In general, [18F]DOPA PET/CT appears to be superior to [18F]FDG PET/CT in detecting and locating lesions in patients with recurrent MTC, especially when calcitonin exceeds 150 pg/mL, CEA is ≥5 ng/mL, or calcitonin DT is between 1 and 2 years. The gene discussed is CEACAM5; the disease is medullary thyroid gland carcinoma.