Altered diffusion tensor in multiple sclerosis normal-appearing brain tissue: cortical diffusion changes seem related...

Area of Science:

• Neuroimaging
• Neurology
• Biomedical Engineering

Background:

• Multiple sclerosis (MS) is a chronic neurological disease characterized by demyelination and axonal damage.
• Conventional MRI often underestimates the extent of tissue damage in MS, as lesions do not fully represent the disease's global impact.
• Diffusion Tensor Imaging (DTI) offers advanced insights into white and gray matter microstructural integrity.

Purpose of the Study:

• To separately investigate normal-appearing white matter (NAWM) and normal-appearing gray matter (NAGM) in MS patients using DTI.
• To assess microstructural changes in NAWM and cortical NAGM in vivo.
• To correlate DTI metrics with clinical disability in MS.

Main Methods:

• Acquisition of whole-brain apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps in 64 MS patients and 20 healthy controls using a stimulated echo acquisition mode (STEAM) DTI sequence.
• Identification of NAWM and NAGM using conventional magnetic resonance (MR) images.
• Histogram and regional analyses of ADC and FA values, followed by multiple linear regression to assess associations with clinical disability.

Main Results:

• Significant global FA decreases and ADC increases were observed in MS NAWM compared to controls.
• MS cortical NAGM showed significantly decreased FA and increased ADC in regional analyses.
• NAGM-ADC histogram peak height was more strongly associated with clinical disability than T2 lesion load in relapsing-remitting/secondary progressive MS patients.

Conclusions:

• Tissue damage is present in both NAWM and cortical NAGM in MS patients.
• Microstructural changes in cortical NAGM are significantly associated with clinical disability.
• DTI-derived metrics of cortical damage offer valuable prognostic information in MS, potentially exceeding that of T2 lesion load.