Water Content, T1 relaxation and Diffusion MRI Correlates of Antiphospholipid Antibodies in Primary Progressive Multiple Sclerosis

Motivation: Antiphospholipid antibodies (aPLA) target the phospholipid bilayer of cell membranes. Understanding the relationship between advanced MRI metrics and aPLA may assist in establishing imaging biomarkers for PPMS. Goal(s): To assess aPLA associations with MRI-derived water content, T1 relaxation, and diffusion metrics in PPMS and RRMS lesions and normal appearing white matter (NAWM). Approach: 20 PPMS and 33 RRMS participants underwent 3T MRI and same-day venous blood sampling for IgM/IgG aPLA. Results: Specific aPLA, including IgM-sphingomyelin, were correlated with NAWM water content and T1 relaxation, as well as lesion tissue fibre fraction, non-restricted fraction, radial diffusivity, and restricted fraction in PPMS, but not RRMS. Impact: Biological immune factors that impact MRI metrics may change depending on the subtype of MS being imaged. It is possible that the specificity of advanced MRI varies across MS phenotypes and further investigation is warranted.