DEXA (Bone Density Analysis)
To accurately detect osteoporosis, doctors commonly use DEXA bone densitometry scan to safely and painlessly measure bone density and bone loss by taking a low dose x-ray of your lower spine and hips.
Sometimes, an additional low-dose x-ray image, called VFA (Vertebral Fracture Assessment), is performed of the entire spine. This test allows doctors to see existing vertebral fractures, which may indicate the need for more aggressive treatment, even if bone density results are in the “normal” range.
When doctors detect bone loss in the earliest stage, treatment, along with preventative measures, are more successful.
The DEXA test also assesses your risk for developing fractures. It is effective in tracking the effects of treatment for osteoporosis and other conditions that can cause bone loss. Bone density testing is recommended for:
- Post-menopausal women age 60 or older who have risk factors for developing osteoporosis
- Patients with a personal or maternal history of hip fracture or smoking
- Post-menopausal women who are tall (over 5 feet 7 inches) or thin (less than 125 pounds)
- Men and women who have hyperparathyroidism
- Men and women who over an extended period have taken medications that are known to cause bone loss
For more information on this topic, please visit: radiologyinfo.org Bone Densitometry (DEXA, DXA)
Planning for your procedure
How should I prepare for this procedure?
- Refrain from taking calcium supplements for at least 24 hours beforehand
- Wear comfortable clothing and avoid garments that have zippers, belts or buttons made of metal
- Inform your technologist if you’ve recently had a barium examination or have been injected with a contrast material for a CT or radioisotope scan
- Inform your technologist if there is a possibility you may be pregnant
DEXA bone densitometry is a simple, painless, and non-invasive procedure. During your exam, you will lie on a padded table while the bone densitometry system scans two or more areas, usually your hip and spine. Unlike typical x-ray machines, radiation exposure during bone densitometry is extremely low. The entire process takes only minutes to complete. It involves no injections or invasive procedures, and if you have no zippers or metal buttons on your clothing, you can remain fully clothed. However, all women are required to remove only their bras prior to taking the exam.
Depending on the equipment used and the parts of the body being examined, the test takes approximately 20 minutes. You’ll lie on a padded table with an x-ray generator below and a detector (an imaging device) above. It is important that you remain as still as possible during the procedure to ensure a clear and useful image.
The results of a DEXA bone density exam are interpreted by a radiologist and forwarded to your doctor. However, some doctors may prefer to interpret their patients’ scans. Your test results will be in the form of two scores:
T score – This number shows the amount of bone you have compared to a young adult of the same gender with peak bone mass. A score above -1 is considered normal. A score between -1 and -2.5 is classified as osteopenia: the first stage of bone loss. A score below -2.5 is defined as osteoporosis. It is used to estimate your risk of developing a fracture.
Z score – This number reflects the amount of bone you have compared to other people in your age group and of the same size and gender. If it is unusually high or low, it may indicate a need for further medical tests.
