Recent advances in spectral CT contrast agents for gastrointestinal tract imaging.

Computed tomography (CT) represents one of the most widely utilized and clinically effective imaging techniques for gastrointestinal diseases. Specifically, spectral CT, as an advanced evolution of conventional CT, has significantly improved diagnostic accuracy. The creation of high-performance and biocompatible contrast agents is essential for achieving superior visualization of the gastrointestinal tract and facilitating accurate disease identification. Recent studies reveal that small molecule- and nanoparticle-based contrast agents with high atomic number elements demonstrate significant promise in gastrointestinal diagnostics via spectral CT imaging. Therefore, this review systematically discusses the synthesis, characteristics and advantages of small molecule- and nanoparticle-based contrast agents, with emphasis on their utility in gastrointestinal imaging, disease diagnosis, and therapeutic interventions. Furthermore, the limitations and future directions of current contrast agents are also evaluated, offering a foundation for the design of novel gastrointestinal spectral CT contrast agents.