Simultaneous estimation of cortical bone thickness and acoustic wave velocity using a multivariable optimization...

Area of Science:

• Biomedical Engineering
• Materials Science
• Medical Imaging

Background:

• Accurate characterization of bone properties is crucial for diagnosing and monitoring skeletal diseases.
• Existing methods for measuring bone thickness and acoustic properties can be limited in precision or scope.
• Ultrasound techniques offer non-invasive potential for bone assessment.

Purpose of the Study:

• To develop and validate a simultaneous method for determining compact bone layer thickness and longitudinal wave velocity using reflected ultrasound waves.
• To address challenges in measuring thin bone layers where wave propagation time is shorter than the pulse duration.
• To establish a robust computational model for accurate acoustic echo simulation.

Main Methods:

• A "soft tissue - compact bone layer - cancellous bone" model was developed for echo-simulations.
• The method involves fitting the temporal spectrum of simulated reflected waves to experimentally measured spectra.
• A cost function based on least square error and a simulated annealing algorithm were used for parameter optimization.

Main Results:

• The method successfully estimated bone thickness and acoustic wave velocity in both a bone phantom and a calf femur.
• For the calf femur, relative errors for thickness ranged from 0.4% to 5.5%, and velocity error was 3.1%.
• For artificial bone, thickness errors ranged from 1.9% to 10.8%, and velocity errors ranged from 3.9% to 4.5%.

Conclusions:

• The proposed ultrasound method enables simultaneous and accurate determination of compact bone layer thickness and longitudinal wave velocity.
• The technique is effective even for thin bone layers and demonstrates good accuracy in experimental validations.
• This approach holds promise for improved non-invasive bone assessment in clinical and research settings.