SUVmax of 18F-FDG PET/CT in the differential diagnosis of benign and malignant thyroid nodules according to tumor volume

BACKGROUND The aim of this study was to investigate whether the maximum standardized uptake value (SUVmax) measured on fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) could be used as the primary means of differential diagnosis of thyroid nodules when tumor volume is assessed. METHODS We studied 192 patients who underwent preoperative 18F-FDG PET/CT followed by thyroidectomy. We evaluated the correlation between the volume of thyroid nodules, 18F-FDG uptake on visual analysis, and the mean SUVmax measured on 18F-FDG PET/CT. RESULTS When stratified by tumor volume, the mean SUVmax was higher in malignant than in benign nodules in nodules≥1 cm3 (p<0.001). However, it did not differ between benign and malignant nodules smaller than 1 cm3. At a cut-off value of SUVmax of 6, the respective sensitivities of 18F-FDG PET/CT, ultrasonography, and fine needle aspiration cytology were 60.8, 96.4, and 99.1%, and the respective specificities were 95.9, 98.2, and 96.8%. CONCLUSIONS 18F-FDG PET/CT is limited as a primary modality in the differential diagnosis of benign and malignant thyroid nodules because of its low sensitivity.