(Ultrafast CT, Electron-Beam Computed Tomography, EBCT, Cine CT Scan)
Computed tomography (CT or CAT scan) is a diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than standard X-rays.
In standard X-rays, a beam of energy is aimed at the part of the body being studied. A plate behind the body part captures the variations of the energy beam after it passes through skin, bone, muscle, and other tissue. While much information can be obtained from a regular X-ray, a lot of detail about internal organs and other structures is not available.
In computed tomography, the X-ray beam moves in a circle around the body. This allows many different views of the same organ or structure, and provides much greater detail. The X-ray information is sent to a computer which interprets the X-ray data and displays it in two-dimensional (2D) form on a monitor.
A new technology, called ultrafast CT scan, is now being used to diagnose heart disease. Ultrafast CT, or electron-beam computed tomography (EBCT) can take multiple images of the heart within the time of a single heartbeat, thus providing much more detail about the heart's function and structures, and also greatly decreasing the amount of time required for a study. Ultrafast CT scans can detect very small amounts of calcium within the heart and the coronary arteries. This calcium has been shown to indicate that lesions that may eventually block off one or more coronary arteries and cause chest pain, or even a heart attack, are in the beginning stages of formation. Thus, ultrafast CT scanning may be used by doctors as a means to diagnose early coronary artery disease in certain people, especially in individuals who have no symptoms of the disease.
Other related procedures that may be used to assess the heart include resting and exercise electrocardiogram (ECG or EKG), Holter monitor, signal-averaged ECG, cardiac catheterization, chest X-ray, computed tomography (CT scan) of the chest, echocardiography, electrophysiological studies, magnetic resonance imaging (MRI) of the heart, myocardial perfusion scans, and radionuclide angiography. Please see these procedures for additional information.
Reasons for the procedure
Some reasons for which an ultrafast CT may be performed include, but are not limited to, the following:
To assess the condition of the coronary arteries
To assess heart tissue damage after a heart attack (also called myocardial infarction, or MI)
To assess the patency (openness) of coronary artery bypass grafts
Ultrafast CT is used primarily for the diagnosis of coronary artery disease, particularly in persons who have no symptoms of the disease but who have significant risk factors for the disease. Ultrafast CT should not be considered a substitute for cardiac catheterization. Computed tomography measurement of coronary calcium is not considered relevant in patients who have already had a heart attack or undergone coronary bypass surgery or coronary angioplasty.
There may be other reasons for your doctor to recommend an ultrafast CT.
Risks of the procedure
You may want to ask your doctor about the amount of radiation used during the CT procedure and the risks related to your particular situation. It is a good idea to keep a record of your past history of radiation exposure, such as previous CT scans and other types of X-rays, so that you can inform your physician. Risks associated with radiation exposure may be related to the cumulative number of X-ray examinations and/or treatments over a long period of time.
If you are pregnant or suspect that you may be pregnant, you should notify your health care provider. Radiation exposure during pregnancy may lead to birth defects.
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.
Before the procedure:
Your doctor or the technician will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
Generally, no prior preparation, such as fasting or sedation, is required prior to an ultrafast CT.
Notify the technologist if you are pregnant or suspect you may be pregnant.
Notify the technologist if you have any body piercing on your chest and/or abdomen.
Based on your medical condition, your doctor may request other specific preparation.
During the procedure
An ultrafast CT may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor's practices.
Generally, an ultrafast CT follows this process:
You will be asked to remove any jewelry or other objects that may interfere with the procedure.
If you are asked to remove clothing, you will be given a gown to wear.
You will lie on a scan table that slides into a large, circular opening of the scanning machine. Pillows and straps may be used to prevent movement during the procedure.
The technologist will be in another room where the scanner controls are located. However, you will be in constant sight of the technologist through a window. Speakers inside the scanner will enable the technologist to communicate with and hear you. You will have a call button so that you can let the technologist know if you have any problems during the procedure. The technologist will be watching you at all times and will be in constant communication.
The scanner will begin to rotate around you and low-dosage X-rays will pass through the body for short amounts of time. You will hear clicking sounds, which are normal.
The X-rays absorbed by the body's tissues will be detected by the scanner and transmitted to the computer. The computer will transform the information into an image to be interpreted by the radiologist.
It will be important for you to remain very still during the procedure.
At intervals, you will be instructed to hold your breath, or to not breathe, for a few seconds. You will then be told when you can breathe. You should not have to hold your breath for longer than a few seconds, so this should not be uncomfortable.
Once the procedure has been completed, you will be removed from the scanner.
You may be asked to wait for a short time while the radiologist reviews the scans to make sure they are clear and complete.
After the procedure
You should be able to resume your normal diet and activities, unless your doctor instructs you differently.
Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.