Diffusion-tensor MR imaging of cortical lesions in multiple sclerosis: initial findings

Area of Science:

• Neuroimaging
• Radiology
• Neurology

Background:

• Multiple sclerosis (MS) is a chronic demyelinating disease affecting the central nervous system.
• Cortical lesions are increasingly recognized as significant contributors to MS disability.
• Accurate characterization of MS cortical lesions is crucial for understanding disease progression.

Purpose of the Study:

• To prospectively measure fractional anisotropy (FA) and mean diffusivity (MD) directly within cortical lesions of multiple sclerosis (MS) patients.
• To investigate microstructural differences between MS cortical lesions and normal-appearing gray matter.

Main Methods:

• Acquisition of advanced magnetic resonance imaging (MRI) including diffusion-tensor imaging (DTI), double inversion-recovery (DIR), and phase-sensitive inversion-recovery (PSIR).
• Utilized nonlinear elastic image registration to precisely align diffusion-weighted images with DIR images.
• Defined regions of interest on cortical lesions identified on DIR and validated with PSIR images for FA and MD quantification.

Main Results:

• Significantly elevated FA and MD values were observed in MS cortical lesions compared to healthy control gray matter.
• Analysis of diffusion tensor imaging (DTI) histograms revealed a significant decrease in peak FA and a significant increase in peak MD in MS patients.
• These quantitative DTI metrics indicate distinct microstructural alterations within MS cortical lesions.

Conclusions:

• The combination of DIR, PSIR, and nonlinear image registration enables direct, focal measurement of FA and MD in MS cortical lesions.
• These findings provide direct evidence of microstructural abnormalities in MS cortical lesions using advanced MRI techniques.
• This methodology offers a potential tool for more precise assessment and monitoring of MS neuropathology.