Modern Technology in Multi-Shell Diffusion MRI Reveals Diffuse White Matter Changes in Young Adults With...

Area of Science:

• Neuroimaging
• Neurology
• Biomedical Engineering

Background:

• Relapsing-remitting multiple sclerosis (RRMS) is characterized by white matter damage.
• Current imaging techniques have limitations in fully characterizing these microstructural changes.
• Advanced diffusion MRI offers potential for more detailed investigation.

Purpose of the Study:

• To characterize white matter microstructural changes in RRMS using advanced diffusion MRI.
• To explore associations between imaging findings and clinical symptoms (cognition, fatigue, depression).

Main Methods:

• High angular resolution diffusion imaging (HARDI) with multi-shell schemes and free water correction.
• Probabilistic tractography robust to crossing fibers and lesions.
• Tractometry for bundle-wise analysis and tract-profiling.
• Neuropsychological testing including cognitive, fatigue, and depression scales.

Main Results:

• Significant differences in 11 of 14 white matter bundles between RRMS patients and controls.
• Reduced fractional anisotropy and increased diffusivities indicating demyelination.
• Increased free water fraction in specific tracts (e.g., fornix).
• Evidence of axonal swelling and increased fiber complexity in some bundles.
• Depressive symptoms associated with diffusion abnormalities in the right superior longitudinal fasciculus.

Conclusions:

• Tissue-specific diffusion MRI measures reveal widespread white matter abnormalities in RRMS.
• The combined methodology (free-water imaging, advanced tractography) offers a novel approach for MS research.
• Advanced diffusion MRI provides deeper insights into demyelination, edema, and fiber alterations in RRMS.