Frecuencia de malignidad en incidentalomas tiroideos detectados con tomografía por emisión de positrones/ tomografía computada (PET/CT) con F18-FDG de cuerpo entero DaviD LaDrón De guevara h. 1 , cLauDia munizaga m. a , naTaLia garcía s. a , caroLina LeTeLier B. 2 , aLex wash F. 1 Frequency of malignancy in thyroid incidentalomas detected by whole body 18F-FDg PEt/Ct Background: Thyroid incidentalomas detected by 18 F-Fludeoxyglucose (FDG) PET/CT are defined as an incidental and unexpected thyroid focus present in a patient studied for a non-thyroid disease. Aim: To assess the frequency of malignancy of nodular thyroid incidentalomas, and their association with 18 F-FDG avidity (standard uptake value (SUV) max). Material and Methods: Whole body PET/CT performed from December 2008 to December 2017 were reviewed selecting those that showed nodular thyroid foci. Glands with diffuse increased uptake were excluded. Thyroid ultrasonography and fine-needle aspiration cytology (FNAC) performed after PET/CT were reviewed. Bethesda score and SUVmax were correlated. Results: Of 5,100 whole body 18F-FDG PET/CT, 119 showed a thyroid nodular uptake (2.3%). Forty eight percent of these patients were studied with FNAC or surgery, 50% of which (29/58) were confirmed as malignant. Benign nodules showed significantly lower 18 F-FDG uptake (n = 20,