Back Pain Health Center

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 and bismuth used for another test. These substances show 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. For more information, 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. For more information, see the topic Myelogram.