Background Our aim was to evaluate the role of the Thyroid Imaging Reporting and Data System (TIRADS) in the risk stratification of thyroid incidentalomas detected on 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG-PET/CT) scans. Methods Eighty-seven thyroid nodules in 84 patients showing incidentally detected increased uptake on 18F-FDG-PET/CT who also had ultrasonography (US)-guided fine needle aspiration performed were included. On review of the US images, a TIRADS category was assigned to each thyroid nodule based on the number of suspicious US features. The correlation between the TIRADS category and the standard uptake values (SUV) on 18F-FDG-PET/CT were calculated and compared. Results Of the 87 thyroid nodules, 47 (54%) were benign, and 40 (46%) were malignant. The malignancy rate of the TIRADS categories were as follows: 9% for category 3, 15% for category 4a, 39% for category 4b, 72% for category 4c, and 100.0% for category 5. Combining the TIRADS with the SUV showed increased specificity and positive predictive value but decreased sensitivity and negative predictive value compared with TIRADS alone (all P < .05). The area under the receiver operating characteristics curve value of TIRADS was the greatest, comparable with the combined TIRADS and SUV (0.737 to 0.724, P = .788). Conclusion TIRADS may be applied in the risk stratification of thyroid incidentalomas detected on 18F-FDG-PET/CT. Considering the high malignancy rate of thyroid incidentalomas showing increased 18F-FDG uptake, ultrasonography-guided fine needle aspiration is mandatory even if there are no suspicious features present on US.
All Science Journal Classification (ASJC) codes