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DEXA
What is Radiography-based (X-ray) Bone Densitometry? To detect osteoporosis accurately, doctors use an enhanced form of x-ray technology called dual-energy x-ray absorptiometry (DXA or DEXA). DEXA bone densitometry is today's established standard for measuring bone mineral density (BMD). DEXA is a quick, painless procedure for measuring bone loss. Measurement of the lower spine and hips are most often done. What are some common uses of the procedure? DEXA bone densitometry is most often used to diagnose osteoporosis, a condition that often affects women after menopause but may also be found in men. Osteoporosis involves a gradual loss of calcium, causing the bones to become thinner, more fragile and more likely to break. The DEXA test can also assess your risk for developing fractures. If your bone density is found to be low, you and your physician can work together on a treatment plan to help prevent fractures before they occur. DEXA is also effective in tracking the effects of treatment for osteoporosis or for other conditions that cause bone loss.
How should I prepare for the procedure? On the day of the exam eat normally, but don't take calcium supplements for at least 24 hours beforehand. Wear loose, comfortable clothing, avoiding garments that have zippers, belts or buttons made of metal. How is the procedure performed? The DEXA bone density test takes 10 minutes. You may be asked to undress and put on a hospital gown. Then you'll lie on a padded table with an x-ray generator below and a detector (an imaging device) above. Most often, doctors focus on bone loss in the spine and hip where most osteoporosis-related fractures happen. During an examination of the spine, your legs will be supported on a padded box to flatten your pelvis and lower (lumbar) spine. To assess your hip, the technologist will place your foot in a brace that rotates the hip inward. In both cases the detector is slowly passed over the area, generating images on a computer monitor. Who interprets the results and how do I get them? The results of a DEXA bone density exam are interpreted by a radiologist*, who is a physician specially trained to diagnose conditions and diseases by obtaining and interpreting medical images. The radiologist will send an interpretation of your results and a signed report to your primary care physician who will work with you to develop a treatment plan. Usually available within a few days, your test results will be in the form of two scores: T score - This number shows the amount of bone you have compared with 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 with 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. * Many DEXA scans are interpreted by other physicians such as rheumatologists and endocrinologists. What are the benefits vs. risks? Benefits DEXA bone density testing is the most accurate method available for the diagnosis of osteoporosis. It is also considered an accurate estimator of fracture risk. It will not tell whether you will or will not have a fracture, but gives relative risk of suffering a fracture, just as cholesterol and blood pressure help determine risk for heart disease. A low reading should not cause you to be anxious but may help you set healthy goals. As with other diseases and conditions, early detection is the key to prevention of further bone loss and eventual fractures. DEXA equipment is widely available making DEXA bone densitometry testing convenient for patients and doctors alike. Risks No complications are expected with the DEXA procedure. Source: radiologyinfo.org |
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