title: Positron emission tomography with F-18-deoxyglucose in patients with differentiated thyroid carcinoma, elevated thyroglobulin levels, and negative iodine scans.
abstract: BACKGROUND
  In patients with differentiated thyroid carcinoma, elevated serum levels of thyroglobulin (hTg) may occur in spite of otherwise negative diagnostic procedures and in particular in spite of a negative iodine-131 scan. Positron emission tomography with F-18-deoxyglucose (FDG-PET) is a potentially useful method for the detection of metastatic lesions or the recurrence of thyroid cancer. We aimed to investigate whether FDG-PET is capable of detecting metastatic lesions or recurrence in patients with differentiated thyroid carcinoma, elevated serum levels of thyroglobulin, and otherwise negative diagnostic procedures, including the iodine-131 scan.
  
  
  METHODS
  From a group of 500 patients with differentiated thyroid carcinoma, a subgroup of 32 patients had elevated serum hTg-levels, negative iodine- 131 scans, negative cervical and abdominal ultrasound, and negative X-ray of the chest. In 12 of these patients (hTg 77.8+/-94.3 ng/ml, range 1.5-277 ng/ml, median 20 ng/ml), FDG-PET was performed. All but one FDG-PET study was performed in a state of hypothyroidism (TSH 75.8+/-32.2 microIU/ml, range 31-116 microIU/ml, median 74.6 microIU/ml).
  
  
  RESULTS
  In 6 of the 12 patients investigated, the FDG-PET was positive. In three of the patients, the diagnosis was confirmed by computed tomography or magnetic resonance imaging. In patients with a positive FDG-PET finding, the hTg level was 146.7+/-90.1 ng/ml (23-277 ng/ml, median 144.5 ng/ml). In contrast, in patients with a negative finding the hTg level was only 9.0+/-7.6 ng/ml (range 1.5-17 ng/ml, median 8.1 ng/ml), P=0.01.
  
  
  CONCLUSIONS
  These preliminary results show that in patients with differentiated thyroid carcinoma, elevated hTg levels, and otherwise negative "conventional" diagnostic procedures, FDG-PET is helpful in detecting metastatic lesions.
authors.affiliation: Klinik und Poliklinik für Nuklearmedizin, Westfälische Wilhelms-Universität Münster, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Altenvoerde
authors.forename: H
authors.initials: H
authors.lastname: Lerch
authors.forename: T
authors.initials: T
authors.lastname: Kuwert
authors.forename: P
authors.initials: P
authors.lastname: Matheja
authors.forename: M
authors.initials: M
authors.lastname: Schäfers
authors.forename: O
authors.initials: O
authors.lastname: Schober
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000097:blood / Q000000981:diagnostic imaging* / Q000473:pathology; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D002291:Carcinoma, Papillary / Q000097:blood / Q000000981:diagnostic imaging* / Q000473:pathology; D003952:Diagnostic Imaging; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007457:Iodine Radioisotopes; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012680:Sensitivity and Specificity; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood / Q000000981:diagnostic imaging* / Q000473:pathology; D013972:Thyrotropin / Q000097:blood; D014055:Tomography, Emission-Computed
chemical_list: D014408:Biomarkers, Tumor; D007457:Iodine Radioisotopes; D019788:Fluorodeoxyglucose F18; D013972:Thyrotropin; D013954:Thyroglobulin