Myelin water imaging reflects clinical variability in multiple sclerosis

Area of Science:

• Neuroimaging
• Radiology
• Neurology

Background:

• Conventional MRI in multiple sclerosis (MS) shows poor correlation between clinical disability and disease markers in primary progressive MS (PPMS).
• PPMS is characterized by diffuse and global myelin loss, necessitating advanced imaging techniques.
• Myelin water fraction (MWF) imaging offers a potential method to quantify myelin content.

Purpose of the Study:

• Evaluate the efficacy of whole-brain MWF imaging in PPMS.
• Determine the reproducibility of MWF estimates in PPMS.
• Compare MWF values between PPMS patients and healthy controls.
• Establish the relationship between MWF and clinical disability in PPMS.

Main Methods:

• Seventeen PPMS patients and seventeen age-matched controls underwent whole-brain multi-component relaxation imaging to measure MWF.
• MWF reduction analysis included histogram, white matter skeleton, and voxel-wise approaches.
• Correlations were performed between MWF values and clinical disability measures (Expanded Disability Status Scale).

Main Results:

• PPMS patients exhibited significantly reduced global normal-appearing white matter MWF (6%, p=0.04) compared to controls.
• Focal lesions showed substantially lower MWF values than white matter in both groups.
• Diffuse MWF reduction along the white matter skeleton correlated significantly with increased clinical disability, particularly in specific brain regions.
• A significant correlation was found between the volume of significantly reduced MWF and overall clinical disability (p=0.008, R=0.58).

Conclusions:

• Whole-brain MWF imaging is reproducible and sensitive to diffuse myelin loss in PPMS.
• Reduced MWF in specific white matter regions reflects clinical disability in PPMS patients.
• MWF imaging provides a valuable tool for assessing disease activity and progression in PPMS.