TG and metastatic neoplasm: In the post-operative follow-up scenario, 18F-FDG PET/CT can be used to identify lesions in patients in whom there is a suspicion of non-iodine–avid metastatic disease (based on elevated basal and/or stimulated Tg and negative radioiodine scan, i.e., Tg+/scan), classically termed as ‘TENIS’.