9.4T MRI-derived myelin measures in post-mortem brain blocks reveal unprecedented spatial characteristics in Multiple Sclerosis lesions

Motivation: Assessing the focal characteristics and extent of microstructural damage and regeneration in MS patients is essential for understanding disease pathogenesis and developing novel therapeutic approaches. Goal(s): Assessing whether advanced DWI-based measures can provide novel insights into damage and repair in MS lesions. Approach: Multimodal 9.4T MRI was acquired on lesion-containing post-mortem brain blocks from a patient with MS. The derived metrics include ultra-high-resolution R2*, multishell-DWI-based MD, FA, intra-axonal(Vintra), extra-axonal(Vextra), CSF(VCSF) volume fractions and Myelin-Water-fraction(MWF). Myelin Basic Protein(MBP) immunohistochemistry was employed as myelin 'ground-truth'. Results: Vintra revealed spatial inhomogeneities in ROIs within/surrounding MS lesions and stronger association with MBP staining than the corresponding MWF. Impact: The unprecedented spatial resolution and contrast obtained in post-mortem brain blocks imaged 9.4T MRI open a new window into the assessment of mechanisms leading to focal pathology appearance and evolution in Multiple Sclerosis.