Nano-Sized CT Contrast Agents *

This chapter summarizes the recent progresses made in nano-sized computed tomography (CT) contrast agents. It focuses on the nanosized CT contrast agents and their applications. Nano-sized CT contrast agents are advantageous because a number of heavy atoms can be delivered to a target receptor at the region of interest. Long-circulating liposomal CT contrast agents are advantageous especially when repeated CT imaging is required. Various gold nanoparticles were studied as CT contrast agents. In addition to lanthanide chelates, nano-sized CT contrast agents can be prepared by encapsulating lanthanide ions within emulsion or synthesis of lanthanide-doped inorganic nanomaterials. Novel CT contrast agents with suitable K-edge energies and long circulation times are expected to accelerate innovation in CT imaging. Since intravenously injected nanoparticles are cleared by reticuloendothelial system-rich organs such as liver, nano-sized CT contrast agents can be used to diagnose hepatic tumors or liver metastases.