CT Angiogram

A CT angiogram (computed tomography angiogram) is a medical imaging test that uses a special type of X-ray and a computer to create detailed pictures of your blood vessels. A special dye, called contrast material, is injected into a vein to help highlight your arteries and veins, allowing doctors to see if there are any blockages, narrowing, or other issues within them.

What is CT Angiogram?

A CT angiogram (CTA) is an imaging test that combines a computed tomography (CT) scan with an injection of contrast material to produce detailed images of blood vessels throughout your body. This advanced imaging technique helps doctors visualize the inside of your arteries and veins, making it easier to detect problems like blockages, aneurysms, or other abnormalities that might not be visible on a standard CT scan.

During a CTA, X-rays are taken from many different angles around your body. A computer then processes these X-ray images to create cross-sectional slices, or "slices," of your blood vessels. The contrast material, often containing iodine, is injected into a vein, usually in your arm. As this dye travels through your bloodstream, it makes your blood vessels appear bright white on the CT images, allowing radiologists to clearly see their structure and identify any issues. This test is non-invasive, meaning it does not involve surgery, and it provides highly detailed images that can help diagnose various conditions affecting your circulatory system. It can be used to examine blood vessels in many parts of the body, including the heart, brain, lungs, kidneys, and legs.

Why it's ordered

A CT angiogram is typically ordered to diagnose or evaluate conditions affecting your blood vessels, such as blockages, narrowing, or bulges. Your doctor might recommend this test if they suspect you have a problem with blood flow or the structure of your arteries or veins, helping to guide treatment decisions or plan for surgical procedures.

Doctors often order a CTA to look for specific problems in the blood vessels. For example, it can detect an aneurysm, which is a bulge in the wall of an artery that could potentially rupture. It can also identify stenosis, which is a narrowing of blood vessels, often caused by plaque buildup (atherosclerosis), restricting blood flow. Other reasons for ordering a CTA include finding blood clots, such as those in the lungs (pulmonary embolism), or identifying arteriovenous malformations (AVMs), which are abnormal connections between arteries and veins. It can also be used to evaluate the extent of damage after an injury, plan for surgeries like bypass grafts, or assess the effectiveness of previous treatments affecting blood vessels.

How to prepare

Preparing for a CT angiogram usually involves discussing your medical history and current medications with your doctor, especially regarding allergies, kidney function, and diabetes. You may be asked to avoid eating or drinking for a few hours before the test, and you will need to remove any metal objects or jewelry prior to the scan.

Before your CTA, it's crucial to inform your doctor about any allergies you have, particularly to iodine or contrast dyes, as these are used in the procedure. You should also tell them if you have kidney disease, diabetes (especially if you take metformin), asthma, or thyroid problems, as these conditions can affect how your body reacts to the contrast material. Blood tests may be done beforehand to check your kidney function. If you are pregnant or think you might be, inform your doctor immediately, as the radiation from the CT scan could pose a risk to the fetus. If you are breastfeeding, you might be advised to pump and store breast milk before the test and avoid breastfeeding for a short period after the scan, typically 12 to 24 hours, to allow the contrast material to clear from your system. You will also be asked to remove all metal objects, such as jewelry, eyeglasses, dentures, and hairpins, as these can interfere with the CT images.

What to expect during

During a CT angiogram, you will lie on a movable table that slides into a large, donut-shaped CT scanner. A healthcare professional will insert an intravenous (IV) line, usually in your arm, to inject the contrast material. You will need to remain very still and may be asked to hold your breath briefly at certain times to ensure clear images are captured.

Once the IV line is in place, the contrast material will be injected. As the dye enters your bloodstream, you might feel a warm flush throughout your body, a metallic taste in your mouth, or a sensation similar to needing to urinate. These feelings are usually normal and temporary. The CT scanner itself is a large machine with an opening in the center; you will lie on a table that moves through this opening. During the scan, you will be alone in the room, but a technologist will be in an adjacent room, able to see, hear, and speak with you through an intercom. They will give you instructions, such as when to hold your breath. The machine may make humming or clicking noises. The entire procedure typically takes about 30 to 60 minutes, depending on the area being examined. After the scan, the IV line will be removed, and you can usually resume your normal activities.

