Computed Tomography (CT) Scan of the Spine

Why It Is Done

A CT scan of the spine is done to:

• Look at the bones of the spine (vertebrae).
• Find problems of the spine, such as tumors, fractures, deformities, infection, or narrowing of the spinal canal (spinal stenosis).
• Find a herniated disc of the spine.
• Check to see if osteoporosis has caused compression fractures.
• Check on problems of the spine that have been present since birth (congenital).
• Look at problems seen during a standard X-ray test.
• Check how well spinal surgery or therapy is working for a spine problem.

How To Prepare

Before the CT scan, tell your doctor if you:

• Are or might be pregnant.
• Are allergic to any medicines, including iodine dyes.
• Have a heart condition, such as heart failure.
• Have diabetes.
• Take metformin. You may have to adjust your medicine for a day before and after the test.
• Have had kidney problems.
• Have asthma.
• Have had multiple myeloma.
• Have had an X-ray test using barium contrast material (such as a barium enema) in the past 4 days. Barium shows up on X-ray films and makes it hard to see the picture clearly.
• Become very nervous in small spaces. You need to lie still inside the CT scanner, so you may need a sedative to help you relax.

Arrange for someone to take you home in case you get a sedative for the test.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, or how it will be done. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?).

How It Is Done

A CT scan is usually done by a radiology technologist. The pictures are usually read by a doctor (radiologist). Other doctors also may review a CT scan.

You may need to take off any jewelry. You will need to take off all or most of your clothes, depending on which area is studied. You may be able to wear your underwear for some scans. You will be given a gown to use during the test.

During the test, you will lie on a table that is attached to the CT scanner.

The table slides into the round opening of the scanner, and the scanner moves around your body. The table will move while the scanner takes pictures. You may hear a click or buzz as the table and scanner move. It is very important to lie still during the test.

During the test, you may be alone in the scanning room. But the technologist will watch you through a window. You will be able to talk to the technologist through a two-way intercom.

The test will take about 30 to 60 minutes. Most of this time is spent getting ready for the scan. The actual scan only takes a few seconds.

CT scan with contrast (CT myelogram)

A standard CT scan may be done before the contrast material for a CT myelogram is given. The dye is usually put in the space around your spinal cord. A sample of the fluid from the spinal canal (cerebrospinal fluid) may be taken out so other tests can be done on it.

If dye is placed in your back, you will lie on your stomach or on your side on a table. The dye is usually put in your lower back but may be put in at the base of your skull. The skin over the site may be shaved. It will be cleaned. The area around the site may be numbed with medicine.

The table may be tilted or you may be moved into different positions so the dye moves to different areas of the spine.

You need to lie very still so the dye stays in the right place for clear pictures. Your pulse, breathing rate, and blood pressure may be checked during the test.

In some cases, the dye can also be put in a vein (IV) in your arm.

A CT scan with contrast material usually takes 15 to 30 minutes. Drink lots of liquids for 24 hours after the scan to help flush the dye out of your body.

How It Feels

The test will not cause pain. The table you lie on may feel hard, and the room may be cool. It may be hard to lie still during the test.

Some people feel nervous inside the CT scanner.

If you get medicine to help you relax or if contrast material is used, you may have an IV put in your hand or arm. You may feel a quick sting or pinch when the IV is started. The dye may make you feel warm and flushed and give you a metallic taste in your mouth. Some people feel sick to their stomach or get a headache. Tell the technologist or your doctor how you are feeling.

If you have dye put in your back, you may feel a sting or pinch when the needle is put in.

After a test in which the dye is put in your back, you will be told to keep your head up and to not bend over or lie flat. This will help prevent headaches and seizures.

What Affects the Test

The following may stop you from having the test or may change the test results:

• Pregnancy. CT scans are not usually done during pregnancy.
• Barium used for another test. Barium shows up on a CT scan. If a CT scan of the lower back is needed, it should be done before any tests that use barium, such as a barium enema.
• Metal objects in the body. These items, such as surgical clips or metal in joint replacements, may prevent a clear view of the body area.
• You are not able to lie still during the test.

What To Think About

• Sometimes your CT test results may be different than those from other types of X-ray tests, magnetic resonance imaging (MRI), or ultrasound scans, because the CT scan provides a different view.
• Children who need a CT scan may need special instructions for the test. If the child is too young to hold still or is afraid, the doctor may give the child a medicine (sedative) to help him or her relax.
• If your child is scheduled for a CT scan, talk with your child's doctor about the need for the scan and the risk of radiation exposure to your child.
• CT results are often compared to positron emission tomography (PET) results to help find cancer. Some new scanners do both scans at the same time.
• MRI may give more information than a CT scan about the spinal discs and spinal cord. To learn more, see the topic Magnetic Resonance Imaging (MRI).
• When a CT scan of the spine is done with a myelogram, it is called a CT myelogram. An MRI of the spine is often done in place of a CT myelogram. To learn more, see the topic Myelogram.