Abstract

Purpose

Alternating magnetic field (AMF) tissue interaction models are generally not validated. Our aim was to develop and validate a coupled electromagnetic and thermal model for estimating temperatures in large organs during magnetic nanoparticle hyperthermia (MNH).

Materials and methods

Coupled finite element electromagnetic and thermal model validation was performed by comparing the results to experimental data obtained from temperatures measured in homogeneous agar gel phantoms exposed to an AMF at fixed frequency (155 ± 10 kHz). The validated model was applied to a three-dimensional (3D) rabbit liver built from computed tomography (CT) images to investigate the contribution of nanoparticle heating and nonspecific eddy current heating as a function of AMF amplitude.

Results

Computed temperatures from the model were in excellent agreement with temperatures calculated using the analytical method (error < 1%) and temperatures measured in phantoms (maximum absolute error <2% at each probe location). The 3D rabbit liver model for a fixed concentration of 5 mg Fe/cm³ of tumor revealed a maximum temperature ∼44 °C in tumor and ∼40 °C in liver at AMF amplitude of ∼12 kA/m (peak).

Conclusion

A validated coupled electromagnetic and thermal model was developed to estimate temperatures due to eddy current heating in homogeneous tissue phantoms. The validated model was successfully used to analyze temperature distribution in complex rabbit liver tumor geometry during MNH. In future, model validation should be extended to heterogeneous tissue phantoms, and include heat sink effects from major blood vessels.

中文翻译：

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验证用于估计磁性纳米粒子热疗过程中温度的耦合电磁和热模型

摘要

目的

交变磁场 (AMF) 组织相互作用模型通常未经验证。我们的目标是开发并验证电磁和热耦合模型，用于估计磁性纳米粒子热疗 (MNH) 期间大型器官的温度。

材料和方法

通过将结果与在固定频率 (155 ± 10 kHz) 暴露于 AMF 的均质琼脂凝胶体模中测量的温度获得的实验数据进行比较，进行耦合有限元电磁和热模型验证。将经过验证的模型应用于根据计算机断层扫描 (CT) 图像构建的三维 (3D) 兔肝脏，以研究纳米颗粒加热和非特异性涡流加热作为 AMF 振幅函数的贡献。

结果

模型计算出的温度与使用分析方法计算的温度（误差 < 1%）以及模型中测量的温度（每个探头位置的最大绝对误差 < 2%）非常一致。肿瘤固定浓度为 5 mg Fe/cm ³的 3D 兔肝脏模型显示，肿瘤中的最高温度为 ∼44 °C，肝脏中的最高温度为 ∼40 °C，AMF 振幅为 ∼12 kA/m（峰值）。

结论

开发了经过验证的电磁和热耦合模型来估计均匀组织模型中涡流加热引起的温度。经过验证的模型成功用于分析 MNH 期间复杂的兔肝肿瘤几何形状的温度分布。未来，模型验证应扩展到异质组织模型，并包括主要血管的散热效应。