You will lie on a narrow table that slides into the center of the CT scanner.
Once you are inside the scanner, the machine's x-ray beam rotates around you. (Modern "spiral" scanners can perform the exam without stopping.)
A computer creates separate images of the body area, called slices. These images can be stored, viewed on a monitor, or printed on film. Three-dimensional models of the cervical spine can be created by adding the slices together.
You must be still during the exam. Movement can cause blurred images. You may need hold your breath for short periods of time.
The scan take 10-15 minutes.
How to prepare for the test
Some exams use a special dye, called contrast, that is put into your body before the test starts. Contrast helps certain areas show up better on the x-rays.
Contrast can be given in different ways:
It may be given through a vein (IV) in your hand or forearm.
It may be given as an injection into the space around the spinal cord.
If contrast is used, you may also be asked not to eat or drink anything for 4-6 hours before the test.
Let your doctor know if you have ever had a reaction to contrast. You may need to take medicines before the test to avoid this problem.
Before having the contrast, tell your health care provider if you take the diabetes medicine metformin (Glucophage). You may need to take extra steps before the test if you take this drug.
Too much weight can cause damage to the scanner's working parts. Find out if the CT machine has a weight limit if you weight more than 300 pounds.
You will wear a hospital gown during the study. You will need to take off all jewelry.
How the test will feel
Some people may have discomfort from lying on the hard table.
Contrast given through an IV may cause a slight burning feeling, a metal taste in the mouth, and a warm flushing of the body. These feelings are normal and go away in a few seconds.
Why the test is performed
CT makes detailed pictures of the body very quickly. The test may help look for:
Disc herniations and compression of the spinal cord
Results are considered normal if the cervical spine looks okay.
What abnormal results mean
Abnormal results may be due to:
Birth defects of the cervical spine
What the risks are
Risks of CT scans include:
Being exposed to radiation
Allergic reaction to contrast dye
CT scans expose you to more radiation than regular x-rays. Having many x-rays or CT scans over time may raise your risk for cancer, but the risk from any one scan is small. Talk to your doctor about this risk and how it weighs against the benefits of the test.
Some people have allergies to contrast dye. Let your doctor know if you have ever had an allergic reaction to injected contrast dye.
The most common type of contrast given into a vein contains iodine. If a person with an iodine allergy is given this type of contrast, nausea or vomiting,sneezing, itching,or hives may occur.
If you must have this type of contrast, your doctor may give you antihistamines (such as Benadryl) or steroids before the test.
The kidneys help remove iodine out of the body. People with kidney disease or diabetes may need to get extra fluids after the test to help flush the iodine out of the body.
Rarely, the dye may cause a life-threatening allergic response called anaphylaxis. If you have any trouble breathing during the test, you should notify the scanner operator immediately. Scanners come with an intercom and speakers, so the operator can hear you at all times.
Gardocki RJ, Camillo FX. Other discorders of the spine. In: CanaleST, Beaty JH, eds. Campbells's Operative Orthopaedics. 12th ed. Philadelphia, Pa: Mosby Elsevier; 2012:chap 44.
Grainger RG, Thomsen HS, Morcos SK, Koh DM, Roditi G. Intravascular contrast media for radiology, CT, and MRI. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 2.
Shaw AS, Dixon AK. Multidetector computed tomography. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 4.
C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.