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A computed tomography angiogram (CT angiogram) is a test that uses X-rays to provide detailed pictures of the heart and the blood vessels that go to the heart, lung, brain, kidneys, head, neck, legs, and arms.
During a CT angiogram, you lie on a table that passes through a doughnut-shaped opening in the scanner. A special dye (contrast material) is put in a vein (IV) in your arm or hand to make the blood vessels easier to see on the scan. If you are having this test to look at your heart and the blood vessels that go to it (coronary arteries), you may be given a medicine called a beta-blocker to slow your heart rate during the test.
Benefits and limitations
A CT angiogram is a less invasive test than a standard angiogram. A standard angiogram involves threading a thin tube called a catheter through an artery in your arm or leg up to the area being studied. But with a CT angiogram, no tubes are put in your body.
If your doctor sees that one or more of your blood vessels are narrowed or blocked, you may need a standard angiogram anyway to double-check the abnormal results from the CT angiogram. This is more likely to happen if your doctor is considering surgery to treat the narrowing or blockage.
If your doctor finds a major blockage in one of your blood vessels during a CT angiogram, you won't be able to get an angioplasty right away to clear the blockage. You will need a separate procedure. But if you have a standard angiogram and the doctor finds a major blockage, he or she can perform an angioplasty during the angiogram.
Why It Is Done
A CT angiogram is done to look for:
- A blood clot in the lungs (pulmonary embolism).
- A narrowing (stenosis) or blockage in the coronary arteries. This can occur when there is a buildup of fat (cholesterol) and calcium in the arteries. This buildup is called plaque.
- Heart problems, such as pericarditis (inflammation of the pericardial sac around the heart) and damage or injury to the heart valves.
- A bulge (aneurysm) or tear (dissection) in the aorta, which is a large blood vessel that carries blood from the heart to the rest of the body.
- A narrowing of arteries in the legs and in other parts of the body (peripheral arterial disease).
- An abnormal pattern of blood vessels that may be a sign of a tumour.
How To Prepare
Talk to your doctor about all your health conditions before the test. For example, tell your doctor all of the medicines you take, if you are or might be pregnant, if you're allergic to any medicines, or if you take metformin.
Tell your doctor if you get nervous in tight spaces. You may get a medicine to help you relax. If you think you'll get this medicine, be sure you have someone to take you home.
You may be asked not to eat or drink anything for several hours before the test. Your doctor will let you know if there are certain foods or liquids you should avoid.
If you are breastfeeding, you may want to pump enough breast milk before the test to get through 1 to 2 days of feeding. The radioactive tracer used in this test can get into your breast milk and is not good for the baby.
How It Is Done
Before the test
- Take off any jewellery and any other metal objects.
- Take off all or most of your clothes. You will be given a gown to wear during the test.
During the test
- A dye (contrast material) will be put in a vein in your arm or hand. If you are having a CT angiogram to look at your heart and the blood vessels that go to it (coronary arteries), you may be given a medicine called a beta-blocker to slow your heart rate during the test.
- The table slides into the round opening of the scanner. The table will move during the scan. The scanner moves inside the doughnut-shaped casing around your body.
- You will be asked to hold still during the scan. You may be asked to hold your breath for short periods.
- You may be alone in the scanning room. But a technologist will watch you through a window and talk with you during the test.
How long the test takes
A CT angiogram usually takes 30 to 60 minutes but could take up to 2 hours.
How It Feels
The test will not cause pain, but some people feel nervous inside the CT scanner.
If a medicine to help you relax (sedative) or dye is used, you may feel a quick sting or pinch when the IV is started. The dye may make you feel warm and flushed and give you a metallic taste in your mouth. Some people feel sick to their stomach or get a headache. Tell the technologist or your doctor how you are feeling.
The chance of a CT angiogram causing a problem is small.
- There is a chance of an allergic reaction to the contrast material.
- Anytime you're exposed to radiation, there's a small chance of damage to cells or tissue. That's the case even with the low-level radioactive tracer used for this test. But the chance of damage is very low compared with the benefits of the test.
- If you breastfeed and are concerned about whether the dye used in this test is safe, talk to your doctor. Most experts believe that very little dye passes into breast milk and even less is passed on to the baby. But if you prefer, you can store some of your breast milk ahead of time and use it for a day or two after the test.
Results of a CT angiogram are usually ready for your doctor in 1 to 2 days.
The blood vessels look normal, and blood flow is not reduced.
The heart and heart valves look normal.
One or more blood vessels are partially or completely blocked.
The heart or the heart valves look abnormal.
A narrow spot in an artery may suggest that a blood clot or a deposit of fat and calcium is reducing blood flow through the blood vessel.
An abnormal pattern of blood vessels may be a sign that a tumour is present.
Current as of: December 19, 2022
Author: Healthwise Staff
Rakesh K. Pai MD, FACC - Cardiology, Electrophysiology
E. Gregory Thompson MD - Internal Medicine
Martin J. Gabica MD - Family Medicine
Adam Husney MD - Family Medicine
George Philippides MD - Cardiology
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