J Nucl Med 2001 Mar;42(3):414-9
Comparison of (18)F-FDG, (131)I-Na, and (201)Tl in Diagnosis of Recurrent or
Metastatic Thyroid Carcinoma.
Shiga T, Tsukamoto E, Nakada K, Morita K, Kato T, Mabuchi M, Yoshinaga K, Katoh
C, Kuge Y, Tamaki N.
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: Y
0.05). CONCLUSION: 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.
