title: Diagnostic 131I whole-body scintigraphy 1 year after thyroablative therapy in patients with differentiated thyroid cancer: correlation of results to the individual risk profile and long-term follow-up.
abstract: OBJECTIVE
  (131)I whole-body scan (WBS) and serum thyroglobulin (TG) are important in detecting thyroid remnants or recurrent disease in patients with differentiated thyroid cancer. Usually, a diagnostic WBS is carried out 6 months after ablation to exclude residual disease. We retrospectively analysed results of a second routine diagnostic WBS and TG measurements at 1 year after thyroablation and correlated these to the risk profile of patients with long-term follow-up.
  
  
  METHODS
  A total of 197 patients were followed up after thyroidectomy and ablative (131)I therapy. Follow-up included clinical examination, radioiodine WBS and thyroid-stimulating hormone (TSH), free thyroxine and TG measurements at 3-6 months and 1 year after ablation. WBS (+) patients received a therapeutic activity of (131)I. The risk profile of patients was defined according to clinical results before the 1-year control. Clinical results at 1 year after ablation were analysed in correlation to the patient risk profile and long-term follow-up data (mean 7.2 years).
  
  
  RESULTS
  One year after thyroablation, 95.8% of low-risk patients had no residual disease when diagnostic WBS was carried out using 370 MBq (131)I; 4.2% of low-risk patients had residual disease at this time point. In the high-risk group of this cohort, 54.5% were disease-free 1 year after ablation, but 45.5% demonstrated residual disease. After the 1-year control, 94% of all applied radioiodine therapies were executed in the high-risk group, compared with 6% in the low-risk group (p < 0.01).
  
  
  CONCLUSIONS
  A second routine WBS 1 year after thyroablation is not indicated in low-risk patients. Risk stratification according to the early clinical course effectively identified patients with higher likelihood of persistent or recurrent disease in the long-term follow-up.
authors.affiliation: Department of Clinical Radiology, Ludwig-Maximilians University of Munich, Munich, Germany. Frank.Berger@med.uni-muenchen.de
authors.forename: Frank
authors.initials: F
authors.lastname: Berger
authors.forename: Ulla
authors.initials: U
authors.lastname: Friedrich
authors.forename: Peter
authors.initials: P
authors.lastname: Knesewitsch
authors.forename: Klaus
authors.initials: K
authors.lastname: Hahn
mesh_terms: D055011:Ablation Techniques; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002454:Cell Differentiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D018570:Risk Assessment; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000601:surgery*; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D013997:Time Factors; D051598:Whole Body Imaging; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes