Comparison of 18F-FDG, 131I-Na, and 201Tl in Diagnosis of Recurrent or Metastatic Thyroid Carcinoma

摘要

id="p-1">There are several reports about the usefulness of 18F-FDG PET in thyroid cancer. However, few studies have compared FDG PET with 131I and 201Tl 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 131I and 201Tl 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 201Tl 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 131I uptake in only 18 lesions (38%). FDG uptake was concordant with 201Tl uptake in 44 lesions (94%). Only one lesion was negative for FDG uptake and positive for 201Tl uptake, and two lesions were positive for FDG uptake and negative for 201Tl uptake. A significant correlation was seen between the TBR of 201Tl and that of FDG (r = 0.69; P 0.05). >Conclusion: These data indicate that for detecting metastatic lesions, FDG PET and 131I scintigraphy may provide complementary information, whereas FDG PET may provide results similar to those of 201Tl scintigraphy. Thus, the combination of 131I scintigraphy and FDG PET (or 201Tl scintigraphy) is the method of choice for detecting metastatic thyroid cancer after total thyroidectomy.