New MR imaging contrast agents.

Many new MR contrast agents are undergoing laboratory development, are in clinical trials, or are being used for routine clinical applications. These agents function by targeting specific receptors that allow the agent to accumulate within the reticuloendothelial system, the hepatobiliary system, or the blood pool. Each agent has unique properties that offer advantages over unenhanced and gadolinium chelate-enhanced MR imaging. Use of these agents, however, requires an understanding of their current and potential clinical indications and inherent limitations. This article reviews the development, evaluation, and clinical application of a number of these agents, including ferumoxides, Mn-DPDP, AMI-227, SHU-555A, Gd-EOB/DTPA, Gd-BOPTA, and MS-325.