Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.
Department of Psychology, Stanford University, CA, USA.
Neuroimage. 2018 Nov 1;181:645-658. doi: 10.1016/j.neuroimage.2018.06.060. Epub 2018 Jun 21.
Diffusion MRI tractography is essential for reconstructing white-matter projections in the living human brain. Yet tractography results miss some projections and falsely identify others. A challenging example is the optic radiation (OR) that connects the thalamus and the primary visual cortex. Here, we tested whether OR tractography can be optimized using quantitative T1 mapping. Based on histology, we proposed that myelin-sensitive T1 values along the OR should remain consistently low compared with adjacent white matter. We found that complementary information from the T1 map allows for increasing the specificity of the reconstructed OR tract by eliminating falsely identified projections. This T1-filtering outperforms other, diffusion-based tractography filters. These results provide evidence that the smooth microstructural signature along the tract can be used as constructive input for tractography. Finally, we demonstrate that this approach can be applied in a case of multiple sclerosis, and generalized to the HCP-available MRI measurements. We conclude that multimodal MRI microstructural information can be used to eliminate spurious tractography results in the case of the OR.
弥散磁共振成像轨迹追踪对于重建活体人脑的白质投射至关重要。然而，轨迹追踪的结果会错过一些投射并错误地识别其他投射。一个具有挑战性的例子是连接丘脑和初级视觉皮层的视神经放射（optic radiation，OR）。在这里，我们测试了是否可以使用定量 T1 映射来优化 OR 轨迹追踪。基于组织学，我们提出 OR 上的髓鞘敏感 T1 值应该与相邻白质相比保持一致地低。我们发现 T1 图谱的补充信息可以通过消除错误识别的投射来提高重建 OR 轨迹的特异性。这种 T1 过滤比其他基于扩散的轨迹追踪过滤效果更好。这些结果提供了证据表明，沿轨迹的平滑微观结构特征可以用作轨迹追踪的建设性输入。最后，我们证明了这种方法可以应用于多发性硬化症的病例中，并推广到 HCP 可用的 MRI 测量中。我们的结论是，多模态 MRI 微观结构信息可用于消除 OR 中虚假的轨迹追踪结果。
