Visualization of Tumor Heterogeneity in Advanced Medullary Thyroid Carcinoma by Dual-Tracer Molecular Imaging

Abstract We present the case of a 60-year-old man with medullary thyroid carcinoma and hepatic, osseous, and lymph node metastases who underwent peptide receptor radionuclide therapy with 177 Lu-DOTATOC. After 2 cycles, 68 Ga-DOTATOC PET/CT revealed multiple nonavid lesions. To assess whether the patient would be eligible for prostate-specific membrane antigen (PSMA)–targeted radioligand therapy, a PSMA PET/CT was conducted. PSMA PET/CT identified increased PSMA expression in both 68 Ga-DOTATOC–avid and nonavid lesions. As such, dual-radiotracer PET/CT may allow for insights into the complexities of tumor heterogeneity in patients with medullary thyroid carcinoma, which may pave the way for subsequent therapeutic algorithms.