256-Slice CT Scan

OHSU is the first cardiac facility in the region to offer advanced 256-slice CT scan diagnostic imaging equipment. This diagnostic tool takes super-fast pictures of a moving heart using X-rays and displays it in a three-dimensional (3D) format on a computer monitor. By providing much more detail about the heart's function and structures, the 256-slice CT scan helps experts detect the earliest stages of heart disease so that they can treat it and prevent it from progressing further.

What is a 256-slice computed tomography scan (CT scan)?

3-D rendering of a heart using 256-slice CT scanner

Computed tomography (CT or CAT scan) is an advanced diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. The CT scan shows detailed images of any part of the body, including bones, muscles, fat, and organs. CT scans are more detailed than standard X-ray imaging, which beams energy directly at the part of the body being studied and is displayed in two-dimensional (2D) form.

The 256-slice CT provides a quantum leap in imaging and is now being used to diagnose heart disease. This advanced scanner achieves whole imaging of the heart within a short time span using low dose radiation, providing much more visual detail about the heart's function and structures. The images are then reconstructed in 3D format to help determine strength of the heartbeat and plaque deposits within the coronary arteries. These deposits may eventually block one or more coronary arteries and cause chest pain or even a heart attack. That's why physicians may use the 256-slice CT scanning device as a means of diagnosing early or advanced coronary artery 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

The 256-slice CT scanner is used primarily for the diagnosis of coronary artery disease, particularly for persons with chest pain and low to intermediate risk profiles, and for those who have had inconclusive results from a stress test. Some reasons for which a 256-slice CT scan may be performed include, but are not limited to, the following:

  • To assess the condition of the coronary arteries
  • To assess the patency (openness) of coronary artery bypass grafts
  • To assess cardiac structure and morphology.

Risks of the procedure

You may want to ask your physician 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 physician. Radiation exposure during pregnancy may lead to birth defects.

There may be other risks depending upon your specific medical condition. Be sure to discuss any concerns with your physician prior to the procedure.

Before the procedure

  • Your physician 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 a 256-slice 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 upon your medical condition, your physician may request other specific preparation.

During the procedure

A 256-slice 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 physician’s practices.

Generally, a 256-slice 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.
  • Children undergoing a scan may be more comfortable in the OHSU Ambient Experience environment. This is a room design that includes lighting, animation and audio elements to relax and reassure your child.
  • 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 physician instructs you differently. Your physician may give you additional or alternate instructions after the procedure, depending on your particular situation.