Development of nanoparticles and quantum dots as alternatives to iodinated contrast agents for mono-modal and bi-modal computed tomography imaging.

Medical imaging plays a pivotal role in disease screening, early detection, and diagnosis. Among the various imaging modalities, computed tomography (CT) is one of the most widely utilized in clinical practice, offering high-resolution anatomical images critical for disease investigation. To enhance the visibility of tissues with similar densities, contrast agents are often required. Iodinated contrast agents, the most commonly used, are effective but have significant limitations, including short circulation times, the need for high-concentration injections, restricted tissue targeting, and potential side effects such as nephrotoxicity. These challenges have spurred the development of next-generation contrast agents. Nanostructured materials, particularly nanoparticles and quantum dots, have emerged as promising alternatives due to their superior X-ray attenuation, extended circulation times, and potential for multi-modal imaging applications such as CT/MRI and CT/fluorescence. Their unique properties, including small size, large surface area, and tunable functionalization enable targeted imaging and reduced side effects, making them ideal candidates for advanced diagnostics. This review highlights the recent advancements in synthesizing and optimizing nanostructured contrast agents based on their elemental composition, synthesis techniques, and imaging properties. It underscores the transformative potential of nano-based agents in enhancing diagnostic accuracy while minimizing adverse effects, marking a significant step forward in medical imaging technology.