fMRI （Functional Magnetic Resonance Imaging） is a relatively new technique that uses MRI （Magnetic Resonance Imaging） to measure the hemodynamic response （change in blood flow） related to neural activity in the ...fMRI （Functional Magnetic Resonance Imaging） is a relatively new technique that uses MRI （Magnetic Resonance Imaging） to measure the hemodynamic response （change in blood flow） related to neural activity in the brain. This paper aims to explore and identify the obstacles facing the implementation and applications of IMRI in radiology departments within Jeddah city by analyzing related data received by direct questionnaires and interviews with all the people working in MRI units in Jeddah city and finds that the major obstacle is lacking of awareness of fMRI among medical professionals and their training.展开更多
To evaluate the effect of the positive-indefinite matrix on the diffusion tensor-derived parameters, a modified algorithm is proposed for calculating these parameters. Magnetic resonance （MR） diffusion tensor images...To evaluate the effect of the positive-indefinite matrix on the diffusion tensor-derived parameters, a modified algorithm is proposed for calculating these parameters. Magnetic resonance （MR） diffusion tensor images of five healthy volunteers are collected. The diffusion sensitive gradient magnetic fields are applied along 25 directions and the diffusion weighting value is 1 000 s/mm^2. Many positive-indefinite diffusion tensors can be found in the white matter area, such as the genu and the splenium of corpus callosum. Due to the positive-indefinite matrix, the mean diffusivity （MD） and the fractional anisotropy （FA） are under-estimated and over-estimated by using the conventional algorithm. Thus, the conventional algorithm is modified by using the absolute values of all eigenvalues. Results show that both the robustness and the reliability for deriving these parameters are improved by the modified algorithm.展开更多
为弥补传统的广义线性模型(generalized linear model,GLM)方法的不足,并探索模式识别在运动脑科学当中的应用价值。使用支持向量机(support vector machine,SVM)模式识别算法,以低频振幅(fractional amplitude of low-frequency fluctu...为弥补传统的广义线性模型(generalized linear model,GLM)方法的不足,并探索模式识别在运动脑科学当中的应用价值。使用支持向量机(support vector machine,SVM)模式识别算法,以低频振幅(fractional amplitude of low-frequency fluctuations,fALFF)、局部一致性(regional homogeneity,ReHo)和度中心度(degree centrality,DC)作为学习特征,对射击运动组和滑冰运动组(分类1)、射击运动组和对照组(分类2)以及速滑运动组和对照组(分类3)之间进行二分类,并计算每一个脑区在分类算法当中的权重。使用留一交叉验证法计算分类正确率,使用总的准确率、接受者操作特性曲线(receiver operating characteristic curve,ROC)、以及预测准确率来衡量机器分类算法的优劣性。结果表明:分类1中SVM算法的正确率较高且分类效果更稳定,总的准确率(total accuracy,tACC)可以维持在96.67%以上,曲线下面积(area under curve,AUC)均为1,说明SVM算法对区分不同项目运动员脑静息态功能特征时更有优势;在分类2和分类3中,SVM算法效果取决于使用的指标。其中,使用fALFF或者综合使用三个静息态指标的分类效果较稳定(tACC均在80%以上,AUC均在0.88以上);小脑在分类1算法中占较多的权重,提示不同运动项目运动员的脑功能活动之间差异最明显的部位主要在小脑上。而分类2和3中,除了小脑,还有一些与运动执行和控制及其他功能活动相关的脑区参与了算法的构成。通过SVM分类算法的应用获得较为理想的结果,展示了模式识别方法在运动科学领域的应用价值。研究成果有助于体育科学研究者从新的角度更加全面地理解运动与脑的关系。展开更多
