Optimizing nanoparticle selection and drive field properties for simultaneous MPI and hyperthermia

Abstract

Among the various hyperthermia therapies, Magnetic Fluid Hyperthermia (MFH) using superparamagnetic iron oxide SPIOs has gained interest due to its ability to potentially target and provide a localized heating of the cancerous tissue. In MFH, SPIOs injected into the specific tumor site or functionalized to target the cancerous tissue are heated up by application of an alternating magnetic field. However, injected SPIOs may diffuse to the nearby healthy tissue or may not target the cancerous tissue with 100% efficiency, which in turn cause unwanted heating of the healthy tissue. A recently proposed focused hyperthermia technique spatially limits the heating by utilizing a field free region together with the alternating field [1]. This setup is almost identical to that of a Magnetic Particle Imaging (MPI) scanner: the focused hyperthermia setup employs a strong static magnetic field gradient to saturate all SPIOs outside of a small field free region. Upon applying a time varying excitation field, only the nanoparticles at this field free region react and heat up. Given that these concepts are essentially the same as the field free point (FFP) and drive field used in MPI [2-4], focused hyperthermia and MPI can be performed simultaneously on the same setup.