FOLH1 and neoplasm: For diagnostic PET, tumor cells can be marked withfluoride 18F or other radiopharmacons attached to ligands that arecharacteristic for tumor cell metabolism, such as fluorodeoxyglucose (FDG), orligands that specifically bind to tumor cells, that is, prostate specific membraneantigen (PSMA) to detect prostate cancer cells.2 By using such imaging modalities, even small tumor cell clusters can bedetected in the human body.3