CALCA and medullary thyroid gland carcinoma: 18F-FDG PET/CT is often performed in selected MTC patients with suspected dedifferentiated tumors with short calcitonin-doubling times or when 18F-DOPA and 68Ga-DOTATATE are unavailable [13, 41], explaining the paucity of 18F-FDG PET/CTs available for this study.