Computed tomography Computed Tomography (CT) In computed tomography (CT), which used to be called computed axial tomography (CAT), an x-ray source and x-ray detector rotate around a person. In modern scanners, the x-ray detector usually... read more 
(CT) may be used to detect structural abnormalities of the heart, the sac that envelops the heart (pericardium), major blood vessels, lungs, and supporting structures in the chest.
Multidetector CT, a very rapid CT scanner can take a picture during a single heartbeat. Such rapid CT scanning (called CT coronary angiography) is sometimes used to evaluate the arteries that supply blood to the heart (coronary arteries). Typically, a contrast agent Labeling with a radionuclide In radionuclide scanning, radionuclides are used to produce images. A radionuclide is a radioactive form of an element, which means it is an unstable atom that becomes more stable by releasing... read more (a substance that can be seen on x-rays) is injected into the person's vein. The person is asked not to breathe during a scan so that the image will not be blurred.
Electron beam CT, previously called ultrafast or cine CT, is used mainly to detect calcium deposits in the coronary arteries, an early sign of coronary artery disease Overview of Coronary Artery Disease (CAD) Coronary artery disease is a condition in which the blood supply to the heart muscle is partially or completely blocked. The heart muscle needs a constant supply of oxygen-rich blood. The coronary... read more 
. Doctors are still trying to determine the best way to use this test within the overall evaluation of whether people have coronary artery disease.
Computed tomography angiography (CTA) is a type of CT that is used to produce three-dimensional images of the major arteries of the body, except the coronary arteries. The images are similar in quality to those produced by conventional angiography Angiography In angiography, x-rays are used to produce detailed images of blood vessels. It is sometimes called conventional angiography to distinguish it from computed tomography (CT) angiography and magnetic... read more . CTA can be used to detect narrowing of the arteries supplying organs and aneurysms and tears in major arteries. CTA can also detect clots that have broken off within a vein, traveled through the venous bloodstream, and lodged in the small arteries of the lungs (pulmonary emboli Pulmonary Embolism (PE) Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more ).
Unlike conventional angiography, CTA is not an invasive procedure. The radiopaque contrast agent is injected into a vein rather than into an artery as in angiography. CTA usually takes less than 1 to 2 minutes. Since the contrast agent can cause damage to the kidneys, this test is avoided in people who have kidney problems.
