Objective The percentage of patients with thyroid cancer incidentally diagnosed during a 18F-fluorodeoxyglucose Positron Emission Tomography with computed tomography (CT) (FDG-PET/CT) for nonthyroid diseases ranges between 26% and 50%. Design Retrospective assessment of the clinical and pathological features of thyroid incidentalomas at FDG-PET/CT, aiming to identify potential predictors of malignancy. Patients Fifty-two patients with incidental thyroid uptake at FDG-PET/CT were retrospectively included [38 W, age 64 ·1 ± 12 ·5 years (mean ± SD)]. An arbitrary cut-off level of 5 ·0 for the 'maximum standardized uptake value' (SUV max) was chosen to differentiate benign from malignant tumours. Complete thyroid function, neck ultrasonography (US) features, and cyto-histological results were reported for all cases. Results In our institution, the prevalence of incidental thyroid 18F-fluorodeoxyglucose (18F-FDG) uptake was nearly 1 ·76%. The prevalence of focal uptake correlated with greater risk of malignancy (P <0 ·01). In particular, the euthyroidism (P <0 ·003) and a SUV max >5 ·0 (P <0 ·0001) were associated with the diagnosis of thyroid cancer. Diffusely increased FDG-PET/CT uptake in the thyroid was related to benign conditions. Conclusions The presence of focal uptake with high SUV max and euthyroidism correlate with high likelihood of malignancy. Performing a neck US would have to be recommended in all patients with euthyroidism and an incidental FDG-PET/CT focal thyroid uptake. We do not suggest to use FDG-PET/CT as a screening tool for thyroid cancer in the general population, because of both its high cost and low incidence of thyroid incidentaloma at FDG-PET/CT.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism