To date, only two PET radiotracers are available to image astrogliosis.5 Of these, the most well-known is 11C-deuterium-L-deprenyl (11C-DED), which binds irreversibly to the monoamine oxidase-B (MAO-B) and has been used to study Alzheimer’s disease, Creutzfeldt-Jakob disease, amyotrophic lateral sclerosis, and focal epilepsy.6–9 MAO-B is expressed on the outer mitochondrial membrane and is highly related with astrocytes. Here, MAOB is linked to early-onset autosomal dominant Alzheimer disease.