Diffusion metrics correlate with the relaxometric constant Dr of the χ-separation model

Motivation: χ-separation method relies on assuming a certain relaxometric constant (Dr) calculated as the mean of a group of healthy subjects. Recently, we demonstrated that it is subject-specific. Goal(s): The goal of this study was to evaluate the correlation between Dr and microstructural metrics obtained from diffusion tensor and diffusion kurtosis imaging (DTI and DKI). Approach: We regressed between Dr against DTI and DKI diffusion metrics in a cohort of healthy controls. Results: Results showed a positive correlation with fractional anisotropy and axial diffusivity, and a negative correlation with mean and radial kurtosis. Impact: Understanding how the relaxometric constant of the χ-separation method (Dr) depends on microstructural diffusion metrics will define its personalization. This, in turn, will impact on how we assess the presence of different magnetic susceptibility sources in the brain.