(Gadolite® oral Suspension) An oral paramagnetic MRI contrast agent to enhance delineation of the bowel. Zeolites are hydrated aluminosilicates with large holes that can provide a temporary home for guest molecules like gadolinium. Zeolites modified with Gd (III) are effective positive MRI contrast agents for gastrointestinal application.

Macromolecular Gd labeled albumins are a new class of contrast agents with a wide range of use e.g., MR angiography, breast MRI, perfusion MRI, Lung perfusion, etc.
Marketed gadolinium-based albumin-bound contrast media are e.g., MultiHance®, and Vasovist™; other prototypes are in development. Malignant tumors often show an increased uptake and metabolism of plasma proteins, especially albumin. Contrast agents with large molecules are delivered to all tissues, but only accumulate in those with leaky vessels by tumor capillaries (tumor neovessels). MRI tumor perfusion studies with Gd labeled albumin can show the success of tumor therapy by quantitative decrease in MR signal of the malignant tissue after therapy compared to before. In addition, the study of tumor sensitivity to a therapy with drug-labeled albumins seems possible.
After renal transplantation, MRI may diagnose albuminuria caused by glomerular disease with an albumin-bound blood pool contrast agent

See also Blood Pool Agents, Intravascular Contrast Agents, Contrast Enhanced MRI.

Short name: PLLGd-DTPA, generic name: (Gd-DTPA)n-polylysine, chemical compound: Gd-DTPA poly(L-lysine-Gd-diethylenetriamine-N,N,N',N'',N''-pentaacetic acid), central moiety: Gd2+, relaxivity: r1=13.1, B0=0.23T
A polymeric MRI contrast agent under development (preclin., Bayer Schering Pharma AG, Berlin, Germany) with advantages in both MRA and in the differential diagnosis of tumors, particularly in perfusion studies of the myocardium and potential in MR lung perfusion. Dozens of the relatively small molecule Gd-DTPA is bound covalently to polylysine, a large molecular weight backbone. The stable, highly water-soluble agent does not diffuse through the endothelium of the vascular system; it is subject to renal elimination.

After a bleeding, blood goes through several transitions regarding magnetic properties, intra- and extracellular distribution and content of proteins and water. Oxyhaemoglobin is degraded to deoxyhaemoglobin and further to methaemoglobin, ferritin and haemosiderin. These molecules can be characterized by their magnetic susceptibility effect. Oxyhaemoglobin is diamagnetic with no practical influence on the magnetic field. All degradation products are paramagnetic (deoxyhaemoglobin, methaemoglobin) or even superparamagnetic (ferritin, haemosiderin).

See also Haemoglobin, Blood Oxygenation Level Dependent Contrast.

Isomers are molecules with the same chemical formula and often with the same kinds of bonds between atoms, but in which the atoms are arranged differently.

See also Isotope.