MAPT and Alzheimer disease: Both in vitro and in vivo assessments have indicated that [11C]PBB3 is capable of detecting diverse tau conformers, such as tau fibrils in AD and corticobasal degeneration.6 Other tau radioligands have also been applied to the detection of tau lesions in patients with PSP,8, 9, 10, 11, 12, 13, 14, 15 but evidence for the ability of PET imaging with these radiocompounds to separate PSP subjects from controls as well as the relationships between PET signals and clinical severity of PSP are still inconclusive.