因18 氟- 去氧葡萄糖正子攝影斷層掃瞄/ 電腦斷層掃瞄的廣泛應用，意外發現甲狀腺顯影或偶見瘤之機會漸增。回顧文獻主要分為兩大類，一為甲狀腺瀰漫性顯影，盛行率約為0.6-4.5%，常見的病因為慢性甲狀腺炎、葛瑞夫氏症、橋本氏甲狀腺炎、甲狀腺低下症、及正常變異。惡性的機率和一般族群相似，故通常被認為是良性的疾病。臨床建議可檢測病人的甲狀腺功能及甲狀腺自體抗體以幫助診斷。另一大類為局部病灶型，又稱為甲狀腺偶見瘤，其盛行率約為1-4%，而有14-59%之機率為惡性腫瘤，其中又以甲狀腺乳突細胞癌為最常見。臨床建議要做的後續評估包括超音波及細針穿刺細胞學檢查，以排除癌症之可能。

Significant uptake of the thyroid is often identified on whole-body F18-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.