Bone Mineral densitometry (BMD) is used most often 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 and structural changes, causing the bones to become thinner, more fragile, and more likely to break. The BMD 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. BMD testing is also effective in tracking the effects of treatment for osteoporosis or for other conditions that cause bone loss.

BMD testing takes about 20 minutes. You may be asked to undress and put on a hospital gown. Then you will lie on a padded table with an x-ray generator below and a detector (an imaging device) above.

Most often radiologists 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 device that rotates the hip inward. In both cases, the detector is slowly passed over the area, generating images on a computer monitor.

On the day of the exam, eat normally, but don’t take calcium supplements for at least 24 hours beforehand. Please wear loose, comfortable clothing, avoiding garments that have zippers, belts, or buttons made of metal. Inform your physician and staff at Annex Medical Imaging if you recently had a barium examination or have been injected with a contrast material for a computed tomography (CT) scan or radioisotope scan; you may have to wait 10-14 days before undergoing a DEXA test. Women should always inform their physician, radiologist, and x-ray technologist if there is a possibility they are pregnant.

The results of the exam are interpreted by a radiologist (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.

The BMD unit measures bone density in the hip and spine. The BMD unit has a large, flat table and an “arm” suspended overhead. During the x-ray exposure the arm moves over the patient’s body. How does the procedure work?

The BMD unit sends a thin beam of low-dose x-rays through the area of the body being examined. The radiation is absorbed by a detector and information is sent to a computer.

All BMD units feature special software to compute the data and display them on a computer monitor, allowing your radiologist to make an accurate diagnosis. The amount of radiation used is extremely small—less than one tenth the dose of a standard chest x-ray.