Diffusion tensor tractography-based group mapping of the pyramidal tract in relapsing-remitting multiple sclerosis...

Area of Science:

• Neuroimaging
• White Matter Diseases
• Diffusion Tensor Imaging

Background:

• Relapsing-remitting multiple sclerosis (RRMS) is characterized by white matter abnormalities.
• Previous studies used histogram and region-of-interest methods, but specific fiber tract changes remain understudied.

Purpose of the Study:

• To investigate abnormal diffusion in the normal-appearing pyramidal tract (PYT) of RRMS patients using diffusion tensor tractography-based group mapping.
• To explore the underlying mechanism of these diffusion changes.

Main Methods:

• Constructed a PYT probability map from 20 healthy controls using deterministic tractography.
• Applied the map to 29 RRMS patients to calculate diffusion indices: fractional anisotropy (FA), directionally averaged diffusion coefficient (D(av)), axial diffusion coefficient (λ1), and radial diffusion coefficient (λ23).

Main Results:

• RRMS patients showed higher D(av) and λ23, and lower FA in the normal-appearing PYT compared to controls.
• PYT lesions in RRMS patients exhibited higher λ23 and lower FA than normal-appearing PYT.
• Diffusion indices in normal-appearing PYT correlated significantly with PYT lesion volumes.

Conclusions:

• Confirmed abnormal diffusion in the normal-appearing PYT of RRMS patients.
• Suggests Wallerian degeneration as the likely mechanism for these observed changes.