BARIUM CONTRAST MEDIA

Barium contrast media appear radiopaque on a radiograph due to barium sulphate having a higher atomic number than soft tissues. Barium sulphate is inert with no osmotic potential and is not absorbed or acted upon by alimentary secretions.

There is a wide variety of barium sulphate preparations used in veterinary radiography and some of the preparations available at the time of writing are shown in Figure 1. None of these preparations is authorized for veterinary use and most are POM.

Options:

• Barium paste is primarily used to highlight abnormalities of oesophageal mucosa
• A barium meal (barium paste added to food) is best for identifying functional abnormalities.

Use:

• Barium contrast media are used for studies of the gastrointestinal (GI) tract.
• Barium-impregnated polyethylene spheres (BIPS) may be used to assess intestinal transit times and gastric emptying rate, as well as to detect obstructions.
• As with all contrast studies, plain radiographs should be obtained prior to the administration of barium.
• Barium paste is used for oesophageal studies as it adheres to the mucosa. Barium can also be mixed with food to evaluate the oesophagus and may demonstrate strictures or dilatations not seen with liquid barium or paste.
• Liquid barium may be used to evaluate any part of the GI tract and is used alone for evaluation of the stomach and intestines. Flavoured preparations designed for human use may be unpalatable for some animals.

Safety and handling:

• Skin irritation may occur with skin contact.
• Take care not to spill barium on the patient’s coat; any spills should be carefully cleaned off.

Contraindications and complications:

• Barium is insoluble and should not be used outside the GI tract.
• A barium study should not be performed <24 hours before endoscopy.
• Leakage of barium into body cavities may lead to granulomatous reactions or adhesions.
• If perforation of the GI tract is suspected, low-osmolar water-soluble contrast media, rather than barium media, should be used.
• Care should be taken when administering barium to dysphagic animals, distressed patients, or those with swallowing disorders or laryngeal paralysis, as aspiration of barium into the bronchi and lungs may occur and can result in aspiration pneumonia.
• If inappropriately sized BIPS are used, mechanical obstruction of the GI tract can occur.
• May cause constipation, transient diarrhoea and abdominal pain.

Figure 1: Preparations of barium sulphate used in veterinary radiography.

IODINATED CONTRAST MEDIA

Iodinated contrast media appear radiopaque on a radiograph due to iodine having a higher atomic number than soft tissues. Water-soluble iodinated contrast media are available in ionic and non-ionic forms, and a wide range is available. The more commonly used ones are detailed in Figure 1. None is authorized for veterinary use and most are POM.