Computed Tomography (CT or CAT) Scan of the Spine

By Sara Foster

(Spinal CT Scan, CT of the Spine or Back)

Procedure overview

What is a CT or CAT scan of the spine?

Computed tomography (CT or CAT scan) is a noninvasive diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce both horizontal and axial images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including 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 much information can be obtained from a standard X-ray, a lot of detail about internal organs and other structures is not available.

In computed tomography, the 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 be seen more clearly. Contrast examinations may require you to fast for a certain period of time before the procedure. Your physician will notify you of this prior to the procedure.

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

Other related procedures that may be used to diagnose problems of the spine include X-rays, magnetic resonance imaging (MRI) of the spine, and positron emission tomography (PET) scan of the spine. Please see these procedures for additional information.

Anatomy of the spine

The spinal column is made up of 33 vertebrae that are separated by spongy disks and classified into distinct areas.

  • The cervical area consists of seven vertebrae in the neck.

  • The thoracic area consists of 12 vertebrae in the chest area.

  • The lumbar area consists of five vertebrae in the lower back area.

  • The sacrum has five, small fused vertebrae.

  • The four coccygeal vertebrae fuse to form one bone, called the coccyx or tailbone.

The spinal cord, a major part of the central nervous system, is located in the vertebral canal and reaches from the base of the skull to the upper part of the lower back. The spinal cord is surrounded by the bones of the spine and a sac containing cerebrospinal fluid. The spinal cord carries sense and movement signals to and from the brain and controls many reflexes.

Reasons for the procedure

A CT scan of the spine may be performed to assess the spine for a herniated disk, tumors and other lesions, the extent of injuries, structural anomalies such as spina bifida (a type of congenital defect of the spine), blood vessel malformations, or other conditions, particularly when another type of examination, such as X-rays or physical examination, is not conclusive. CT of the spine may also be used to evaluate the effects of treatment of the spine, such as surgery or other therapy.

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

Risks of the procedure

You may want to ask your physician about the amount of radiation used during the CT procedure and the risks related to your particular situation. It is a good idea to keep a record of your past history of radiation exposure, such as previous CT scans and other types of X-rays, so that you can inform your physician. Risks associated with radiation exposure may be related to the cumulative number of X-ray examinations and/or treatments over a long period of time.

If you are pregnant or suspect that you may be pregnant, you should notify your physician. Radiation exposure during pregnancy may lead to birth defects. If it is necessary for you to have a CT of the spine, special precautions will be made to minimize the radiation exposure to the fetus.



What's Causing Your Symptoms?