Service de Neurochirurgie, Hôpital neurologique et neurochirurgical Pierre Wertheimer, Hospices Civils de Lyon, 59 Bd Pinel, 69003, Lyon, France.
Laboratoire CREATIS, CNRS UMR5220, Inserm U1206, INSA-Lyon, Université de Lyon I, Lyon, France.
Neuroradiology. 2020 Sep;62(9):1079-1094. doi: 10.1007/s00234-020-02442-8. Epub 2020 May 4.
The spinal cord (SC) is a dense network of billions of fibers in a small volume surrounded by bones that makes tractography difficult to perform. We aim to provide a review collecting all technical settings of SC tractography and propose the optimal set of parameters to perform a good SC tractography rendering. The MEDLINE database was searched for articles reporting "spinal cord" "tractography" in "humans". Studies were selected only when tractography rendering was displayed and MRI acquisition and tracking parameters detailed. From each study, clinical context, imaging acquisition settings, fiber tracking parameters, region of interest (ROI) design, and quality of the tractography rendering were extracted. Quality of tractography rendering was evaluated by several objective criteria proposed herein. According to the reported studies, to obtain a good tractography rendering, diffusion tensor imaging acquisition should be performed with 1.5 or 3 Tesla MRI, in the axial plane, with > 20 directions; b value: 1000 s mm; right-left phase-encoding direction for cervical SC; isotropic voxel size; and no slice gap. Concerning the tracking process, it should be performed with determinist approach, fractional anisotropy threshold between 0.15 and 0.2, and curvature threshold of 40°. ROI design is an essential step for providing good tractography rendering, and their placement has to consider partial volume effects, magnetic susceptibility effects, and motion artifacts. The review reported herein highlights that successful SC tractography depends on many factors (imaging acquisition settings, fiber tracking parameters, and ROI design) to obtain a good SC tractography rendering.
脊髓（SC）是一个密集的纤维网络，位于体积较小的骨骼周围，这使得束流追踪技术难以实施。我们旨在提供一份综述，收集所有 SC 束流追踪的技术设置，并提出最佳的参数组合，以进行良好的 SC 束流追踪渲染。我们在 MEDLINE 数据库中搜索了报告“脊髓”“束流追踪”在“人类”中的文章。只有在显示束流追踪渲染并且详细描述 MRI 采集和追踪参数的情况下，才选择研究。从每项研究中，提取了临床背景、成像采集设置、纤维追踪参数、感兴趣区（ROI）设计以及束流追踪渲染的质量。通过本文提出的几个客观标准来评估束流追踪渲染的质量。根据报告的研究，为了获得良好的束流追踪渲染，应在 1.5 或 3 Tesla MRI 上进行扩散张量成像采集，在轴位上进行，方向数>20；b 值：1000 s/mm；颈椎 SC 的左右相位编码方向；各向同性体素大小；无切片间隙。关于追踪过程，应使用确定性方法进行，各向异性分数阈值在 0.15 到 0.2 之间，曲率阈值为 40°。ROI 设计是提供良好束流追踪渲染的关键步骤，其放置必须考虑部分容积效应、磁化率效应和运动伪影。本文综述强调，成功的 SC 束流追踪取决于许多因素（成像采集设置、纤维追踪参数和 ROI 设计），以获得良好的 SC 束流追踪渲染。