Understanding your results

After your CT angiogram, a radiologist, a doctor specializing in interpreting medical images, will analyze the pictures and send a report to your referring physician. Your doctor will then discuss the findings with you, explaining what the results mean in the context of your overall health and medical history, and outline any next steps or treatment options.

The radiologist will look for any abnormalities in your blood vessels, such as blockages, narrowing, bulges (aneurysms), or tears (dissections). They will also assess the size, shape, and location of any identified issues. It's important to remember that the radiologist provides a detailed report, but your doctor is the one who will interpret these findings in relation to your specific symptoms, other test results, and medical history. Normal results indicate that your blood vessels appear healthy and there are no significant blockages or structural problems. Abnormal results could point to various conditions, such as atherosclerosis (hardening of the arteries), blood clots, or an aneurysm. Your doctor will explain what these findings mean for you and discuss whether further tests, lifestyle changes, medications, or other treatments are necessary. Do not try to interpret the images yourself; always wait for your doctor's explanation.

Risks

While generally safe, a CT angiogram carries some potential risks, including an allergic reaction to the contrast material, kidney damage, and exposure to a small amount of radiation. Your doctor will discuss these risks with you and ensure the benefits of the test outweigh the potential downsides, especially if you have pre-existing health conditions.

One of the main risks is an allergic reaction to the contrast material, which contains iodine. Mild reactions, such as hives or itching, occur in about 1 in 20 people (5%). More severe reactions, like difficulty breathing or swelling, are rare, affecting about 1 in 1,000 to 1 in 10,000 people (0.1% to 0.01%). Medical staff are prepared to manage these reactions if they occur. Another concern is potential kidney damage, particularly for individuals with pre-existing kidney disease. The contrast dye is processed by the kidneys, and in some cases, it can temporarily worsen kidney function. Your doctor will assess your kidney health before the test and may take precautions, such as ensuring you are well-hydrated. There is also exposure to a small amount of ionizing radiation from the X-rays. While the risk of radiation-induced cancer from a single scan is very low, it is a cumulative risk over a lifetime. For pregnant individuals, CTA is generally avoided due to the potential risk to the developing fetus. Rarely, complications at the IV injection site, such as bruising or infection, can occur.

Frequently asked questions

How long does a CT angiogram take?

The actual scanning part of a CT angiogram is quite quick, often lasting only a few minutes. However, the entire appointment, including preparation (like inserting an IV line) and post-scan observation, typically takes about 30 to 60 minutes from start to finish.

Will I feel pain during a CT angiogram?

Most people do not experience pain during a CT angiogram. You might feel a brief pinch when the IV is inserted for the contrast dye. When the dye is injected, you may feel a warm sensation, a metallic taste, or a feeling of needing to urinate, but these are usually temporary and not painful.

Can I eat or drink before a CT angiogram?

In most cases, you will be asked to avoid eating solid foods for a few hours before your CT angiogram. You may be allowed to drink clear liquids up until a certain time. Your doctor or the imaging center will provide specific instructions tailored to your situation.

What is the contrast material used in a CT angiogram?

The contrast material used in a CT angiogram is typically an iodine-based dye. This special dye is injected into your bloodstream and helps to highlight your blood vessels on the CT images, making them appear brighter and allowing doctors to see them more clearly.

Is a CT angiogram safe if I have kidney problems?

If you have kidney problems, a CT angiogram carries a higher risk of kidney damage due to the contrast material. Your doctor will carefully assess your kidney function before the test and may take precautions, such as adjusting the contrast dose or ensuring you are well-hydrated, or they might recommend an alternative imaging test.

What happens if I move during the CT angiogram?

It is very important to stay as still as possible during a CT angiogram. Movement can blur the images, making them difficult to interpret. If you move, the technologist may need to repeat parts of the scan, which could prolong the procedure and increase your radiation exposure slightly.

Sources

• MedlinePlus — CT Angiogram
• Mayo Clinic — CT Angiogram
• Cochrane Library — CT Angiogram