In the case of dedifferentiated thyroid cancer, two meta-analyses demonstrated that diagnostic sensitivity increases with the use of PET/CT for the detection of residual disease or recurrence in cases with elevated Tg levels and no evidence of RAI uptake [15,16]. For this reason, the ATA guidelines strongly recommend performing this study in high-risk patients with elevated Tg and negative RAI imaging [7]. The gene discussed is TG; the disease is thyroid gland carcinoma.