Sinerem® is the brand name (same as Combidex®) for an ultrasmall superparamagnetic iron oxide (USPIO) to detect metastatic disease in lymph nodes. Metastatic nodes show less uptake of this MRI contrast agent, which results in less signal decrease and allows the differentiation of normal lymph nodes from normal-sized, metastatic nodes.
Lymph node imaging with Sinerem® is performed 24 to 36 hours after slow infusion. Normal lymph nodes turn black post contrast, namely on T2* weighted images. Metastatic lymph nodes remain unchanged in signal intensity.
Indication and Diseases: Cancer, Imaging for diagnosis, Lymphatic disorders.
See Ferumoxtran, and Classifications, Characteristics, etc.

Guerbet decided in 2007 to withdraw its Marketing Authorisation Application (MAA) for Sinerem.

(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..

Short name: Ami 227, generic name: Ferumoxtran, (USPIO)
Ferumoxtran is a substance of the class of ultrasmall superparamagnetic iron oxide used as a lymph node specific contrast agent for MRI.
See also Combidex®, Sinerem® and Ultrasmall Superparamagnetic Iron Oxide.
Partner(s): Cytogen Corporation, National Cancer Institute. An approvable letter was received from the U.S. Food and Drug Administration for Combidex in June 2000. Advanced Magnetics, Inc. has submitted a complete response to the approvable letter received from the U.S. Food and Drug Administration, which was accepted by the FDA and assigned a user fee goal date of March 30, 2005. In Europe, a Dossier (the European equivalent of a NDA) was submitted by Advanced Magnetics' European partner, Guerbet SA, to the European Medicines Evaluations Agency in December 1999. (Sinerem® is the brand name for this USPIO in Europe manufactured by Guerbet, Combidex® by Advanced Magnetics for the U.S. market)
Advanced Magnetics, Inc. changed its name in July 2007 to AMAG Pharmaceuticals Inc.

Contrast agent with a preferential intracellular distribution.
Intracellular agents (such as manganese derivatives and ultrasmall superparamagnetic iron oxide), exhibit a flow- and metabolism-dependent uptake. These properties may allow delayed imaging, similar to isotopic methods.
Phospholipid liposomes are rapidly sequestered by the cells in the reticuloendothelial system (RES), primarily in the liver. For imaging of the liver, liposomes may be labeled with MR contrast medium, both positive (T1-shortening) paramagnetic media, and negative (T2-shortening) superparamagnetic media.
Several other nonliposome MR contrast media are also taken up by the RES, e.g.:
Other MR contrast agents accumulate selectively in the hepatocytes, e.g.:

(VSOP = very small superparamagnetic iron oxide particles) This new class of contrast agents with smaller particle size than SPIO offers advantages for MR angiography. SPIO particles are usually coated with an organic polymer such as dextran, carboxydextran or polyethylene glycol, which limits the minimal overall particle size that can be obtained. VSOP-C184 consists of an aqueous solution of superparamagnetic iron oxide particles with a citrate coating and the overall particle size of 4-8 nm.
Short name: VSOP-C184, central moiety: Fe, concentration: 29 g Fe/l, relaxivity: R1=20.1, R2=37.1, B0=0.94 T.