title: The local efficacy of I-131 for F-18 FDG PET positive lesions in patients with recurrent or metastatic thyroid carcinomas.
abstract: OBJECTIVE
  The aim of this study was to evaluate the local efficacy of I-131 for F-18 fluorodeoxyglucose positron emission tomography (FDG PET)-positive lesions.
  
  
  METHODS
  Whole-body FDG PET/CT was performed on 37 patients (55 cases: 16 men, 21 women; age range: 24-82 years; mean age ± standard deviation: 60.5 ± 16.0 years) with differentiated thyroid cancer after total thyroidectomy. The metastatic or recurrent lesions were divided into 5 categories: primary tumor bed, lymph node, lung, bone, and other. The well-defined lesions were measured on CT, and the sizes were compared before and after radioactive iodine therapy.
  
  
  RESULTS
  The analysis was performed on 37 patients with 44 lesions (lymph node:24, lung:16, bone:4). Sixteen lesions (70%) were increased and 7 (30%) showed no change or reduction when there was positive accumulation on FDG PET/CT and negative accumulation on I-131 (F(+)I(-)) group. In the positive accumulation for both FDG PET/CT and I-131 (F(+)I(+)) group, 5 lesions (63%) were increased and 3 (37%) showed no change or reduction. There was no significant difference for the tendency to increase in size between the F(+)I(-) and the F(+)I(+) groups.
  
  
  CONCLUSIONS
  Lesions which show positive accumulations on FDG PET/CT have a greater tendency to increase in size. FDG-avid lesions are resistant to radioactive iodine therapy with or without I-131 uptake.
authors.affiliation: Department of Radiology, Okayama University Hospital, Kita-ku, Okayama, Japan. ko.taro1201@gmail.com
authors.forename: Kotaro
authors.initials: K
authors.lastname: Yoshio
authors.forename: Shuhei
authors.initials: S
authors.lastname: Sato
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Okumura
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Katsui
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Takemoto
authors.forename: Etsuji
authors.initials: E
authors.lastname: Suzuki
authors.forename: Norihisa
authors.initials: N
authors.lastname: Katayama
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Kaji
authors.forename: Susumu
authors.initials: S
authors.lastname: Kanazawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D002454:Cell Differentiation; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006801:Humans; D007457:Iodine Radioisotopes / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography; D012008:Recurrence; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D016896:Treatment Outcome; D047368:Tumor Burden / Q000187:drug effects; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D019788:Fluorodeoxyglucose F18