This is a prospective, single-center, open-label, two-cohort clinical study evaluating the safety, tolerability, biodistribution, radiation dosimetry, and diagnostic performance of \[68Ga\]Ga-ELI411 PET imaging in adult patients with solid tumors. Eligible patients with an indication for 18F-FDG PET imaging will receive a single intravenous administration of \[68Ga\]Ga-ELI411 followed by serial PET imaging. Imaging findings will be compared with conventional imaging, histopathology, and clinical follow-up when applicable. The study will also evaluate tracer biodistribution, radiation dosimetry, and lesion detection performance compared with standard 18F-FDG PET imaging.