What Does Cardiac CT Show?

Many x-ray pictures are taken during a cardiac CT scan. A computer puts the pictures together to make a three-dimensional (3D) picture of the whole heart. This picture shows the inside of the heart and the structures that surround the heart.

Cardiac CT

Figure A shows the exterior of the heart. The arrow shows the point of view of the cardiac CT image. The inset image shows the position of the heart in the body. Figure B is a cardiac CT image showing the coronary arteries on the surface of the heart. This is a picture of the whole heart put together by a computer.

Cardiac CT is a common test for finding and/or evaluating:

• Calcium buildup in the walls of the coronary arteries. This type of CT scan is called a coronary calcium scan. Calcium in the coronary arteries may be an early sign of coronary heart disease (CHD). In CHD, a fatty substance called plaque narrows the coronary (heart) arteries and limits blood flow to the heart.
• CHD. If contrast dye is used during cardiac CT, it helps highlight the coronary arteries on the x-ray pictures. This can show whether the coronary arteries are narrowed or blocked (which may cause chest pain or a heart attack).
• Problems with heart function and heart valves. Doctors may recommend cardiac CT instead of echocardiography or cardiac MRI (magnetic resonance imaging) for some people.
• Problems with the aorta. The aorta is the main artery that carries oxygen-rich blood from the heart to the body. Cardiac CT can detect two serious problems in the aorta:
  • Aneurysm. An aneurysm is a diseased area of a blood vessel wall that bulges out. Aneurysms can be life threatening if they burst.
  • Dissection. Dissection can occur if the layers of the aortic artery wall peel away from each other. This condition can cause pain and may be life threatening.
• Blood clots in the lungs. A cardiac CT scan also may be used to find a pulmonary embolism (PE). A PE is a sudden blockage in a lung artery, usually due to a blood clot that traveled to the lungs from one of the legs. This is a serious but treatable condition.
• The pulmonary veins. The pulmonary veins carry blood from the lungs to the heart. Problems with these veins may lead to atrial fibrillation (AF), an irregular heart rhythm. The pictures that cardiac CT creates of the pulmonary veins can help guide procedures used to treat AF.
• Pericardial disease. This is a disease that occurs in the pericardium, the sac around your heart. A cardiac CT takes clear, detailed pictures of the pericardium.

Cardiac CT also may be used before or after certain heart procedures, such as cardiac resynchronization therapy and coronary artery bypass grafting. A cardiac CT can help your doctor pinpoint the areas of the heart or blood vessels where the procedure should be done. The scan also can help your doctor check your heart after the procedure.

Because the heart is in motion, a fast type of CT scanner, called multidetector computed tomography (MDCT), may be used to take high-quality pictures of the heart. MDCT also may be used to detect calcium in the coronary arteries.

Another type of CT scanner, called electron-beam computed tomography (EBCT), also is used to detect calcium in the coronary arteries.