What is a CT 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. Healthcare providers can get much information from a standard X-ray. But it doesn't 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. It displays it in a 2-D 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 IV (intravenous) line. The IV is inserted into the hand or arm. Contrast 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 bones of the spine (vertebrae), 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.

Why might I need a CT scan of the spine?

A CT scan of the spine may be used to check the spine for:

• A herniated disk

• Tumors or other lesions

• Structural problems, such as spina bifida. This is a problem with the spine a person is born with (congenital)

• Blood vessel problems

• Infections

A CT scan may be done when another type of exam, such as an X-ray, MRI, or physical exam, doesn't give enough information.

A CT of the spine may also be used to assess the effects of treatment of the spine. This includes surgery or other therapy.

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

What are the risks of 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, depending on the region of the body being examined. But it may be up to 100 to 800 times greater than a normal chest X-ray. It's a good idea to keep a record of your radiation exposure. This includes previous CT scans and other types of X-rays, so that you can tell your provider. Risks linked to radiation exposure may be related to the number of X-ray exams or treatments over a long period.

Tell your healthcare provider if you're pregnant or think you may be. Radiation exposure during pregnancy may lead to birth defects. If you need to have a CT of the spine, special precautions will be taken to reduce the radiation exposure to the fetus.

If you're breastfeeding, ask your healthcare provider if you need to delay breastfeeding after getting contrast.

If contrast dye is used, there is a risk for allergic reaction to the dye. Tell your healthcare provider well before the exam if you're allergic to or sensitive to medicines, contrast, or iodine. They may prescribe medicines to reduce the risk for allergic reactions. Most people won't have any problems from contrast dye, but be sure to tell your provider if you've ever had a reaction to any contrast dye. Having a seafood allergy won't stop you from getting 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 likely to have kidney damage after contrast exposure.

Tell your healthcare provider if you are taking the diabetes medicine metformin. You may be told to stop taking this medicine before the scan.

There may be other risks depending on your specific health condition. Talk about any concerns with your healthcare provider before the test.

How do I get ready for a CT scan of the spine?

• The CT technologist will explain the test and you can ask questions. 

• If your CT scan involves the use of contrast dye, you'll be asked to sign a consent form that gives permission to do the scan. Read the form carefully and ask questions if anything is unclear.

• Tell the technologist if you've ever had a reaction to any contrast dye or if you're allergic to iodine.

• You don't usually need to fast 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 you need to fast.

• Tell your provider about all prescription and over-the-counter medicines, vitamins, herbs, and supplements you're taking.

• Tell your provider about any recent illnesses or other health conditions you have, such as heart disease, kidney disease, asthma, diabetes, or thyroid problems. These can increase the risk for problems.

• Tell the technologist if you're pregnant or think you may be.

• Tell the technologist if you have any body piercings on your chest or stomach.

• If you're claustrophobic, talk with your healthcare provider about taking medicine for relaxation before the test.

• Your provider may have other instructions on how to get ready.

What happens during a CT scan of the spine?

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'll 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're asked to remove clothing, you'll be given a gown to wear.

3. If you're to have a scan done with contrast, a healthcare professional will start an IV (intravenous) line in your hand or arm for injection of the contrast dye.

4. You'll 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 keep you still during the scan.

5. The technologist will be in another room where the scanner controls are located. But you'll be in constant sight of the technologist through a window. Speakers inside the scanner will allow the technologist to talk with you and hear you. You'll 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'll 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 sent 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'll 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. Tell the technologist if you feel pain or tingling at the IV site after injection.

11. Tell the technologist if you feel any breathing difficulties, sweating, numbness, or heart palpitations.

12. When the test has been completed, you'll 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 reduce any discomfort or pain.

What happens after a CT scan of the spine?

If contrast dye was used, you may be watched for a period for any side effects or reactions to the contrast dye. These include 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. Any of these 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 provider tells you differently.

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

Next steps

Before you agree to the test or 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 you will get the results

• Who to call after the test or procedure if you have questions or problems

• How much you will have to pay for the test or procedure