Functional pathway-defined MRI diffusion measures reveal increased transverse diffusivity of water in multiple...

Area of Science:

• Neuroimaging
• Neurology
• Biophysics

Background:

• Water diffusion properties are sensitive to microscopic white matter changes in multiple sclerosis (MS).
• Standard MRI measures of disease burden in MS often show weak correlations with patient disability.
• Advanced MRI techniques may offer more sensitive indicators of neurological changes and functional impact.

Purpose of the Study:

• To investigate diffusion properties of the interhemispheric white matter pathway connecting supplementary motor areas (SMA) in MS patients.
• To assess the correlation between diffusion metrics and clinical disability in MS.
• To explore the utility of advanced MRI in reflecting disease status more accurately.

Main Methods:

• Utilized functional MRI and Diffusion Tensor Imaging (DTI)-based fiber tracking.
• Defined the white matter pathway connecting bilateral SMA in 16 MS patients and 16 controls.
• Measured Fractional Anisotropy (FA), Mean Diffusivity (MD), and longitudinal (λ1) and transverse (λ2) diffusivity along the SMA pathway.

Main Results:

• MS patients exhibited significantly lower mean FA and higher mean MD, λ1, and λ2 compared to controls (P < 0.02).
• Transverse diffusivity (λ2) showed a significant negative correlation with the Multiple Sclerosis Functional Composite (MSFC) (r = -0.341, P < 0.05).
• The Nine-hole Peg Test, a component of MSFC, correlated significantly with transverse diffusivity (r = 0.392, P < 0.02).

Conclusions:

• Diffusion MRI metrics, particularly transverse diffusivity, reflect white matter microstructural changes in MS.
• Probing functional pathways with advanced MRI measures, like DTI, provides a better reflection of MS disease status and disability.
• These findings suggest potential for improved monitoring and assessment of MS progression using diffusion MRI of specific white matter tracts.