A regularization-free elasticity reconstruction method for ultrasound elastography with freehand scan

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Computational Mechanics

Background:

• Ultrasound elastography requires regularization and boundary conditions for tissue elasticity reconstruction (e.g., Young's modulus).
• Choosing regularization parameters and obtaining in vivo boundary conditions are significant practical challenges.

Purpose of the Study:

• To develop a more applicable ultrasound elastography algorithm.
• To eliminate the need for regularization and boundary force/displacement information in elasticity reconstruction.

Main Methods:

• Utilized bicubic B-spline for tissue displacement field estimation.
• Employed a finite element inversion scheme with a modulus boundary condition to reconstruct Young's modulus.
• Validated the method through simulations and experiments on tissue-mimicking phantoms.

Main Results:

• Achieved high accuracy in Young's modulus reconstruction with low relative error (-3.43 ± 0.43%) and root-squared-mean error (16.94 ± 0.25%) in simulations.
• Significantly reduced hardening artifacts in Young's modulus images compared to strain images.
• Accurately depicted inclusion size and position in both simulated and experimental phantom studies.

Conclusions:

• The developed method accurately reconstructs tissue Young's modulus, reducing artifacts and improving delineation of inclusions.
• Eliminates the need for regularization and measurement of boundary conditions, simplifying clinical use.
• Facilitates freehand scanning, enhancing its applicability in clinical settings.