title: Quantitative single-photon emission computed tomography/computed tomography for technetium pertechnetate thyroid uptake measurement.
abstract: OBJECTIVE
  Technetium pertechnetate (TcO4) is a radioactive tracer used to assess thyroid function by thyroid uptake system (TUS). However, the TUS often fails to deliver accurate measurements of the percent of thyroid uptake (%thyroid uptake) of TcO4. Here, we investigated the usefulness of quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) after injection of TcO4 in detecting thyroid function abnormalities.
  
  
  METHODS
  We retrospectively reviewed data from 50 patients (male:female = 15:35; age, 46.2 ± 16.3 years; 17 Graves disease, 13 thyroiditis, and 20 euthyroid). All patients underwent TcO4 quantitative SPECT/CT (185 MBq = 5 mCi), which yielded %thyroid uptake and standardized uptake value (SUV). Twenty-one (10 Graves disease and 11 thyroiditis) of the 50 patients also underwent conventional %thyroid uptake measurements using a TUS.
  
  
  RESULTS
  Quantitative SPECT/CT parameters (%thyroid uptake, SUVmean, and SUVmax) were the highest in Graves disease, second highest in euthyroid, and lowest in thyroiditis (P < 0.0001, Kruskal-Wallis test). TUS significantly overestimated the %thyroid uptake compared with SPECT/CT (P < 0.0001, paired t test) because other TcO4 sources in addition to thyroid, such as salivary glands and saliva, contributed to the %thyroid uptake result by TUS, whereas %thyroid uptake, SUVmean and SUVmax from the SPECT/CT were associated with the functional status of thyroid.
  
  
  CONCLUSIONS
  Quantitative SPECT/CT is more accurate than conventional TUS for measuring TcO4 %thyroid uptake. Quantitative measurements using SPECT/CT may facilitate more accurate assessment of thyroid tracer uptake.
authors.affiliation: Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seoul World Class University, Department of Molecular Medicine and Biopharmaceutical Science, Graduate School of Convergence Science and Technology, Seoul National University, Suwon Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine Department of Nuclear Medicine, Konkuk University Medical Center Institute of Radiation Medicine, Medical Research Center, Seoul National University, Seoul, Korea.
authors.forename: Hyunjong
authors.initials: H
authors.lastname: Lee
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: Yeon-Koo
authors.initials: YK
authors.lastname: Kang
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Moon
authors.forename: Young
authors.initials: Y
authors.lastname: So
authors.forename: Won Woo
authors.initials: WW
authors.lastname: Lee
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D012189:Retrospective Studies; D000072098:Single Photon Emission Computed Tomography Computed Tomography; D013670:Sodium Pertechnetate Tc 99m / Q000493:pharmacokinetics*; D013959:Thyroid Diseases / Q000000981:diagnostic imaging* / Q000378:metabolism*; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000378:metabolism*
chemical_list: D019275:Radiopharmaceuticals; D013670:Sodium Pertechnetate Tc 99m