Progressive change in primary progressive multiple sclerosis normal-appearing white matter: a serial diffusion...

Area of Science:

• Neuroimaging
• Neurology
• Biomedical Engineering

Background:

• Primary progressive multiple sclerosis (PPMS) is characterized by significant disability despite smaller visible lesions on conventional MRI.
• Damage in normal-appearing brain tissue (NABT) is hypothesized to contribute to PPMS pathogenesis.
• Diffusion-weighted MRI (DW-MRI) offers insights into microstructural tissue changes by probing water diffusion.

Purpose of the Study:

• To investigate diffusion changes in the NABT of PPMS patients over one year using DW-MRI.
• To explore the relationship between diffusion changes, lesion volume, and clinical disability in PPMS.

Main Methods:

• DW-MRI was used to measure the average apparent diffusion coefficient (ADCav) in 10 regions of interest within the normal-appearing thalamus and normal-appearing white matter (NAWM).
• Measurements were taken over one year in 15 PPMS patients and compared to six healthy controls.
• Correlation analysis was performed between ADCav, T2/T1 lesion volumes, and the MS Functional Composite Measure for disability assessment.

Main Results:

• PPMS patients exhibited an increase in ADCav in NAWM over 12 months, unlike healthy subjects.
• This increase in ADCav was associated with growing T2 and T1 lesion volumes.
• ADCav in frontal NAWM correlated with patient disability scores on the MS Functional Composite Measure.

Conclusions:

• Serial DW-MRI can detect progressive microstructural changes in the NAWM of PPMS patients.
• The findings suggest a partial link between the pathological processes affecting NAWM and lesion formation in PPMS.
• DW-MRI-assessed changes in water diffusion within NAWM are clinically relevant for understanding PPMS progression and disability.