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.
Figure A is an illustration of the outside 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.
Doctors use cardiac CT to detect or evaluate:
- Coronary heart disease (CHD). In CHD, a waxy substance called plaque narrows the coronary arteries and limits blood flow to the heart. Contrast dye might be used during a cardiac CT scan to show whether the coronary arteries are narrow or blocked. When contrast dye is used, the test is called a coronary CT angiography, or CTA.
- 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 CHD.
- 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-u-rism). An aneurysm is a diseased area of a blood vessel wall that bulges out. An aneurysm can be life threatening if it bursts.
- Dissection. A dissection is a split in one or more layers of the artery wall. The split causes bleeding into and along the layers of the artery wall. This condition can cause pain and may be life threatening.
- A pulmonary embolism (PE). A PE is a sudden blockage in a lung artery, usually due to a blood clot.
- Problems in the pulmonary veins. The pulmonary veins carry blood from the lungs to the heart. Problems with these veins may lead to an irregular heart rhythm called atrial fibrillation (AF). The pictures that cardiac CT creates of the pulmonary veins can help guide procedures used to treat AF.
- Problems with heart function and heart valves. In some cases, doctors may recommend cardiac CT instead of echocardiography or cardiac MRI (magnetic resonance imaging) to look for problems with heart function or heart valves.
- Pericardial disease. This is a disease that occurs in the pericardium, the sac around your heart. Cardiac CT can create clear, detailed pictures of the pericardium.
- Results of coronary artery bypass grafting (CABG). In CABG, arteries from other areas in your body are used to bypass (that is, go around) narrow coronary arteries. A CT scan can help determine whether the grafted arteries remain open after the surgery.
Doctors also might recommend cardiac CT scans before or after other heart procedures, such as cardiac resynchronization therapy. A CT scan 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), might be used to take high-quality pictures of the heart. MDCT also might 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.