Computed Tomography (CT or CAT) Scan of the Spine

Computed tomography is an imaging test that uses X-rays and a computer to make detailed images of the body. A CT scan shows details of 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 body part 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 healthcare providers can get much information from a standard X-ray, it does not give a lot of detail about internal organs and other structures.

In a CT scan, an X-ray beam moves in a circle around the body. This allows many different views of the same organ or structure. The X-ray information is sent to a computer that interprets the X-ray data and displays it in a two-dimensional (2D) form on a monitor.

CT scans may be done with or without "contrast." Contrast refers to a substance taken by mouth or injected into an intravenous (IV) line that causes the particular organ or tissue under study to show up more clearly on the scan.

CT scans of the spine can provide more detailed information about the vertebrae (bones of the spine), the disks between the vertebrae, and other spinal structures and tissues than standard X-rays of the spine. CT scans can give healthcare providers more information related to injuries or diseases of the spine.

A CT scan of the spine may be used to check the spine for a herniated disk, tumors or other lesions, the extent of spinal injuries, structural defects such as spina bifida (a type of congenital defect of the spine), blood vessel malformations, infections, or other conditions. A CT scan may be done when another type of exam, such as an X-ray, MRI, or physical exam, does not provide enough information.

A CT of the spine may also be used to assess the effects of treatment of the spine, such as surgery or other therapy.

There may be other reasons for your healthcare provider to recommend a CT scan of the spine.

You may want to ask your healthcare provider about the amount of radiation used during the CT scan and the risks related to your particular situation. Radiation from CT scans varies, but may be up to 100 times greater than a normal chest X-ray. It is a good idea to keep a record of your radiation exposure, such as previous CT scans and other types of X-rays, so that you can inform your healthcare provider. Risks associated with radiation exposure may be related to the cumulative number of X-ray exams or treatments over a long period.

If you are pregnant or think you may be, tell your healthcare provider. Radiation exposure during pregnancy may lead to birth defects. If it’s necessary for you to have a CT of the spine, special precautions will be taken to reduce the radiation exposure to the fetus.

Nursing mothers should discuss with their healthcare provider whether to delay breastfeeding after receiving contrast. There are conflicting recommendations on this topic.

If contrast dye is used, there is a risk for allergic reaction to the dye. Tell your healthcare provider if you are allergic to or sensitive to medicines, contrast, or iodine. Studies show that most people will not have an adverse reaction from contrast dye. But, you will need to let your healthcare provider know if you have ever had a reaction to any contrast dye, or any kidney problems. A seafood allergy is not a contraindication for contrast.

Tell your healthcare provider if you have any kidney problems. In some cases, the contrast dye can cause kidney failure. People with kidney disease are more prone to kidney damage after contrast exposure.

There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your healthcare provider before the test.

• The CT technologist will explain the test and you can ask questions. 
• If your CT scan involves the use of contrast dye, you will be asked to sign a consent form that gives permission to do the procedure. Read the form carefully and ask questions if anything is unclear.
• Tell the technologist if you have ever had a reaction to any contrast dye, or if you are allergic to iodine.
• Generally, there is no fasting (not eating) requirement before a CT scan, unless a contrast dye is to be used. Your healthcare provider will give you special instructions ahead of time if contrast is to be used and if you will need to withhold food and drink.
• Tell your healthcare provider of all medicines (prescribed and over-the-counter), vitamins, herbs, and supplements that you are taking.
• Tell the technologist if you are pregnant or think you may be.
• Tell the technologist if you have any body piercings on your chest or stomach.
• If you are claustrophobic, discuss taking medicine before the test with your healthcare provider.
• Based on your medical condition, your healthcare provider may request other specific preparation.

CT scans can be done on an outpatient basis or as part of your hospital stay. Steps may vary depending on your condition and your healthcare provider’s practices.

Generally, a CT scan of the spine follows this process:

1. You will be asked to remove any clothing, jewelry, or other objects that may interfere with the test, such as eyeglasses, hairpins, dentures, and possibly hearing aids.
2. If you are asked to remove clothing, you will be given a gown to wear.
3. If you are to have a scan done with contrast, a healthcare professional will start an intravenous (IV) line in your hand or arm for injection of the contrast dye.
4. You will lie on a narrow table that slides into a large, circular opening of the ring-shaped scanning machine. Pillows and straps may be used to help prevent movement during the scan.
5. 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 allow the technologist to talk to you and hear you. You will have a call button so that you can let the technologist know if you have any problems during the scan. The technologist will be watching you at all times and will be in constant communication.
6. The scanner will start to rotate around you and X-rays will pass through your body for short amounts of time. You will hear clicking and whirring sounds, which are normal.
7. 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.
8. It will be important for you to stay very still during the scan. You may be asked to hold your breath for a short time at various times during the scan.
9. If contrast dye is used, you will be removed from the scanner after the first set of scans has been completed. A second set of scans will be taken after the contrast dye has been given.
10. If contrast dye is used, you may feel some effects when the dye is injected into the IV line. These effects include a warm flushing sensation, a salty or metallic taste in the mouth, a brief headache, or nausea. These effects usually only last for a few moments.
11. Tell the technologist if you feel any breathing difficulties, sweating, numbness, or heart palpitations.
12. When the test has been completed, you will be removed from the scanner.
13. If an IV line was inserted, it will be removed.
14. You may be asked to wait for a short time while the radiologist examines the scans to make sure they are clear.

While the CT test itself causes no pain, having to lie still for the length of the test might be uncomfortable, particularly if you’ve recently been injured or had surgery. The technologist will use all possible comfort measures and complete the test as quickly as possible to minimize any discomfort or pain.

If contrast dye was used, you may be watched for a period for any side effects or reactions to the contrast dye, such as itching, swelling, rash, or trouble breathing. Tell the radiologist or your healthcare provider right away if you notice any of these symptoms.

If you notice any pain, redness, or swelling at the IV site after you go home, tell your healthcare provider as this could be a sign of infection or other type of reaction.

Otherwise, there is no special type of care needed after a CT scan of the spine. You may go back to your usual diet and activities unless your healthcare provider tells you differently.

Your healthcare provider may give you other instructions after the test, depending on your situation.

Before you agree to the test or the procedure make sure you know:

• The name of the test or procedure
• The reason you are having the test or procedure
• What results to expect and what they mean
• The risks and benefits of the test or procedure
• What the possible side effects or complications are
• When and where you are to have the test or procedure
• Who will do the test or procedure and what that person’s qualifications are
• What would  happen if you did not have the test or procedure
• Any alternative tests or procedures to think about
• When and how will you get the results
• Who to call after the test or procedure if you have questions or problems
• How much will you have to pay for the test or procedure