Presented by- MD Monsur Rahman MPT in Musculoskeletal Disorders

1. BONE- MINERAL DENSITY

2. BONE DENSITOMETRY
A bone densitometry scan is an enhanced form of X-ray
technology used to measure the bone mineral (calcium)
content or bone loss and density of specific skeletal
sites or whole body.

4. ▶ The examination is also called a DEXA scan, QDR scan or BMD
measurement.
▶ THE MOST VERSATILE AND WIDELY USED TECHNIQUE : DXA or
DEXA (Dual energy X-Ray Absorptiometry)
▶ DEXA is most often performed on the lower spine and hips.
Portable Dexa devices, including some that use ultrasound
waves rather than Xrays measure the wrist fingers or heel and
sometimess used for screening purposes.
▶ A bone densitometry scan measures the calcium content in the
bones, which can’t be evaluated in an ordinary XRAY. An Xray is
more reliable when it comes to detecting a recent bone fracture.

5. ▶ Osteoporosis undetected and overlooked until 1920.
▶ The first publication about bone mass appeared in 1930s.
▶ Radiographic absorptiometery Xray taken and compared to a standard
radiograph.
▶ Radiogammetry introduced in the 1960s in response to the
measurement of the bone loss in astronauts.
▶ In 1970 CT was used through the specialized software - Quantitative
CT.
▶ In 1970s and 1980s brought the first dedicated scanners. First SPA then
DPA used radioisotope as a source of radiation.
▶ First commercial DXA scanner introduced in 1987 first used
radioisotope as the Xray source then replaced by the Xray tube.
HISTORY

6. ▶ DEXA bone densitometery is used to diagnose osteoporosis and to assess risk of bone
fracture within the next few years.
▶ Osteoporosis or thin bones is a condition that often affects women after menopause
but may also be found in men. In osteoporosis, gradual loss of calcium causing the
bones to become thinner, more fragile and more likely to break. Its not a form of
arthritis.
▶ DEXA is also effective in tracking the effects of treatment for osteoporosis and other
conditions that cause bone loss. If the patient receives medical treatment for bone loss
then the scan can be repeated after 2 years to assess their progress.
▶ RISK FACTORS FOR OSTEOPOROSIS IN WOMEN:
- menopause - family history
- small bone fracture - advanced age - low calcium diet
↖ inactive lifestyle - Cigarette smoking -GI malabsorption problem
- certain medication use (corticosteroids)
USES

8. ▶ Post menopausal women who is not taking estrogen
▶ Having personal or maternal history of hip fracture or smoking
▶ A man with clinical condition associated with bone loss
▶ A person use medications that are known to cause bone loss,
including corticosteroids such as prednisone, antiseizure
medicines like dilantin or high dose thyroid replacement drugs.
▶ Patient having type 1 diabetes, liver disease, kidney disease or
family history of osteoporosis.
▶ Thyroid condition such as hyperthyroidism.
▶ Parathyroid condition like parathyroidism.
▶ Patients experienced a fracture after mild trauma.
INDICATIONS FOR BONE
DENSITOMETRY

9. ▶ The scan will take between 10 and 30 minutes depending on the equipment
used and the parts of the body examined.
▶ Patients can eat normally before the test but they should not take calcium
supplements for atleast 24 hours before your examination.
▶ Patients should wear loose, comfortable clothing avoiding garments that have
zippers, belts or buttons made of metal.
▶ Patient may be asked to remove some or all of your clothes and to wear a
gown during the exam.
▶ Remove jewellery, eye glasses and any metal objects or clothing that might
interfere with the Xray images
▶ notify the technologist if you may be pregnant
▶ Inform your physician if you recently had a barium examination or have
injected with a contrast material for a computed tomography scan. You may
have to wait 10 – 14 days before undergoing a DEXA test.
Procedure For Bone Densitometry

