Comparison of Tc-99(m)-tetrofosmin with Tl-201 and I-131 in the detection of differentiated thyroid cancer metastases

The purpose of this study was to assess the detectability of metastatic les ions by (99)Tc(m-)tetrofosmin in differentiated thyroid cancer, and to comp are the results with those obtained using Tl-201-chloride and tracer doses of I-131. Twenty-four thyroidectomized patients with metastases were studie d. There were 34 metastases, including 16 lung, nine lymph node and nine bo ne. Radiological studies (chest X-ray, computed tomography and magnetic res onance imaging), serum thyroglobulin assays and histopathological examinati ons were performed to verify the presence of metastases with positive uptak e of the three radionuclides. Increased accumulation of Tc-99(m)-tetrofosmi n was observed in 11 of 16 (68.8%) lung metastases, eight of nine (88.9%) l ymph node metastases and eight of nine (88.9%) bone metastases. Increased a ccumulation of Tl-201 and I-131 was observed in 11 of 16 (both) (68.8%) lun g metastases, eight (88.9%) and three (33.3%), respectively, of lymph node metastases and eight (88.9%) and nine (100%), respectively of bone metastas es. The detectability of thyroid cancer metastases using Tc-99(m)-tetrofosm in, Tl-201 and I-131 was 79.4%, 79.4% and 67.6%, respectively. The combined detectabilities of Tc-99(m)-tetrofosmin and I-131 and of Tl-201 and I-131 were both 88.2%. Tc-99(m)-tetrofosmin and Tl-201 imaging were found to be m ore sensitive than I-131 for the detection of differentiated thyroid cancer metastases, particularly for regional lymph node. The combination of Tc-99 (m)-tetrofosmin and I-131 imaging may be a more sensitive and effective met hod for detecting metastases in differentiated thyroid cancer. ((C) 2000 Li ppincott Williams & Williams).