Numerical simulation of the dependence of quantitative ultrasonic parameters on trabecular bone microarchitecture and elastic constants

Finite- difference numerical simulation of ultrasound propagation in complex media such as cancellous bone represents a fertile to analytical approaches because it can manage the complex 3D bone structure by coupling the numerical computation 3D numerical models of bone microarchitecture obtained from high- resolution imaging modalities. The objective of this work to assess in silico the sensitivity of ultrasound parameters to controlled changes of microarchitecture and variation of elastic The simulation software uses a finite- difference approach based on the Virieux numerical scheme. An incident plane wave propagated through a volume of bone of approximately 5 x 5 x 8 mm(3). The volumes were reconstructed from high- resolution computed tomography data. An iterative numerical scenario of `` virtual osteoporosis'' was implemented using a dedicated processing algorithm in order to modify the initial 3D microstructures. Numerical computations of wave propagation were at each step of the process. The sensitivity to bone material properties was also tested by changing the elastic constants bone tissue. Our results suggest that ultrasonic variables ( slope of the frequency- dependent attenuation coefficient and speed of are mostly influenced by bone volume fraction. However, material properties and structure also appear to play a role. impact of modifications of the stiffness coefficients remained lower than the variability caused by structural variations. This emphasizes the potential of numerical computations tools coupled to realistic 3D structures to elucidate the physical mechanisms of interaction between ultrasound and bone structure and to assess the sensitivity of ultrasound variables to different bone properties. (c) 2006 Elsevier B. V. All rights reserved.