目的:观察2型糖尿病(T2DM)伴认知灵活性减退患者的静息态功能连接(FC)特征改变及其与认知灵活性的相关性。方法:回顾性分析24例T2DM伴认知灵活性减退的患者(T2DM+CD)、34例不伴认知灵活性减退的T2DM患者(T2DM-CD)以及31例健康对照(HC)...目的:观察2型糖尿病(T2DM)伴认知灵活性减退患者的静息态功能连接(FC)特征改变及其与认知灵活性的相关性。方法:回顾性分析24例T2DM伴认知灵活性减退的患者(T2DM+CD)、34例不伴认知灵活性减退的T2DM患者(T2DM-CD)以及31例健康对照(HC)。分别对三组受试者使用威斯康辛卡片分类测试(WCST)、斯特鲁普色词测验(Stroop)评估认知灵活性及功能磁共振(fMRI)扫描,观察三组受试者认知灵活性差异、双侧(L. and R.)纹状体(ST)与背外侧前额叶皮质(dlPFC)之间FC的差异,然后分析了认知灵活性与ST-dlPFC通路FC之间的相关,最后进一步分析了T2DM患病状态和认知灵活性对FC改变的交互效应。结果:与T2DM-CD患者及HC相比,T2DM+CD患者WCST总应答数、错误应答数、持续应答数以及用时明显增多,而正确应答数明显减少;Stroop中T2DM+CD患者的正确数、字色矛盾正确数以及字色无关正确数均低于HC。T2DM+CD患者L.ST-L.dlPFC、R.ST-L.dlPFC、R.ST-R.dlPFC之间的FC减低,R.ST-R.dlPFC之间的FC减低与认知灵活性量表评分相关,且T2DM患病状态和认知灵活性对FC的改变存在交互效应。结论:ST-dlPFC之间的FC减低是T2DM特异性认知灵活性受损的神经机制。展开更多
功能磁共振成像技术(fMRI:functional Magnetic Resonance Imaging)是一种高效的脑成像技术研究方法,为减少fMRI数据的冗余,将其转换为更具分类潜力的特征,提出一个基于孪生网络(SANet:Siamese Network)的特征构造算法SANet,将多个扫描...功能磁共振成像技术(fMRI:functional Magnetic Resonance Imaging)是一种高效的脑成像技术研究方法,为减少fMRI数据的冗余,将其转换为更具分类潜力的特征,提出一个基于孪生网络(SANet:Siamese Network)的特征构造算法SANet,将多个扫描点下的脑区信息类比为图,应用改进的AlexNet网络进行特征构造,并结合增量特征选择策略达到优化分类的目的。通过实验对比3种不同网络结构和4种分类器对SANet模型的影响,并进行消融实验,验证增量特征选择算法对SANet构造特征的分类效果。实验表明,SANet模型能对fMRI数据进行有效构造,且提高原始特征的分类性能。展开更多
To investigate changes of functional activation areas of the cerebral cortex and the connectivity of motor cortex networks （MCNs） in stroke patients during the recovery, five patients with the infarct in their left ...To investigate changes of functional activation areas of the cerebral cortex and the connectivity of motor cortex networks （MCNs） in stroke patients during the recovery, five patients with the infarct in their left hemispheres are recruited. Functional magnetic resonance imaging （fMRI） is performed in the second, fourth, eighth, and sixteenth weeks after the stroke. Images are analyzed using the professional software SPM5 to obtain the bilateral activation of the motor cortex in left and right handgrip tests. MCN data are extracted from the active areas, and the structural and functional characteristic parameters are computed to indicate the connectivity of the network. Results show that the ipsilesional hemisphere recruits more areas with less active extent during the handgrip test, compared with the contralesional hemisphere. MCN shows a higher overall degree of statistical independence and more statistical dependence among motor areas with the gradual recovery. It can help physicians understand the recovery mechanism.展开更多
本研究应用功能磁共振成像(functional magnetic resonance imaging,fMRI)技术,检测了健康人大脑和小脑参与空间记忆的认知过程。通过对10名右利手健康志愿者进行一项短时空间记忆任务作业的同时进行脑功能磁共振扫描,实验采用组块设计...本研究应用功能磁共振成像(functional magnetic resonance imaging,fMRI)技术,检测了健康人大脑和小脑参与空间记忆的认知过程。通过对10名右利手健康志愿者进行一项短时空间记忆任务作业的同时进行脑功能磁共振扫描,实验采用组块设计,任务与对照任务交替进行,数据采用SPM99软件进行数据分析和脑功能区定位。结果显示:当统计阈值设定为P<0.0001时,大脑皮层和右侧小脑一起被显著激活;大脑皮层所激活的脑区有双侧顶叶的楔前叶、顶上小叶、缘上回(BA7/40,BA:Brodma-nn Area),双侧前额上、中、下回(BA6/9/47),双侧枕叶和枕颞交界处(BA18/19/37),右侧海马回;左侧中脑黑质及被盖部也被激活。上述结果提示:小脑和大脑皮层一起参与了空间记忆的认知过程。展开更多
文摘fMRI （Functional Magnetic Resonance Imaging） is a relatively new technique that uses MRI （Magnetic Resonance Imaging） to measure the hemodynamic response （change in blood flow） related to neural activity in the brain. This paper aims to explore and identify the obstacles facing the implementation and applications of IMRI in radiology departments within Jeddah city by analyzing related data received by direct questionnaires and interviews with all the people working in MRI units in Jeddah city and finds that the major obstacle is lacking of awareness of fMRI among medical professionals and their training.
