title: Tc-99m imaging in thyroidectomized differentiated thyroid cancer patients immediately before I-131 treatment.
abstract: OBJECTIVE
  The aim of this study was to evaluate the clinical role of technetium-99m pertechnetate (Tc-99m) imaging in thyroidectomized differentiated thyroid cancer patients immediately before radioiodine-131 (I-131) treatment (Tx).
  
  
  METHODS
  Eighty-six consecutive post-total-thyroidectomy patients (15 men, 71 women; mean age: 46.8 years) with pathologically diagnosed differentiated thyroid cancer were retrospectively studied. Tc-99m imaging immediately before I-131 Tx using both patient-based and lesion-based measurements were analyzed and were further compared with those of post-Tx I-131 whole-body scans.
  
  
  RESULTS
  For patients with unequivocally positive Tc-99m uptake, the sensitivity was 77% (patient-based) and 59% (site-based). The positive predictive value (PPV) was 100% for both patient-based and site-based measurements. If equivocal Tc-99m uptake was counted as positive, the sensitivity was 83 and 67%, and the PPV was 100 and 99% for patient-based and site-based measurements, respectively.
  
  
  CONCLUSIONS
  (a) To increase sensitivity yet maintaining high PPV, equivocal Tc-99m uptake should be considered a positive finding. (b) The nearly 100% PPV of Tc-99m imaging immediately before I-131 Tx for remnant detection suggests that Tc-99m imaging not only serves as an alternative to low-dose I-131 scanning in the low-risk post-thyroidectomy patients but also provides a clue for the subsequent I-131 therapeutic dosage and even for the outcome prediction.
authors.affiliation: aDepartment of Nuclear Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei Departments of bGeneral Surgery cNuclear Medicine, Changhua Christian Hospital, Changhua dDepartment of Nuclear Medicine and Anesthesiology, Chi-Mei General Hospital, Tainan, Taiwan.
authors.forename: Chi-Jung
authors.initials: CJ
authors.lastname: Tsai
authors.forename: Cheng-Yi
authors.initials: CY
authors.lastname: Cheng
authors.forename: Daniel Hueng-Yuan
authors.initials: DH
authors.lastname: Shen
authors.forename: Shou Jen
authors.initials: SJ
authors.lastname: Kuo
authors.forename: Lien-Yen
authors.initials: LY
authors.lastname: Wang
authors.forename: Chiang-Hsuan
authors.initials: CH
authors.lastname: Lee
authors.forename: Jhi-Joung
authors.initials: JJ
authors.lastname: Wang
authors.forename: Ming-Che
authors.initials: MC
authors.lastname: Chang
authors.forename: Wen-Sheng
authors.initials: WS
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D013670:Sodium Pertechnetate Tc 99m; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000601:surgery; D013965:Thyroidectomy; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D013670:Sodium Pertechnetate Tc 99m