10. ▶ Two types: Central device
Peripheral device
Central DEXA device are usually located in hospitals and
medical offices
↖ Measure bone density in the hip and spine.
↖ Central dexa devices have a large flat table and an arm
suspended overhead
Peripheral DEXA are often available in drug stores and
on mobile health vans.
↖ Measure bone density in the wrist, heel or finger.
DEXA Equipment

11. ▶ DEXA machine send a thin invisible beam of low dose
Xray with two distinct energy peaks through the bones
being examined. 0ne peak is absorbed mainly by soft
tissue and the other by bone. The soft tissue amount
can be subtracted from the total and what remains is a
patient’s bone mineral density.
▶ DEXA machines feature special software that compute
and display the bone density measurements on a
computer monitor.
How does the Procedure work

12. ▶ In Central DEXA examination patients lies on a padded table. An Xray generator
is located below the patient and an imaging device is positioned above.
▶ To assess the spine, the patient’s legs are supported on a padded box to flatten the
pelvis and lumbar spine. To asses the hip the patients foot is placed 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.
▶ The patient must hold very still and may be asked to keep from breathing for a few
seconds while the Xray picture is taken to reduce the possibility of a blurred image.
▶ The PERIHERAL DEXA: test is simpler. The patient finger, hand, forearm or
foot is placed in a small device that obtain a bone density reading within a few
minutes.
▶ Lateral Vertebral Assessment : (LVA) is now being done at many centres. LVA
is a low dose XRAY examination of spine to screen for vertebral fractures that is
performed on the DEXA machine.
▶ In these procedures, under the table a photon generator will pass beneath you, while
an Xray detector camera will pass above the table parallel to the table parallel to the
photon generator beneath, projecting images of the lumbar and hip bones onto a
computer monitor
▶ The computer will calculate the amount of photons that are not absorbed by
Procedure

13. ▶ the bones to determine the bone mineral content.
▶ Bone densitometry testing can determine decreasing
bone density and strength at a much earlier stage when
treatment of the bone weakness can be beneficial.

14. Central DEXA Peripheral DEXA

15. ▶ There is no special type of care following bone densitometry testing. You may
resume to usual diet and activities unless your physician advises you
differently.
▶ TEST RESULTS:
▶ BMD is compared to two norms: Healthy young adults (T-score) and age
mated (Z-score)
▶ T-score: the standard deviation is the difference between your BMD and that
of the healthy young adults . This result is your T score. Positive T scores
indicate the bone is stronger than normal, negative Tscores indicate the bone
is weaker than normal
▶ A score above -1 is considered normal. A score between -1 to -2.5 is classified
as osteopenia, the first stage of bone loss. A score below -2.5 is defined as
osteoporosis.
▶ The risk for bone fracture doubles with every SD below normal (T score of -1 )
has twice the risk for bone fracture as a person with a normal BMD. A person
with a (T score of -2) has 4 times the risk of bone fracture as a person with
normal BMD
After the procedure

17. Report of T score

18. ▶ Z score : This number reflects the amount of bone you have compared with
other people in your age group and of same gender, race, height and
weight. If the score is unusually high or low it may indicate a need for
further medical tests.
▶ Advantages of bone densitometry or DEXA:
- it is simple quick and non invasive procedure.
-Low radiation dose less than 1/10th of chest Xray
- no anesthesia is required
- most accurate method for the diagnosis of osteoporosis and is also
considered an accurate estimator of fracture risk.
- WIDE availability
- ease of use
- short scan time
- high resolution images
- good precision
RISK OF DEXA OR BONE DENSITOMETRY: slight chances of cancer

19. ▶ LIMITATION OF DEXA SCAN:
↖ Centeral Dexa devices are more sensitive than pDEXA devices but they are
also somewhat more expensive
↖ A DEXA test cannot predict who will experience a fracture but can provide
indications of relative risk.
↖ A test done on a peripheral location, such as the heel or wrist, may help
predict the risk of fracture in the spine or hip. But because bone mass tends
to vary from one location to the other, measuring the heel is not as accurate
as measuring spine or hip

20. THANK YOU