基金Supported by the Research Project of Dongguan Higher Education (200910815252)the Beijing Natural Science Foundation(7102102)the Scientific Research Key Program of Beijing Municipal Commission of Ed-ucation(KZ200810025011)~~
文摘To evaluate the effect of the positive-indefinite matrix on the diffusion tensor-derived parameters, a modified algorithm is proposed for calculating these parameters. Magnetic resonance （MR） diffusion tensor images of five healthy volunteers are collected. The diffusion sensitive gradient magnetic fields are applied along 25 directions and the diffusion weighting value is 1 000 s/mm^2. Many positive-indefinite diffusion tensors can be found in the white matter area, such as the genu and the splenium of corpus callosum. Due to the positive-indefinite matrix, the mean diffusivity （MD） and the fractional anisotropy （FA） are under-estimated and over-estimated by using the conventional algorithm. Thus, the conventional algorithm is modified by using the absolute values of all eigenvalues. Results show that both the robustness and the reliability for deriving these parameters are improved by the modified algorithm.
文摘目的:观察2型糖尿病(T2DM)伴认知灵活性减退患者的静息态功能连接(FC)特征改变及其与认知灵活性的相关性。方法:回顾性分析24例T2DM伴认知灵活性减退的患者(T2DM+CD)、34例不伴认知灵活性减退的T2DM患者(T2DM-CD)以及31例健康对照(HC)。分别对三组受试者使用威斯康辛卡片分类测试(WCST)、斯特鲁普色词测验(Stroop)评估认知灵活性及功能磁共振(fMRI)扫描,观察三组受试者认知灵活性差异、双侧(L. and R.)纹状体(ST)与背外侧前额叶皮质(dlPFC)之间FC的差异,然后分析了认知灵活性与ST-dlPFC通路FC之间的相关,最后进一步分析了T2DM患病状态和认知灵活性对FC改变的交互效应。结果:与T2DM-CD患者及HC相比,T2DM+CD患者WCST总应答数、错误应答数、持续应答数以及用时明显增多,而正确应答数明显减少;Stroop中T2DM+CD患者的正确数、字色矛盾正确数以及字色无关正确数均低于HC。T2DM+CD患者L.ST-L.dlPFC、R.ST-L.dlPFC、R.ST-R.dlPFC之间的FC减低,R.ST-R.dlPFC之间的FC减低与认知灵活性量表评分相关,且T2DM患病状态和认知灵活性对FC的改变存在交互效应。结论:ST-dlPFC之间的FC减低是T2DM特异性认知灵活性受损的神经机制。
文摘功能磁共振成像技术(fMRI:functional Magnetic Resonance Imaging)是一种高效的脑成像技术研究方法,为减少fMRI数据的冗余,将其转换为更具分类潜力的特征,提出一个基于孪生网络(SANet:Siamese Network)的特征构造算法SANet,将多个扫描点下的脑区信息类比为图,应用改进的AlexNet网络进行特征构造,并结合增量特征选择策略达到优化分类的目的。通过实验对比3种不同网络结构和4种分类器对SANet模型的影响,并进行消融实验,验证增量特征选择算法对SANet构造特征的分类效果。实验表明,SANet模型能对fMRI数据进行有效构造,且提高原始特征的分类性能。
基金Supported by the National Natural Science Foundation of China (30670543)~~
文摘To investigate changes of functional activation areas of the cerebral cortex and the connectivity of motor cortex networks （MCNs） in stroke patients during the recovery, five patients with the infarct in their left hemispheres are recruited. Functional magnetic resonance imaging （fMRI） is performed in the second, fourth, eighth, and sixteenth weeks after the stroke. Images are analyzed using the professional software SPM5 to obtain the bilateral activation of the motor cortex in left and right handgrip tests. MCN data are extracted from the active areas, and the structural and functional characteristic parameters are computed to indicate the connectivity of the network. Results show that the ipsilesional hemisphere recruits more areas with less active extent during the handgrip test, compared with the contralesional hemisphere. MCN shows a higher overall degree of statistical independence and more statistical dependence among motor areas with the gradual recovery. It can help physicians understand the recovery mechanism.
文摘本研究应用功能磁共振成像(functional magnetic resonance imaging,fMRI)技术,检测了健康人大脑和小脑参与空间记忆的认知过程。通过对10名右利手健康志愿者进行一项短时空间记忆任务作业的同时进行脑功能磁共振扫描,实验采用组块设计,任务与对照任务交替进行,数据采用SPM99软件进行数据分析和脑功能区定位。结果显示:当统计阈值设定为P<0.0001时,大脑皮层和右侧小脑一起被显著激活;大脑皮层所激活的脑区有双侧顶叶的楔前叶、顶上小叶、缘上回(BA7/40,BA:Brodma-nn Area),双侧前额上、中、下回(BA6/9/47),双侧枕叶和枕颞交界处(BA18/19/37),右侧海马回;左侧中脑黑质及被盖部也被激活。上述结果提示:小脑和大脑皮层一起参与了空间记忆的认知过程。
