title: 68Ga-DOTATOC PET/CT in Patients with Iodine- and 18F-FDG-Negative Differentiated Thyroid Carcinoma and Elevated Serum Thyroglobulin.
abstract: This study evaluated the impact of68Ga-DOTATOC PET/CT in detecting recurrence or metastases in differentiated thyroid carcinoma (DTC) patients with elevated serum thyroglobulin and both negative radioiodine imaging and negative18F-FDG PET/CT.
  
  
  METHODS
  68Ga-DOTATOC PET/CT (CT without contrast, low-dose) was performed on average 6 wk after negative18F-FDG PET/CT (CT contrast-enhanced, full-dose) in 15 consecutive radioiodine-negative DTC patients with elevated and rising thyroglobulin. Visual assessment of68Ga-DOTATOC PET/CT images used a 4-point scale for classification of lesions (0, no pathologic findings; 1, benign; 2, equivocal; 3, malignant). PET findings were correlated with the histologic subtype of tumor, levels of serum thyroglobulin, and morphologic findings on full-dose CT and neck ultrasound. Histology or clinical and imaging follow-up served as a reference standard. Analysis was performed on a patient and lesion basis.
  
  
  RESULTS
  68Ga-DOTATOC PET/CT was true-positive in 5 patients (10 tumor lesions) and was false-positive in 1 patient. The rate of positive68Ga-DOTATOC PET/CT was significantly higher in poorly differentiated/oxyphilic carcinomas (4/4 patients) than in papillary (1/5) or follicular (0/6) tumors. Thyroglobulin levels tended to be higher in patients with tumor localization on68Ga-DOTATOC PET/CT, but differences were not significant. In 2 of 5 patients with true-positive findings on68Ga-DOTATOC PET/CT, CT alone but not ultrasound identified 2 of 10 tumor lesions, but in both patients68Ga-DOTATOC-PET/CT revealed further tumor lesions not detected on CT alone.
  
  
  CONCLUSIONS
  68Ga-DOTATOC PET/CT should be considered in the case of negative18F-FDG PET/CT in radioiodine-negative DTC patients with elevated and rising thyroglobulin. Imaging with68Ga-DOTATOC appears promising especially in poorly differentiated and oxyphilic subtypes of DTC.
authors.affiliation: Department of Nuclear Medicine, University Hospital Essen, Essen, Germany ina.binse@uk-essen.de.
authors.forename: Ina
authors.initials: I
authors.lastname: Binse
authors.affiliation: Department of Nuclear Medicine, University Hospital Essen, Essen, Germany.
authors.forename: Thorsten D
authors.initials: TD
authors.lastname: Poeppel
authors.affiliation: Department of Nuclear Medicine, University Hospital Essen, Essen, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Ruhlmann
authors.affiliation: Department of Nuclear Medicine, Saarland University Hospital, Homburg, Germany; and.
authors.forename: Samer
authors.initials: S
authors.lastname: Ezziddin
authors.affiliation: Department of Nuclear Medicine, University Hospital Essen, Essen, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Görges
authors.affiliation: Department of Nuclear Medicine, University Hospital Essen, Essen, Germany.
authors.forename: Amir
authors.initials: A
authors.lastname: Sabet
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Beiderwellen
authors.affiliation: Department of Nuclear Medicine, University Hospital Essen, Essen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bockisch
authors.affiliation: Department of Nuclear Medicine, University Hospital Essen, Essen, Germany.
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Rosenbaum-Krumme
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000031:analogs & derivatives*; D009942:Organometallic Compounds; D000072078:Positron Emission Tomography Computed Tomography; D012189:Retrospective Studies; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000000981:diagnostic imaging* / Q000473:pathology; D055815:Young Adult
chemical_list: C499142:Ga(III)-DOTATOC; D007457:Iodine Radioisotopes; D009942:Organometallic Compounds; D019788:Fluorodeoxyglucose F18; D013954:Thyroglobulin; D015282:Octreotide
keywords: DOTATOC PET/CT; SSTR; differentiated thyroid carcinoma; elevated thyroglobulin; recurrence