CT Angiography
Computerized tomographic angiography, also called CT angiography or CTA, is a test that combines the technology of a conventional CT scan with that of traditional angiography to create detailed images of the blood vessels in the body.
In a CT scan, x-rays and computers create images that show cross-sections, or slices, of your body. Angiography involves the injection of contrast dye into a large blood vessel, usually in your leg, to help visualize the blood vessels and the blood flow within them. CT angiography is similar to a CT scan, but the contrast dye is injected into one of your veins shortly before the x-ray image is performed. Because the dye is injected into a vein rather than into an artery, as in traditional angiography, CT angiography could be considered less invasive.
During the study, you will lie down on a table, which passes through a donut-shaped device. Inside the device, a machine takes x-rays in arcs around the area of your body being examined. During the CT angiogram, a dose of contrast dye will be injected into one of your veins. As the dye flows through your circulatory system, it will highlight your blood vessels on the scan. A computer will produce 3-dimensional (3D) images of your blood vessels from the x-ray images.
Your physician will ask you to avoid foods and liquids for about 4 hours before the test. You will probably be allowed to continue taking any prescribed medications, but ask your physician before the exam to be sure.
Before the test is performed, you may be asked to change into a hospital gown and remove all jewelry and other metal objects, which can interfere with x rays.
Contrast material carries a slight risk of causing an allergic reaction. If you know that you are allergic to contrast material or dye, let your physician know before you receive the contrast material. Allergies to iodine or shellfish may place you at increased risk for having an allergy to the contrast dye.
The contrast material is also eliminated by the kidneys and can damage kidney function, especially if you have kidney problems already. Let your doctor know if you have damaged kidney function.
You may be unsuited for CT angiography if you have an allergy to contrast dye, have kidney problems, have severe diabetes, are pregnant, have unstable vital signs, or weigh more than 350 pounds.