Development and validation of a viscoelastic and nonlinear liver model for needle insertion

Area of Science:

• Biomedical Engineering
• Medical Simulation
• Surgical Robotics

Background:

• Accurate organ modeling is crucial for developing effective surgical tools and training simulators.
• Existing models often lack the fidelity to capture complex tissue behaviors like viscoelasticity and nonlinearity.

Purpose of the Study:

• To develop and validate a viscoelastic and nonlinear physical liver model.
• To enable organ model-based needle insertion planning by predicting deformation.
• To determine optimal needle paths considering organ dynamics.

Main Methods:

• Modeled liver material properties using viscoelastic and nonlinear characteristics based on pig liver data.
• Developed the liver model using Finite Element Method (FEM).
• Validated the model through comparative in vitro and in vivo experiments using pig livers.

Main Results:

• The model accurately reproduced nonlinear and viscoelastic displacement responses in vitro (error < 1 mm for forces up to 0.45 N).
• The model demonstrated high fidelity in simulating the nonlinear load increase during in vivo needle insertion.
• Validation confirmed the model's ability to replicate physical liver responses.

Conclusions:

• The developed physical liver model effectively captures complex liver mechanics.
• The model is validated for both in vitro and in vivo conditions.
• This tool enhances the potential for realistic surgical simulations and planning.