Perfluorochemicals are fluorinated organic compounds. Perfluorochemicals can be used in gastrointestinal imaging as a negative contrast agent to reduce signal in the intestine. The MRI signal reduction is caused by the absence of mobile protons.
Perfluoroctylbromide (PFOB)(C8F17Br) is suitable for gastrointestinal use in humans; perfluorononane has been tested in animal models. PFOB is commercially available as Perflubron® (Imagent GI, Alliance). Benefits of this type of contrast media are biologically inertia, immiscibility with water, and a fast transit through the small intestine caused by low surface tension.
Fluosol-DA, a perfluorochemical emulsion has been tested in mice as a tumor specific agent for 19F-MRI.

See also Classifications, Characteristics, etc.

Protons in -CH2- groups, e.g., contained in fatty emulsions, mineral or vegetable oil or sucrose polyester, have a fast relaxation and short T1 time. These agents with short T1-relaxation, if used in gastrointestinal imaging, produce bright signal intensities in the intestine on T1 weighted sequences. Palatable oil emulsions can produce appropriate contrast opacification of the stomach as well as the small bowel, but caused by absorption in the distal small bowel these materials are not suitable for use in MRI colonoscopy.

See also Positive Oral Contrast Agents and Gastrointestinal Paramagnetic Contrast Agents.

California-based research and development company. Alliance has several patents regarding 'microbubble' compositions such as Imagent® that are intended to enhance ultrasound imaging and Imagent GI as a gastrointestinal MRI contrast agent. Another product is Oxygent™, a synthetic 'blood substitute'.

MRI Contrast Agents:

• Imagent GI

Pharmacyclics is a pharmaceutical company developing novel agents to improve current therapeutic approaches to cancer, cardiovascular diseases, and inflammation. The company's proprietary products are derived from its core technology in biometallic chemistry. These products under development are based upon small molecules, which bind metals in a unique way and are capable of capturing and focusing forms of energy used in a variety of medical applications. The company has one product in registration with the FDA, Gadolite® Oral Suspension, a contrast agent for imaging the gastrointestinal tract; two products in clinical development, Gd-Tex (Motexafin gadolinium), a radiation sensitizer, Lu-Tex, a photosensitizer; and several compounds in preclinical development.

MRI Contrast Agents:

A solution of ferric ammonium citrate (Geritol) used to enhance the delineation of the bowel. With T1 weighted magnetic resonance imaging (MRI) the predominantly positive enhancement helps to distinguish organs and tissues that are adjacent to the upper regions of the gastrointestinal tract. Product name found as both Ferriseltz® and FerriSeltz®.