Name a common contrast agent used in gastrointestinal studies.

Barium is widely recognized as a common contrast agent used in gastrointestinal studies. It is particularly effective for imaging the digestive tract during procedures such as barium swallows or barium enemas. The main reason barium is utilized is due to its ability to absorb X-rays, which enhances the contrast of images captured during radiographic examinations. When ingested or introduced into the alimentary canal, barium coats the lining of the gastrointestinal tract, allowing for clearer visualization of structures such as the esophagus, stomach, and intestines. This property makes it invaluable for diagnosing various gastrointestinal conditions, including tumors, strictures, and ulcers.

Other options, such as iodine, are typically used in vascular studies or CT scans, while gadolinium is more commonly associated with MRI procedures. Carbon dioxide is sometimes used to enhance visualization during certain procedures, but barium remains the standard in many routine gastrointestinal studies.