Fluorine-18-FDG and iodine-131-iodide uptake in thyroid cancer.
We conducted a prospective study to define the sensitivity of 131I scintigraphy and 18FDG PET whole-body scanning in the detection of thyroid cancer and metastases.


METHODS
Forty-one patients with differentiated thyroid carcinoma who underwent thyroidectomy and 131I elimination of the remaining thyroid were studied by 18FDG whole-body PET in 52 examinations and by 131I whole-body scanning.


RESULTS
Combined 18FDG and 131I imaging resulted in a sensitivity of about 95%, with alternating uptake of 131I and 18FDG in the metastases: 131I trapping metastases with no 18FDG uptake and 18FDG trapping metastases with no 131I uptake. Five uptake types were differentiated. Alternating uptake was found in about 90% of the patients, which was nearly identical to the sensitivity of the combined 131I/18FDG investigation. In six patients with increasing human thyroglobulin levels, we found that 18FDG whole-body PET localized positive neck metastases of papillary thyroid carcinomas that were histologically confirmed after extirpation.


CONCLUSIONS
Combination 18FDG and 131I whole-body imaging protocol enables detection of local recurrence or metastases on whole-body scans that are often not shown by other imaging methods. Biochemical grading of thyroid cancer may also be possible with this method: Tumors with remaining functional differentiation for hormone synthesis and iodine uptake have low glucose metabolism in more than 95%; tumors without this functional differentiation of 131I uptake show high, glucose metabolism. Fluorine-18-FDG uptake seems to be an indicator of poor functional differentiation, and possibly higher malignancy, in thyroid cancer.
Feine
U
U
Department of Nuclear Medicine, Eberhard Karls University, Tuebingen, Germany.
Lietzenmayer
R
R
Hanke
J P
JP
Held
J
J
Wöhrle
H
H
Müller-Schauenburg
W
W
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000556:secondary; D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging / Q000556:secondary; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging / Q000556:secondary; D003847:Deoxyglucose / Q000031:analogs & derivatives*; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D013965:Thyroidectomy; D014055:Tomography, Emission-Computed
D005462:Fluorine Radioisotopes; D007457:Iodine Radioisotopes; D019788:Fluorodeoxyglucose F18; D003847:Deoxyglucose