MAPT and supranuclear palsy, progressive, 1: Several studies in PSP have explored the association between changes in clinical severity and in vivo neuroimaging markers for microglial activation (eg, [11C]PK11195 PET8 9), tau pathology (eg, [18F]AV-1451 PET19 22–25) and atrophy (eg, structural MRI26–28).