Positron emission tomography with F-18-deoxyglucose in patients with differentiated thyroid carcinoma, elevated thyroglobulin levels, and negative iodine scans.
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.
Altenvoerde
G
G
Klinik und Poliklinik für Nuklearmedizin, Westfälische Wilhelms-Universität Münster, Germany.
Lerch
H
H
Kuwert
T
T
Matheja
P
P
Schäfers
M
M
Schober
O
O
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
D014408:Biomarkers, Tumor; D007457:Iodine Radioisotopes; D019788:Fluorodeoxyglucose F18; D013972:Thyrotropin; D013954:Thyroglobulin