What You’ll Need To Know About Contrast Agents

about contrast agents

After being recommended a diagnostic imaging scan, you may start to research more about these scans. From MRI's to CT scan, these procedures are often simpler and a lot less scary than they may initially seem. When doing your research about a particular scan, you may discover that a certain scan uses contrast agents.

So, what are contrast agents?

Contrast materials are agents used to improve pictures taken in the body with X-Ray machines, CAT Scans, and MRI’s. They come in various forms, however, the most common are liquids, dyes, or pills which are given to the patient before the test. In most cases, patients simply drink the substance. However, it can be administered through an enema rectally or given intravenously through needle or IV. These agents change the way the body interacts with the imaging equipment and enhance the patient’s tissue and organ visibility. Here’s everything you need to know about contrast agents during your medical imaging scan:

Iodine Contrast and Barium Sulfate Used in X-Rays and CT Scans

An iodine substance will be injected into the veins, disks, or the fluid spaces in the spine before undergoing the scan. Barium sulfate is taken by mouth and the patient drinks it before the test. Sometimes it is administered rectally by enema, a procedure that injects liquid into the rectum. Barium sulfate is available in powder, liquid, paste, and tablets.

Oral, Rectal and IV Contrast Agents for X-Rays and CT scan

Barium sulfate is swallowed and used to enhance images of the gastrointestinal tract. This area includes the pharynx, esophagus, stomach, small and large intestines. If your radiologist requires images of your lower gastrointestinal tract, then barium sulfate will be administered through an enema.

Iodine is injected into the veins to enhance images for X-rays and CT scans. It is used to see internal organs, the gastrointestinal tract, veins, arteries, brain, breasts, skin and muscles. Each agent used enhances the doctor’s ability to see the organs needed to make a diagnosis.

MR-Gadolinium for MRI’s

Gladalium is a dye or contrast agent used with MRI scans. It is injected into the veins and significantly improves the quality of images taken. It’s used in about 1 out of 3 MRI’s and improves the accuracy of the diagnosis.

This dye is used to take a closer look at inflammation, blood vessels, and organs. This injection takes 30 second or more to work and you may experience a cold sensation for a few minutes in the site where the dye is injected. However, some patients experience a mild itching in the eyes and skin.

Barium Sulfate

You will be asked to abstain from eating for several hours before the test. Unfortunately, if you’re required to administer the contrast orally, you may not be too pleased with the taste. When given by enema it produces a sense of fullness that passes quickly. Tip to the wise, it’s a good idea to drink plenty of water after the test. Barium sulfate is eliminated through bowel movement causing white feces for a short time after drinking it.

Some of the other symptoms that patients may experience after taking barium sulfate are stomach cramps, diarrhea, constipation, itching, redness, hives and difficulty breathing. Contact your doctor should you experience any severe allergic reactions.


When iodine is injected into your veins you’ll most likely experience a warm sensation and sometimes a metallic taste in your mouth. The needle may cause some discomfort, however, it’s not a painful process. After your scan, be sure to drink plenty of water in order to flush out your system. Mild side effects might be a headache, nausea, itching, wheezing, and rashes. Contact your doctor if you experience serious side effects.

We understand that imaging scans can be intimidating, but we hope that this blog will give you a better idea on how contrast agents and imaging scans are used in tandem. Are you in need of a CT scan or MRI? Book an appointment with one of the best radiology practices in the Bay area today!