Magnetic Field Correlation Imaging Quantifies Demyelination and Axonal Loss

Motivation: Microscopic magnetic field inhomogeneities (μMFIs) carry useful information on tissue microstructure. They have been previously utilised to quantify iron content in-vivo using magnetic field correlation imaging (MFCi), but this technique has never been applied to myelin. Goal(s): To determine whether MFCi can be used as a quantitative technique for myelin. Approach: Comparing simulations of myelin-induced μMFIs and ultrahigh-field ex-vivo MFCi in a rodent model of demyelination. Results: Simulations suggested that demyelination and axonal loss had a measurable effect on MFCi metrics, and ex-vivo imaging showed that MFCi significantly correlated with inhomogenous magnetisation transfer ratio from the same sample. Impact: Magnetic Field Correlation imaging provides quantitative information on changes to myelin status complementary to other MRI techniques, and offers new ways to characterise microstructural changes in neurodegenerative diseases.