荷认知任务下的潜伏期差异具有统计学意义。因此,全脑事件相关电位P300显示正常脑老化主要影响着前额区,且相比于低负荷认知任务,执行高负荷认知任务时更能反映老化对脑功能特征的影响。通过本文以上研究结果,期望可对早期老年痴呆患者的检出具有启示意义。     

静息态功能连接网络对大脑不同水平认知衰退的研究进展

<正>常脑老化和神经退行性疾病等都会引起记忆力、注意能力等认知功能不同程度的衰退,严重影响日常生活。其发生发展的神经机制目前仍不明确,依然是神经科学和医学领域的一个热点问题。大量研究成果表明,基于磁共振的静息态网络(RSNs)对认知功能的改变具有较高的敏感度和特异性。本文调查近几年静息态功能磁共振成像(f MRI)脑功能连接网络对正常脑老化(aging brain)、轻度认知障碍(MCI)和阿尔兹海默病(AD)等不同认知衰退水平受试者的研究,从分析方法、研究结果以及发展趋势等进行了综述,较全面地介绍了在三种不同水平认知衰退条件下脑功能网络的改变,将为正常脑老化和临床疾病的检测提供依据。     

基于增强CT影像组学及形态学征象对非小细胞肺癌脏层胸膜侵犯的预测价值研究

目的探讨基于增强CT影像组学方法及形态学征象在术前预测非小细胞肺癌患者脏层胸膜侵犯(VPI)的效能。方法回顾性研究。纳入2019年1月—2021年1月蚌埠医学院第一附属医院收治的肺癌患者220例, 其中男145例、女75例, 年龄43～89(62.6±10.0)岁, 均行根治性手术治疗。按照术后病理检查确诊有VPI 90例、无VPI 130例。将入组患者按照4∶1的比例随机分配到训练组(176例)与验证组(44例)。基于术前增强CT图像提取影像组学特征, 采用LASSO-logistic回归模型选择动静脉期相关性最高的影像组学特征建立VPI预测模型。利用独立样本t检验和χ2检验筛选临床资料及CT形态学征象等相关变量, 结合最终选择的相关性最高的影像组学特征构建联合模型;绘制受试者工作特征(ROC)曲线, 采用曲线下面积(AUC)评价模型在训练组和验证组中对VPI的预测效能, DeLong检验用于比较模型间AUC的差异。结果从提取出的1 878个影像组学特征中筛选出动脉期及静脉期各10个最具相关性的影像组学特征, 分别用于建立动脉期和静脉期影像组学VPI预测模型。在训练组和验证组中, 静...     

脑肿瘤患者手术前后脑结构网络拓扑属性研究

主要研究脑肿瘤的存在及手术对患者全脑及半脑结构网络拓扑属性的影响。结合弥散张量成像技术(DTI)和图论方法,对10例健康志愿者以及10例脑肿瘤患者进行术前术后全脑及半脑结构网络构建,获得两组受试者脑结构网络拓扑属性参数,以及反映脑认知功能的各项网络指标,并对其进行统计对比分析。结果显示,部分局部参数(包括K_i、L_i、E_nodal、C_i和E_ilocal)在手术前后具有明显差异,且术前组均优于术后组;全脑及半脑各全局网络参数显示,各项参数术前组均优于术后组;同时半脑结构网络分析显示,位于不同脑半球的脑肿瘤对患者脑结构网络所造成的损伤均无统计学差异(P>0.05)。肿瘤的存在以及手术均使得脑肿瘤患者脑结构网络发生改变,大脑的半脑优势化趋势明显降低;手术后结构网络拓扑特性的改变以及小世界属性的增强,验证大脑本身存在的代偿机制以及功能重组现象。     

脑老化中脑年龄预测模型研究综述

大脑会随年龄增长而逐渐发生萎缩与机能衰退,并且这种变化的速度和轨迹在脑区间和个体间存在明显差异。由于神经影像可以反映大脑的健康状态,因此常用于大脑年龄的预测研究。本文对基于神经影像的脑年龄预测模型研究进行了系统的梳理和回顾,根据影像的模态和特征类型对这些研究进行综述,剖析了其优缺点。结果显示,基于神经影像的预测框架具备个体对象脑年龄预测的潜力。最后,本文讨论了脑年龄预测中存在的问题,并对未来的研究方向进行了展望。     

