What is CT angiography?

CT angiography is a type of medical test that combines a CT scan with an injection of a special dye to produce pictures of blood vessels and tissues in a part of your body. The dye is injected through an IV (intravenous) line started in your arm or hand.

A CT scan is a type of X-ray that uses a computer to make images of your body. The dye injected to do CT angiography is called a contrast material because it lights up blood vessels and tissues being studied.

Why might I need CT angiography?

You may need this test if you have a problem that involves the blood vessels of your brain, heart, lungs, kidneys, or other parts of your body. Healthcare providers may use the information from this test to learn more about your condition and to decide the best way to treat you. Some reasons to have a CT angiogram include:

• To find a blood vessel that has become enlarged and may be in danger of rupturing (aneurysm)
  
• To find blood vessels that have become narrowed by atherosclerosis. In this condition, fatty material forms plaques in the walls of arteries.
  
• To find abnormal blood vessel formations inside your brain
  
• To find blood vessels damaged by injury
  
• To find blood clots that may have formed in your leg veins and traveled into your lungs.
  
• To assess a tumor that is fed by blood vessels

Information from CT angiography may help prevent a stroke or a heart attack. This type of test may also help your provider plan cancer treatment or prepare you for a kidney transplant. Your provider may have other reasons for ordering this test.

What are the risks of CT angiography?

There is always a slight risk for cancer from repeated exposure to radiation. But the benefits of getting an accurate diagnosis generally outweigh the risks. No radiation remains in your body after a CT scan.

Other risks include:

• Allergic reactions. Always let your radiologist know if you have a history of allergies or an allergy to contrast material. Reactions to contrast are uncommon. If you have a history of allergic reactions, you may be given medicine to lessen the risk for an allergic reaction before the test.
• Tissue damage. If a large amount of contrast material leaks around your IV site, it can irritate your skin or the blood vessels and nerves just under your skin. It's important to tell your radiologist or radiology technician if you have any pain when the contrast material is injected through your IV line.

Angiography contrast material can damage your kidneys, so you may not be able to have this test if you have severe kidney disease or diabetes.

If you're breastfeeding, there is very little risk to continue breastfeeding after the exam. But you may decide to wait for 24 hours after this test before nursing your baby. If you're pregnant or suspect that you may be pregnant, tell your healthcare provider or radiology technician.

There may be other risks, depending on your specific health condition. Discuss any concerns with your provider or radiology technician before the test.

How do I get ready for CT angiography?

Tell your healthcare provider and your radiology technician about any medicines you take, including herbal supplements and other over-the-counter medicines. It's important to tell your provider and the radiology technician about any health conditions you may have, such as heart disease, diabetes, asthma, thyroid or kidney disease, and any recent illness.

You may be asked to sign an informed consent that describes the risks and benefits of this test. You should discuss the risks and benefits with yourprovider or the radiology technician. Other preparations include:

• You may be asked to stop eating and drinking for several hours before the test.
• You should leave at home all metal objects, such as jewelry or hairpins, because metal can affect CT imaging. You may be asked to remove your eyeglasses, dentures, or hearing aids.
• You should wear loose, comfortable clothing.

Based on your health condition, your provider may have other instructions on how to get ready. 

What happens during CT angiography?

You may have this test done at the hospital or at another outpatient facility. The CT scanner is a large machine with a tunnel that the examining table passes in and out of. Tests may vary depending on your condition and your healthcare provider's practices. 

Here is what may happen during the test:

• You will be placed on the exam table and positioned by a radiology technician.
• An IV line will be placed in your hand or arm.
• You may feel a warm sensation when the contrast material is injected, and you may notice a metallic taste for a brief period.
• The radiology technician will leave the room just before the exam table moves through the scanner. The technician will be able to observe you through a window from an adjacent room and talk with you though an intercom.
• Scanning is painless. You may hear clicking, whirring, and buzzing sounds as the scanner rotates around you.
• You may be asked to hold your breath during parts of the scan.
• Depending on what body area is being scanned, the test may last for about 20 minutes up to an hour or so. You may have to wait a little longer until the technician doing the scan checks the images to make sure they're acceptable.

What happens after CT angiography?

After the test is completed, you'll have your IV line removed. In most cases, you can return to all your normal activities at home. You may be given some additional instructions after the test, depending on your particular situation.

Next steps

Before you agree to the test or the procedure make sure you know:

• The name of the test or procedure
• The reason you're having the test or procedure
• What results to expect and what they mean
• The risks and benefits of the test or procedure
• What the possible side effects or complications are
• When and where you're to have the test or procedure
• Who will do the test or procedure and what that person’s qualifications are
• What would happen if you didn't have the test or procedure
• Any alternative tests or procedures to think about
• When and how you'll get the results
• Who to call after the test or procedure if you have questions or problems
• How much you'll have to pay for the test or procedure