Validation of a coupled electromagnetic and thermal model for estimating temperatures during magnetic nanoparticle hyperthermia

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.

Keywords:

• Hyperthermia
• magnetic nanoparticles
• eddy currents
• electromagnetic modeling
• bioheat transfer
• gel phantom
• verification and validation

Disclosure statement

R.I. and E.L. are inventors of nanoparticle patents. All patents are assigned to either the Johns Hopkins University or Aduro Biosciences, Inc. R.I. consults for Imagion Biosystems and Magnetic Insight and is a member of the Scientific Advisory Board of Imagion Biosystems. All other authors report no conflicts of interest. Additional financial support (A.A.) was provided by School of Science, Engineering, and Technology, the Pennsylvania State University – Harrisburg. The contents of this article is solely the responsibility of the authors and do not necessarily represent the official view of the Pennsylvania State University, Johns Hopkins University, JKTGF, NIH and other funding agencies.

Additional information

Funding

R.I. and E.L. received partial funding from the National Cancer Institute (5R01 CA194574-02). R.I received partial funding from the Jayne Koskinas and Ted Giovanis Foundation for Health and Policy (JKTGF). R.I. and A.A. received partial funding from the National Cancer Institute (5R01 CA247290).