Sensitivity of microwave ablation models to tissue biophysical properties: A first step toward probabilistic modeling and treatment planning
Sensitivity of microwave ablation models to tissue biophysical properties: A first step toward probabilistic modeling and treatment planning
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DOI：
10.1118/1.4947482
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发表时间：
2016-05-01
期刊：
影响因子：
3.8
通讯作者：
Prakash, Punit
中科院分区：
文献类型：
--
作者：
Sebek, Jan;Albin, Nathan;Prakash, Punit
目的：微波消融（MWA）的计算模型在新型器械的设计优化过程中被广泛使用，并且正在考虑用于患者特定的治疗计划。本研究的目的是评估的灵敏度的计算模型MWA组织biophysical properties.Methods：莫里斯方法被用来评估的耦合电磁-热模型，这是实现与有限元法（FEM）的全局灵敏度。有限元模型纳入温度依赖性的组织物理特性。使用六种不同的输出来表征消融区的尺寸和形状以及消融水循环微波消融针的阻抗匹配，研究了模型的可变性。此外，对灵敏度结果进行统计分析，并量化每个输入参数的绝对影响。一个框架，系统地将模型的不确定性治疗planning.Results：共1221模拟，纳入111个随机抽样的起点，进行了建议。组织介电参数，特别是相对介电常数、有效电导率和它们转变为较低值时的阈值温度（即，表示干燥）被确定为消融区形状和天线阻抗匹配的最有影响的参数。在本研究中考虑的热参数中，标称血液灌注率和组织变化阶段的温度间隔被认为是最有影响力的。组织水汽化的潜热和汽化组织的体积热容被认为是影响最小的参数。基于绝对变化的评价，最重要的参数（灌注）对消融面积的影响比最不重要的参数（汽化组织的体积热容）大约40.23倍。另一个重要的输入参数（介电常数）有22.26倍以上的影响消融边缘形状从一个球体的偏差比一个不太重要的参数（潜热肝组织汽化）。结论：介电参数，血液灌注率，和温度间隔，组织变化阶段被发现有最显着的影响MWA模型输出。组织水汽化的潜热和汽化组织的体积热容被认为是影响最小的参数。本研究中确定的模型输出中的非线性可被纳入，以提供患者特定治疗计划的预期消融结局的概率图。(C)2016年美国医学物理学家协会。
Purpose: Computational models of microwave ablation (MWA) are widely used during the design optimization of novel devices and are under consideration for patient-specific treatment planning. The objective of this study was to assess the sensitivity of computational models of MWA to tissue biophysical properties.Methods: The Morris method was employed to assess the global sensitivity of the coupled electromagnetic-thermal model, which was implemented with the finite element method (FEM). The FEM model incorporated temperature dependencies of tissue physical properties. The variability of the model was studied using six different outputs to characterize the size and shape of the ablation zone, as well as impedance matching of the ablation antenna. Furthermore, the sensitivity results were statistically analyzed and absolute influence of each input parameter was quantified. A framework for systematically incorporating model uncertainties for treatment planning was suggested.Results: A total of 1221 simulations, incorporating 111 randomly sampled starting points, were performed. Tissue dielectric parameters, specifically relative permittivity, effective conductivity, and the threshold temperature at which they transitioned to lower values (i.e., signifying desiccation), were identified as the most influential parameters for the shape of the ablation zone and antenna impedance matching. Of the thermal parameters considered in this study, the nominal blood perfusion rate and the temperature interval across which the tissue changes phase were identified as the most influential. The latent heat of tissue water vaporization and the volumetric heat capacity of the vaporized tissue were recognized as the least influential parameters. Based on the evaluation of absolute changes, the most important parameter (perfusion) had approximately 40.23 times greater influence on ablation area than the least important parameter (volumetric heat capacity of vaporized tissue). Another significant input parameter (permittivity) had 22.26 times higher influence on the deviation of ablation edge shape from a sphere than one of the less important parameters (latent heat of liver tissue vaporization).Conclusions: Dielectric parameters, blood perfusion rate, and the temperature interval across which the tissue changes phase were found to have the most significant impact on MWA model outputs. The latent heat of tissue water vaporization and the volumetric heat capacity of the vaporized tissue were recognized as the least influential parameters. Uncertainties in model outputs identified in this study can be incorporated to provide probabilistic maps of expected ablation outcome for patient-specific treatment planning. (C) 2016 American Association of Physicists in Medicine.