血压正常2型糖尿病患者大脑微结构改变的VBM及TBSS研究

目的:基于纤维束示踪空间统计分析(TBSS)研究大脑扩散张量成像(DTI)图像,观察血压正常2型糖尿病(T2DM)患者脑白质微结构的改变,并探讨双侧大脑半球间的脑白质改变方法:本研究纳入20名血压正常的T2DM患者及20名年龄、性别匹配的正常对照。采用3.0T磁共振扫描仪采集大脑结构像和DTI数据,应用基于体素的形态学分析(VBM)和TBSS方法比较两组受试者间的大脑体积,白质各向异性分数(FA)和平均扩散系数(MD)值的差异,以及两组受试者左右侧大脑半球DTI参数比值的差异。结果:与正常对照相比,血压正常的T2DM患者大脑体积未见显著减小(P0.05);大脑白质完整性广泛受损,尤以胼胝体膝部、左侧内囊前肢、辐射冠前上部、扣带束及上额-枕束为著;右侧上辐射冠、后辐射冠、扣带束及上纵束FA值和MD值均有改变(P0.05);双侧大脑半球上辐射冠MD值升高,以左侧升高更为显著(P0.05)。结论:血压正常的T2DM患者双侧大脑半球白质微结构广泛损伤,尤以左侧为著,TBSS分析有助于早期检出上述改变。     

Structural correlates of cognitive domains in normal aging with diffusion tensor imaging

The involvement of brain structures in specific cognitive functions is not straightforward. In order to characterize the brain micro-structural correlates of cognitive domains, 52 healthy subjects, age 25–82 years, completed a computerized neuropsychological battery and were scanned using magnetic resonance diffusion tensor imaging. Factor analysis of 44 different cognitive scores was performed, isolating three cognitive domains—executive function, information processing speed and memory. Partial correlation was conducted between DTI parameters and each of the three cognitive domains controlling for age and motor function. Regions showing significant correlations with cognitive domains are domain-specific and are consistent with previous knowledge. While executive function was correlated with diffusion tensor imaging (DTI) parameters in frontal white matter and in the superior longitudinal fasciculus, information processing speed was correlated with DTI parameters in the cingulum, corona radiata, inferior longitudinal fasciculus, parietal white matter and in the thalamus. Memory performance was correlated with DTI measures in temporal and frontal gray matter and white matter regions, including the cingulate cortex and the parahippocampus. Thus, inter-subject variability in cognitive performance and tissue morphology, as expressed by diffusion tensor magnetic resonance imaging, can be used to relate tissue microstructure with cognitive performance and to provide information to corroborate other functional localization techniques.     

Diffusion tensor imaging reveals evolution of primate brain architectures

Evolution of the brain has been an inherently interesting problem for centuries. Recent studies have indicated that neuroimaging is a powerful technique for studying brain evolution. In particular, a variety of reports have demonstrated that consistent white matter fiber connection patterns derived from diffusion tensor imaging (DTI) tractography reveal common brain architecture and are predictive of brain functions. In this paper, based on our recently discovered 358 dense individualized and common connectivity-based cortical landmarks (DICCCOL) defined by consistent fiber connection patterns in DTI datasets of human brains, we derived 65 DICCCOLs that are common in macaque monkey, chimpanzee and human brains and 175 DICCCOLs that exhibit significant discrepancies amongst these three primate species. Qualitative and quantitative evaluations not only demonstrated the consistencies of anatomical locations and structural fiber connection patterns of these 65 common DICCCOLs across three primates, suggesting an evolutionarily preserved common brain architecture but also revealed regional patterns of evolutionarily induced complexity and variability of those 175 discrepant DICCCOLs across the three species.     

