Comparison of (18)F-FDG, (131)I-Na, and (201)Tl in diagnosis of recurrent or metastatic thyroid carcinoma.
There are several reports about the usefulness of (18)F-FDG PET in thyroid cancer. However, few studies have compared FDG PET with (131)I and (201)Tl scintigraphy. The aim of this study was to evaluate the clinical significance of whole-body FDG PET in differentiated thyroid cancer and to compare the results with those obtained from (131)I and (201)Tl scintigraphy.


METHODS
Whole-body FDG PET was performed on 32 patients (10 men, 22 women; age range, 30-77 y; mean age, 54 y) with differentiated thyroid cancer (5 cases of follicular cancer and 27 of papillary cancer) after total thyroidectomy. An overall clinical evaluation was performed, including cytology, thyroglobulin level, sonography, MRI, and CT, to allow a comparison with functional imaging results for each patient. Metastatic regions were divided into five areas: neck, lung, mediastinum, bone, and other. Multiple lesions in one area were defined as one lesion. The tumor-to-background ratio (TBR) was measured for the lesions that were positive for both (201)Tl uptake and FDG PET uptake.


RESULTS
The number of lesions totaled 47. Forty-one (87%) were detected by all scintigraphic methods. FDG uptake was concordant with (131)I uptake in only 18 lesions (38%). FDG uptake was concordant with (201)Tl uptake in 44 lesions (94%). Only one lesion was negative for FDG uptake and positive for (201)Tl uptake, and two lesions were positive for FDG uptake and negative for (201)Tl uptake. A significant correlation was seen between the TBR of (201)Tl and that of FDG (r = 0.69; P<0.05).


CONCLUSIONS
These data indicate that for detecting metastatic lesions, FDG PET and (131)I scintigraphy may provide complementary information, whereas FDG PET may provide results similar to those of (201)Tl scintigraphy. Thus, the combination of (131)I scintigraphy and FDG PET (or (201)Tl scintigraphy) is the method of choice for detecting metastatic thyroid cancer after total thyroidectomy.
Shiga
T
T
Department of Nuclear Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Tsukamoto
E
E
Nakada
K
K
Morita
K
K
Kato
T
T
Mabuchi
M
M
Yoshinaga
K
K
Katoh
C
C
Kuge
Y
Y
Tamaki
N
N
D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging* / Q000556:secondary*; D000328:Adult; D000368:Aged; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging* / Q000556:secondary*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary; D006801:Humans; D007457:Iodine Radioisotopes; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D019275:Radiopharmaceuticals; D013794:Thallium Radioisotopes; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D014055:Tomography, Emission-Computed
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D013794:Thallium Radioisotopes; D019788:Fluorodeoxyglucose F18