The brain white matter consists of a set of tracts that connect distinct regions of the brain. Segmentation of these tracts is often needed for clinical and research studies. Diffusion-weighted MRI offers unique contrast to delineate these tracts. However, existing segmentation methods rely on intermediate computations such as tractography or estimation of fiber orientation density. These intermediate computations, in turn, entail complex computations that can result in unnecessary errors. Moreover, these intermediate computations often require dense multi-shell measurements that are unavailable in many clinical and research applications. As a result, current methods suffer from low accuracy and poor generalizability. Here, we propose a new deep learning method that segments these tracts directly from the diffusion MRI data, thereby sidestepping the intermediate computation errors. Our experiments show that this method can achieve segmentation accuracy that is on par with the state of the art methods (mean Dice Similarity Coefficient of 0.826). Compared with the state of the art, our method offers far superior generalizability to undersampled data that are typical of clinical studies and to data obtained with different acquisition protocols. Moreover, we propose a new method for detecting inaccurate segmentations and show that it is more accurate than standard methods that are based on estimation uncertainty quantification. The new methods can serve many critically important clinical and scientific applications that require accurate and reliable non-invasive segmentation of white matter tracts.

翻译：脑白质由一组连接大脑不同区域的纤维束构成。对这些纤维束的分割通常是临床和研究的必要步骤。扩散加权磁共振成像提供了独特的对比度来描绘这些纤维束。然而，现有分割方法依赖于中间计算，例如纤维追踪或纤维方向密度估计。这些中间计算进而导致复杂计算，可能引入不必要的误差。此外，这些中间计算通常需要密集的多壳层测量数据，而这些数据在许多临床和研究应用中无法获取。因此，当前方法存在准确率低和泛化能力差的问题。本文提出一种新的深度学习方法，可直接从扩散磁共振成像数据中分割这些纤维束，从而规避中间计算误差。实验表明，该方法的分割准确率可与现有最优方法媲美（平均Dice相似系数为0.826）。与现有最优方法相比，我们的方法在临床研究中常见的欠采样数据以及不同采集协议获取的数据上具有显著更优的泛化能力。此外，我们提出一种检测不准确分割的新方法，并证明其比基于估计不确定性量化的标准方法更准确。这些新方法可服务于众多关键临床和科学应用，这些应用需要准确且可靠的无创白质纤维束分割。