Computed Tomography Angiography (CTA)


Procedure overview

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

A computerized tomography scan, or CT scan, is a type of X-ray that uses a computer to make cross-sectional images of your body. The dye injected to perform CT angiography is called a contrast material because it "lights up" blood vessels and tissues that are being studied.

Reasons for the procedure

You may need this medical test if you have an abnormality that involves the blood vessels of your brain, heart, lungs, kidneys, or other parts of your body. Doctors 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 an aneurysm (a blood vessel that has become enlarged and may be in danger of rupturing)

  • To find blood vessels that have become narrowed by atherosclerosis (fatty material that forms plaques in the walls of arteries)

  • To find abnormal blood vessel formations inside your brain

  • To identify blood vessels damaged by injury

  • To find blood clots that may have formed in your leg veins and traveled into your lungs.

  • To evaluate 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 doctor plan cancer treatment or prepare you for a kidney transplant. Your doctor may have other reasons for ordering this test.

Risks of the procedure

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. The amount of radiation used during CT angiography is considered minimal, so the risk for radiation exposure is low. No radiation remains in your body after a CT scan.

Other risks include:

  • Allergic reactions. Always let your radiologist know if you have any history of allergies or an allergy to contrast material. Reactions to contrast are uncommon. If you have any history of allergic reactions, you may be given medication 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 is important to tell your radiologist or radiology technician if you have any pain when the contrast material is injected through your IV.

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 are breastfeeding, you may want to wait for 12 to 24 hours after this test before nursing your baby. If you are pregnant or suspect that you may be pregnant, you should notify your doctor or radiology technician.

There may be other risks, depending on your specific medical condition. Be sure to discuss any concerns with your doctor or radiology technician before the procedure.

Before the procedure

Tell your doctor and your radiology technician about any medications you take, including herbal supplements and other over-the-counter medications. Also let them know about any medical conditions you may have, such as heart disease, diabetes, asthma, thyroid, or kidney disease, and any recent illness. You may need to alter how you take certain medications before your procedure. 

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

  • You may be asked to stop eating and drinking for several hours before the exam.

  • 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.

  • Wear loose, comfortable clothing.

Based on your medical condition, your doctor may request other specific preparation. 

During the procedure  

You may have this exam 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. Procedures may vary depending on your condition and your doctor's practices. 

Here is what may happen during the exam:

  • You will be placed on the exam table and positioned by a radiology technician.

  • A caregiver will start an IV line 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 examination table moves through the scanner.

  • 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 the scan.

  • The actual scan will be over in 5 to 20 seconds. You may have to wait a little longer until the technician doing the scan checks the images to make sure they are acceptable.

After the procedure

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