White matter/gray matter contrast changes in chronic and diffuse traumatic brain injury

Area of Science:

• Neuroimaging
• Neurology
• Brain Injury Research

Background:

• T1-weighted MRI signal intensity contrast reflects tissue integrity.
• Neurodegenerative diseases and traumatic brain injury (TBI) involve progressive white matter (WM) and gray matter (GM) changes.
• Understanding chronic TBI structural alterations is crucial for patient outcomes.

Purpose of the Study:

• Characterize regional WM/GM intensity contrast patterns in chronic diffuse TBI.
• Assess associations between WM/GM contrast and diffusion tensor imaging (DTI)/fractional anisotropy (FA) for WM damage detection.
• Investigate correlations of WM/GM contrast and FA with cognitive function.

Main Methods:

• Processed T1-weighted MRI scans using FreeSurfer to calculate WM/GM contrast maps.
• Analyzed diffusion tensor images (DTIs) using FMRIB software library to obtain fractional anisotropy (FA) maps.
• Correlated WM/GM contrast and global FA values with cognitive test results.

Main Results:

• WM/GM contrast reduction observed across most brain regions in TBI patients, sparing primary visual and motor areas.
• Global FA values correlated with intensity contrast in associative cerebral regions.
• WM/GM contrast correlated with memory functions; global FA correlated with memory and mental processing speed.

Conclusions:

• Tissue-contrast intensity is a sensitive marker for structural brain damage in chronic, severe, diffuse TBI.
• Fractional anisotropy (FA) is more sensitive than WM/GM contrast for reflecting neuropsychological deficits like impaired processing speed.
• Combined imaging approaches offer comprehensive insights into TBI-related brain changes and cognitive impact.