Bone mineral density

Bone mineral density (BMD) is defined as amount of mineral (calcium hydroxyapatite) per unit of bone.

Measurement

ItBMD can be measured by various methods:

• gamma rays: replaced by radiographic methods
  • single-energy photon absorptiometry- SPA (SPA) was superseded by the introduction of Single X-ray absorptiometry. Both methods measure density at peripheral sites of skeletonin the skeleton (e.g. distal radius, calcaneus). The, but the disadvantage is that, it it cannot measure the trabecular and cortical bone separately. 
  • dual-energy photon absorptiometry- DPA, also (DPA) also has been replaced by dual X-ray absorptiometry (DXA). DXA measures lumbar spine, proximal femur and whole body, but it can also measure peripheral parts of body. It can easily assess the osteoporosis in the vertebrae and proximal femur as well as predict the femoral fractures too.

• x-rays-ray
  • single-energy x-ray absorptiometry- described in single photon absorptiometry
  • dual-energy x-ray absorptiometry (DEXA)- described in dual photon absorptiometry.
  • quantitative computed tomography
  • radiogrammetry

• ultrasound
  • calcaneal ultrasonography- determines bone mineral density and bone strength.
  • Speed Sound (SOS)- measures velocity in the bone.
  • Broadband ultrasound attenuation (BUA)- measures the frequency in the bone.

• MRI
  • spectroscopy
  • quantitative magnetic resonance imaging- depicts changes in the trabecular structures at several sites of the peripheral skeleton. 

See also

• osteoporosis