Advancements in positron emission tomography (PET) imaging tracers are improving cancer diagnosis and treatment personalization. Newly developed peptide-based tracers targeting immune checkpoint proteins, such as PD-L1 in head and neck cancer and glypican-3 in hepatocellular carcinoma, provide superior specificity over conventional FDG tracers. Additionally, a novel ^18F-fluorodeoxysorbitol (^18F-FDS) tracer exhibits high sensitivity for detecting invasive mold infections in immunocompromised patients. These molecular imaging tools enable noninvasive visualization of tumor immune environments and infectious agents, facilitating earlier detection, monitoring, and therapy optimization in oncology and infectious disease management.