title: The incidence of 18F-FDG PET/CT thyroid incidentalomas andthe prevalence of malignancy: a prospective study.
abstract: OBJECTIVE
  To determine the prevalence of malignancy in thyroid incidentalomas (TIs) detected by fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT).
  
  
  METHODS
  18F-FDG PET/CT images were evaluated prospectively for the presence of thyroid uptake. The patients with a TI were evaluated by an endocrinologist according to the predefined diagnostic algorithm. The final diagnosis was obtained clinically and/or by pathology.
  
  
  RESULTS
  TI was detected in 4.2% of 4204 patients. A malignant thyroid nodule was diagnosed in 29% and 33% of the focal and diffuse-focal uptake groups, respectively. However, no malignancy was detected in the diffuse uptake group. The standardized maximum uptake values (SUVmax) of the nodules were significantly higher in patients with thyroid malignancy than in patients with benign nodules (P = 0.006). The calculated cut-off value of SUVmax for malignancy was 3.5. In 2 patients in whom the cytopathological diagnosis was benign, malignancy was diagnosed after total thyroidectomy.
  
  
  CONCLUSIONS
  A malignant nodule was present in one-third of the patients with focal or diffuse-focal uptake. A SUVmax value of 3.5 was considered as a cut-off value for the differentiation of a malignant lesion. Benign cytology in fine-needle aspiration biopsy for 2 patients underestimated a thyroid malignancy.
authors: Department of Nuclear Medicine, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
authors: Mine
authors: M
authors: Şencan Eren
authors: Department of Nuclear Medicine, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
authors: Özhan
authors: Ö
authors: Özdoğan
authors: Department of Internal Medicine, Division of Endocrinology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
authors: Arzu
authors: A
authors: Gedik
authors: Department of Radiology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
authors: Mehmet
authors: M
authors: Ceylan
authors: Department of Pathology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
authors: Merih
authors: M
authors: Güray Durak
authors: Department of Radiology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
authors: Mustafa
authors: M
authors: Seçil
authors: Department of Surgery, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
authors: Mehmet Ali
authors: MA
authors: Koçdor
authors: Department of Internal Medicine, Division of Endocrinology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
authors: Abdurrahman
authors: A
authors: Çömlekçi
authors: Department of Nuclear Medicine, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
authors: Hatice
authors: H
authors: Durak
mesh_terms: D019788:Fluorodeoxyglucose F18; D006801:Humans; D015994:Incidence; D000072078:Positron Emission Tomography Computed Tomography; D015995:Prevalence; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D013964:Thyroid Neoplasms; D016606:Thyroid Nodule; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG; PET scan; cancer; prevalence; second primary; thyroid