Optical studies of changes in bone mineral density

The ability to measure changes in bone-mineral-density (BMD) in-vivo has potential applications in monitoring stress-induced bone remodelling in, for example, competition race horses. In this study we have begun to investigate the potential of optical techniques to monitor such changes via changes in bone optical scattering. Using integrating spheres, we have investigated the optical properties of bone samples taken from the leg of the horse. Since our samples have stable characteristics over the time, we are able to use a single integrating-sphere technique. Diffuse reflection and transmission coefficients have been measured over the wavelength range 520 to 960 nm. Measurements were made on samples immersed in formic acid solution for different lengths of time; this was to investigate the effect of reduction in BMD on the optical properties. The experimental results and a Monte-Carlo based inversion method were used to extract the absorption coefficient and unmodified scattering coefficient of the samples. After full demineralisation scattering coefficient fell by a factor 4. This shows that the calcium-content in bone influences its optical properties considerably. Our experiments confirm the possibility of using optical techniques to determine changes in the BMD of samples.

[1]  M. Kohl,et al.  Near-infrared optical properties of ex vivo human skin and subcutaneous tissues measured using the Monte Carlo inversion technique. , 1998, Physics in medicine and biology.

[2]  Henricus J. C. M. Sterenborg,et al.  Two integrating spheres with an intervening scattering sample , 1992 .

[3]  S G Proskurin,et al.  A New Method of Bone Tissue Measurement Based upon Light Scattering , 1997, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[4]  D T Delpy,et al.  Measurement of the optical properties of the skull in the wavelength range 650-950 nm , 1993, Physics in medicine and biology.

[5]  Valery V. Tuchin,et al.  Tissue optics, light distribution, and spectroscopy , 1994 .

[6]  J. A. Jacquez,et al.  THE THEORY OF THE INTEGRATING SPHERE , 1954 .

[7]  M. Patterson,et al.  Anisotropy of light propagation in human skin , 2000, Physics in medicine and biology.

[8]  I. Yaroslavsky,et al.  Inverse hybrid technique for determining the optical properties of turbid media from integrating-sphere measurements. , 1996, Applied optics.

[9]  P. Kubelka,et al.  New Contributions to the Optics of Intensely Light-Scattering Materials. Part I , 1948 .

[10]  P. Kubelka,et al.  Errata: New Contributions to the Optics of Intensely Light-Scattering Materials. Part I , 1948 .

[11]  R. Anderson,et al.  ANALYTICAL MODELING FOR THE OPTICAL PROPERTIES OF THE SKIN WITH IN VITRO AND IN VIVO APPLICATIONS , 1981, Photochemistry and photobiology.

[12]  J. Clark,et al.  The organization of collagen in cryofractured rabbit articular cartilage: A scanning electron microscopic study , 1985, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[13]  A. H. Taylor.  The measurement of diffuse reflection factors and a new absolute reflectometer , 1920 .

[14]  J. Goodfellow,et al.  The significance of the fine structure of articular cartilage. , 1968, The Journal of bone and joint surgery. British volume.