In vivo optical biopsy of the calcaneous: a novel diagnostic tool for osteoporosis?

In vivo absorption and reduced scattering spectra of the human calcaneous from 650 up to 1000 nm were measured using a laboratory system for time-resolved reflectance and transmittance spectroscopy. Measurements were performed on the calcaneous of volunteers of ages ranging from 26 up to 82 y. Distinct spectral features were observed in the absorption spectrum in the region beyond 900 nm as a function of age. The analysis of the absorption spectra using a linear combination of the key tissue absorbers (bone minerals, water, lipids, oxy- and deoxy-hemoglobin) revealed a general decrease of bone density and increase of lipids with age. These findings suggest a possible use of optical biopsy for the diagnosis of osteoporosis.