A radiotracer containing a synthetic amino acid analogue of L-leucine radiolabeled with fluorine F 18 with potential diagnostic imaging use. Similar to most amino acids, anti-1-amino-3-(18F)fluorocyclobutane-1-carboxylic acid ((18)FACBC) appears to enter cells through the energy-independent L-type amino acid transporter (LAT) system. As an amino acid analogue, this agent is preferentially accumulated by tumour cells due to their increased metabolic needs; however, unlike naturally occuring amino acids, this non-natural amino acid-analogue radiotracer is not metabolized. Accordingly, (18)FACBC accumulates in tumour cells and can potentially be used to image tumours using positron emission tomography (PET).