Localized Intense Uptake in the Skull on 18F-Flortaucipir PET/CT

18 F-Flortaucipir, as a classical Tau protein visualizer, has been widely used in the diagnosis of neurodegenerative diseases, especially Alzheimer disease. This report describes a case of intense uptake of 18 F-Flortaucipir at 2 sites of reduced bone mineral density in the skull, but no radioactivity uptake was seen on 18 F-FDG and 18 F-Florbetapir PET/CT imaging at the same lesion sites. The mechanism behind 18 F-Flortaucipir uptake in focal osteopenia remains unclear. This study provides evidence for the mechanism of the above phenomenon.