title: High Level of Agreement Between Pretherapeutic 124I PET and Intratherapeutic 131I Imaging in Detecting Iodine-Positive Thyroid Cancer Metastases.
abstract: The aim of this retrospective study was to assess the level of agreement between PET and scintigraphy using diagnostic amounts of (124)I and therapeutic amounts of (131)I, respectively, in detecting iodine-positive metastases in patients with differentiated thyroid carcinoma.
  
  
  METHODS
  The study included patients who underwent PET /: CT 24 and 120 h after administration of approximately 25 MBq of (124)I and subsequently underwent imaging 5-10 d after administration of 1-10 GBq of (131)I. For each patient, the intratherapeutic (131)I imaging comprised a whole-body scintigraphy scan and a SPECT/CT scan of the neck to distinguish between metastatic and thyroid remnant tissues. Iodine uptake was rated as a metastatic focus if located outside the thyroid bed. Lesion- and patient-based analyses were performed.
  
  
  RESULTS
  The study included 137 patients with 227 metastases iodine-positive on both functional imaging modalities. In the lesion-based analysis, (124)I PET and (131)I imaging detected 98% (223/227) and 99% (225/227) of the iodine-positive metastases, respectively; the level of agreement between (124)I PET and (131)I imaging was 97% (221/227). Four metastases (3 lymph node and 1 bone) in 4 patients were (124)I-negative but (131)I-positive, and 2 lymph node metastases in 2 patients were (131)I-negative but (124)I-positive. In the patient-based analysis, 61 of the 137 patients presented with iodine-positive metastases. (124)I PET and (131)I imaging detected at least one iodine-positive metastasis in 97% (59/61) and 98% (60/61) of the patients, respectively. The level of agreement was 95% (58/61). Both imaging modalities concordantly identified 76 of 137 patients without pathologic iodine uptake.
  
  
  CONCLUSIONS
  Because of the high level of agreement, pretherapeutic (124)I PET/CT is an adequate methodology in the detection of iodine-positive metastases and can be used as a reliable tool for staging of thyroid cancer patients and individualized treatment planning.
authors.affiliation: Department of Nuclear Medicine, University Hospital, University Duisburg-Essen, Essen, Germany marcus.ruhlmann@uk-essen.de.
authors.forename: Marcus
authors.initials: M
authors.lastname: Ruhlmann
authors.affiliation: Department of Nuclear Medicine, University Hospital, University Duisburg-Essen, Essen, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Jentzen
authors.affiliation: Department of Nuclear Medicine, University Hospital, University Duisburg-Essen, Essen, Germany.
authors.forename: Verena
authors.initials: V
authors.lastname: Ruhlmann
authors.affiliation: Medical Physics Unit, Orsola-Malpighi University Hospital, Bologna, Italy; and.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Pettinato
authors.affiliation: Medical Physics Unit, Service Department, Macerata Hospital, Macerata, Italy.
authors.forename: Gloria
authors.initials: G
authors.lastname: Rossi
authors.affiliation: Department of Nuclear Medicine, University Hospital, University Duisburg-Essen, Essen, Germany.
authors.forename: Ina
authors.initials: I
authors.lastname: Binse
authors.affiliation: Department of Nuclear Medicine, University Hospital, University Duisburg-Essen, Essen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bockisch
authors.affiliation: Department of Nuclear Medicine, University Hospital, University Duisburg-Essen, Essen, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Rosenbaum-Krumme
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000556:secondary*; D002648:Child; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D012334:RNA, Neoplasm; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D051598:Whole Body Imaging / Q000379:methods; D014915:Whole-Body Counting / Q000379:methods; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D012334:RNA, Neoplasm; D019275:Radiopharmaceuticals
keywords: 124I PET/CT; SPECT/CT; radioiodine therapy; thyroid cancer; whole-body scintigraphy