Overview
Bone densitometry, also known as DEXA, uses a small amount of ionizing radiation to produce images of the lumbar spine (lower back) and hips to measure bone loss. It is commonly used to detect osteoporosis and to evaluate the risk for developing fractures due to bone deterioration. A DEXA scan measures the mineral content of the bones such as the hip, spine and/or wrist that are more prone to bone loss. This noninvasive screening exam is the most commonly used method for diagnosing osteoporosis.
Healthcare providers recommend a DEXA scan every two years to assess bone health, osteoporosis and fracture risk. These screening exams are performed on individuals who are 65 or older, have had x-rays that show bone loss, have experienced vertebral fractures, or have other chronic illnesses that put their bone health at risk.
What to Expect During Your DEXA Scan
Your test should take from 10–30 minutes depending on what parts of your body are being scanned.
- If you need to undress and put on a gown, you will first be taken to a private area to change.
- During the exam you will be asked to lie on your back on a padded table while a movable arm passes over your body.
- The technologist will help you get into a position that makes the areas of the body to be imaged—usually the spine and hip—most visible.
- To help with proper positioning, the table may include:
- A box to support your legs and flatten your spine against the table
- A brace to support your foot and rotate your hip inward
- To ensure quality images, the technologist will ask you to lie as still as possible during your scan, but you may breathe normally for the duration of the exam.
How Do I Prepare for My DEXA Scan?
- For at least 24 hours before your exam, do not take calcium supplements or other medications high in calcium, such as antacids.
- Wear comfortable clothing that has no metal zippers or buttons in the abdominal or pelvic areas. If you do not have clothing without metal components, we may ask you to change into scrubs. You may also be asked to remove jewelry, eyeglasses and any metal objects or clothing that might interfere with the x-ray images.
- Be sure to inform your technologist of you have had a barium examination recently, or if you have recently had a contrast material injection for a CT or nuclear medicine study.
- If you believe you may be pregnant, be sure to tell your technologist.
What Do My DEXA Results Mean?
The test compares your bone mineral density (BMD) to that of a "young adult" at peak bone strength and to people of your same age, called "age-matched". The difference between your result and that of a "young adult" is given as a T-score. This information, along with other factors, helps doctors in making a diagnosis. The following T-scores define the amount of bone loss:
• Normal: T-score above -1
• Osteopenic (low bone density): T-score between -1 and -2.5
• Osteoporosis: T-score below -2.5
Your test results combined with other factors give you and your doctor an overall risk of fracture. Knowing your risk of a fracture is important, because there are many ways to prevent osteoporosis and to reduce fracture risks. After reviewing your DEXA Scan results your doctor may suggest a number of steps important in building bone strength. Suggestions may include: exercise, changes in diet, hormone therapy, or other medicines known to improve bone strength.