MAPT and Alzheimer disease: Most show absent-to-weak binding to non-AD tauopathies (e.g., progressive supranuclear palsy [PSP], corticobasal degeneration [CBD], chronic traumatic encephalopathy, molecular subtypes of frontotemporal dementia [FTD]), although 18F-PI-2620 and 18F-PM-PBB3 are currently being evaluated as broader spectrum tau imaging agents.