WHOLE-BODY SCINTIGRAPHY WITH TC-99(M)-MIBI, F-18 FDG AND I-131 IN PATIENTS WITH METASTATIC THYROID-CARCINOMA

We assessed the relative usefulness of whole-body planar scintigraphy with Tc-99(m)-methoxyisobutyl isonitrile (Tc-99(m)-MIBI), 2-[F-18]fluo ro-2-deoxy-D-glucose (F-18-FDG-RS) rectilinear scanning and with diagn ostic and therapeutic doses of I-131, for the detection of local recur rences and metastatic lesions in 12 patients with thyroid carcinoma an d elevated thyroglobulin serum levels. All images were evaluated indep endently by three experienced observers to define the number and locat ion of metastatic lesions. F-18-FDG-RS and Tc-99(m)-MIBI scintigraphy provided similar results, but the tracer that allowed the detection of the highest number of metastases was Tc-99(m)-MIBI. Both Tc-99(m)-MIB I scintigraphy and F-18-FDG-RS appear to be more sensitive than I-131 scintigraphy for the detection of metastases of thyroid carcinoma. Tom ographic acquisitions were also performed on a limited field of view i n each subject and, as expected, F-18-FDG-PET was more sensitive than F-18-FDG-RS. Tc-99(m)-MIBI scintigraphy, a widely available and relati vely non-expensive technique, therefore seems suitable for the assessm ent and follow-up of patients with metastatic thyroid carcinoma and do es not require the withdrawal of hormone therapy for lesion imaging.