GastroMARK® belongs to the negative oral contrast agents (same as Lumirem®, another brand name for ferumoxsil). GastroMARK® is used to distinguish the loops of the bowel from other abdominal structures and physiology. When GastroMARK® is ingested, it flows through and darkens the stomach and the small intestine in 30 to 45 minutes. By more clearly identifying the intestinal loops, GastroMARK® improves visualization of adjacent abdominal tissues such as the pancreas.

The company changed its name from Advanced Magnetics, Inc. to AMAG Pharmaceuticals, Inc. in July 2007.
AMAG Pharmaceuticals, Inc., a biopharmaceutical company, developed and manufactured organ-specific diagnostic contrast agents that provide clearer images during magnetic resonance imaging (MRI) tests used to detect tumors and other abnormalities.
The company had two MRI related products on the market: Feridex I.V. (for the diagnosis of liver lesions) and GastroMARK (used for bowel and abdominal MR imaging). In November 2008, AMAG Pharmaceuticals, Inc. decided to discontinue the manufacturing of Feridex. The development of Combidex as a contrast agent for lymph disease has also been stopped.
The Company has now two commercial products: Feraheme® and GastroMARK®. Feraheme® is the trade name of Ferumoxytol (formerly Code 7228) and is indicated for the treatment of iron deficiency anemia. Feraheme® is also being developed as a diagnostic agent for vascular-enhanced magnetic resonance imaging (MRI) to assess peripheral arterial disease.

MRI Contrast Agents:

Lumirem® belongs to the negative oral contrast agents (same as GastroMARK®, another brand name for ferumoxsil). Lumirem® is used to distinguish the loops of the bowel from other abdominal structures and physiology. When Lumirem® is ingested, it flows through and darkens the stomach and the small intestine in 30 to 45 minutes. By more clearly identifying the intestinal loops, Lumirem® improves visualization of adjacent abdominal tissues such as the pancreas.
Additionally, in Europe Lumirem® is approved for rectal administration to delineate the lower intestinal system.

Mallinckrodt, a Tyco Healthcare company makes and distributes products for respiratory care; bulk and dosage pharmaceuticals, primarily for pain relief and addiction therapy; and imaging agents for magnetic resonance, ultrasound, X-ray, and nuclear medicine applications. With worldwide manufacturing and distribution facilities, as well as worldwide sales offices, Mallinckrodt sells its products worldwide.
GastroMARK® is marketed in the United States by Mallinckrodt, Inc.

In June 2007 Tyco International Ltd. completed the separation of its healthcare business, which is named Covidien. Mallinckrodt, Inc. is now part of Covidien Ltd.

MRI Contrast Agents:

(SPIO) Relatively new types of MRI contrast agents are superparamagnetic iron oxide-based colloids (median diameter greater than 50nm). These compounds consist of nonstoichiometric microcrystalline magnetite cores, which are coated with dextrans (in ferumoxide) or siloxanes (in ferumoxsil). After injection they accumulate in the reticuloendothelial system (RES) of the liver (Kupffer cells) and the spleen. At low doses circulating iron decreases the T1 time of blood, at higher doses predominates the T2* effect.
SPIO agents are much more effective in MR relaxation than paramagnetic agents. Since hepatic tumors either do not contain RES cells or their activity is reduced, the contrast between liver and lesion is improved. Superparamagnetic iron oxides cause noticeable shorter T2 relaxation times with signal loss in the targeted tissue (e.g., liver and spleen) with all standard pulse sequences. Magnetite, a mixture of FeO and Fe2O3, is one of the used iron oxides. FeO can be replaced by Fe3O4.
Use of these colloids as tissue specific contrast agents is now a well-established area of pharmaceutical development. Feridex®, Endorem™, GastroMARK®, Lumirem®, Sinerem®, Resovist® and more patents pending tell us that the last word in this area is not said.
Some remarkable points using SPIO:

See also Superparamagnetism, Superparamagnetic Contrast Agents and Classifications, Characteristics, etc..