Prediction of backscatter coefficient in trabecular bones using a numerical model of three-dimensional microstructure

Area of Science:

• Biomedical Engineering
• Materials Science
• Acoustics

Background:

• Cancellous bone's complex microarchitecture affects ultrasound propagation.
• Understanding ultrasonic backscattering is crucial for bone characterization.

Purpose of the Study:

• To develop and validate a model for ultrasonic backscattering in water-saturated cancellous bone.
• To assess the suitability of a weak scattering medium model for trabecular bone.

Main Methods:

• A theoretical model relating backscatter coefficient to bone microarchitecture's spatial Fourier transform.
• Utilizing 3D numerical images of bone microarchitecture from tomographic reconstructions (10 µm resolution).
• Comparing model predictions with experimental data from 19 bone specimens.

Main Results:

• The model accurately predicts the frequency dependence and magnitude of the backscatter coefficient.
• Experimental validation showed an average accuracy error of approximately 1 dB.
• The model demonstrated robustness, with errors up to 2.2 dB even with inaccurate material property inputs.

Conclusions:

• The proposed model provides accurate predictions for ultrasonic backscattering in cancellous bone.
• Cancellous bone can be effectively described as a weak scattering medium within the 0.4-1.2 MHz frequency range.
• The model's accuracy is minimally affected by variations in bone material properties, though precise human trabecular bone characteristics require further determination.