Department of Radiology, UMDNJ-New Jersey Medical School, Newark, New Jersey, United States of America.
PLoS One. 2012;7(9):e43415. doi: 10.1371/journal.pone.0043415. Epub 2012 Sep 6.
Tractography algorithms have been developed to reconstruct likely WM pathways in the brain from diffusion tensor imaging (DTI) data. In this study, an elegant and simple means for improving existing tractography algorithms is proposed by allowing tracts to propagate through diagonal trajectories between voxels, instead of only rectilinearly to their facewise neighbors. A series of tests (using both real and simulated data sets) are utilized to show several benefits of this new approach. First, the inclusion of diagonal tract propagation decreases the dependence of an algorithm on the arbitrary orientation of coordinate axes and therefore reduces numerical errors associated with that bias (which are also demonstrated here). Moreover, both quantitatively and qualitatively, including diagonals decreases overall noise sensitivity of results and leads to significantly greater efficiency in scanning protocols; that is, the obtained tracts converge much more quickly (i.e., in a smaller amount of scanning time) to those of data sets with high SNR and spatial resolution. Importantly, the inclusion of diagonal propagation adds essentially no appreciable time of calculation or computational costs to standard methods. This study focuses on the widely-used streamline tracking method, FACT (fiber assessment by continuous tracking), and the modified method is termed "FACTID" (FACT including diagonals).
束追踪算法已经被开发出来，以便从弥散张量成像（DTI）数据中重建大脑中的白质通路。在这项研究中，通过允许束沿着体素之间的对角线轨迹传播，而不仅仅是沿着其相邻面的直线传播，提出了一种优雅而简单的方法来改进现有的束追踪算法。利用一系列测试（使用真实和模拟数据集）来展示这种新方法的几个优点。首先，包括对角线束传播降低了算法对坐标轴任意方向的依赖性，从而减少了与该偏差相关的数值误差（这里也进行了演示）。此外，包括对角线可以在定量和定性上降低结果对噪声的敏感性，并显著提高扫描协议的效率；也就是说，获得的束在较短的扫描时间内（即，在较短的扫描时间内）更快地收敛到具有高信噪比和空间分辨率的数据集中的束。重要的是，对角线传播的加入基本上不会给标准方法增加显著的计算时间或计算成本。本研究集中于广泛使用的流线追踪方法 FACT（通过连续追踪进行纤维评估），并将修改后的方法称为“FACTID”（包括对角线的 FACT）。
