What is Computed Tomography (CT)?

Computed tomography (CT), also called a CAT scan, uses X-ray and computer equipment to capture selected cross-sections of organs, several types of tissue, the skull and other parts of the body. CT scans beam radiation around the part of the body being studied. The X-rays passing through the body are processed through a computer, which layers each cross-sectional view on top of another for a highly complex image. The images (together and separated) are viewed on a large high-definition digital screen.

What are some common uses of CT?

• Diagnosing cancer including studies to:
  • Guide biopsies and other minimally invasive procedures
  • Plan surgery
  • Determine surgical respectability
• Studying the chest and abdomen
• Diagnosing and treating spinal problems and injuries to the hands, feet and other skeletal structures
• Measuring bone mineral density for the detection of osteoporosis
• Identifying injuries to the liver, spleen, kidneys or other internal organs
• Detecting, diagnosing and treating vascular diseases that can lead to stroke, kidney failure or even death
• Evaluation for coronary artery disease (coronary CTA)
• Evaluation for colon cancer (virtual colonoscopy)

How should I prepare for a CT scan?

• Wear comfortable, loose-fitting, metal-free clothing. Depending on the scan, you may be asked to change into a gown.
• You may be asked to remove any clothing, jewelry, hair pins, eyeglasses, hearing aids, dentures or other objects that may interfere with the scan.
• You may be asked not to eat or drink before the exam depending upon the body area to be examined.
• If taking medications, please ask your healthcare provider if you should take them prior to your test.
• Bring a list of your medications to the exam.
• If you are pregnant or suspect there is a possibility you are pregnant, please inform the technologist.

What should I expect during this exam?

Depending on the images needed, the CT exam may take five minutes to an hour. However, very detailed exams may take longer.

• A CT is generally painless.
• The technologist positions you on the CT table and pillows are used to help keep you still and in the proper position during the scan. The table will move slowly into the CT scanner opening. Depending on the body area being examined, the increments of movement may be small and almost undetectable, or large enough to feel the motion. Relax and remain as still as you can.
• You will be asked to hold your breath for a few seconds at certain times.
• To enhance the visibility of certain tissues or blood vessels, use of different contrast materials may be required. Depending on the type of examination, contrast material may be injected through an IV, swallowed or administered by enema. Before administering the contrast material, you should inform the technologist of the following:
  • Any allergies, especially to medications or iodine
  • Whether you have a history of diabetes, asthma, kidney problems, heart or thyroid conditions. These conditions may indicate a higher risk of reaction to the contrast material or potential problems eliminating the material after the exam.
• You will be alone in the room during your scan; however, your technologist can see, hear and speak with you.
• To determine if more images are needed, you may be asked to wait until the images are reviewed.

What will I experience during the contrast preparation?

Depending on the type of scan you are having, your preparation may differ. To enhance the visibility of body tissue or blood vessels, use of different contrast materials may be administered by:

• Mouth: You may be asked to swallow water or contrast material, a liquid that allows the radiologist to better see the stomach, small bowel and colon. Some patients find the taste of the contrast material slightly unpleasant, but tolerable.
• Enema: For a study of the colon, your exam may require the administration of the contrast material by enema. You will experience a sense of abdominal fullness and may feel an increasing need to expel the liquid. The discomfort is generally mild.
• IV injection: To enhance the appearance between normal and abnormal tissue in organs, like the liver and spleen, and to better define the blood vessels and kidneys, a contrast material is commonly injected through an IV into a vein. You might feel:
  • Some discomfort when the IV is inserted. You may also feel a warm sensation at the site during the contrast injection.
  • Flushed or a metallic taste in your mouth. These are common reactions which disappear in a minute or two.
  • A mild itching sensation. If the itching persists or is accompanied by hives, it can be easily treated with medication.

Note: In very rare cases, you may experience shortness of breath or swelling in the throat or other parts of the body. These can be indications of a more serious reaction to the contrast material. Your technologist should be notified immediately.

What will happen after the test?

• After the test, you may have to wait briefly on the table while the technologist ensures the images are clear.
• You should be able to return to normal activities right away.
• You can remove the bandage from the IV site an hour or so after the test. If the IV site becomes red, swollen or painful 1 to 2 days later, contact your healthcare provider.
• Any contrast that may have been given will pass naturally out of your body in your urine within a day. Drink plenty of fluids to help pass the contrast, unless you are on fluid restriction.
• Your healthcare provider will contact you with your test results.