What is contrast media

If you need to have gadolinium contrast, the radiologist will use one of these lower risk types of gadolinium contrast. It is now thought that less than 1 in people with severe kidney function impairment who have these lower-risk types of gadolinium contrast will develop NSF.

It is often possible to carry out MRI without using any gadolinium contrast agents, and this is preferred where possible for patients with very poor kidney function or who are on dialysis. This occurs mainly in people who have large amounts of iodine-containing contrast medium given into an artery such as with coronary angiography or complex interventional procedures or if they have more than one CT scan using intravenous contrast in a short period of time; that is, hours to 1—2 days.

If you are on permanent dialysis, you are not at risk of worsened kidney function if you receive iodine contrast agents. If you have any questions or concerns, you can discuss the use of contrast media with your own doctor or specialist who is referring you for the radiology test, and about the need for a kidney function test or any special medication that might be required before having the test.

Any concerns can also be discussed with medical staff where you are having the scan or procedure; that is, the radiographer medical imaging technologist who will carry out the scan, or to the radiologist specialist doctor who interprets the images and provides your referring doctor or specialist with a report.

What is an octreotide scan? Nuclear medicine uses radioactive materials to diagnose or treat diseases. An octreotide scan is one…. What are the prerequisites for having an ascitic tap done? Prior imaging is required to confirm the presence and accessibility…. What are the generally accepted indications for an ultrasound guided prostate biopsy? The generally accepted indications for an ultrasound guided…. What is a bone mineral density scan?

A dual-energy X-ray absorptiometry scan DXA , or bone density scan, is a special…. It issues no invitation to any person to act or rely upon such opinions, advices or information or any of them and it accepts no responsibility for any of them. The content of this publication is not intended as a substitute for medical advice. Some of the tests and procedures included in this publication may not be available at all radiology providers.

Each person should rely on their own inquires before making decisions that touch their own interests. Find information about a clinical radiology procedure or test: Refine search Reset. A very small percentage of patients may develop a delayed allergic reaction with a rash which can occur hours to days after an imaging exam with an iodine-based contrast media. Most are mild, but severe rashes may require medication after discussion with your doctor.

Patients with impaired kidney renal function should be given special consideration before receiving iodine-based contrast media by vein or artery. Such patients are at risk for developing contrast-induced nephropathy, in which the pre-existing kidney damage is worsened. Some conditions increase the risk of an allergic or adverse reaction to iodine-based contrast media.

These include:. Being at increased risk for an allergic or adverse reaction to contrast media does not necessarily mean a patient cannot undergo an imaging exam with contrast media. Some medications are sometimes given before the contrast media is administered to lessen the risk of an allergic reaction in susceptible patients. The contrast media used in MR called gadolinium is less likely to produce allergic reactions than the iodine-based media used for X-rays and CT scanning.

Very rarely, patients are allergic to gadolinium-based contrast media and experience hives and itchy eyes. Reactions usually are mild and easily controlled by medication. Severe reactions are rare. Nephrogenic Systemic Fibrosis NSF , a thickening of the skin, organs and other tissues, is a rare complication in patients with kidney disease that undergo an MR with contrast media.

Gadolinium-based contrast media may be withheld in some patients with severe kidney disease. If a barium-sulphate contrast media given orally or rectally will be used during your exam, you will be asked not to eat for several hours before your exam begins.

If the contrast media will be given rectally, you may also be asked to cleanse your colon with a special diet and medication possibly including an enema before your exam. If you swallow the contrast media, you may find the taste mildly unpleasant; however, most patients can easily tolerate it. If your contrast media is given by enema, you can expect to experience a sense of abdominal fullness and an increasing need to expel the liquid.

The mild discomfort will not last long. Barium-sulphate contrast media are expelled from the body with feces. You can expect bowel movements to be white for a few days. Some patients may experience changes in their normal bowel movement patterns for the first 12 to 24 hours. When an iodine-based contrast media is injected into your bloodstream, you may have a warm flushed sensation and a metallic taste in your mouth that lasts for a few minutes.

The needle may cause you some discomfort when it is inserted. Once it is removed, you may experience some bruising. When the gadolinium is injected, it is normal to feel coolness at the site of injection, usually during a minute or two. For all of the above administrations of contrast media barium sulphate, iodine-based, and gadolinium-based : if you have not been sedated, no recovery period is necessary. You may resume your usual activities and normal diet immediately after the exam.

It is important to increase your fluid intake after an imaging exam involving a contrast media to help remove the contrast media from your body. Prior to any imaging exam, women should always inform their caregiver if there is any possibility that they are pregnant.

Many imaging tests and contrast media administrations are avoided during pregnancy to minimise risk to the baby. For CT imaging, if a pregnant woman must undergo imaging with an iodine-based contrast media, the patient should have a discussion with her doctor to understand the potential risks and benefits of the contrast-enhanced scan. Barium-sulfate compounds are the most common contrast materials administered orally, but it can also be administered rectally.

Barium-sulfate compounds are available in several forms, including powder that is mixed with water before administration, liquid, paste and tablet. X-rays and CTs work by passing an x-ray beam through your body to an x-ray detector, which absorbs the x-rays to create an image. Depending on their density, your bones and body tissues can also absorb the x-ray to slow the beam down or stop it completely. In this way, the x-ray beams form "shadows" that represent the tissues and organs on the images.

Iodine-based and barium-sulfate contrast materials limit or block the x-rays' ability to pass through the tissue. This changes how the blood vessels, organs and other body tissues containing the iodine-based or barium-sulfate compounds appear in the x-ray or CT images. Doctors typically request the oral administration of barium-sulfate contrast materials to enhance x-ray and CT images of the gastrointestinal tract, including the pharynx and esophagus, stomach, small intestine or large intestine, also known as the colon.

Physicians typically order rectal administration of barium-sulfate contrast to enhance x-ray and CT scans of the small intestine and colon. Clinicians order the intravenous injection of iodine-based contrast to enhance x-ray and CT images of internal organs, such as the heart and lungs, gastrointestinal tract, arteries and veins, the brain, breast tissue and soft tissues of the body, such as muscles and fat.

Gadolinium is the key component in the most frequently used MRI contrast material. MRIs use powerful magnets that affect protons, which are parts of a proton that have a positive electrical charge.

Protons are constantly spinning, but usually different rates and angles, depending on the various properties of the tissue; in other words, protons in a healthy bit of tissue might spin differently than do the protons of unhealthy tissue. The magnetic field causes the protons to spin out of equilibrium. When the magnetic field is turned off, the protons realign with the magnetic field at different rates, depending on the type of tissue; they also release different amounts of energy, depending on tissue type.

Gadolinium alters the magnetic properties of water molecules to increase the speed at which protons realign with the magnetic field; the faster the protons, the brighter the image. Doctors order the intravenous injection of gadolinium to enhance MRI images of internal organs, gastrointestinal tract, blood vessels, the brain, breast tissue and soft tissues of the body.

Saline salt water and air also make good contrast materials in imaging exams. Ultrasound imaging, especially ultrasound imaging of the heart, may use microbubbles and microspheres that help organs and tissues appear brighter on ultrasound. These contrast materials are suitable for assessing how well blood moves through organs, detecting blood clots, finding abnormalities in the heart, and detecting masses in the liver or kidney.

For more information about contrast materials used in various types of imaging tests, talk with your doctor or radiologist.