In a glioma model, PET-MRI using [18F]-fluoroethyltyrosine ([18F]-FET) (amino acid metabolism) and N, N-diethyl-2-[4-(2-18 F-fluoroethoxy)phenyl]-5,7-dimethylpyrazolo[1,5-a]pyrimidine-3-acetamide ([18F]-DPA-714) (translocator protein) was applied to understand the role of glioma-associated microglia and macrophages (GAMMs) in glioma initiation, monitor in vivo therapy-induced GAMM depletion after colony-stimulating factor 1 receptor (CSF1R) targeted therapy, and observe GAMM repopulation after drug withdrawal [20]. The gene discussed is CSF1R; the disease is glioma.