Your doctor has arranged for you to undergo an MRI or CT Scan and you’re feeling a little lost in the midst of it all. So, start at square one. What are these medical imaging scans? These painless, safe scans take images of the inside of your body to check for various abnormalities. The machine takes photos of organs and specific areas of the body inside. In some cases, the radiologist will require a contrasting agent to be administered in order to view internal structures more clearly. Next step, what are contrasting 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 sometime 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 headache, nausea, itching, wheezing, and rashes. Contact your doctor if you experience serious side effects.

It’s certainly not uncommon to feel confused or lost when dealing with medical exams that you haven’t been exposed to. Feel free to reach out to our staff if you have any questions about your upcoming exam. We’re here to answer any of your questions and soothe any of your concerns. If you’re in need of an MRI or a CT scan, schedule an appointment with us at here.