Diffusion MRI (dMRI) tractography algorithms reconstruct streamlines that represent the underlying white-matter fascicles, allowing to study the human connectome in vivo. Yet the identification of specific white-matter tracts is still challenging. A major source contributing to this difficulty is the inherent ambiguity in the dMRI signal. Different fascicle configurations can give rise to the same dMRI signal at the voxel level, and any local error in fiber tracking can propagate and lead to global effects in tractography results.
The goal of this work is to test the hypothesis that accurate mapping of the long range white-matter projections can be optimized by introducing complementary information derived from a different measurement, of 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.