Noninvasive assessment of bone structure

Noninvasive Raman spectroscopy of rat tibiae: approach to in vivo assessment of bone quality

We report on in vivo noninvasive Raman spectroscopy of rat tibiae using robust fiber-optic Raman probes and holders designed for transcutaneous Raman measurements in small animals. The configuration allows placement of multiple fibers around a rat leg, maintaining contact with the skin. Bone Raman data are presented for three regions of the rat tibia diaphysis with different thicknesses of overlying soft tissue. The ability to perform in vivo noninvasive Raman measurement and evaluation of subtle changes in bone composition is demonstrated with rat leg phantoms in which the tibia has carbonated hydroxylapatite, with different carbonate contents. Our data provide proof of the principle that small changes in bone composition can be monitored through soft tissue at anatomical sites of interest in biomedical studies.

Sex and ethnic differences in bone architecture

Technologic developments and applications such as dual energy x-ray absorptiometry, magnetic resonance imaging, and computed tomography have enabled researchers to assess bone quantity (ie, bone mineral density) and bone quality (ie, bone architecture), which are two important and independent contributions to bone strength. Recent studies on sex differences in bone architecture indicate that a number of biomechanical variables lead to increased bone strength in males compared with females. Ethnic differences in bone architecture are less clear-cut, indicating a need to identify and test the social and biologic variables that race and ethnicity represent. New methods using magnetic resonance imaging technology may become important in creating efficient and reliable in vivo methods of assessing features of bone architecture that are relevant to fracture risk and contribute to the elucidation of sex and ethnic differences in osteoporosis.

Current technologies in the evaluation of bone architecture

In the context of osteoporosis, bone quality (which encompasses trabecular bone and cortical bone architecture), bone mineralization, turnover, and microdamage are all important, as are bone density and total content. Noninvasive assessment of bone quality has recently received considerable attention because bone density alone is not a surrogate for fracture prevalence and occurrence, and does not completely explain the therapeutic efficacy of emerging treatments. This paper focuses on the assessment of trabecular bone architecture, one of the factors that governs bone strength and may be categorized as a contributor to bone quality. The methodologies described include micro-computed tomography, magnetic resonance imaging, and computerized analysis of radiographic patterns of trabecular bone.