Tractometry of shear stiffness and damping ratio using diffusion weighted imaging and magnetic resonance elastography

Motivation: Advancements in diffusion MRI enable more complete characterization of white matter tracts with magnetic resonance elastography-derived properties via tractometry. Goal(s): We apply tractometry to measure tract shear stiffness and damping ratio. Approach: For a sample of 44 adults, MRE measures were co-registered to tractogram space and sampled, along with diffusion scalars. Results: Patterns in both shear stiffness and damping ratio were not strongly explained by diffusion metrics in either the corpus callosum or the superior longitudinal fasciculus. This highlights that while shear stiffness has some spatial relationship with diffusion anisotropy, elastography provides unique structural information with limited mutual information from diffusion MRI. Impact: As biomarker discovery continues to incorporate the more spatially informative tract profiles from tractometry, this approach offers researchers and clinicians the ability to spatially sample both diffusion- and elastography-based structural information to better characterize white matter tract structural health.