Exploring the Role of [Ga]Ga-DOTAGA-IAC and Comparison of Its Diagnostic Performance with [F]F-FDG PET/CT in Radioiodine Refractory Differentiated Thyroid Carcinoma.

Integrin antagonist complex (IAC), a novel αvβ3 integrin antagonist peptidomimetic, has emerged as a promising agent for molecular imaging of tumor angiogenesis. This study evaluates the biodistribution and clinical efficacy of [Ga]Ga-DOTAGA-IAC PET/CT in detecting radioiodine-refractory differentiated thyroid carcinoma (RAIR-DTC), comparing its diagnostic performance with [F]F-FDG PET/CT. In this prospective pilot study, RAIR-DTC patients underwent whole-body imaging with [F] F-FDG PET/CT, followed by [Ga]Ga-DOTAGA-IAC PET/CT. Biodistribution patterns of [Ga]Ga-DOTAGA-IAC were assessed. Lesions with abnormal, nonphysiologic tracer uptake (showing activity exceeding mediastinal blood pool) were considered positive for disease. Imaging findings were compared between the two modalities, and quantitative metrics, including SUV, metabolic tumor volume, and total lesion glycolysis, were analyzed statistically. Among 30 patients with RAIR-DTC, [Ga]Ga-DOTAGA-IAC PET/CT revealed predominant physiological tracer uptake in the kidneys. [F]F-FDG PET/CT identified 97 lesions, predominantly nodal (73.2%), while [Ga]Ga-DOTAGA-IAC PET/CT detected 34 lesions, 50% of which were nodal. Few patients exhibited multiple lesions with varying uptake grades, with 20% showing coexisting higher-grade lesions (grade II or above) on [Ga]Ga-DOTAGA-IAC PET/CT. Angiogenesis imaging using [Ga]Ga-DOTAGA-IAC PET/CT demonstrates limited sensitivity for lesion detection in patients with RAIR-DTC compared with [F]F-FDG PET/CT. However, the potential of [Ga]Ga-DOTAGA-IAC as a diagnostic tool for other cancers has been used in other cancers with positive imaging characteristics warranting further exploration.