Clinical significance of incidental thyroid uptake on F18- fluorodeoxyglucose positron emission tomography

Significant uptake of the thyroid is often identified on whole-body F ¹⁸-fluorodeoxyglucose positron emission tomography (FDG-PET/CT) at who performed this exam for the reason other than thyroid malignancy. The prevalence of diffuse type uptake image is about 0.6-4.5%, can be considered at low risk of malignancy. Chronic thyroiditis and autoimmune thyroiditis are the common etiology. Checking autoimmune thyroid antibodies and thyroid function evaluation are suggested. Focal uptake on FDG-PET/CT was thyroid incidentaloma or named as thyroid PEToma, having the prevalence of 1-4%. Which are more likely to have malignancy (14-59%) and the most diagnosis is papillary thyroid cancer. The usefulness for differentiation of standardized uptake value is still no consensus. Further evaluation such as fine-needle aspiration cytology or surgical intervention is suggested.