Zhang Jinao, Lay Remi Jacob, Roberts Stuart K, Chauhan Sunita
Department of Mechanical and Aerospace Engineering, Monash University, Clayton, Victoria, Australia.
Department of Mechanical and Aerospace Engineering, Monash University, Clayton, Victoria, Australia.
Comput Methods Programs Biomed. 2021 Jan;198:105789. doi: 10.1016/j.cmpb.2020.105789. Epub 2020 Oct 8.
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.
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.
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.
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.
准确高效地预测软组织温度对于热消融计算机辅助治疗系统至关重要。它可用于预测组织温度和消融体积，以进行个性化治疗规划和图像引导干预。在数值计算方面，这需要对耦合的计算生物热传递和生物力学进行完全非线性建模以及高效的求解过程；然而，现有研究仅考虑了生物热分析或耦合线性分析，未进行完全耦合的非线性分析。
我们基于有限应变热弹性和总拉格朗日显式动力学，提出了一种耦合热粘超弹性有限元算法。它考虑了以下两方面的耦合非线性分析：（i）软组织变形下的生物热传递；（ii）热膨胀/收缩引起的软组织变形。所提出的方法考虑了软组织的各向异性、有限应变、温度依赖性、热学和粘弹性行为，并通过GPU加速实现实时计算。
所提出的方法能够在四面体和六面体有限元网格中，以高计算速度对经历大变形的各向异性软组织进行热粘弹性动力学分析，用于热消融手术模拟。我们还通过肝脏热消融模拟展示了该方法在临床应用中的转化优势。
所提出方法的关键优势在于，它能够对软组织的各向异性、有限应变、温度依赖性、热学和粘弹性行为进行完全非线性建模，而不是像现有方法那样进行线弹性、线性粘弹性和仅热学建模。它还为计算机辅助治疗系统提供了高计算速度，使操作人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。
