title: Thyroid incidentalomas on FDG PET/CT in patients with non-thyroid cancer - a large retrospective monocentric study.
abstract: BACKGROUND
  The purpose of this study was to compare the incidence of thyroid cancer among patients with primary non-thyroid cancer, who showed focal thyroid uptake in (18)F-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT).
  
  
  METHODS
  We reviewed a total of 22,674 FDG PET/CTs performed at our institution between March 2005 and June 2011. A retrospective review was conducted on 433 non-thyroid cancer patients (male: n = 90, female: n = 343) who had thyroid incidentaloma on FDG PET/CT. In 286 patients, diagnostic confirmation was done by ultrasound-guided fine needle aspiration biopsy (FNAB).
  
  
  RESULTS
  Among 22,674 FDG PET/CT scans, 483 subjects (2.1%) showed focal thyroid uptake. Among the 286 patients who underwent FNAB, 280 were included in the study. Of those, 68 patients (24.3%) demonstrated papillary thyroid carcinoma on the final pathologic findings. We divided patients into 7 groups depending on the primary cancer.
  
  
  CONCLUSIONS
  In patients with cancer of non-thyroid origin, incidental FDG uptake in the thyroid gland was observed in 2.1% and associated with a 24.3% risk for well-differentiated thyroid carcinoma. However, there was no statistically significant difference in the malignant risk of focal FDG uptake of the thyroid gland according to the underlying primary non-thyroid cancer type.
authors.affiliation: Department of Nuclear Medicine, Pusan National University Hospital, Busan, Republic of Korea.
authors.forename: Heeyoung
authors.initials: H
authors.lastname: Kim
authors.forename: Seong-Jang
authors.initials: SJ
authors.lastname: Kim
authors.forename: In-Joo
authors.initials: IJ
authors.lastname: Kim
authors.forename: Keunyoung
authors.initials: K
authors.lastname: Kim
mesh_terms: D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000706:statistics & numerical data*; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D015995:Prevalence; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000453:epidemiology*; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18