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Updated: Jun 14, 2026
Comprehensive Autopsy Program for Individuals with Multiple Sclerosis
Published on: July 19, 2019
Water content changes in new multiple sclerosis lesions have a minimal effect on the determination of myelin water
Irene M Vavasour1,2, Kimberley L Chang3, Anna J E Combes4
1Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada.
Background And Purpose:
Myelin water fraction (MWF) is a histopathologically validated in vivo myelin marker. As MWF is the proportion of water with a short T2 relative to the total water, increases in water from edema and inflammation may confound MWF determination in multiple sclerosis (MS) lesions. Total water content (TWC) measurement enables calculation of absolute myelin water content (MWC) and can be used to distinguish edema/inflammation from demyelination. We assessed what influence changes in total water might have on MWF by calculating MWC values in new MS lesions.
Methods:
3T 32-echo T2 relaxation data were collected monthly for 6 months from six relapsing-remitting MS participants. TWC was determined and multiplied with MWF images to calculate corrected MWC images. The effect of this water content correction was examined in 20 new lesions by comparing mean MWF and MWC over time.
Results:
On average, at lesion first appearance, lesion TWC increased by 6.4% (p = .003; range: -1% to +21%), MWF decreased by 24% (p = .006; range: -70% to +12%), and MWC decreased by 20% (p = .026; range: -68% to +21%), relative to prelesion values. Average TWC in lesions then gradually decreased, whereas MWF and MWC remained low. The shape of the MWF and MWC lesion evolution curves was nearly identical, differing only by an offset.
Conclusion:
MWF mirrors MWC and is able to monitor myelin in new lesions. Even after taking into account water content increases, MWC still decreased at lesion first appearance attributed to demyelination.
Insights
Myelin water fraction (MWF) can accurately monitor myelin loss in multiple sclerosis (MS) lesions. Correcting for total water content confirms demyelination, even with increased fluid in lesions.
Area of Science:
- Neuroimaging
- Biomarkers
- Multiple Sclerosis Research
Background:
- Myelin water fraction (MWF) is a validated in vivo marker for myelin.
- Edema and inflammation can increase total water content (TWC), potentially confounding MWF measurements in multiple sclerosis (MS) lesions.
- Calculating absolute myelin water content (MWC) using TWC can differentiate demyelination from edema/inflammation.
Purpose of the Study:
- To assess the influence of changes in TWC on MWF in new MS lesions.
- To calculate MWC values and compare them with MWF over time in MS lesions.
Main Methods:
- Collected 3T 32-echo T2 relaxation data monthly for 6 months from six relapsing-remitting MS participants.
- Determined TWC and multiplied it with MWF images to calculate corrected MWC images.
- Examined the effect of water content correction in 20 new lesions by comparing mean MWF and MWC over time.
Main Results:
- At lesion appearance, TWC increased by 6.4%, MWF decreased by 24%, and MWC decreased by 20% relative to prelesion values.
- TWC gradually decreased in lesions over time, while MWF and MWC remained low.
- The evolution curves for MWF and MWC were nearly identical, differing only by an offset.
Conclusions:
- MWF effectively mirrors MWC and can monitor myelin in new MS lesions.
- MWC decreased at lesion onset, confirming demyelination even after accounting for increased water content.
