What is a DEXA Scan?
To accurately detect osteoporosis, doctors commonly use DEXA bone densitometry (the gold standard) to measure bone density and bone loss safely and painlessly 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) will be performed of the entire spine. This 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 can also assess 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 have been taking medications that are known to cause bone loss for an extended period of time
Tell me a little bit about osteoporosis
- Osteoporosis affects an estimated 75 million people in Europe, USA and Japan
- Women who develop a vertebral fracture are at substantial risk for additional fracture within the 1-2 years
- By 2050, the worldwide incidence of hip fracture in men is projected to increase by 310% and 240% in women.
- Hip fractures cause the most morbidity with reported mortality rates up to 20-24% in the first year after a hip fracture.
- 10 million Americans are estimated to have osteoporosis. About 34 million more are at risk.
- Worldwide, osteoporosis causes more than 8.9 million fractures annually, resulting in an osteoporotic fracture every 3 seconds.
What happens during the bone densitometry exam?
During your exam, you will lay 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 as long as you have no zippers or metal buttons on your clothing, you can remain fully clothed.
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.
- Let your technologist know if you’ve recently had a barium examination or have been injected with a contrast material for a CT or radioisotope scan.
- Let your technologist know if there is a possibility you are pregnant.
What can I expect during this exam?
Depending on the equipment used and the parts of the body being examined, the test takes approximately 20 minutes.
You may be asked to undress and put on a gown.
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 detector is scanned over the area, generating images on a computer monitor.
DEXA bone densitometry is a simple, painless, and non-invasive procedure. Once on the examination table, you may be asked to remain still and to hold an awkward position for a short period of time while the machine takes measurements.
Who interprets the results and how do I get them?
The results of a DEXA bone density exam are interpreted by a radiologist and forwarded to your doctor. 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.
For more information on this topic, please visit www.Radiologyinfo.org.