Non-Invasive Determination of Bone Quality Markers by Monte Carlo Modeling and Optical Spectroscopy

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Summary: Diseases of bone fragility such as osteoporosis require bone quality monitoring, typically done by dual X- ray absorptiometry (DXA) assessment of bone mineral density (BMD). Bone health index (BHI) and metacarpal index (MCI) are other measures of bone quality based on radiographic geometric assessment of the metacarpal bones obtained from a planar hand X-ray. These approaches all use ionizing radiation, which is of concern in some populations, and may not be easily accessed in low-resource communities. Nevertheless, X- ray data from the metacarpal bones have been shown to be a significant predictor of fracture risk at the vertebrae and hip, and to correlate with DXA-determined BMD. Here, we propose development of an alternative approach for metacarpal assessment for bone health, near infrared (NIR) spectroscopy combined with a fiber optic probe. This is a non-invasive modality based on low energy non-ionizing radiation that can also yield molecular information related to the quality of material or tissue being evaluated. In the current proposal, NIR spectroscopic analysis of bone quality will be optimized in a multi-step approach. Specific optical properties of metacarpal bones and the overlying tissues will be obtained, and then used as input into Monte Carlo modeling of photon penetration through skin and bone. These data will then be used to inform and optimize the design of NIR fiber optic probes such that the spectral data collected preferentially comes from bone, as opposed to overlying tissues. Advancing NIR spectroscopy for clinical assessment of bone quality will require the careful development of application-specific probes and techniques for spectral analysis uniquely tailored for measurement of the metacarpal bone. Development of this modality could eventually lead to the development of straight-forward, cost effective approaches for community screening of bone health.