Structural organization of the prefrontal white matter pathways in the adult and aging brain measured by diffusion tensor imaging

Previous diffusion tensor imaging (DTI) studies confirmed the vulnerability of frontal callosal fibers to normal aging. The present study extended this examination systematically to other prefrontal white matter regions. Structural magnetic resonance imaging and DTI datasets were acquired from 69 healthy subjects aged 22–84 years. The prefrontal white matter was parcellated into several anatomical sub-regions: medial and lateral orbitofrontal white matter, dorsolateral prefrontal white matter, and medial prefrontal white matter, using reliable DTI-tractography protocols. Tract-specific characteristics were calculated using Matlab. Regression models were used to determine the relationship between age and structural integrity of white matter tracts. The results of our study demonstrate regional age-related changes in the prefrontal white matter tracts of the human brain. This study was cross-sectional and therefore additional longitudinal studies are needed to confirm our findings.     

PM滤波方法对提高不同b值弥散张量成像图像质量的应用研究

目的在不同b值条件下,研究PM滤波方法对提高弥散张量成像（DTI）技术图像质量的作用。方法在b值为800～2800s／mm2的条件下分别对模体及志愿者实施DTI．利用改进的PM滤波方法对获得的弥散加权成像（DWI）图像进行处理后求解张量参数．得到反映水分子各向异性扩散程度的FA图。通过比较标准FA图与处理后FA图间的均方根误差（RMSE）．评价PM滤波的效果。结果随着b值的升高,图像信噪比逐渐降低．FA误差逐渐增大。当b值小于2000s／mm2时．经过PM滤波后．可得到RMSE较低的后处理图像。结论b值在1000．2000s／mm2范围内,应用PM滤波方法是提高人脑DTI图像质量的一种有效手段．     

磁共振扩散张量成像评价小儿脑病的初步应用

目的应用扩散张量成像（DTI）来进一步评价小儿脑疾病，探讨DTI的诊断价值。方法对15例患各种脑病的小儿进行MRI检查，其中男性10例，女性5例，年龄为生后3天至11岁（平均年龄4．8岁）。采用Philips Intera Achieva 3．0 Tesla的超导MRI仪，用回波平面成像（EPI）的DTI技术，b为800s／mm^2，15个方向。观察彩色分数各向异性（FA）图和三维彩色编码图。结果15例患儿中，发育畸形2例，分别是胼胝体发育不良、巨脑回；脑室旁白质软化（PVL）7例；缺氧缺血性脑病3例；脑软化2例；脑积水1例。在巨脑回病例，常规MRI见右侧脑回发育不良，呈巨脑回畸形，右侧脑室扩大，在DTI上见右侧病变区白质束明显较对侧少。胼胝体发育不良病例在DTI张量图见胼胝体菲薄。在PVL和缺氧缺血性脑病病例均可见白质纤维束在放射冠颜色混杂，方向性混乱。脑软化病例可见白质纤维束部分中断。在脑积水病例可见白质束受压推移。结论DTI能够显示白质束的走向、绕行、交叉及推挤、中断等异常，可能对今后评估小儿脑病的预后转归有帮助。     

基于DTI复杂网络的两性大脑差异性研究

为解释男女大脑差异是如何影响人们的思维和行为的,我们利用DTI复杂网络技术对男女两性大脑的差异性进行了定量分析。将44例健康志愿者分成男女两组,利用磁共振弥散张量成像对志愿者进行扫描和数据采集,通过构建脑白质纤维结构网络,并结合图论知识和复杂网络特征度量参数,对男女大脑结构差异及其在功能上的体现进行分析。对两组志愿者的脑结构网络分析发现,男女两组志愿者均具有小世界属性。结构网络局部参数分析显示,男女在涉及语言、情感、运动、方向感等的脑区具有显著差异。男女两性大脑生理结构的差别确实会导致大脑在功能上出现差别,两性大脑在功能上的差别可认为是两性在负责相关功能的脑区所具有的差异所导致。     

White matter microstructure of the cingulum and cerebellar peduncle is related to sustained attention and working memory: A diffusion tensor imaging study

The non-invasive imaging technique of diffusion tensor imaging (DTI) has been used to investigate the microstructural properties of white matter (WM). The present study investigated whether individual differences in the WM structure of normal subjects as measured by fractional anisotropy (FA) values correlate with cognitive performance in terms of sustained attention and working memory. Subjects underwent DTI and performed the Continuous Performance Test (CPT) and N-back task. FA values throughout the brain were correlated with behavioral performance on a voxel-by-voxel basis to investigate relationships between WM microstructure and cognitive function. The discriminability index of CPT correlated positively with FA of the right cingulum. Accuracy of the 2-back task correlated positively with FA in bilateral cerebellar peduncles. WM microstructure of the right cingulum and bilateral cerebellar peduncles appears related to cognitive function such as sustained attention and working memory in the human brain.     

