title: Comparison of I-123 and I-131 for whole-body imaging after stimulation by recombinant human thyrotropin: a preliminary report.
abstract: OBJECTIVE
  Many studies have established I-123 whole-body scanning (WBS) as an alternative to I-131 WBS in the evaluation of differentiated thyroid cancer. Similarly, recombinant human thyroid-stimulating hormone (rhTSH) has been shown to be an effective alternative to thyroid hormone withdrawal in the stimulation of TSH levels for WBS. The purpose of the current investigation was to compare the ability of rhTSH-stimulated I-123 WBS to that of rhTSH-stimulated I-131 WBS in the evaluation of thyroid cancer.
  
  
  METHODS
  The reports of 101 consecutive I-123 WBS and 101 consecutive I-131 WBS were analyzed. All patients had undergone near-total thyroidectomy, were considered to have a low risk for recurrence, and had rhTSH-stimulated serum thyroglobulin levels measured at the time of imaging. Findings of an examination were considered positive if either residual thyroid tissue was detected on imaging or the serum thyroglobulin level was greater than 2 ng/dl.
  
  
  RESULTS
  The results of rhTSH-stimulated I-123 scans and thyroglobulin levels were concordant in 91 (90%) cases, whereas the results of rhTSH-stimulated I-131 scans and thyroglobulin levels were concordant in 85 (84%) cases. I-123 WBS detected 9 foci of disease in 6 patients, whereas I-131 WBS detected 10 foci of disease in 9 patients.
  
  
  CONCLUSIONS
  The results of this preliminary investigation are promising regarding the utility of rhTSH-stimulated I-123 WBS as an alternate approach to rhTSH-stimulated I-131 WBS in patients at low risk for recurrence.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Anderson
authors.forename: Stephanie
authors.initials: S
authors.lastname: Fish
authors.forename: Khozaim
authors.initials: K
authors.lastname: Nakhoda
authors.forename: Hongming
authors.initials: H
authors.lastname: Zhuang
authors.forename: Abass
authors.initials: A
authors.lastname: Alavi
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Mandel
mesh_terms: D002277:Carcinoma / Q000097:blood / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000556:secondary*; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D018365:Neoplasm, Residual; D011877:Radionuclide Imaging; D011994:Recombinant Proteins; D012189:Retrospective Studies; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood / Q000473:pathology*; D013972:Thyrotropin
chemical_list: D007457:Iodine Radioisotopes; D011994:Recombinant Proteins; D013972:Thyrotropin; D013954:Thyroglobulin