Short name: SHU 555 A, generic name: Ferucarbotran
A RES-directed MRI contrast agent (SPIO) made-up of a colloidal sol of iron oxide nanoparticles coated with carboxydextran (Resovist®, Cliavist™).
It is used for the detection and characterization of especially small focal liver lesions and offers the opportunity to make a reliable diagnosis at a very early stage of patients with suspected liver tumors.
Bayer Schering Pharma AG announced that it has received marketing approval for the liver-specific contrast agent Resovist® in Japan. See Contrast Agents and Superparamagnetic Contrast Agents.

Small particles of ferrite are used as superparamagnetic contrast medium in MR imaging (appearing predominantly dark on MRI). These agents exhibit strong T1 relaxation properties, and due to susceptibility differences to their surroundings also produce a strongly varying local magnetic field, which enhances T2 relaxation to darken the contrast media containing structures.
Superparamagnetic contrast agents are also known by the abbreviation SPIO's (small particle iron oxide or superparamagnetic iron oxide) and USPIO's (ultrasmall particle iron oxide or ultrasmall superparamagnetic iron oxide).
Two types of USPIO will be available on the market as blood pool agents, while SPIO's have been used as darkening contrast agents for liver imaging. As particulate matter they are taken up by the RES. Very small particles of less than 300 nanometers also remain intravascular for a prolonged period of time and thus can serve as blood pool agents.

See also the related poll result: 'The development of contrast agents in MRI is'