This post was written by Lois Wilson, RT(R), CT, MR, ARRT, director, corporate imaging, Parkview Health.
Contrast materials are substances used to make specific organs, blood vessels or types of tissue more visible during imaging exams. In this post, we'll outline the types of commonly used contrast agents and key considerations for patients.
How they are used
The type of contrast agent a radiologist uses will depend on the kind of scan you're having and the part of the body being examined. These can include:
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Iodine-based substances are used primarily in X-ray imaging, such as computed tomography (CT) scans, to enhance the visibility of soft tissues and blood vessels. They absorb X-rays to make the surrounding areas in the body appear brighter.
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Gadolinium-based agents, made from a rare magnetic earth metal, are used in magnetic resonance imaging (MRI) to detect tumors, inflammation, blood clots and infections.
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Air (Negative) is used in X-rays to displace fluids or contrast agents in the body cavities, such as the stomach or intestines.
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Microbubbles are small gas-filled spheres with shells made of materials like lipids or polymers that allow them to reflect ultrasound waves more intensely than surrounding tissues. When used during echocardiograms, they help improve the visibility of structures in the heart.
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Barium, given orally or via enema, coats the digestive tract and blocks X-rays, making it easier for radiologists to see abnormal tissues during X-ray or fluoroscopy.
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Radioisotope tracer is a small amount of radioactive material given during a nuclear medicine scan that travels through the body and collects in specific organs or areas.
Safety check
Contrast agents are generally harmless, but your care team will consider several factors to determine which agent is most appropriate for your scan and which will provide the most accurate imaging.
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Allergies and prior reactions. Always tell your provider if you have had any mild to severe reactions to contrast before. You may be given medication such as steroids or antihistamines to offset those symptoms during the scan.
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Kidney function. Some contrast agents can affect kidney function, especially in those with pre-existing kidney disease. Your provider may order a blood test before the scan to assess your kidney health.
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Pregnancy and breastfeeding. Let your provider know if you're pregnant or breastfeeding. Some contrast agents are not used during pregnancy unless essential. Depending on the contrast agent used, you may need to pause breastfeeding temporarily after some imaging tests.
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Medications. Certain medications, like metformin, may interact with iodinated contrast. Your doctor may advise you to temporarily stop taking some medicines before and after the scan.
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Hydration. If your scan does not require fasting, staying well-hydrated before and after the exam can help flush the contrast from your system and reduce kidney strain.
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Informed consent. Your care team should explain the risks, benefits and alternatives before proceeding with any exam. Always ask questions if you're unsure about any aspect of the procedure.
To explore Parkview’s full range of imaging services, visit our website here.