纹状体内囊梗死上肢运动功能损害大脑脚弥散张量成像研究

目的应用弥散张量成像(DTI)技术研究纹状体内囊梗死患者大脑脚扩散改变情况,分析其与上肢运动功能损害的关系。方法选择急性起病的缺血性脑卒中患者15例,其中男性8例,女性7例;年龄47~80岁,平均年龄62.6岁。平均受教育年限9.7年。MRI诊断为单侧上肢运动功能损害的纹状体内囊梗死。于发病后2周时行DTI,测量两侧大脑脚的各向异性分数(FA)、平均扩散率(MD)值,计算两侧FA的不对称指数(AI),对AI和受累上肢的FM功能评分进行相关分析。结果发病后2周时患侧大脑脚FA值较健侧降低(0.66±0.08 vs 0.73±0.06,P=0.02);两侧MD值差异无统计学意义(0.92±0.11 vs 0.94±0.09,P=0.51);AI与受累上肢的FM评分呈显著负相关(r=-0.95,P0.01)。结论 DTI可以早期检测到纹状体内囊梗死患者大脑脚的扩散变化,大脑脚部位锥体束的完整性与受累上肢的运动功能关系密切,DTI检查可以为纹状体内囊梗死的临床评估提供量化的影像学参考。     

Core brain networks interactions and cognitive control in internet gaming disorder individuals in late adolescence/early adulthood

Regardless of whether it is conceptualized as a behavioral addiction or an impulse-control disorder, internet gaming disorder (IGD) has been speculated to be associated with impaired cognitive control. Efficient cognitive behavior involves the coordinated activity of large-scale brain networks, however, whether the interactions among these networks during resting state modulated cognitive control behavior in IGD adolescents remain unclear. Twenty-eight IGD adolescents and twenty-five age-, gender-, and education-matched healthy controls participated in our study. Stroop color-word task was conducted to evaluate the cognitive control deficits in IGD adolescents. Functional connectivity and Granger Causal Analysis were employed to investigate the functional and effective connections within and between the salience, central executive, and default mode networks. Meanwhile, diffusion tensor imaging was used to assess the structural integrity of abnormal network connections. The abnormal functional connectivity within central executive networks and effective connectivity within salience network in IGD adolescents were detected. Moreover, the inefficient interactions between these two brain networks were observed. In addition, we identified reduced fractional anisotropy in salience network, right central executive network tracts, and between-network (the anterior cingulate cortex-right dorsolateral prefrontal cortex tracts) pathways in IGD individuals. Notably, we observed a significant correlation between the effective and structural connection from salience network to central executive network and the number of errors during incongruent condition in Stroop task in both IGD and control subjects. Our results suggested that impaired cognitive control in IGD adolescents is likely to be mediated through the abnormal interactions and structural connection between intrinsic large-scale brain networks.     

Neuropsychiatric applications of DTI - a review

Psychiatric disorders are common throughout the world and are a leading cause of disability. There is a growing appreciation of the importance of connectivity to brain function. Disruption of this connectivity can result in brain dysfunction manifested in impaired cognitive functioning and the development of clinical symptoms. White matter forms the basis of anatomical connectivity. Diffusion tensor imaging (DTI) is a useful tool for examining and quantifying white matter microstructure. Clinical research studies in alcoholism, HIV-1 infection, geriatric depression and schizophrenia using DTI have revealed abnormalities in white matter microstructure. The use of complementary imaging methods may be helpful in further characterizing these abnormalities. Other psychiatric disorders may also have white matter involvement amenable to study with DTI. Advances in acquisition and analysis methods will be necessary to further advance work in this field. The study of animal models and postmortem tissue may be helpful in elucidating the neurobiological underpinnings of abnormalities observed with DTI.