Photoacoustic measurement of bone health: A study for clinical feasibility

In this work, the feasibility of photoacoustic PA imaging and characterization of bone was investigated. Through the experiments on ex vivo bovine femur heads, the optical and ultrasonic penetrations in bone which determines the PA detection depth were investigated. Then, the feasibility of performing photoacoustic imaging of bone via the raster scan of a focused transducer was explored. The images from bovine ribs before and after treatment using ethylenediaminetetraacetic acid (EDTA) demonstrate that PA image can reflect the changes in bone microstructure as results of the treatment. By performing PA spectral analysis (PASA), bone micro-features can be quantitatively assessed, and bone specimens before and after EDTA treatment can be differentiated. Moreover, the feasibility of assessing the chemical changes in bone specimens by using multi-wavelength PA (MWPA) measurement and spectral unmixing method was also evaluated. The results quantified from PA measurements verified the decreased mineral and blood contents in trabecular bone after the EDTA treatment. This study on bovine bones with sizes comparable to human bones suggests that PA techniques could contribute to clinical management of osteoporosis and other bone diseases.