LAUSR

Rationale: The management of radioiodine refractory differentiated thyroid cancer (RAIR-DTC) represents a major challenge in thyroid cancer. The American Thyroid Association guidelines recommend the use of tyrosine kinase inhibitors (TKIs) for RAIR-DTC that does not respond to conventional treatment. Currently, imaging modalities that predict the response to TKI treatment based on morphological and functional features are lacking. we report a case of a patient with progressive RAIR lung metastases who underwent 2-deoxy-2-[18F]fluoro-D-glucose and 99technetiumm-three polyethylene glycol spacers-arginine-glycine-aspartic acid (99Tcm-3PRGD2) dual-tracer imaging and investigate the value of this imaging strategy for determining subsequent therapeutic schedules. Patient concerns: A 52-year-old man with advanced RAIR-DTC and progressive lung metastasis. After TKI treatment [sorafenib] lost its clinical benefits, the patient’s therapeutic response was evaluated as progressive disease. 2-deoxy-2-[18F]fluoro-D-glucose PET/CT and 99Tcm-3PRGD2 SPECT/CT were performed. There were multiple FDG-positive lesions in the lung. However, 99Tcm-3PRGD2 SPECT/CT showed only 1 lesion in the right middle pulmonary lobe with arginine-glycine-aspartic positivity. Diagnosis: RAIR-DTC. Interventions: Radiofrequency ablation was performed for only the lesion with RDG and FDG positivity. Outcomes: The patient quickly achieved partial response. Lessons: This case indicates that for progressive RAIR metastases, patients can benefit more from prioritizing treatment for lesions that are both arginine-glycine-aspartic and FDG positive.