Nanoparticles in computed tomography

The last decade has brought about major advances in cancer treatment, including the development of highly conformal radiation treatments and robotic and endoscopic surgery. These techniques rely on accurate target delineation and visualization of tumor targets, and require accuracy on the millimeter scale. Therefore, a key priority in cancer research involves the development of highly sensitive and specific imaging techniques that could vastly improve treatment capabilities through early detection of millimetersized tumors. Computed Tomography (CT) is among the most convenient imaging/diagnostic tools in hospitals today in terms of availability, efficiency and cost. Undisputedly, this is one of the leading technologies applied in overall cancer management. As a diagnostic tool, the CT provides valuable anatomical information regarding tumor location, size and spread. However, the sensitivity of the CT is limited in the detection of sub-centimeter lesions and its specificity is relatively low, resulting in ~ 15% false positive results (noncancerous findings that are interpreted as tumors) [1]. Therefore, improving current CT capabilities is critical to cancer detection. This aim can be achieved by expanding the role of the CT beyond its present structural imaging capabilities and providing it with functional and molecular-based imaging capacities as well. This need escalated the development of nanoparticles as the next generation CT contrast agents. Nanoparticles are expected to play a major role in the future of medical diagnostics due to their many advantages over the conventional contrast agents, such as prolonged blood circulation time, controlled biological clearance pathways and specific molecular targeting capabilities. This chapter will describe the basic design principles of nanoparticle-based CT contrast agents and review the state-of-the-art developments and clinical applications of blood pool, passive and active targeting CT contrast agents.