The Role of 18F-Fluorodeoxyglucose Positron Emission Tomography in the Prognostication, Diagnosis, and Management of Thyroid Carcinoma.

18F-fluorodeoxyglucose positron emission tomography (FDG-PET) plays an increasingly important role in the prognostication, diagnosis, and management of thyroid carcinoma. For patients diagnosed with primary or persistent/recurrent thyroid carcinoma, a finding of FDG-PET positivity implies a more aggressive tumor biology and a distinct mutational profile, both of which carry prognostic significance. Therefore, FDG-PET positivity may be a useful potential risk factor for preoperative risk stratification in primary thyroid carcinoma. This information may help in the planning of subsequent treatment strategy such as the extent of thyroidectomy, prophylactic central neck dissection, and radioiodine ablation. FDG-PET scan has also been found to be a useful adjunct in characterizing indeterminate thyroid nodules on fine needle aspiration cytology. However, larger-sized prospective studies are required to validate this finding. FDG-PET or FDG-PET/CT scan has become the imaging of choice in patients with a negative whole-body radioiodine scan, but with an abnormally raised thyroglobulin level after total thyroidectomy and radioiodine ablation.