Mapping Short Association Fibers in Relation to Long-Range White Matter Tracts Using Quantitative Diffusion Tractography

Motivation: Short association fibers (SAFs) play an important role in cortical connections, however, their relationship to long-range (LR) white matter pathways remain unclear. Goal(s): We aim to map SAFs in relation to 63 LR tracts and conduct volumetric analyses to better characterize structural connectivity at this interface. Approach: We applied advanced quantitative diffusion tractography, leveraging a large-scale dataset with 1054 healthy participants (22-37 years old). Results: Volumetric distributions characterized bundle-specific SAF and LR tract patterns. Notably, projection pathways demonstrated higher LR:SAF volumetric ratios whereas association and commissural pathways had the lowest LR:SAF ratios. Impact: This study provides novel insights into the structural connectivity of SAFs in relation to LR tracts. Furthermore, the quantitative volumetric analyses of bundle-specific SAFs establish normative distributions, which will serve as necessary baselines for future studies in disease states.