title: Difference of clinical and radiological characteristics according to radioiodine avidity in pulmonary metastases of differentiated thyroid cancer.
abstract: OBJECTIVE
  To evaluate differences in clinical, radiological and laboratory findings between pulmonary metastasis with and without radioiodine avidity in thyroidectomized differentiated thyroid cancer (DTC) patients with pulmonary metastasis who underwent high-dose I-131 treatment.
  
  
  METHODS
  A total of 105 DTC patients with pulmonary metastasis (age, 48.7 ± 16.8 years; women/men, 78/27) were included. Clinical characteristics, chest computed tomography (CT), F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET)/CT and thyroid-stimulating hormone (TSH)-stimulated serum thyroglobulin (s-Tg) level were compared between patients with and without radioiodine uptake in metastatic lung lesions. The response to I-131 treatment was evaluated with follow-up study.
  
  
  RESULTS
  Eighty-nine patients (84.8 %, whole-body scan positive [WBSP] group) showed radioiodine uptake at pulmonary metastasis on post I-131 treatment whole-body scan (WBS) and 16 patients (15.2 %, WBS negative [WBSN] group) did not show uptake at pulmonary lesions on the WBS. Ninety percent and 87 % of the WBSP group had visible metastatic lesions on CT and F-18 FDG PET/CT; however, all of the patients in the WBSN group showed lesions on CT and F-18 FDG PET/CT. In seven (6.7 %) of 105 patients, CT and F-18 FDG PET/CT could not detect pulmonary lesions, which were diagnosed by post I-131 treatment WBS. Complete disease remission was achieved in six (5.7 %) patients and all of them were in the WBSP group.
  
  
  CONCLUSIONS
  Metastatic lesion was not visualized on chest CT or F-18 FDG PET/CT in 6.7 % of DTC patients with pulmonary metastasis and the lesion was visualized only on post I-131 treatment WBS. Complete remission was achieved in 5.7 % of DTC patients with pulmonary metastasis and the cured metastases were non-visualizing or micronodular lesions on chest CT and demonstrated radioiodine avidity on post I-131 treatment WBS.
authors.affiliation: Department of Nuclear Medicine, Kyungpook National University School of Medicine and Hospital, 50, Samduk 2-ga, Jung Gu Daegu, 700-721 Republic of Korea.
authors.forename: Do-Hoon
authors.initials: DH
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Kyungpook National University School of Medicine and Hospital, 50, Samduk 2-ga, Jung Gu Daegu, 700-721 Republic of Korea.
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Jung
authors.affiliation: Department of Nuclear Medicine, Kyungpook National University School of Medicine and Hospital, 50, Samduk 2-ga, Jung Gu Daegu, 700-721 Republic of Korea.
authors.forename: Seung Hyun
authors.initials: SH
authors.lastname: Son
authors.affiliation: Department of Nuclear Medicine, Kyungpook National University School of Medicine and Hospital, 50, Samduk 2-ga, Jung Gu Daegu, 700-721 Republic of Korea.
authors.forename: Choon-Young
authors.initials: CY
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Kyungpook National University School of Medicine and Hospital, 50, Samduk 2-ga, Jung Gu Daegu, 700-721 Republic of Korea.
authors.forename: Chae Moon
authors.initials: CM
authors.lastname: Hong
authors.affiliation: Department of Nuclear Medicine, Kyungpook National University School of Medicine and Hospital, 50, Samduk 2-ga, Jung Gu Daegu, 700-721 Republic of Korea.
authors.forename: Shin Young
authors.initials: SY
authors.lastname: Jeong
authors.affiliation: Department of Nuclear Medicine, Kyungpook National University School of Medicine and Hospital, 50, Samduk 2-ga, Jung Gu Daegu, 700-721 Republic of Korea.
authors.forename: Sang-Woo
authors.initials: SW
authors.lastname: Lee
authors.affiliation: Department of Nuclear Medicine, Kyungpook National University School of Medicine and Hospital, 50, Samduk 2-ga, Jung Gu Daegu, 700-721 Republic of Korea.
authors.forename: Jaetae
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Nuclear Medicine, Kyungpook National University School of Medicine and Hospital, 50, Samduk 2-ga, Jung Gu Daegu, 700-721 Republic of Korea.
authors.forename: Byeong-Cheol
authors.initials: BC
authors.lastname: Ahn
keywords: Differentiated thyroid cancer; I-131 treatment; Pulmonary metastasis; Radioiodine avidity