For two decades diffusion fiber tractography has been used to probe both the spatial extent of white matter pathways and the region to region connectivity of the brain. In both cases, anatomical accuracy of tractography is critical for sound scientific conclusions. Here we assess and validate the algorithms and tractography implementations that have been most widely used - often because of ease of use, algorithm simplicity, or availability offered in open source software. Comparing forty tractography results to a ground truth defined by histological tracers in the primary motor cortex on the same squirrel monkey brains, we assess tract fidelity on the scale of voxels as well as over larger spatial domains or regional connectivity. No algorithms are successful in all metrics, and, in fact, some implementations fail to reconstruct large portions of pathways or identify major points of connectivity. The accuracy is most dependent on reconstruction method and tracking algorithm, as well as the seed region and how this region is utilized. We also note a tremendous variability in the results, even though the same MR images act as inputs to all algorithms. In addition, anatomical accuracy is significantly decreased at increased distances from the seed. An analysis of the spatial errors in tractography reveals that many techniques have trouble properly leaving the gray matter, and many only reveal connectivity to adjacent regions of interest. These results show that the most commonly implemented algorithms have several shortcomings and limitations, and choices in implementations lead to very different results. This study should provide guidance for algorithm choices based on study requirements for sensitivity, specificity, or the need to identify particular connections, and should serve as a heuristic for future developments in tractography.

中文翻译：

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运动系统中标准实践的tractography算法的解剖学准确性-松鼠猴脑的组织学验证。

二十年来，扩散纤维束摄影术已被用来探测白质通路的空间范围以及大脑区域间的连通性。在这两种情况下，超声检查的解剖学准确性对于合理的科学结论都是至关重要的。在这里，我们评估和验证最广泛使用的算法和tractography实现-通常是由于易于使用，算法简单或开源软件提供的可用性。将四十个影像学检查结果与同一只松鼠猴大脑上初级运动皮层中组织学示踪剂定义的地面真相进行比较，我们评估了在体素大小以及更大的空间域或区域连通性上的影像保真度。没有算法在所有指标上都成功，事实上，一些实现无法重建大部分路径或无法确定主要连通点。精度最取决于重建方法和跟踪算法，以及种子区域以及如何利用该区域。即使相同的MR图像充当所有算法的输入，我们也注意到结果的巨大差异。另外，在距种子的距离增加时，解剖学准确性显着降低。一份对人体解剖学中的空间误差的分析表明，许多技术难以正确地留下灰质，并且许多技术仅揭示了与感兴趣的相邻区域的连通性。这些结果表明，最常用的实现算法有几个缺点和局限性，实现中的选择导致非常不同的结果。