Validation of MRI diffusion models using synchrotron radiation imaging in custom microstructural phantoms

Motivation: Diffusion MRI (dMRI) has been traditionally validated by 2D-histochemistry; Synchrotron X-ray phase contrast tomography (XPCT) has provided high resolution images that might be used for more accurate validation. Goal(s): Our aim is to show the impact of validating dMRI using XPCT. Approach: A brain-mimicking phantoms was acquired by dMRI and XPCT. In dMRI, diffusion time-dependent data were used to estimate fiber calibres RMR and disorder correlation length lc. In XPCT, the same quantities (RXPCTMR,aXPCT) were calculated from the distribution of fibers' diameters. Results: We obtained values RMR=(6.9±0.1)μm and lc~(8.5±0.2)μm, comparable to RXPCTMR=7.86μm and aXPCT=13.0μm. Impact: A multi-scale approach based on XPCT has been proposed for validating dMRI models applied on DW data obtained on brain-mimicking phantoms. The agreement between dMRI and XPCTresults pave the way for new possibilities of dMRI validation in ex-vivo brain samples.