Assessment of cortical bone microstructure and material properties using high resolution scanning acoustic microscopy

Combined evaluation of bone microstructural and mechanical information remains a challenging task which is required for bone phenotyping or accurate finite element modeling. Our objective was to assess the value of quantitative scanning acoustic microscopy (SAM) for bone characterization in comparison to synchrotron radiation computed tomography (SR-CT). Ten specimens of human cortical bone (radius) were investigated using SR-CT and SAM (200 MHz) with spatial resolution of 10 and 8 μm, respectively. An image fusion and analysis software was developed to derive site-matched estimates of (1) microstructural parameters, e.g., haversian cavity density and mean diameter and porosity, and (2) tissue properties such as mineral density (MD, SR-CT) and acoustic impedance (Z, SAM) for distinct anatomical regions of interest (osteons, interstitial tissue). Local stiffness c33 was derived from the combination of MD and Z. An almost perfect correlation was found for all microstructural indices derived by both techniques. Impedance was correlated to the square of MD (R2=0.39, p