Characterizing topological patterns in amnestic mild cognitive impairment by quantitative water diffusivity.
Characterizing topological patterns in amnestic mild cognitive impairment by quantitative water diffusivity.
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DOI：
10.3233/jad-140882
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发表时间：
2014-11
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通讯作者：
Bing Zhang;Xin Zhang;Fang Zhang;Ming Li;C. Schwarz;Jian-ge Zhang;Z. Yin;Lai Qian;Hui Zhao;Kun Wang;Chuan-shuai Tian;Haiping Yu;Weibo Chen;Fangfei Lu;Wenbo Wu;Qing X. Yang;Yun Xu;B. Zhu
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作者：
Bing Zhang;Xin Zhang;Fang Zhang;Ming Li;C. Schwarz;Jian-ge Zhang;Z. Yin;Lai Qian;Hui Zhao;Kun Wang;Chuan-shuai Tian;Haiping Yu;Weibo Chen;Fangfei Lu;Wenbo Wu;Qing X. Yang;Yun Xu;B. Zhu
来自弥散张量成像的平均弥散性（MD）显示出其评估阿尔茨海默病（AD）前驱期失忆性轻度认知障碍（aMCI）灰质微观结构完整性损伤的能力。然而，关于皮质MD在认知疾病中构建的小世界拓扑网络知之甚少。在这项工作中，我们测量了aMCI （n = 30）和AD （n = 30）患者与认知正常（CNs）对照（n = 30）的全脑皮质MD，并利用图论分析构建了皮质弥散性网络。与中枢神经网络相比，aMCI和AD患者表现出异常的皮质扩散网络小世界特性（更高的聚类程度和更长的路径长度），反映出较不理想的拓扑组织。此外，aMCI患者的平均网络连接程度低于CNs，但高于AD。此外，通过多元回归分析，发现双侧海马及相关边缘系统等11个中枢区域的MD与蒙特利尔认知评估评分呈负相关。在这些中枢区域中，与CN相比，aMCI中右侧嗅觉皮层和中眶回与其他大脑区域的连通性被破坏的时间早于其他9个区域。综上所述，皮质扩散率在拓扑网络组织、平均连接程度和aMCI中枢区域中断方面的变化可能有助于识别AD前驱期患者，并反映神经退行性变的微观结构恶化。
Mean diffusivity (MD) derived from diffusion tensor imaging has shown its ability to assess the microscopic structural integrity damage of gray matter in amnestic mild cognitive impairment (aMCI), a prodromal stage of Alzheimer's disease (AD). However, little is known about the small world topology networks constructed by cortical MD in cognitive disease. In this work, we measured the cortical MD in the entire brain in patients with aMCI (n = 30) and AD (n = 30) compared with cognitive-normal (CNs) controls (n = 30), and then constructed the cortical diffusivity network by using graph-theoretical analysis. Compared with CNs, patients with aMCI and AD showed abnormal small-world property of cortical diffusivity networks (higher degree of clustering and longer path length), reflecting a less optimal topological organization. Moreover, the mean degree of connections of network in aMCI patients was characterized by lower than CNs but higher than AD. In addition, 11 hub regions were identified by negative correlations between MD and the score of Montreal Cognitive Assessment after multiple regression analysis, including bilateral hippocampi and related limbic system. Among those hub regions, the connectivity of the right olfactory cortex and middle orbital gyrus to the rest of brain regions were disrupted earlier than the other 9 regions in aMCI when compared to CN. In conclusion, the change of cortical diffusivity in topological network organization, mean degree of connections, and disrupted hub regions in aMCI may serve to identify patients in the prodromal stage of AD and reflect microstructural deterioration of neurodegeneration.