Infrequent false positive [ 18 F]flutemetamol PET signal is resolved by combined histological assessment of neuritic and diffuse plaques

The performance of [ F]flutemetamol amyloid PET against histopathological standards of truth was the subject of our recent article in Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring (2017;9:25-34). This viewpoint article addresses infrequently observed discordance between visual [ F]flutemetamol PET image readings and histopathology based solely on neuritic plaque assessment by CERAD criteria, which is resolved by assessing both neuritic and diffuse plaques and/or brain atrophy. [ F]flutemetamol PET signal corresponds predominantly to neuritic plaque pathology but is also influenced by the presence of diffuse plaques. This could allow for detection of diffuse amyloid deposits in the early stages of AD dementia, particularly in the striatum where diffuse amyloid is most commonly observed.