title: The influence of thyroglobulin on functional imaging in differentiated thyroid cancer.
abstract: OBJECTIVE
  Recombinant human thyroid stimulating hormone (rhTSH) for an exogenous stimulation of TSH and consequent thyroglobulin (hTG) synthesis has reinitiated a discussion about the usefulness of diagnostic procedures for the follow-up of differentiated thyroid cancer (DTC).
  
  
  METHODS
  Fifty consecutive patients with DTC who received whole-body iodine scintigraphy (WBS) and positron emission tomography (PET) were evaluated.
  
  
  RESULTS
  The work-up was normal in 18/50. In 32 patients, functional imaging detected DTC. In 44% exogenous TSH stimulation with rhTSH was used and thyroxin was withdrawn in the others. The hTG under stimulation ranged from 0.8 to 5.004 ng x ml(-1). It was below 2 ng x ml(-1) in four (12.5%) patients. In total, 91 tumour sites were identified by positron emission tomography (PET) and 47 sites by WBS. PET and WBS showed corresponding uptake in 38% of lymph node, 48% of parenchymal and 43% of bone metastases. PET detected additional 53% of lymph node (WBS 9%), 38% of parenchymal (WBS 14%) and 28.5% of bone metastases.
  
  
  CONCLUSIONS
  It is concluded that PET is more sensitive than WBS for the detection of DTC. The follow-up of DTC patients with hTG levels alone misses a significant number of true positive cases. Its use should therefore be restricted to selected low risk patients only.
authors.affiliation: Department of Nuclear Medicine, Hospital of the Johann W. Goethe University, Frankfurt, Germany. christian.menzel@em.uni-frankfurt.de
authors.forename: C
authors.initials: C
authors.lastname: Menzel
authors.forename: K
authors.initials: K
authors.lastname: Zaplatnikov
authors.forename: M
authors.initials: M
authors.lastname: Diehl
authors.forename: N
authors.initials: N
authors.lastname: Döbert
authors.forename: N
authors.initials: N
authors.lastname: Hamscho
authors.forename: F
authors.initials: F
authors.lastname: Grünwald
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007457:Iodine Radioisotopes; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000000981:diagnostic imaging*; D013972:Thyrotropin; D014055:Tomography, Emission-Computed / Q000379:methods*; D014915:Whole-Body Counting / Q000379:methods*
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D013972:Thyrotropin; D013954:Thyroglobulin