High-b diffusivity of MS lesions in cervical spinal cord using ultrahigh-b DWI (UHb-DWI)

Area of Science:

• Neuroimaging
• Diffusion-weighted MRI
• Spinal Cord Imaging

Background:

• Multiple Sclerosis (MS) involves white matter damage in the central nervous system.
• Cervical spinal cord (CSC) white matter is frequently affected in MS.
• Quantitative MRI techniques are needed to characterize MS lesions in the CSC.

Purpose of the Study:

• To investigate the signal characteristics of high b-value diffusion-weighted imaging (Hb-DWI) in the CSC white matter.
• To compare quantitative diffusion values between healthy controls, normal-appearing white matter (NAWM) in MS patients, and MS lesions within the CSC.

Main Methods:

• Hb-DWI data were acquired from 7 MS patients with CSC lesions and 7 healthy controls using a 3T MRI scanner.
• Axial images utilized a 2D single-shot DW stimulated EPI sequence with reduced FOV and a CSC-dedicated coil.
• High-b diffusion coefficient (D_H) was calculated by fitting signal-b curves to mono- or bi-exponential functions.

Main Results:

• Averaged D_H values in MS posterior column lesions were significantly higher (0.767 × 10^-3 mm²/s) than in healthy control posterior (0.0312 × 10^-3 mm²/s) and lateral columns (0.0505 × 10^-3 mm²/s).
• Signal-b curves in MS patients showed faster decay and lower signal intensities compared to healthy controls.
• Distinct differences in signal-b curves and D_H values were observed between MS lesions, NAWM, and healthy control white matter.

Conclusions:

• Hb-DWI effectively differentiates MS lesions in the CSC from healthy white matter.
• Altered quantitative diffusion values are indicative of demyelination in MS.
• Further research, including animal models, is necessary to fully elucidate the role of Hb-DWI in demyelination and remyelination processes.