Coupled electromagnetic–thermal modeling of ferromagnetic implants in porous tissue for hyperthermia

Ferromagnetic implant hyperthermia (FIH) involves heat generation from metallic implants via eddy-current and magnetic hysteresis losses. Conventional Pennes-based models neglect convective transport in porous tissue, limiting accuracy near implants. This work develops an experimentally validated electromagnetic–thermal framework that incorporates both Pennes and porous-media formulations to examine implant-mediated heating. The porous-media model shows improved agreement with liver-phantom experiments, particularly in the transient regime, due to explicit treatment of interstitial convection. A key finding is that heating increases with magnetic flux density and implant diameter but exhibits a peak at a critical implant size, beyond which thermal dissipation dominates and restricts further temperature rise. This nonlinear transition arises from the competition between eddy-current power deposition and conduction–convection heat losses in surrounding tissue. Tissue porosity further modulates these trends by enhancing convective spreading of thermal energy. These results identify field strength, implant geometry, and tissue microstructure as governing parameters for controlled and predictable implant-based hyperthermia. The validated framework provides a physically grounded basis for optimizing implant design and magnetic-field excitation in pre-clinical FIH treatment planning and device design.