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Updated: May 30, 2025
Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
Published on: February 19, 2021
An MRI assessment of mechanisms underlying lesion growth and shrinkage in multiple sclerosis
Ermelinda De Meo1, Ferran Prados Carrasco1,2,3, J William L Brown4
1NMR Research Unit, Queen Square Multiple Sclerosis Centre, UCL Queen Square Institute of Neurology, University College London, London, UK.
Objective:
To assess the pathological mechanisms contributing to white matter (WM) lesion expansion or contraction and remyelination in multiple sclerosis (MS).
Methods:
We assessed 1,613 lesions in 49 people with relapsing-remitting MS in the CCMR-One bexarotene trial (EudraCT 2014-003145-99). We measured lesion orientation relative to WM tracts, surface-in gradients and veins. Jacobian deformation was used to assess lesion expansion over 6 months, while magnetization transfer ratio (MTR) imaging was used to assess remyelination.
Results:
At baseline, 33% of lesions were aligned with veins, 2% along WM tracts, 0% with surface-in gradients, and 4% orthogonal to veins. No significant differences were observed in lesion shape, while lesions aligned with surface-in gradients and with veins had lower volume compared to all remaining orientations. At follow-up, 13% of lesions expanded and 7% contracted. The directions for both expansion and contraction were 18% and 8%, respectively, along WM tracts, 20% and 15% parallel to veins, 22% and 23% orthogonal to veins and 0% and 1% along surface-in gradients. Bexarotene had no effect on lesion expansion or contraction, but MTR significantly increased in lesions aligned with surface-in gradients and veins.
Interpretation:
Lesion expansion and shrinkage are affected by venous and WM tract factors, but these do not influence bexarotene's capacity to promote remyelination. This, instead, appears to be affected by surface-in factors. To limit lesion expansion and maximize tissue repair, multiple processes may need to be targeted.
