Unlocking Myelin Mysteries: Could 31-Phosphorous Solid-State NMR be the key to quantitative MRI of myelin membrane morphology?

Motivation: Improved sensitivity to changes in myelin membranes may be achieved by phosphorous (31P) solid-state NMR (ssNMR), enabling more direct evaluation of neurodegeneration. Goal(s): To demonstrate how ssNMR proton cross-polarization (CP) may be more sensitive to membrane morphology than 31P alone. Approach: Using porcine neural tissue, we conducted a series of 31P ssNMR experiments that characterize the myelin phospholipid involvement in 31P-CP and CP’s sensitivity to variations in membrane composition, orientation, and dynamics. Results: The CP signal is highly sensitive to the amount and orientation of myelin between grey and white matter samples across neural regions, and may better detect changes in membrane structure. Impact: Improved sensitivity to subtle variations in myelin membrane morphology using the 31P ssNMR method of CP has the potential for in vivo MRI use, and could lead to earlier diagnosis, as well as enhanced disease and treatment monitoring.