一种基于扩散张量成像(DTI)得出的皮质-皮质连接性测量指标。

A DTI-derived measure of cortico-cortical connectivity.

作者信息

Zalesky Andrew, Fornito Alex

机构信息

Melbourne Neuropsychiatry Centre, University ofMelbourne, 3053 Carlton South, Australia.

出版信息

IEEE Trans Med Imaging. 2009 Jul;28(7):1023-36. doi: 10.1109/TMI.2008.2012113. Epub 2009 Jan 13.

Abstract

We arm researchers with a simple method to chart a macroscopic cortico-cortical connectivity network in living human subjects. The researcher provides a diffusion-magnetic resonance imaging (MRI) data set and N cortical regions of interest. In return, we provide an N xN structural adjacency matrix (SAM) quantifying the relative connectivity between all cortical region pairs. We also return a connectivity map for each pair to enable visualization of interconnecting fiber bundles. The measure of connectivity we devise is: 1) free of length bias, 2) proportional to fiber bundle cross-sectional area, and 3) invariant to an exchange of seed and target. We construct a 3-D lattice scaffolding (graph) for white-matter by drawing a link between each pair of voxels in a 26-voxel neighborhood for which their two respective principal eigenvectors form a sufficiently small angle. The connectivity between a cortical region pair is then measured as the maximum number of link-disjoint paths that can be established between them in the white-matter graph. We devise an efficient Edmonds-Karp-like algorithm to compute a conservative bound on the maximum number of link-disjoint paths. Using both simulated and authentic diffusion-tensor imaging data, we demonstrate that the number of link-disjoint paths as a measure of connectivity satisfies properties 1)-3), unlike the fraction of intersecting streamlines-the measure intrinsic to most existing probabilistic tracking algorithms. Finally, we present connectivity maps of some notoriously difficult to track longitudinal and contralateral fasciculi.

摘要

我们为研究人员提供了一种简单的方法,用于绘制活体人类受试者的宏观皮质-皮质连接网络。研究人员提供一个扩散磁共振成像(MRI)数据集和N个感兴趣的皮质区域。作为回报,我们提供一个N×N的结构邻接矩阵(SAM),用于量化所有皮质区域对之间的相对连接性。我们还会返回每对区域的连接图,以便可视化相互连接的纤维束。我们设计的连接性度量标准为:1)无长度偏差;2)与纤维束横截面积成正比;3)种子区域和目标区域交换时不变。我们通过在26体素邻域内的每对体素之间绘制连接来构建白质的三维晶格支架(图),条件是它们各自的两个主特征向量形成足够小的角度。然后,将皮质区域对之间的连接性测量为在白质图中它们之间可以建立的最大链路不相交路径数。我们设计了一种类似Edmonds-Karp的高效算法,以计算链路不相交路径最大数量的保守界限。使用模拟和真实的扩散张量成像数据,我们证明,与大多数现有概率追踪算法所固有的相交流线分数不同,作为连接性度量的链路不相交路径数满足属性1)-3)。最后,我们展示了一些追踪难度极高的纵向和对侧束的连接图。

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