To investigate the brain penetration of [18F]Favipiravir between normal and neurodegenerative disease conditions, we performed PET imaging studies with [18F]Favipiravir in transgenic AD mice (5 × FAD; strain name: B6SJL-Tg(APPSwFlLon, PSEN1*M146L*L286V)6799Vas/Mmjax) and wild-type (WT) mice. The gene discussed is PSEN1; the disease is Alzheimer disease.