An anisotropic capillary based phantom for validation of diffusion-relaxation models

Motivation: We aim to create a universal procedure for experimental verification of diffusion models using model systems based on glass capillaries. Goal(s): Spatially ordered glass capillaries mimics the characteristic geometry of white matter and are ideal for performing a 'stress test' of various diffusion models. We aim to verify this through diffusion and relaxation measurements at varying spatial directions and time scales. Approach: Combined diffusion- and relaxation-weighted MRI based measurements verify the geometry of the glass capillaries at different spatial scales. Results: The glass capillary phantom was established as a ground truth model for modelling of white matter at different diffusion and relaxation regimes. Impact: Glass capillaries present a unique object with simple physical and geometrical features mimicking white matter. We tested a glass capillary phantom in terms of a diffusion-relaxation model using conventional sequences and provide a simple theoretical interpretation of experimental results.