The Australian e-Health Research Centre, The Commonwealth Scientific and Industrial Research Organisation (CSIRO), Brisbane, Australia.
The Australian e-Health Research Centre, The Commonwealth Scientific and Industrial Research Organisation (CSIRO), Brisbane, Australia.
Neuroimage. 2020 May 1;211:116646. doi: 10.1016/j.neuroimage.2020.116646. Epub 2020 Feb 18.
Diffusion MRI tractography is commonly used to delineate white matter tracts. These delineations can be used for planning neurosurgery or for identifying regions of interest from which microstructural measurements can be taken. Probabilistic tractography produces different delineations each time it is run, potentially leading to microstructural measurements or anatomical delineations that are not reproducible. Generating a sufficiently large number of streamlines is required to avoid this scenario, but what constitutes "sufficient" is difficult to assess and so streamline counts are typically chosen in an arbitrary or qualitative manner. This work explores several factors influencing tractography reliability and details two methods for estimating this reliability. The first method automatically estimates the number of streamlines required to achieve reliable microstructural measurements, whilst the second estimates the number of streamlines required to achieve a reliable binarised trackmap than can be used clinically. Using these methods, we calculated the number of streamlines required to achieve a range of quantitative reproducibility criteria for three anatomical tracts in 40 Human Connectome Project datasets. Actual reproducibility was checked by repeatedly generating the tractograms with the calculated numbers of streamlines. We found that the required number of streamlines varied strongly by anatomical tract, image resolution, number of diffusion directions, the degree of reliability desired, the microstructural measurement of interest, and/or the specifics on how the tractogram was converted to a binary volume. The proposed methods consistently predicted streamline counts that achieved the target reproducibility. Implementations are made available to enable the scientific community to more-easily achieve reproducible tractography.
弥散磁共振成像轨迹追踪常用于描绘白质束。这些描绘可用于神经外科规划，或用于识别可从中获取微观结构测量值的感兴趣区域。概率性轨迹追踪每次运行时都会产生不同的描绘，可能导致微观结构测量值或解剖描绘不可重现。为了避免这种情况，需要生成足够数量的轨迹线，但“足够”的标准难以评估，因此通常以任意或定性的方式选择轨迹线计数。本工作探讨了影响轨迹追踪可靠性的几个因素，并详细介绍了两种估计这种可靠性的方法。第一种方法自动估计实现可靠微观结构测量所需的轨迹线数量，而第二种方法则估计实现可用于临床的可靠二进制轨迹图所需的轨迹线数量。使用这些方法，我们在 40 个人类连接组计划数据集的三个解剖轨迹中计算了实现一系列定量重现性标准所需的轨迹线数量。通过使用计算出的轨迹线数量重复生成轨迹图来检查实际的重现性。我们发现，所需的轨迹线数量因解剖轨迹、图像分辨率、扩散方向数量、所需的可靠性程度、感兴趣的微观结构测量值以及/或如何将轨迹图转换为二进制体积等因素而异。所提出的方法始终预测了达到目标重现性所需的轨迹线计数。提供了实现，以使科学界更容易实现可重现的轨迹追踪。
