FIG. 15.

Conceptual example of (a) deterministic (Ref. 20) and (b) probabilistic (Ref. 145) streamline tractography based on the diffusion tensor model. The white lines in (a) represent fiber tract pathways that were reconstructed by following the principal diffusion directions (see the glyphs shown in the blue region of interest) in consecutive steps, initiated bidirectionally at the indicated locations (i.e., “seed points”). For each of the pathways in (a), there is no information available about the precision/dispersion that is associated with their tract propagation. By contrast, the set of multiple (1000) lines shown in (b) provides a feel for the degree of uncertainty related to the tract reconstruction initiated from the single seed point. Note that the same underlying tractography algorithm (Ref. 20) was used for both examples, but in (b), each tract pathway was calculated from a “different” diffusion tensor data set that was created with the wild-bootstrap approach (Ref. 145).