(LOCM) Low-osmolar contrast media have a wide range of indications due to their lower side effects. The type of contrast media is an important risk factor for an adverse reaction.
LOCM have not completely replaced contrast media with higher osmolality due to their higher cost. Guidelines of professional organizations give recommendations for the selective use of low-osmolar contrast media for certain high-risk patients.
There are ionic and nonionic iodinated contrast materials with low osmolality available:
An adverse reaction occurs in low-risk patients who receive conventional ionic contrast agents more often than in high-risk patients who receive nonionic LOCM.

See also Contrast Enhancement, Biliary Contrast Agents, Safety of Contrast Agents and Contrast-Induced Nephropathy.

An anaphylactic reaction is a generalized allergic effect (also called anaphylactic shock). Allergic or anaphylactoid reactions range from sneezing, urticaria and itching, bronchospasm, facial and laryngeal edema to life-threatening symptoms including cardiovascular collapse, shock and respiratory distress.
Iodinated contrast materials are safe and widely used. However, anaphylactoid reactions occur rarely after administration of x-ray contrast agents. Most hypersensitivity symptoms appear short time after the intravenous, oral, rectal or other application (e.g., retrograde pyelography), only few are delayed by hours.
Patients with a history of allergic, asthmatic or reactions to contrast agents are at increased risk of anaphylaxis. Pre-treatment with corticosteroids and antihistamines decreases the incidence of an adverse reaction.

An arthrography is a radiographic examination of a joint (such as the knee, shoulder, hip, elbow or wrist) that requires an injection of a contrast medium into the joint space.
For an opaque x-ray arthrography a water-soluble iodinated contrast agent is injected and a series of fluoroscopic controlled images is produced. Magnetic resonance arthrography combines the arthrogram with MRI. A small quantity of gadolinium contrast agent is added to the injection into the joint space. The traditional radiographic images are followed by an MRI of the extremities. A non-invasive possibility is an indirect MR arthrography, which doesn't require the injection into the joint. The dye is given prior to the imaging procedure.
The contrast fluid produces a bright signal and allows evaluation of small defects of the joint capsule, assessment of articular surface and labral cartilage, and in case of an indirect arthrogram also of the surrounding soft tissue. If a gaseous medium is used, this exam is called pneumoarthrography and a combination with liquid contrast is used in double-contrast arthrography.
MR arthrography is often used to evaluate hip and acetabular labrum, shoulder rotator cuff and glenoid labrum (see Shoulder MRI), and less often in wrist and knee MRI studies. Also combinations of CT and nuclear medical techniques with arthrography are available.

Barium sulfate (BaSO4) is an inert and insoluble white powder with high density. Barium belongs chemically to the group of heavy metals. Mixed with water and additional ingredients (e.g., sweetening agents), barium sulfate is the preferred positive contrast agent for abdominal x-ray and computed tomography examinations. The extremely low solubility of barium sulfate protects patients from absorbing harmful amounts of the metal (water soluble metal compounds are often highly toxic). The high density in x-ray examinations is related to the high atomic number, since large nuclei absorb x-rays much better than smaller nuclei.
Barium sulfate agents for opacification of the gastrointestinal tract are not absorbed or metabolized and are resistant to dilution. These contrast agents are opaque white suspensions and usually swallowed or administered as an enema. They provide better delineation of mucosal details and are less expensive than water-soluble iodinated contrast media. The elimination rate is a function of gastrointestinal transit time. After GI application, it leaves the body with the feces.

Contraindications of barium sulfate products in case of known or suspected:

The Germany-based pharmaceutical company is the result of the take-over of Schering AG by Bayer AG in 2006. The Bayer Schering Pharma AG is part of the Bayer HealthCare AG, which represents the pharmaceutical part of the Bayer Group. Activities of the Bayer Schering Pharma AG are Diagnostic Imaging, Hematology & Cardiology, Oncology, Primary Care, Specialized Therapeutics and Women's Healthcare. The diagnostic imaging part's contrast agents for MRI, x-ray and CT are 'world-market leaders'.
See also Bayer HealthCare Pharmaceuticals.