Free water derived by multi-shell diffusion MRI reflects tau/neuroinflammatory pathology in Alzheimer's disease

Area of Science:

• Neuroimaging
• Neurology
• Biomarker Discovery

Background:

• Free-water (FW) imaging is a novel diffusion MRI analysis technique.
• FW imaging has potential to detect neuroinflammation and neurodegeneration.
• Its utility in Alzheimer's disease (AD) requires further validation.

Purpose of the Study:

• To evaluate the efficacy of FW imaging as a biomarker in Alzheimer's disease.
• To correlate FW imaging findings with tau/inflammatory and amyloid positron emission tomography (PET) markers.
• To assess the relationship between FW imaging and cognitive function in AD.

Main Methods:

• Seventy-one participants (40 healthy controls, 31 AD-spectrum) underwent multi-shell diffusion MRI, 18F-THK5351 PET, 11C-Pittsburgh compound B PET, and neuropsychological testing.
• Participants were classified into healthy controls and AD-spectrum groups based on amyloid PET and cognitive function.
• Analyses included group comparisons of FW and PET, and correlations between FW, PET markers, and cognitive scores.

Main Results:

• A significant positive correlation was observed between FW imaging and 18F-THK5351 uptake in the temporal lobes of the AD-spectrum group.
• Negative correlations were found between FW imaging and cognitive function in the temporal lobe and cingulate gyrus.
• Negative correlations were also identified between 18F-THK5351 uptake and cognitive function in these same regions.

Conclusions:

• FW imaging demonstrates potential as a biomarker for tau pathology in Alzheimer's disease.
• FW imaging findings correlate with cognitive decline in AD patients.
• This technique may serve as a valuable tool for assessing neuroinflammation and degeneration in AD.