Cancer Risk of Focal Thyroid Incidentaloma in Patients Undergoing 18F-fluorodeoxyglucose Positron Emission Tomography–Computed Tomography Studies: Local Experience in a Single Centre

Full Article

BT Kung, CP Wong, KS Chu, TK AuYong, CM Tong

Hong Kong J Radiol 2010;13:120-4

Objectives: To determine the prevalence of focal thyroid fluorodeoxyglucose positron emission tomography– computed tomography incidentaloma in our locality and evaluate the rate of malignancy.

Methods: A retrospective review of 1407 individual patients who underwent fluorodeoxyglucose positron emission tomography–computed tomography imaging in a clinical positron emission tomography centre, Queen Elizabeth Hospital, from December 2006 to August 2007 was performed. Thyroid incidentaloma was generally regarded as any newly identified thyroid lesion encountered during imaging studies in patients without a history of thyroid disease. We defined it as an incidental finding of abnormally increased fluorodeoxyglucose uptake in the thyroid gland of a patient without a history of thyroid disease. Among identified patients, those who underwent further investigations were analysed using the electronic patient record system in our institution. Corresponding findings from surgical biopsy, fine needle aspiration, and histopathological findings were reviewed.

Results: Of 1407 subjects, 45 (3.2%) showed focal incidentaloma, 30 of whom were not followed up further, and in 15 (33%) a histopathological diagnosis was obtained. Among the latter, 6 (40%) of the thyroid lesions turned out to be malignant.

Conclusions: The point prevalence of focal thyroid incidentaloma identified by fluorodeoxyglucose positron emission tomography–computed tomography in this study was 3.2%. In all, 33% of focal thyroid incidentaloma patients underwent further histopathological investigation in our institution. In this study, there was no statistically significant difference in maximum standardised uptake value between malignant and benign nodules. Of those patients with focal thyroid incidentalomas that had been clinically selected for further investigation or surgery, 40% had malignant lesions. Further investigation of this patient group may be warranted lest it affects prognosis and management.






方法:回顧研究2006年12月至2007年8月期間伊利沙伯醫院臨床PET中心接受FDG PET-CT檢測的1407 位病人。甲狀腺偶發瘤的一般定義為本身並無甲狀腺病史的病人在影像學檢查中發現新的甲狀腺病 灶。本研究的定義為本身並無甲狀腺病史的病人在PET-CT檢查中發現其甲狀腺區FDG攝取異常增 加。透過本院的電子病歷系統,再分析這些病人的進一步檢查結果,回顧其手術切片、細針穿刺細 胞學檢查、及組織病理學有關結果。

結果:在1407名病人中,45名(3.2%)有甲狀腺偶發瘤,其中30名未有隨訪。餘下15名(33%)接 受組織病理學檢查的病人中,有6名(40%)的甲狀腺病灶為惡性。

結論:本研究發現局部甲狀腺偶發瘤的FDG PET-CT檢出率為3.2%。甲狀腺偶發瘤患者中有33%進一 步接受組織病理學檢查。比較惡性與良性的病灶顯示兩者的最大標準化FDG攝取值並無統計學顯著 性。進一步接受檢查或手術的病人中,有40%為甲狀腺惡性病變。為免影響預後及治療,應為有甲 狀腺偶發瘤的病人作進一步檢查。