MR imaging of the liver. Contrast agents.

Contrast agents are needed for improvement of lesion detection and lesion characterization on hepatic MR imaging. According to their biodistribution, contrast agents are classified into extracellular, hepatocyte-targeted, macrophage-monocytic phagocytic system(MPPS)-targeted, and blood-pool contrast agents. Dynamic MR imaging of the liver enhanced with extracellular gadolinium chelates improves lesion characterization. Hepatocyte-targeted and MPPS-targeted contrast agents improve lesion detection. Hepatocyte-targeted contrast agents that have an initial extracellular distribution phase and blood-pool contrast agents offer a potential for improvement of both detection and characterization of focal hepatic lesions.