Through our efforts to develop new TSPO ligands, we now report the synthesis and in vitro and in vivo evaluation of the novel 18F-labelled 2-phenyl-imidazo[1,2-a]pyridine analogue [18F]1, named [18F]CB251 in Fig. 1, as a TSPO-selective PET radiotracer that is useful for imaging activated microglia, as well as TSPO-rich brain tumours. Here, TSPO is linked to brain neoplasm.