Several PET radiotracers have been trialled for imaging prolactinomas, including 11C-raclopride and 11C-N-methylspiperone (dopamine D2 receptor ligands) [35, 36], 18F-fluorodeoxyglucose (metabolic activity as per the Warburg effect) [37, 38], and 11C-methionine [taken up via the L-type amino acid transporter 1 (LAT1) at sites of peptide synthesis] [38–41]. This evidence concerns the gene SLC7A5 and prolactin-producing pituitary gland adenoma.