18F-radioactivity uptake and washout in the brain of mouse models of AD. Dynamic PET scans were performed for 60 min after [18F]flutemetamol injection, and presented time-radioactivity curves represent 18F-radioactivity uptake and washout in the frontal cortex (FC) and cerebellum (CB), expressed as percent of the injected dose (ID) per gram of brain tissue (%ID/g). Data are representative of (a) APP23 (21 months), (b) Tg2576 (22 months) and (c) APPswe-PS1dE9 (19 months) transgenic mice. (Insets) FC/CB ratios were calculated for 60 min dynamic scans. Only APP23 mice showed higher 18F-radioactivity in FC than in CB in the later time frames; thus, they had increasing FC-to-CB ratios.