What is a CT (CAT) scan?
CT (computed tomography) angiography (CTA) is an examination that uses x-rays to visualize blood flow in arterial and venous 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 sizable catheter and injecting contrast material into a large artery or vein, CTA is a much 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
