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.

Paramagnetic substances, for example Gd-DTPA solutions, are used as MRI oral contrast agents in gastrointestinal imaging to depict the lumen of the digestive organs. Different Gd-DTPA solutions or zeolites containing gadolinium can be used e.g., for diagnosis of delayed gastric emptying, diagnosis of Crohn's disease etc.
Low concentrations of gastrointestinal paramagnetic contrast agents cause a reduction in T1 relaxation time; consequently, these agents act on T1 weighted images by increasing the signal intensity of the bowel lumen. High concentrations cause T2 shortening by decreasing the signal, similar to superparamagnetic iron oxide. Gd-DTPA chelates are unstable at the low pH in the stomach, therefore buffering is necessary for oral use.

See also Gadopentetate Gastrointestinal, Gadolinium Zeolite, Negative Oral Contrast Agents, Gastrointestinal Superparamagnetic Contrast Agents, and Ferric ammonium citrate.

The characteristics of a hepatobiliary contrast agent are specific liver uptake and excretion via the biliary system. The paramagnetic substance (e.g. manganese, gadolinium) is taken up by normal hepatocytes. Diseased liver tissue did not include hepatocytes or their function is disturbed. Therefore, the signal of healthy liver tissue increases on T1 weighted sequences, but not in the liver lesions.
Another type of liver imaging contrast agent is superparamagnetic iron oxide. These particles accumulate in the reticuloendothelial system (RES) of the liver, and darken the healthy liver tissue in T2 weighted images. RES cells (including Kupffer cells) are existing in healthy liver tissue, in altered tissue with reduced RES activity or without RES cells the contrast agent concentration is also low or not existing, which improves the liver to lesion contrast.
Benefits of hepatobiliary contrast agents:
Differences of a hepatobiliary contrast agent compared with a targeted contrast agent for Kupffer cells:
See also Superparamagnetic Contrast Agents, Hepatobiliary Chelates, Liver Imaging, Endoremâ„¢, Primovistâ„¢, and Classifications, Characteristics, etc.

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

Nanoparticles may be utilize as a new class of uniform, biodegradable and non-toxic superparamagnetic contrast agents (Fe3O4). The preparation process of these particles is simple, does not involve any toxic material and the yield is close to 100%. The particles are usually of varying sizes from several to several hundred nanometer. They are irregular in shape and highly light-absorbing. They have no magnetic hysteresis at ambient temperatures, which is characteristic of superparamagnetic materials. Each magnetic nanoparticle is composed of a very thin organic nucleus (5-10%) and a thick shell of magnetite.
Different techniques were established for coating these magnetite nanoparticles with several functional and biocompatible polymers. Both the coating and the magnetite production processes are controllable, so that it is possible to prepare particles with a specific size of each particle component as well as particles coated with protein ligands for tissue specific imaging applications.

A limitation of abdominal MRI can be the assessment of malignancies by difficulties to distinguish bowel from other organs or malignant masses. The use of oral contrast agents can reduce this problem. Properties of an ideal oral contrast agent are little or no absorption by the stomach or intestines, complete excretion, no motion or susceptibility artifacts, and uniform marking of the GI tract.
Gastrointestinal MRI contrast agents are divided in materials with bright appearance or dark appearance. The choice of a negative or a positive oral contrast agent depends on the specific problem or the pulse sequence.

See also Positive Oral Contrast Agents, Negative Oral Contrast Agents, Gastrointestinal Diamagnetic Contrast Agents, Gastrointestinal Paramagnetic Contrast Agents and Gastrointestinal Superparamagnetic Contrast Agents.

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