Computed tomography (CT) is a test that combines X-rays and computer scans. It creates detailed pictures of bones and soft tissues, such as organs and blood vessels.
It is often necessary to use a special dye (contrast) to make a part of your body show up more clearly on the X-ray. If you need the dye, you may get it as something to drink and/or through an IV (intravenous line). If you drink the contrast dye, it must be consumed an hour prior to the scan.
Little preparation is needed for a CT scan. As long as you do not have congestive heart failure and are not on dialysis, you should drink 64 ounces of water before your exam. If possible, start drinking 12 hours before your scheduled appointment time. This is to keep you hydrated. You do not need a full bladder for the test, and you may use the restroom.
If you are getting a CT scan of your chest or heart, you should stop drinking or eating caffeine several hours before your exam.
All jewelry and other metallic objects must be removed from the area being scanned. This includes metal that is often part of clothing such as snaps, belts and underwire bras. You should wear comfortable clothing.
You will need to arrive at least 60 minutes before your appointment time to check in and complete paperwork. This will also provide time to get your IV started, if necessary. If you need to drink the contrast dye, you should arrive at least 90 minutes before your appointment time.
During the scan, you will lie on a special table. The table will move you through the center of the doughnut-shaped CT scanner. As you are moved through the scanner, you will need to stay as still as possible. Nothing will touch you. You may be asked to hold your breath for a few seconds as each scan is made.
Most CT scans take 15 to 20 minutes. You should plan for your entire visit to be at least 1½ hours. In some cases it may take longer.
You can usually go back to your normal activities and diet. If you were given the dye and you did not drink the recommended amount of water before your CT scan, you should drink 64 ounces of water over a 12-hour period after the exam, unless you have congestive heart failure or are on dialysis.