title: What is the role of florine-18 fluorodeoxyglucose/positron emission tomography/computed tomography imaging in well-differentiated thyroid cancers with negative iodine-131 scan high thyroglobulin and normal anti-thyroglobulin levels.
abstract: OBJECTIVE
  This retrospective study aims to assess the cut-off value of thyroglobulin (Tg) levels in nux or metastatic well-differentiated thyroid cancers (DTCs) with normal anti-Tg levels using with fluorodeoxyglucose/positron emission tomography/computed tomography (FDG PET/CT).
  
  
  METHODS
  We reviewed FDG PET/CT images of 104 patients with well DTC (28 men, 76 women) whose: Iodine-131 (131 I) whole-body scanning was negative but had elevated Tg with normal anti-Tg levels.
  
  
  RESULTS
  The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of florine-18-FDG PET/CT findings were found to be 95.92%, 87.27%, 87.04%, 96.00%, and 91.35%, respectively. The best Tg cut-off value was found to be 10.4 ng/ml. In the Tg level <10.4 ng/ml group, the sensitivity, specificity, PPV, NPV, and accuracy of FDG PET/CT were found to be 94.1%, 91.30%, 88.8%, 95.4%, and 92.5%, respectively. In the other group, which Tg level ≥10.4 ng/ml, sensitivity, specificity, PPV, NPV, and accuracy of FDG PET/CT exams were found to be 96.8%, 84.3%, 86.1%, 96.4%, and 90.6%, respectively.
  
  
  CONCLUSIONS
  FDG PET/CT imaging is a valuable imaging method in the evaluation of patients with elevated serum Tg levels and normal anti-Tg levels. Furthermore, it has potential utility in the dedifferentiation of active foci that are present, and in assessing optimal decision making during follow-up.
authors.affiliation: Department of Nuclear Medicine, Cerrahpasa Medical Faculty, Istanbul University, Fatih, Istanbul, Turkey.
authors.forename: Rana Kaya
authors.initials: RK
authors.lastname: Döner
authors.affiliation: Department of Nuclear Medicine, Cerrahpasa Medical Faculty, Istanbul University, Fatih, Istanbul, Turkey.
authors.forename: Sait
authors.initials: S
authors.lastname: Sager
authors.affiliation: Department of Nuclear Medicine, Cerrahpasa Medical Faculty, Istanbul University, Fatih, Istanbul, Turkey.
authors.forename: Fatma Arzu
authors.initials: FA
authors.lastname: Görtan
authors.affiliation: Department of Nuclear Medicine, Cerrahpasa Medical Faculty, Istanbul University, Fatih, Istanbul, Turkey.
authors.forename: Özge Vural
authors.initials: ÖV
authors.lastname: Topuz
authors.affiliation: Department of Nuclear Medicine, Cerrahpasa Medical Faculty, Istanbul University, Fatih, Istanbul, Turkey.
authors.forename: Reşit
authors.initials: R
authors.lastname: Akyel
authors.affiliation: Department of Nuclear Medicine, Cerrahpasa Medical Faculty, Istanbul University, Fatih, Istanbul, Turkey.
authors.forename: Betül
authors.initials: B
authors.lastname: Vatankulu
authors.affiliation: Department of Oncology, Cerrahpasa Medical Faculty, Istanbul University, Fatih, Istanbul, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Baran
authors.affiliation: Department of Endocrine Surgery, Cerrahpasa Medical Faculty, Istanbul University, Fatih, Istanbul, Turkey.
authors.forename: Serkan
authors.initials: S
authors.lastname: Teksoz
authors.affiliation: Department of Nuclear Medicine, Cerrahpasa Medical Faculty, Istanbul University, Fatih, Istanbul, Turkey.
authors.forename: Kerim
authors.initials: K
authors.lastname: Sönmezoglu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers; D002648:Child; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000175:diagnosis* / Q000628:therapy; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D007457:Iodine Radioisotopes; C006606:anti-thyroglobulin; D019788:Fluorodeoxyglucose F18; D013954:Thyroglobulin