title: Clinical implication of F-18 FDG PET/CT for differentiated thyroid cancer in patients with negative diagnostic iodine-123 scan and elevated thyroglobulin.
abstract: This study aims to investigate the usefulness of F-18 FDG PET/CT in differentiated thyroid cancer (DTC) with elevated serum thyroglobulin (Tg) but negative iodine-123 (I-123) scan.
  
  
  METHODS
  Twenty patients with histopathologically proven DTC, negative diagnostic I-123 scan, and elevated serum Tg levels were prospectively submitted to F-18 FDG PET/CT evaluation. The histopathologic findings consisted of 19 papillary thyroid cancers, 1 follicular thyroid cancer.
  
  
  RESULTS
  F-18 FDG PET/CT identified lesions in 18 out of 20 patients, giving a sensitivity of 90%. Thirteen of the 18 patients revealed limited loco-regional disease. Remaining 5 patients showed distant metastases, consisting of 4 patients with lung metastases and 1 patient with bone metastasis. Two patients revealed negative F-18 FDG PET/CT findings.
  
  
  CONCLUSIONS
  F-18 FDG PET/CT is suitable for the detection and precise localization of loco-regional recurrences and distant metastases of DTC in patients with elevated serum Tg but negative I-123 whole body scan.
authors.affiliation: Department of Nuclear Medicine, Pusan National University Hospital, Busan, Republic of Korea. growthkim@daum.net
authors.forename: Seong-Jang
authors.initials: SJ
authors.lastname: Kim
authors.forename: Tae Hong
authors.initials: TH
authors.lastname: Lee
authors.forename: In-Ju
authors.initials: IJ
authors.lastname: Kim
authors.forename: Yong-Ki
authors.initials: YK
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D005188:False Negative Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D014408:Biomarkers, Tumor; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D013954:Thyroglobulin