Background and objectives

Accurate and efficient prediction of soft tissue temperatures is essential to computer-assisted treatment systems for thermal ablation. It can be used to predict tissue temperatures and ablation volumes for personalised treatment planning and image-guided intervention. Numerically, it requires full nonlinear modelling of the coupled computational bioheat transfer and biomechanics, and efficient solution procedures; however, existing studies considered the bioheat analysis alone or the coupled linear analysis, without the fully coupled nonlinear analysis.

Methods

We present a coupled thermo-visco-hyperelastic finite element algorithm, based on finite-strain thermoelasticity and total Lagrangian explicit dynamics. It considers the coupled nonlinear analysis of (i) bioheat transfer under soft tissue deformations and (ii) soft tissue deformations due to thermal expansion/shrinkage. The presented method accounts for anisotropic, finite-strain, temperature-dependent, thermal, and viscoelastic behaviours of soft tissues, and it is implemented using GPU acceleration for real-time computation.

Results

The presented method can achieve thermo-visco-elastodynamic analysis of anisotropic soft tissues undergoing large deformations with high computational speeds in tetrahedral and hexahedral finite element meshes for surgical simulation of thermal ablation. We also demonstrate the translational benefits of the presented method for clinical applications using a simulation of thermal ablation in the liver.

Conclusion

The key advantage of the presented method is that it enables full nonlinear modelling of the anisotropic, finite-strain, temperature-dependent, thermal, and viscoelastic behaviours of soft tissues, instead of linear elastic, linear viscoelastic, and thermal-only modelling in the existing methods. It also provides high computational speeds for computer-assisted treatment systems towards enabling the operator to simulate thermal ablation accurately and visualise tissue temperatures and ablation zones immediately.

中文翻译：

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面向热消融治疗的软组织实时有限应变各向异性热粘弹性动力学分析

背景和目标

准确，有效地预测软组织温度对于计算机辅助热消融治疗系统至关重要。它可用于预测组织温度和消融量，以进行个性化的治疗计划和图像引导的干预。从数值上讲，它要求对计算的生物传热和生物力学耦合进行完全非线性建模，并需要有效的求解程序。但是，现有研究仅考虑生物热分析或耦合线性分析，而没有完全耦合非线性分析。

方法

基于有限应变热弹性和总拉格朗日显式动力学，我们提出了一种热粘粘超弹性有限元算法。它考虑了（i）软组织变形下的生物热传递和（ii）由于热膨胀/收缩引起的软组织变形的耦合非线性分析。提出的方法考虑了软组织的各向异性，有限应变，温度相关，热和粘弹性行为，并且使用GPU加速进行实时计算。

结果

所提出的方法可以实现各向异性软组织的热粘弹动力学分析，该各向异性软组织在四面体和六面体有限元网格中以较高的计算速度进行了较大的计算速度，以进行外科手术热消融模拟。我们还演示了使用肝脏热消融的模拟方法为临床应用提供的翻译优势。

结论

该方法的主要优点在于，它可以对软组织的各向异性，有限应变，温度相关，热和粘弹性行为进行完全非线性建模，而不是线性弹性，线性粘弹性和仅热建模。现有方法。它还为计算机辅助治疗系统提供了很高的计算速度，从而使操作员能够准确模拟热消融并立即可视化组织温度和消融区域。