Computerized Tomography

Home » Computerized Tomography » Contrast Dye

Contrast Dye

There's a popular misconception that using intravenous dye for CT scans makes everything better and easier to see. But that is not always true. Although rare, some patients suffer allergic reactions to the dye. And finally, the newer contrast agents are quite expensive. But there are times when dye is definitely needed, such as for detecting the spread of malignancy in the brain or liver. In situations where patients are allergic to contrast, MRI can be an excellent alternative. The contrast used in MRI are unlike the CT dyes, and the likelihood of a reaction is even more rare.

If your doctor and/or radiologist decides that you need a contrast scan, make sure that you have mentioned an allergic history (especially to previous dye injections). Also ask if you really need the dye, and if you do, request a newer, milder dye.

When Is a CT Necessary?
The CT scanner has become the key player in the imaging arsenal. The places where CT is not used include breast diagnosis (generally), obstetrics, and in looking at the various soft tissue structures that make up the joints. Other than those few exceptions, CT is most often the procedure of choice. Head CT has become almost a standard part of any work-up for conditions such as trauma; severe headache; prolonged, persistent headache; and changes in mental status.

In other places in the body, radiologists do fine needle aspirations (biopsies) under CT guidance, as well as under ultrasound guidance. In some institutions, the abdominal CT scan has become the screening test for severe abdominal pain when renal stones, appendicitis, or diverticulitis is suspected.

The CT study of the pulmonary arteries has become an exceptionally important tool in the diagnosis of life-threatening pulmonary clots (emboli). The list of applications for CT seems to be growing daily.

Risks and Potential Complications
The only risk of a CT scan is radiation, the same risk as all other x-ray tests. If intravenous contrast is used, there is a risk for a reaction as well. Overall, the risks of CT are minimal.

What Actually Happens?
Prior to the study, a technologist or nurse will probably interview you. If you do not receive intravenous contrast, the test is very easy to take. You will be asked to lie (usually on your back) on the CT table, which is often padded and concave to receive your body. Unless you have severe back pain while lying supine, or you are severely claustrophobic, this should not be an unpleasant experience. Of course, you will be apprehensive and nervous, but the test should be over very quickly.

Depending on the nature of your study, you may be asked to drink variable amounts of oral contrast before the test. Most of these preparations, though not delicious, are tolerable. Unlike many MRI gantries, the CT gantry is relatively open and only the most claustrophobic patients have a problem.

What Is It like Afterward?
If you have the oral dye, and especially if it's barium, make sure that you drink lots of liquids. The oral dyes used for CT are much less dense than those used in the upper GI series, and the potential of impaction is much less. Those who have had the IV dye should have no postprocedural problems. Delayed reactions are exceedingly rare.

Obtaining the results of the CT scan depend on many factors, including the urgency of the study, the seriousness of the problem, and the staffing in the x-ray department. For urgent studies the results should be known quickly. If you have the test early in the morning, you should know the results by late afternoon or the following day at the latest.

Can you ask the radiologist about his or her impressions right after the test? Often the radiologist is elsewhere and may not be available for an initial impression. Also, CT scans are very involved studies that require numerous images, may require reformatting, and may also require review of previous studies. There is a long way to go from raw data to diagnosis with CT scans, all of which may take a bit of time.

© 1998-2008 Healthcommunities.com, Inc. All Rights Reserved.

Computerized Tomography Resources

	Join Our CT Scan Forum Do you have a question, want to share medical advice, or just need to discuss your situation with someone else having a similar experience? The healthchannels forum is a resource for everyone to share and discuss their health and medical needs with others.	Advertising Disclaimer
	Living with...Share your story Do you have a personal health story that you would like to share with others? As a source of free patient education, our goal is to provide our users with trustworthy information and support from others. That's why we've started our "Living with..." sections.
	Our "Living With..." support pages are a place to share experiences about living with a certain condition, disease, disorder, or illness and for loved ones of those dealing with health-related issues. Many people, especially when newly diagnosed, find comfort in knowing that others are having a similar experience. Help others by sharing your story. View stories already submitted.
	Stay Updated Sign up for our newsletter and receive important updates on the medical conditions that are most important to you.
Are you interested in becoming a nurse? Take this test. Advertising Disclaimer To quickly access health information from your website's browser, download Healthcommunities.com's healthchannels toolbar. Advertising Disclaimer