Remarkable 99mTc-FAPI-46 Uptake in a Patient With Anaplastic Thyroid Carcinoma: A Promising Step in Theranostic Field

Fibroblast activation protein (FAP)-targeted radionuclides are known as a promising step in cancer diagnosis and treatment (theranostic), although it is still a subject under investigation. We present a patient with anaplastic thyroid carcinoma who underwent 99mTc-FAPI-46 SPECT/CT for the evaluation of metastatic disease. Several metastatic sites were found with considerable 99mTc-FAPI-46 uptake. Malignant FAPI uptake was observed in the large calcified thyroid mass, mediastinal lymph node, both lungs, liver, few skeletal sites, and around knees prostheses. Given the notable uptake of lesions, the patient was considered as a candidate for FAP-targeted radionuclide therapy.