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Osteoporosis Health Centre
Diagnosis |
Other tests for osteoporosis
Conventional X-Rays
X-rays only detect osteoporosis after it has become severe. However, they are useful for detecting compression fractures in the spine.
Single Photon Absorptiometry (SPA)
This test uses gamma rays, which are similar to x-rays. It can only measure cortical bone density in the peripheral or extremities of the skeleton, such as the forearm or wrist.
Dual Photon Absorptiometry (DPA)
DPA uses two different gamma ray energies, and can measure BMD in the trabecular bone of the lower spine and leg.
SPA and DPA were the best tests available in the 1970s and 80s. But they have long scanning times (one hour) and are less precise than the newer methods.
Quantitative Ultrasound (QUS):
Other tests for osteoporosis measure bone density. Quantitative Ultrasound measures bone quality. QUS measures how the ultrasound beam changes as it passes through the foot. This is called Broad Band Ultrasonic Attenuation, or BUA. BUA can tell us about the structure, elasticity, and strength of the bones. These factors are strongly co-related to bone density, and help predict the risk of fracture.
QUS:
- takes an ultrasound scan of a person's heel. This is an easily accessible area that contains trabecular bone - the type of bone that changes with age like the lumbar spine does.
- measures the changes in the ultrasound beam and the speed of the beam as it passes through the foot.
- is simple, quick and portable.
- involves no exposure to radiation.
Peripheral Dual Energy X-Ray Absorptiometry (pDEXA)
Measures BMD at the periphery or ends of the skeleton, like the forearm or heel. The advantages of pDEXA include:
- a short scan time (5 minutes)
- portability, so that it can be taken to people in remote areas
- low cost
- a small radiation dose
Peripheral Quantitative Computed Tomography (pQCT)
Measures BMD in the appendages, most often the forearm. It gives a true density reading, measured in terms of volume. It also determines separate cortical, trabecular and total BMD. This method allows doctors to analyze a cross-sectional image of the trabecular bone. Advantages include:
- a short scan time (10 minutes)
- a very small radiation dose (less than 1/12 of a chest X-ray)
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Radiographic Absorptiometry (RA)
RA was used in the past to measure BMD, but its precision and accuracy were poor.
The radiograph is sent to a laboratory and analyzed using a computer.
RA:
- is widely available using conventional X-ray equipment
- is quick and inexpensive
- has a small radiation dose
Magnetic Resonance Imaging (MRI)
Uses magnetic forces to get high resolution or detailed images of any part of the body. Although it is mostly used now to diagnose diseases of the organs, such as cancer, it can also be used to measure BMD and get information on the trabecular bone structure.
MRI:
- does not use radiation as X-rays do
- is time consuming and costly, and its usefulness is still being studied
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