Prevalence and clinical significance of incidental uptake in F18 fluordeoxyglucose positron emission tomography/computed scanning in the thyroid gland

BACKGROUND
Expanding use of 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) has resulted in an increased frequency of thyroid incidentalomas. The study aimed to determine the prevalence of thyroid incidentalomas, the risk of cancer and the usefulness of maximum standard uptake value (SUVmax) for detecting malignancy.
MATERIAL AND METHODS
The study reviewed FDG PET-CT performed at our institution from 2013 to 2020. When investigated, a benign or malignant diagnosis was established.
RESULTS
1.8% of patients had an FDG thyroid uptake from 21594 studies performed. Among focal incidentalomas with further investigation, the rate of malignancy was 26.5% and the SUVmax value was higher in benign than in malignant lesions (10.6 [3.1–51.2] and 5.7[2.3–66], p <0.05). 23.3% of malignant diagnoses were related to potentially aggressive tumours.
CONCLUSION
The high rates of malignancy suggest the need for a standardised approach for focal thyroid incidentalomas discovered on an FDG PET-CT.