Nir Talia M, Villalon-Reina Julio E, Prasad Gautam, Jahanshad Neda, Joshi Shantanu H, Toga Arthur W, Bernstein Matt A, Jack Clifford R, Weiner Michael W, Thompson Paul M
Imaging Genetics Center, Institute for Neuroimaging & Informatics, University of Southern California, Los Angeles, CA, USA.
Department of Neurology, UCLA School of Medicine, Los Angeles, CA, USA.
Neurobiol Aging. 2015 Jan;36 Suppl 1(0 1):S132-40. doi: 10.1016/j.neurobiolaging.2014.05.037. Epub 2014 Aug 27.
Characterizing brain changes in Alzheimer's disease (AD) is important for patient prognosis and for assessing brain deterioration in clinical trials. In this diffusion weighted imaging study, we used a new fiber-tract modeling method to investigate white matter integrity in 50 elderly controls (CTL), 113 people with mild cognitive impairment, and 37 AD patients. After clustering tractography using a region-of-interest atlas, we used a shortest path graph search through each bundle's fiber density map to derive maximum density paths (MDPs), which we registered across subjects. We calculated the fractional anisotropy (FA) and mean diffusivity (MD) along all MDPs and found significant MD and FA differences between AD patients and CTL subjects, as well as MD differences between CTL and late mild cognitive impairment subjects. MD and FA were also associated with widely used clinical scores. As an MDP is a compact low-dimensional representation of white matter organization, we tested the utility of diffusion tensor imaging measures along these MDPs as features for support vector machine based classification of AD.
表征阿尔茨海默病（AD）患者的脑部变化对于患者预后以及在临床试验中评估脑部退化情况具有重要意义。在这项扩散加权成像研究中，我们采用一种新的纤维束建模方法，对50名老年对照者（CTL）、113名轻度认知障碍患者以及37名AD患者的白质完整性进行了研究。在使用感兴趣区图谱对纤维束成像进行聚类之后，我们通过每个纤维束的纤维密度图进行最短路径图搜索，以得出最大密度路径（MDP），并在不同受试者之间进行配准。我们计算了所有MDP上的各向异性分数（FA）和平均扩散率（MD），发现AD患者与CTL受试者之间的MD和FA存在显著差异，CTL与晚期轻度认知障碍受试者之间的MD也存在差异。MD和FA还与广泛使用的临床评分相关。由于MDP是白质组织的一种紧凑低维表示形式，我们测试了沿这些MDP的扩散张量成像测量值作为基于支持向量机的AD分类特征的效用。
