Multiexponential T2 and Magnetization Transfer MRI of Demyelination and Remyelination in Murine Spinal Cord

Neuroimage, 2009 · DOI: 10.1016/j.neuroimage.2008.12.071 · Published: May 1, 2009

Simple Explanation

This study uses a mouse model to investigate demyelination and remyelination in the spinal cord, similar to what happens in multiple sclerosis. Lysolecithin is injected to cause demyelination, and then the body naturally tries to repair the damage. The researchers used two types of MRI (qT2 and MTR) to measure changes in the myelin (the protective coating around nerve fibers) over time. These MRI techniques provide quantitative measures of myelin content. The MRI results were compared with traditional staining methods (histology) to confirm the presence of demyelination and remyelination. The aim was to see if the MRI methods could accurately track these changes in the spinal cord.

Study Duration

4 weeks

Participants

Adult (6-8 week, 23-29 g) C57BL/6 male mice

Evidence Level

Not specified

Key Findings

1
The myelin water fraction (MWF) and geometric mean T2 value significantly decreased at 14 days post-injection, indicating demyelination. By 28 days, these values returned to control levels, suggesting remyelination.
2
The magnetization transfer ratio (MTR) was significantly decreased at 14 days post-injection and remained low over the entire 28-day study period. This suggests that MTR may not fully recover with remyelination in this model.
3
The study found that changes detected by qT2 (specifically MWF) more closely matched the time course of myelin changes observed with histological staining compared to MTR, suggesting qT2 may be a more sensitive measure of remyelination in this model.

Research Summary

This study investigated the use of quantitative MRI techniques (qT2 and MTR) to assess demyelination and remyelination in a mouse model of multiple sclerosis. Lysolecithin was injected into the spinal cord to induce demyelination, followed by spontaneous remyelination. The study found that myelin water fraction (MWF) as measured by qT2 decreased during demyelination and returned to control levels during remyelination, mirroring histological findings. However, magnetization transfer ratio (MTR) remained low throughout the study, even after remyelination. The results suggest that qT2, particularly MWF, may be a more sensitive marker of remyelination than MTR in this lysolecithin-induced demyelination model. The difference between qT2 and MTR changes may provide additional insights into the early stages of remyelination.

Practical Implications

Improved MRI techniques for MS

The study suggests that multicomponent T2 MRI, specifically myelin water fraction (MWF), may be a more sensitive and accurate tool for monitoring myelin changes in MS patients compared to traditional MTR.

Understanding Remyelination

The research provides insights into the complex process of remyelination and highlights the differences in sensitivity between different MRI markers. This could lead to a better understanding of the mechanisms underlying remyelination and how to promote it.

Therapeutic Development

The study provides a non-invasive method for evaluating the effectiveness of potential remyelinating therapies in preclinical studies. By using qT2 and MTR, researchers can track myelin changes in vivo and assess the impact of different treatments.

Study Limitations

1
The study was conducted in a mouse model of demyelination, which may not fully reflect the complexity of MS lesions in humans.
2
MTR values did not return to control levels with early remyelination.
3
Lack of electron microscopy for definitive assessment of the remyelination.

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