Short name: Gd-DTPA-BMA, generic name: Gadodiamide, chemical compound: Gd-diethylenetriaminepentaacetate-bis(methylamide), central moiety: Gd
A paramagnetic MRI contrast agent (nonionic) with a small molecular weight linear chelate. Due to the linkage of two DTPA molecules through amide bonds the molecule is uncharged and has a low osmolality. The substance is excreted almost exclusively by the kidneys.

See also Nonionic Intravenous Contrast Agents and Omniscan®.

(Gd) Gadolinium is a Lanthanide element that is paramagnetic in its trivalent state.
This paramagnetic substance is used for MR imaging because of the effect of strongly decreasing the T1 relaxation times of the tissues to which gadolinium has access. When injected during magnetic resonance imaging, gadolinium will tend to change signal intensities by shortening the T1 time in its surroundings.
The relaxivity of gadolinium is an important measure of its efficacy, which is dependent on the chemical properties of the complex. The gadolinium ion cannot be used in its chloride, sulfate, or acetate forms because of poor tolerance and low solubility in water in the neutral pH range. Although toxic by itself, gadolinium can be given safely in a chelated form such as DTPA, that still retains much of its strong effect on relaxation times (relaxivity).

See also Dotarem®, Gadovist®, MultiHance®, Omniscan®, OptiMARK®, and Contrast Agents, the info sheet gives an overview and more in-dept information about different types of MRI contrast agents.

Radiographic low-osmolar nonionic contrast agents have less side effects and fewer nephrotoxicity than ionic, high-osmolar agents. Gadolinium-based MRI contrast agents have a different formulation from iodinated X-ray contrast media, and there is no known cross sensitivity between these two types of contrast agents. Intravenous MRI contrast agents, specifically the gadolinium chelates have a high safety and lack of nephrotoxicity compared with X-ray contrast media.
The used gadolinium chelates differ in following properties: linear (e.g., gadodiamide and gadoversetamide have nonionic linear structures) vs. macrocyclic cores, and ionic vs. nonionic types. The nonionic molecules have lower osmolality and viscosity, which increase digestibility at greater concentrations, and make faster bolus injections conceivable. The macrocyclic molecules (e.g., gadoteridol has a nonionic macrocyclic ring structure) are more stable and show fewer tendencies to dissociate free Gd.

See also ProHance®, Omniscan®, OptiMARK®, Ionic Intravenous Contrast Agents.

See also the related poll result: 'MRI will have replaced 50% of x-ray exams by'

Magnetic relaxation in tissues can be enhanced using contrast agents. The most commonly used for MRI are the paramagnetic contrast agents, which have their strongest effect on the T1, by increasing T1 signal intensity in tissues where they have accumulated.
MRI collects signal from the water protons, but the presence of these contrast agents enhances the relaxation of water protons in their vicinity. Paramagnetic contrast agents contain magnetic centers that create magnetic fields approximately one thousand times stronger than those corresponding to water protons. These magnetic centers interact with water protons in exactly the same way as the neighboring protons, but with much stronger magnetic fields, and therefore, have a much greater impact on relaxation rates, particularly on T1. In MRI, contrast agents are routinely injected intravenously to help identify areas of hypervascularity, as in malignant tumors.

See also Contrast Agents, Gadovist®, MultiHance®, Omniscan®, OptiMARK®.

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