Magnetic hyperthermia in tissue-like media: Finite element simulation, experimental validation, parametric variations, and calibration studies

Abstract

We report the experimental characterization and finite element modeling of magnetic fluid hyperthermia (MFH) in tissue-like media using tetramethyl ammonium hydroxide coated superparamagnetic iron oxide magnetic nanoparticles (MNPs) of size ∼19.6 ± 1.2 nm, prepared using a co-precipitation technique. MFH properties are probed for the MNPs in ∼1 wt. % agar, resembling the tumor and surrounding normal tissues. The field-induced temperature rise (ΔT) is experimentally measured in real-time utilizing an infrared camera. A finite element model (FEM) is utilized to simulate the spatiotemporal variations in the thermal profiles, which are found to be in good agreement with the experimental data. FEM-based parametric studies reveal that the thermal conductivity of the medium is the most significant parameter influencing the thermal profiles. The spatiotemporal variations in the thermal profiles are numerically studied for seven different tissues, and the obtained results indicate the highest ΔT for the breast tissue in the tumor and the surrounding regions, which is due to the lowest volumetric specific heat and the highest thermal conductivity of the breast tissue, respectively. Numerical studies on the thermal profiles for sub-surface tumors with parametrically varying depths indicate a strong exponential correlation between the surface and tumor temperature, where the regression coefficients are found to be correlated with the thermo-physical properties of the tissues. The obtained findings are beneficial for developing a simplistic and easily deployable framework for a priori generation of the thermal profiles for various tissues during MFH, which is useful for appropriate planning and parameter selection for MFH-based therapy.