CT Angiography

Computed tomography angiography (CTA) is an examination that uses x-rays to visualize blood flow in blood vessels throughout the body, from arteries serving the brain to those bringing blood to the lungs, kidneys, and arms and legs. CT combines the use of x-rays with computerized analysis of the images. Beams of x-rays are passed from a rotating device through the area of interest in the patient's body from several different angles to create cross-sectional images, which then are assembled by computer into a three-dimensional picture of the area being studied. Compared to catheter angiography, which involves placing a catheter and injecting contrast material into an artery or vein, CTA is a less invasive and more patient-friendly procedure; contrast material is injected into a small peripheral vein by using a small needle or catheter. This type of exam has been used to screen large numbers of individuals for arterial disease. Most patients undergo CT angiography without being admitted to a hospital.

CTA is also used to detect narrowing or obstruction of arteries in the chest, abdomen, pelvis, arms, legs and in the carotid arteries,which bring blood from the heart to the brain. When a stent has been placed to restore blood flow in a diseased artery, CTA will show whether it is serving its purpose.

Examining arteries in the brain may help reach a correct diagnosis in patients who complain of headaches, dizziness, ringing in the ears or fainting. Injured patients may benefit from CTA if there is a possibility that one or more arteries have been damaged. In patients with a tumor, it may be helpful for the surgeon to know the details of arteries feeding the growth.

What to expect with your procedure

Preparing for your procedure

Most of the time for a CTA examination is spent setting everything up. Actually recording the images takes only seconds. After changing into a hospital gown and having an IV set up, you will answer questions about things that might complicate the exam (such as allergies), and then you will lie down on a narrow table. The part of your body to be examined will be placed inside the opening of the CT unit with the aid of criss-crossed positioning lights. A test image is taken to determine the best position, and a small dose of contrast material may be given to see how long it takes to reach the area under study. Then the IV is hooked up to an automatic injector, contrast material is injected, and the scan begins. Afterward, the images will be reviewed and, if necessary, some will be repeated.

CTA takes about 10 to 25 minutes from the time the actual examination begins. Overall, you can expect to be in or near the examining room for 20 to 60 minutes. You may feel warm all over when contrast is injected, but you should not feel pain at any time. Any CT study requires that you remain still during the exam. Pillows and foam pads may help make it more comfortable. At the same time, the nurse or technologist may use pads or Velcro straps to keep an area of your body from moving. The examination table will move into and out of the scanner opening, but it is not enclosed, and only a small part of your body will be inside at any one time. You may be asked to hold your breath for 10 to 25 seconds to be sure that the images will not be blurred. During the time that no actual imaging is taking place, you are free to ask questions or talk to the technologist, but friends or relatives will not be allowed in the examining room. Once the needed images have been recorded, you will be free to leave. You can eat immediately, and it is a good idea to drink plenty of fluids in the hours after the exam to help flush contrast material out of the system.