title: Timing of post 131I ablation diagnostic whole body scan in differentiated thyroid cancer patients. Less than four months post ablation may be too early.
abstract: OBJECTIVE
  to determine whether the first three months after 131I ablation is too early to perform radioiodine diagnostic whole body scintigraphy (dxWBS) in differentiated thyroid carcinoma patients.
  
  
  METHODS
  The files of 462 patients who were treated for DTC in our hospital were reviewed. All patients underwent surgical thyroidectomy. 146 patients had data available on a. a dxWBS which was performed less than four months (max 120 days) after 131I ablation with concurrent stimulated TSH stimulated thyroglobulin (Tg) measurement without further therapeutic measures between ablation and dxWBS and b. a second dxWBS or 131I therapy (rxWBS) within 1.5 years after ablation.
  
  
  RESULTS
  A discordance between the initial and follow-up scan was found in 25/129 (19%) patients: of 54 patients with a positive initial dxWBS, scan results of a second dxWBS or rxWBS obtained with a suitable distance to the initial scan contradicted the initial one in 15 patients (27%). New lesions were discovered in 10/74 negative first dxWBS cases (14%). A discordance between the initial and follow-up stimulated Tg was found in 5/129 (4%) patients: 2/90 (2%) of patients with a negative stimulated Tg at initial dxWBS subsequently showed a positive results whereas 3/29 (10%) patients with an initially positive Tg showed a negative Tg level at the second procedure.
  
  
  CONCLUSIONS
  Less than four months after 131I ablation is too early to perform radioiodine diagnostic whole body scintigraphy with concurrent TSH stimulated Tg measurement. The identification of the right, later, timepoint however requires further research.
authors.forename: M
authors.initials: M
authors.lastname: Winter
authors.forename: J
authors.initials: J
authors.lastname: Winter
authors.forename: A
authors.initials: A
authors.lastname: Heinzel
authors.forename: F F
authors.initials: FF
authors.lastname: Behrendt
authors.forename: T
authors.initials: T
authors.lastname: Krohn
authors.forename: F M
authors.initials: FM
authors.lastname: Mottaghy
authors.affiliation: Frederik A. Verburg MD PhD, RWTH University Hospital Aachen, Department of Nuclear Medicine, Pauwelsstraße 30, 52074 Aachen, Germany, Tel +49/(0)241/803 66 19, Fax +49/(0)241/808 25 20, E-mail fverburg@ukaachen.de.
authors.forename: F A
authors.initials: FA
authors.lastname: Verburg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy / Q000379:methods; D003951:Diagnostic Errors / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D013997:Time Factors; D016896:Treatment Outcome; D051598:Whole Body Imaging / Q000379:methods*; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals
keywords: 131I ablation; Differentiated thyroid cancer; diagnostic whole body scintigraphy; treatment success