Comparison of Myelin Fraction Maps Acquired with mcUTE, T2 Relaxation and Magnetization Transfer

Motivation: Several neurological diseases are associated with impaired myelin development or demyelination. Current MRI methods for myelin quantification show high variability, and often do not align with pathology. Goal(s): Optimization of a multi-contrast multi-resolution 3D-UTE sequence (mcUTE) for myelin mapping and comparison with other MRI approaches and histology. Approach: Myelin fraction maps were acquired ex vivo in a sheep brain using an optimized mcUTE protocol, T2-relaxation measurements and magnetization transfer, and results were compared with electron-microscopy. All sequences were also tested on five healthy volunteers at 3T. Results: While all approaches showed high consistency across human volunteers, mcUTE showed highest correlation with electron-microscopy results. Impact: mcUTE reliably provides whole-brain myelin fraction maps and high-resolution water-excited anatomical image data in less than 15min at a clinical MRI system. Ex vivo results showed that myelin imaging using mcUTE is highly consistent with electron microscopy.