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CTA
CTA (Computed Tomographic Angiography) is an alternative to MRA procedures for individuals with a pacemaker, an embedded neurostimulator, insulin or chemotherapy port, or shrapnel or other metal fragments somewhere in the body.
What is CT Angiography?
CT angiography, or 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 angels so as to create cross-sectional images, which then are assembled by computer into a three-dimensional picture of the area being studied.
What are some common uses of the procedure?
CTA is commonly used to:
- Examine the pulmonary arteries in the lungs to rule out pulmonary embolism, a serious but treatable condition.
- Visualize blood flow in the renal arteries in patients with high blood pressure and those suspected of having kidney disorders. A special computerized method of viewing the images makes CT renal angiography a very accurate examination.
- Identify aneurysms in the aorta or in other major blood vessels. Also to identify dissection in the aorta or its major branches.
- Identify a small aneurysm or arterio-venous malformation inside the brain that can be life-threatening.
- Detect atherosclerotic disease that has narrowed the arteries to the legs.
- CTA is also used to detect narrowing or obstruction of arteries in the carotid arteries bringing blood from the heart to the brain.
Is Coronary CT Angiography Safe?
Not only is this technique invaluable for delineation of the body’s blood vessels, it is also relatively safe, convenient and much less invasive than traditional angiography where a sizable catheter is generally threaded through a vein or artery. In many cases, CT angiography may eliminate the need for surgery. The major risk associated with CT angiography is an allergic reaction to contrast materials used to improve the visualization of the veins and arteries.
How should I prepare for this procedure?
Wear comfortable, loose-fitting clothing. You may be given a gown to wear during the procedure. Metal objects such as jewelry, eyeglasses, dentures and hairpins should not be worn since they could negatively affect the CT images. You may also be asked to remove hearing aids and dental work, such as bridges and dentures. You may be asked not to eat or drink anything for several hours before the exam, especially if contrast material will be used. You should inform your technologist or physician of any medications you are taking and whether or not you have any allergies, especially to contrast materials. You should also tell your technologist or physician of any recent illnesses, if you are pregnant or have other medical conditions such as a history of heart disease, asthma, diabetes, and kidney disease or thyroid problems. Women who are breastfeeding may find it advisable to pump breast milk ahead of time so that it can be used until all the contrast material has been removed from your body.
What should I expect during this exam?
Although you are on the exam table for just a few minutes, the overall procedure takes about half an hour. A nurse or technologist will insert an intravenous line (IV) into your hand or arm and a small amount of contrast material may be injected to see how long it takes to reach the area to be examined. After this, the CT table with you on it will be moved quickly through the scanner to determine the correct starting position for the scan and a test image will be taken. The actual exam will begin after this and you will move slowly through the scanner. At all times a technologist will be able to see, hear and speak with you. You may be asked to hold your breath during the scanning. When the exam is complete your IV will be removed.
If intravenous contrast material is used, you may experience a warm, flushed sensation and a metallic taste in your mouth that lasts for a few minutes. Minor reactions include itching and hives which can be relieved with medication. Light-headedness or difficulty breathing indicate a more severe allergic reaction and you should tell the technologist or nurse about it. After the exam, and depending upon whether or not contrast material was used, you can return to your normal activities.