What is computed tomography 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 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.

Why might I need computed tomography angiography?

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. 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 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 healthcare provider plan cancer treatment or prepare you for a kidney transplant. Your healthcare provider may have other reasons for ordering this test.

What are the risks for a computed tomography 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. 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 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 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 will need to wait for 24 hours after this test before nursing your baby. If you are pregnant or suspect that you may be pregnant, you should notify your healthcare provider or radiology technician.

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

How do I prepare for a CTA?

PRECAUTIONS: If you are pregnant or think you may be pregnant, please check with your doctor before scheduling the exam. Other options will be discussed with you and your doctor.

CLOTHING: You may be asked to change into a patient gown. If so, a gown will be provided for you. A lock will be provided to secure all personal belongings. Please remove all piercings and leave all jewelry and valuables at home.

CONTRAST MEDIA: CT scans are most frequently done with and without a contrast media. The contrast media improves the radiologist's ability to find structures that are abnormal.

• Some patients should not have an iodine-based contrast media. If you have problems with your kidney function, please inform us in advance. We may be able to perform the scan without the contrast media or may be able to find an alternate imaging exam.

• You will be asked to sign a consent form that will detail the risks and side-effects associated with contrast media injected through an intravenous (IV) line (small tube placed in a vein).

ALLERGY: Please inform the access center representative when you schedule your scan if you have had an allergic reaction to any contrast media. IV contrast will not be administered if you have had a severe or anaphylactic reaction to any contrast media in the past. Mild to moderate reactions warrant a plan that includes taking medication prior to the CT examination. These plans will be discussed with you in detail when you schedule your exam. Any known reactions to a contrast media should be discussed with your personal physician.

EAT/DRINK: If your study was ordered without contrast, you can eat, drink and take your prescribed medications prior to your exam. If your doctor orders a CT scan with contrast, do not eat anything three hours before your CT scan. You are encouraged to drink clear liquids. You may also take your prescribed medications prior to your exam.

• If you are undergoing a chest CTA, do not consume any caffeine or exercise three hours prior to your appointment.

DIABETICS: Diabetics should eat a light breakfast or lunch three hours prior to the scan time. Depending on your oral medication for diabetes, you may be asked to discontinue use of the medication for 48 hours after the CT examination. Detailed instructions will be given following your examination.

MEDICATION: All patients can take their prescribed medications as usual.

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

What happens during computed tomography 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 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 are acceptable.

What happens after computed tomography angiography?

After the test 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 test, depending on your particular situation.