Because FFDI demonstrated similar or even superior potency in the cells to that of the standard iNOS inhibitors such as L-NMMA, FEITU, or MITU [14], therefore, in this report, based on FFDI, we developed (4′-amino-5′,8′-difluoro-1′H-spiro[piperidine-4,2′-quinazolin]-1-yl)(4-[18F]fluorophenyl)methanone ([18F]FBAT) as a tracer to detect iNOS expression in mice injected with lipopolysaccharide (LPS) to induce brain inflammation. The gene discussed is NOS2; the disease is brain inflammatory disease.