Tau PET overlap index correlation with neuropathological findings

Area of Science:

• Neuroimaging
• Neuropathology
• Biomarkers

Background:

• Tau positron emission tomography (PET) overlap index (OI) shows potential for improved signal-to-noise in longitudinal imaging.
• Early detection of tau pathology requires validation against neuropathological data.

Purpose of the Study:

• To validate the tau PET OI against neuropathological diagnoses.
• To compare the concordance of OI and standardized uptake value ratios (SUVRs) with neurofibrillary tangle (NFT) severity.

Main Methods:

• Fifty-seven participants with serial tau PET (flortaucipir) and autopsy data were analyzed.
• Tau PET OI and SUVRs were compared across different neuropathological diagnoses.

Main Results:

• Tau PET OI demonstrated higher concordance with entorhinal cortex NFT severity than SUVR, especially in early Braak stages (52.2% vs. 13.0% positivity).
• OI identified tau deposits spatially corresponding to immunohistochemical and autoradiography findings in both AD and non-AD tauopathies.

Conclusions:

• The OI enhances the detection of early and localized tau pathology in serial tau PET imaging.
• OI serves as a sensitive imaging metric for Alzheimer's disease and certain non-Alzheimer's tauopathies.