Fig. 4.

Overview of tractography methods. From the four-shell MGH-USC HCP data, the b=10,000 s/mm² and b = 1,000s/mm² shells were extracted. Orientations were reconstructed with constrained spherical deconvolution (CSD) from the b=10,000s/mm² shell and with multi-shell multi-tissue CSD (MSMT-CSD) from all four shells. Streamline tractography was performed with these two approaches and used to annotate 42 tracts manually in 16 subjects. The lower shell (b = 1,000s/mm², 64 directions) was used to reconstruct the same tracts automatically, with TRACULA or with a multi-ROI approach. For TRACULA, anatomical priors for each subject were obtained from the other 15 subjects and global probabilistic tractography was performed. For the multi-ROI approach, inclusion and exclusion masks were obtained from summing the manually defined ROIs of the other 15 subjects in template space. Local probabilistic tractography was constrained by these ROIs. The same ball-and-stick (BS) diffusion model was used for both TRACULA and the multi-ROI approach.