Liver-specific MR imaging contrast agents.

Liver-specific MR imaging contrast agents consist of iron oxide particles or specially designed paramagnetic complexes targeting either the reticulo-endothelial system of the liver or the hepatocytes. These agents enhance the relaxation of water molecules in normal liver tissue and are excluded from abnormal tissue, such as metastases. Relaxation enhancement provides a map of normal liver function, increasing conspicuity of focal abnormalities. Understanding the indications and use of these agents is a central challenge for radiologists practicing liver MR imaging.