Quantifying Extent, the Spatial Distribution of Flortaucipir PET Uptake, in an Autopsy Cohort and its Correspondence to Post‐Mortem Staining of Alzheimer’s Disease Biomarkers

In Alzheimer’s disease, neurofibrillary tangle (NFT) burden can be characterized in postmortem staining and in vivo NFT‐specific flortaucipir PET by increases in intensity and spatial distribution. Previous work compared intensity based standard uptake value ratios (SUVRs) from Early Tau and MUBADA volumes of interest (VOIs) in detecting Braak stage pathology. We propose a measure called Extent to quantify the spatial distribution of NFT‐specific uptake in flortaucipir PET from the Phase III study AV‐1451‐A16 and compare against Early Tau and MUBADA SUVRs in detecting Braak stage pathology and post‐mortem amyloid burden.