Myelin volume fraction imaging with MRI.

Area of Science:

• Neuroimaging
• Biophysics
• Histology

Background:

• Magnetic Resonance Imaging (MRI) is crucial for studying myelin development and diseases.
• Current MRI techniques correlate with myelin but don't quantify total myelin volume fraction.
• Accurate myelin volume fraction is essential for assessing myelin microstructure, like calculating the g-ratio.

Purpose of the Study:

• To develop and validate a volumetric MRI model for absolute myelin volume fraction measurement.
• To compare MRI-derived myelin volume fraction with quantitative histology.
• To investigate MRI myelin measures' sensitivity to axon geometry and their potential for g-ratio estimation.

Main Methods:

• Developed a volumetric white matter model to relate MRI measures to myelin volume fraction.
• Validated the model in control mice and models of hypo- and hypermyelination.
• Compared MRI results with quantitative histology.

Main Results:

• The MRI volumetric model showed strong agreement with histological myelin volume fraction across different models.
• Demonstrated the sensitivity of MRI myelin measures to changes in axon geometry.
• Confirmed the potential for estimating the g-ratio using MRI.

Conclusions:

• The developed MRI volumetric model accurately quantifies myelin volume fraction.
• This method provides a reliable, non-invasive tool for myelin assessment in vivo.
• The approach holds significant promise for advancing the study of myelin-related disorders and microstructure.