Assessment of Bone Health & a DXA Scan
What is osteoporosis?
Osteoporosis is often known as a "silent disease" as there are rarely signs and symptoms until you have lost a significant amount of bone. It is a disease condition where your bones become brittle and break easily without any trauma or following trivial injury. Reduction in bone mineral density, deterioration of bone micro-architecture contribute to loss of bone strength and increase in brittleness of your bone.
Are you at risk of getting osteoporosis?
Following are known risk factors for someone to suffer from osteoporosis:
- female - advanced age
- small frame (BMI < 19 kg/m2) - family history of osteoporosis
- sedentary lifestyle - low calcium and vitamin D intake
- excessive alcohol and tobacco use - certain medicines (steroids, anti-convulsants)
- eating disorders - Asians and Caucasian
- early menopause (both natural and surgical menopause)
How do I know I am suffering from osteoporosis?
Osteoporosis is often called a "silent disease". You might present to your doctors for recurrent back pain, associated with loss of height and hunched back. The signs and symptoms occur after a significant amount of bone loss leading on to fractures of your spine. Some might not even know they are suffering from this disease until one day they present to their doctors with painful fracture hip or wrist!
If you have the above risk factors, you should consult your doctor for further examination and investigation. Bone mineral density measurement using DXA scan is the gold standard method to confirm the presence of osteoporosis. The diagnosis will be based on the WHO criteria on BMD measurement from DXA scan.
What is a DXA scan?
DXA (Dual Energy X-Ray Absorptiometry) technology has been used widely worldwide for assessment of bone health. Bone Mineral Density (BMD) measured using DXA scan on our lumbar spine, hip and distal radius (wrist) has been used as diagnostic tool by WHO to confirm presence of osteoporosis. DXA is also used to monitor the response to treatment for patients with osteoporosis.
DXA scan uses very minimal amount of x-ray to measure your bone mineral density. You just need to lie down on the scan machine for about 5 minutes. Scan will be done on your lumbar spine, hip, whole body or your wrist. Images as well as the bone mineral density on the regions scanned will be produced immediately. Your doctor will then interpret the results for you and informing you whether you have normal BMD, low BMD known as osteopenia or you are suffering from osteoporosis.
How is a DXA scan done?
Your name, age, height, body weight and ethnicity will be entered into th DXA scan first before your test. These information will be used to compare your results to a normal reference group. You will then be lying on your back after changing. Belt buckles, metal or thick plastic buttons and metal jewelry will need to be removed from the region of scan. After proper positioning by your technician, the scan will then be started. It takes just about five to ten minutes for a standard scan.
Is the test safe?
Even though DXA uses x-ray for scanning, the amount of x-ray absorbed by the patient is only about 1/10th of that received from a chest x-ray. The x-ray dose from the BMD test is comparable to the naturally occurring radiation you are exposed to in one week.
What do I expect from my doctor after my DXA scan?
Based on the results and pictures shown on the result sheet, your doctor will interpret the result for you based on the WHO criteria for osteoporosis. Based on WHO definition for osteoporosis, a T-score will be used to diagnose the presence of osteoporosis. Your doctor will also look at the risk factors that you might have. By combining these informations on risk factors and BMD result, your doctor will advise you whether you need long term treatment and which treatment option suits you best. Your doctor will also advise when is the next time you should repeat your DXA scan to assess whether your bone mineral density has improved.
||Osteopenic (low bone density)
||–1 to –2.5
Assessment of Body Composition Analysis (BCA)
DXA has been recognized as the most accurate and precise tool to measure body composition including bone mineral content, lean body tissue mass, fat tissue mass as well as percentage of fat in our body. This provides information which is of paramount important in patients with obesity and is undergoing slimming program, patients with various endocrine disorders as well as for pediatric assessment.
Why do we measure body composition?
By stepping on the weighing scale at every visit to your doctor's clinic is helpful to monitor your body weight. It is at best a crude and imprecise method to assess your health. Measuring body composition using DXA technology provides a much more complete and precise information than measuring your body weight and your body mass index (BMI).
How is DXA useful in measuring you BCA?
DXA uses a small amounts of x-ray to produce your total body image. Two different energy levels are produced by the x-ray that are absorbed differently by bone, lean and fat tissue. The difference in x-ray absorption by different tissues will be captured by the computer and then determine the amount of bone, lean and fat tissues across the whole body and in specific regions.
How is the BCA being done using DXA?
Your name, age, height, body weight and ethnicity will be entered into th DXA scan first before your test. These information will be used to compare your results to a normal reference group. You will then be lying on your back after changing. Belt buckles, metal or thick plastic buttons and metal jewelry will need to be removed from the region of scan. After proper positioning by your technician, the scan will then be started. It takes just about ten minutes for a standard scan.
What information do I get from the BCA scan?
From the DXA scan on BCA, your total body composition is calculated for various regions which include your arms, legs, trunk and total body. Results will be displayed for percentage of your body fat, muscle mass and lean body mass. This will provide you the important information on the body composition in all regions. By modifying your life style, dietary habit, exercise or with other intervention, you may monitor all the results in a subsequent scan.
iDXA, also known as intelligent DXA, is the highest range and most precise DXA scanner available under General Electric (GE). It provides stunning image clarity, advanced diagnostic capabilities and workflow efficiency. The iDXA's open architecture and larger table accommodate patients up to 450 lbs (204kg) and allow for easy positioning of tall or heavy patients. iDXA is can be used for the measurement of different regions for different indications.
The uses of iDXA
- Bone Mineral Density Measurements
- Lumbar spine (AP) - best site to predict vertebral fracture
- Femur - best site to predict hip fracture
- Dual femur -Automated dual-scan analysis for optimal fracture risk assessment
- Forearm (Distal radius) - recommended if spine/femur are not available for measurement
- Lateral Vertebral Assessment (LVA) - 2 minute DXA imaging technique, visually identify deformities and fractures
- Anterior Posterior Vertebral Assessment - visually identify vertebral deformities and fractures
- Total Body Bone Density - excellent "third" site when spine and/or hip are not available, excellent for pediatric, sports medicine and wellness
- Incorporation of FRAX (WHO risk assessment for 10 year fracture probability)
FRAX Estimates 10-year fracture probability. Hip fracture is one of the major osteoporotic fracture (spine, hip, forearm or shoulder). Measurement of 10 years fracture probability is done based on femoral neck BMD and clinical risk factors
- Total Body Composition Analysis (BCA)
iDXA provides direct measurement of tissue - measure accurately the lean body mass, fat mass and bone mass, excellent for pediatric, sports medicine, wellness and slimming. Accurate measurement of body composition can provide valuable information for assessing, monitoring and treating a variety of diseases and disorders. Body composition measurement with iDXA can look beyond weight and traditional body mass index (BMI) to determine body fat distribution.
Click here to view more photographs of the iDXA equipment.