Bone CT Scan

Computed Tomography Scan of the Bones, Skeletal CT Scan

In bone CT scan, a body scanner delivers x-rays to selected bones or joints—such as the shoulder, spine, hip, or pelvis—at many different angles. A computer compiles this information to construct highly detailed, cross-sectional images, which are then displayed on a TV monitor and recorded on x-ray film. In some cases, a contrast dye may be injected to enhance detail of the bones and the soft tissue inside and around the bones on the images.

A variation of bone CT scan, called myelography, involves injection of a contrast dye directly into the spinal canal to provide fine detail of the spine, spinal cord, and surrounding tissues.

Purpose of the Bone CT Scan

• To identify abnormalities in the upper and lower spine, such as herniated discs and spinal stenosis (a narrowing of the spinal canal), that may be causing back pain and/or referred pain to the lower extremities
• To detect and assess the extent of primary or metastatic bone tumors, and tumors in the soft tissue surrounding bones
• To diagnose joint abnormalities, such as fractures through the joint surface and certain tumors, that are difficult to detect with other methods
• To determine the location of an abscess
• To evaluate skeletal changes in osteoporosis and other metabolic bone diseases
• To diagnose bone loss (osteoporosis), which is common in women after menopause and also may occur in men
• To evaluate fracture risk
• To detect unusually active formation of bone

Who Performs Bone CT Scan

• A radiology technician

Special Concerns about Bone CT Scan

• Pregnant women should not undergo this test because exposure to ionizing radiation may harm the fetus.
• People with allergies to iodine or shellfish may experience an allergic reaction to iodine-based contrast dyes.
• Painkillers may be administered to people with significant bone or joint pain if remaining still during the exam is likely to cause discomfort.
• People who experience claustrophobia may find it difficult to undergo a CT scan, which takes place in a narrow, tunnel-like structure.
• This test may not be possible for severely overweight individuals (over 300 lbs).

Before the Bone CT Scan

• Avoid taking calcium supplements for at least 24 hours before the test
• Inform your doctor if you have an allergy to iodine or shellfish. You may be given a combined antihistamine-steroid preparation to reduce the risk of an allergic reaction to the contrast dye.
• Tell your doctor if you suffer from claustrophobia. He or she may prescribe a sedative to help you tolerate the procedure.
• Tell your doctor if you had a recent barium examination, computed tomography (CT) scan with contrast material or radioisotope scan. A period of 10 to 14 days is necessary between these procedures and a bone scan.
• Tell your doctor if you are pregnant or may be pregnant.
• If a contrast dye is to be used or if sedation is anticipated, you will be instructed to fast for 4 hours before the test.
• You will be asked to remove your clothes, jewelry, and any metal objects and put on a hospital gown.

What You Experience during Bone CT Scan

• You will lie on your back on a narrow table that is then advanced into the CT scanner.
• The scanner, which encircles you, rotates around you taking pictures at different intervals and from various angles. You will feel the table move during the test.
• You must remain as still as possible because any movement can distort the images on the scan.
• The examiner may advise you on how to control your breathing at several points during the procedure.
• A contrast dye may be administered through an intravenous (IV) needle or catheter inserted in a vein in your arm. You may feel a brief warm, flushing sensation after the injection; rarely, some people experience nausea and possibly vomiting.
• The test typically takes 30 to 60 minutes.

Risks and Complications of Bone CT Scan

• CT scanning involves exposure to low levels of radiation.
• Some people may experience an allergic reaction to the iodine-based contrast dye, which can cause symptoms such as nausea, sneezing, vomiting, hives, and occasionally a life-threatening response called anaphylactic shock. Emergency medications and equipment are kept readily available.

After the Bone CT Scan

• You are free to resume your normal diet and activities.
• If a contrast dye was used, you are encouraged to drink clear fluids to avoid dehydration and help flush the material out of your system.
• Blood may collect and clot under the skin (hematoma) at the dye injection site; this is harmless and will resolve on its own. For a large hematoma that causes swelling and discomfort, apply ice initially; after 24 hours, use warm, moist compresses to help dissolve the clotted blood.
• Delayed allergic reactions to the contrast dye, such as hives, rash, or itching, may appear 2 to 6 hours after the procedure. If this occurs, your doctor will prescribe antihistamines or steroids to ease your discomfort.

Results of Bone CT Scan

• A physician will examine the recorded images for evidence of abnormalities in the bones or joints being examined.
• If a definitive diagnosis can be made, appropriate treatment will be initiated, depending on the specific problem.
• In some cases, additional tests may be needed to establish a diagnosis and determine the extent of the problem. For example, magnetic resonance imaging may provide better detail of the soft tissues near the spine.

Source:

The Johns Hopkins Consumer Guide to Medical Tests

Simeon Margolis, M.D., Ph.D., Medical Editor

Updated by Remedy Health Media