Mechanical properties of brain tissue in-vivo: experiment and computer simulation
Mechanical properties of brain tissue in-vivo: experiment and computer simulation
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DOI：
10.1016/s0021-9290(00)00120-2
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发表时间：
2000-11-01
影响因子：
2.4
通讯作者：
Bednarz, P
中科院分区：
文献类型：
--
作者：
Miller, K;Chinzei, K;Bednarz, P
神经外科手术的真实计算机模拟需要将脑组织的机械特性纳入到数学模型中。神经外科计算机模拟的可能应用包括非刚性配准、虚拟现实训练和手术规划系统以及执行微创脑外科手术的机器人设备。近年来，已经提出了许多脑组织的本构模型，包括单相和双相。然而，它们中的大多数的主要缺陷是它们是使用体外获得的实验数据来鉴定的，并且不确定它们是否可以应用于现实的体内环境。在本文中，我们试图证明我们以前提出的脑组织超粘弹性本构模型可以应用于模拟手术过程。描述了一种体内压痕实验。外科手术中典型的加载速度的力-位移曲线是向上凹陷的，其中不包含可用于确定有意义的弹性模数的线性部分。为了正确分析实验数据，建立了脑的三维非线性有限元模型。磁共振成像技术被用来获得模型所需的几何信息。用数值解得到的力-位移曲线形状与实验值非常相似。预测力比实验期间记录的力低约31%。考虑到模型中的系数是基于体外获得的实验数据确定的，并且生物组织的机械特性具有很大的变异性，这种一致性可以被认为是非常好的。通过适当增加描述组织瞬时硬度的材料参数，可以在不改变模型结构的情况下，几乎完美地再现实验曲线。数值研究还表明，即使在中等应变情况下，脑组织的线性粘弹性模型也不适合模拟脑组织的变形。(C)2000爱思唯尔科学有限公司。保留所有权利。
Realistic computer simulation of neurosurgical procedures requires incorporation of the mechanical properties of brain tissue in the mathematical model. Possible applications of computer simulation of neurosurgery include non-rigid registration, virtual reality training and operation planning systems and robotic devices to perform minimally invasive brain surgery. A number of constitutive models of brain tissue, both single-phase and bi-phasic, have been proposed in recent years. The major deficiency of most of them, however, is the fact that they were identified using experimental data obtained in vitro and there is no certainty whether they can be applied in the realistic in vivo setting. In this paper we attempt to show that previously proposed by us hyper-viscoelastic constitutive model of brain tissue can be applied to simulating surgical procedures. An in vivo indentation experiment is described. The force-displacement curve for the loading speed typical for surgical procedures is concave upward containing no linear portion from which a meaningful elastic modulus might be determined. In order to properly analyse experimental data, a three-dimensional, non-linear finite element model of the brain was developed. Magnetic resonance imaging techniques were used to obtain geometric information needed for the model. The shape of the force-displacement curve obtained using the numerical solution was very similar to the experimental one. The predicted forces were about 31% lower than those recorded during the experiment. Having in mind that the coefficients in the model had been identified based on experimental data obtained in vitro, and large variability of mechanical properties of biological tissues, such agreement can be considered as very good. By appropriately increasing material parameters describing instantaneous stiffness of the tissue one is able, without changing the structure of the model, to reproduce experimental curve almost perfectly. Numerical studies showed also that the linear, viscoelastic model of brain tissue is not appropriate for the modelling brain tissue deformation even for moderate strains. (C) 2000 Elsevier Science Ltd. All rights reserved.