MAPT and supranuclear palsy, progressive, 1: Compared to using the conventional inferior cerebellar GM tau-PET reference [49], we found that referencing [18F]PI-2620 to the novel temporo-orbital WM reference yielded (i) stronger bilateral basal ganglia tau-PET signal in PSP vs. HC, (ii) larger group differences between PSP vs. disease controls in 4R target regions, and (iii) significant associations of pallidum [18F]PI-2620 PET signal with clinical disease severity.