Differences in early and late mild cognitive impairment tractography using a diffusion tensor MRI.

Area of Science:

• Neuroimaging
• Neurology
• Biomarkers

Background:

• Alzheimer's disease (AD) progression is challenging to detect in its early stages.
• Mild cognitive impairment (MCI) represents a transitional phase, with subgroups like early MCI and late MCI requiring differentiation.
• Current diagnostic tools may benefit from advanced imaging biomarkers for earlier and more precise assessment.

Purpose of the Study:

• To investigate the utility of diffusion tensor MRI tractography in differentiating early and late MCI subgroups.
• To explore the potential of limbic system fiber connectivity as an imaging biomarker for early AD progression.
• To assess the correlation between this imaging feature and the apolipoprotein E epsilon 4 allele.

Main Methods:

• Diffusion tensor MRI tractography was applied to white and gray matter regions in an AD imaging database.
• Nerve fibers connecting to the hippocampus, thalamus, and amygdala were extracted using two algorithms: fiber assignment by continuous tracking and Runge Kutta.
• The number of fibers touching these regions of interest was quantified as the primary imaging feature.

Main Results:

• The quantified number of fibers successfully distinguished between early MCI and late MCI subgroups.
• This imaging feature demonstrated a significant correlation with the apolipoprotein E epsilon 4 allele, a known AD genetic marker.
• Tractography analysis extended beyond white matter to include AD-affected gray matter regions.

Conclusions:

• Diffusion tensor MRI tractography, specifically analyzing limbic system fiber connectivity, can differentiate MCI subgroups.
• The number of fibers touching key brain regions may serve as a valuable imaging biomarker for early AD detection.
• This approach could complement existing region of interest-based biomarkers in AD research and clinical practice.