MAPT and Alzheimer disease: Noteworthy, preliminary data also suggest that [18F]PI-2620 might not only be able to visualize the 3R/4R tau isoform combination in AD, but also the 4R isoform in 4R-tauopathies such as PSP/CBD (https://www.alzforum.org/news/conference-coverage/next-generation-tau-pet-tracers-strut-their-stuff).