Application of 99m Tc-FAPI-46 Imaging in a Patient With Medullary Thyroid Carcinoma : Navigating the Landscape of Novel Radiotracers.

We present the case of a 58-year-old man with metastatic medullary thyroid carcinoma refractory to conventional therapies, including peptide receptor radionuclide therapy. Despite multiple interventions, serum calcitonin and carcinoembryonic antigen levels continued to rise. Subsequent evaluation with 99m Tc-FAPI-46 revealed remarkable uptake in metastatic lesions, suggesting a potential role for FAPI-labeled radioisotopes in the management of medullary thyroid carcinoma. This case underscores the emerging utility of FAPI-targeted radiotracers in oncologic nuclear medicine and highlights the need for further research in this promising area.