HYPER: pre-clinical device for spatially-confined magnetic particle hyperthermia

Abstract

Purpose

Magnetic particle hyperthermia is an approved cancer treatment that harnesses thermal energy generated by magnetic nanoparticles when they are exposed to an alternating magnetic field (AMF). Thermal stress is either directly cytotoxic or increases the susceptibility of cancer cells to standard therapies, such as radiation. As with other thermal therapies, the challenge with nanoparticle hyperthermia is controlling energy delivery. Here, we describe the design and implementation of a prototype pre-clinical device, called HYPER, that achieves spatially confined nanoparticle heating within a user-selected volume and location.

Design

Spatial control of nanoparticle heating was achieved by placing an AMF generating coil (340 kHz, 0–15 mT), between two opposing permanent magnets. The relative positions between the magnets determined the magnetic field gradient (0.7 T/m–2.3 T/m), which in turn governed the volume of the field free region (FFR) between them (0.8–35 cm³). Both the gradient value and position of the FFR within the AMF ([−14, 14]_x, [−18, 18]_y, [−30, 30]_z) mm are values selected by the user via the graphical user interface (GUI). The software then controls linear actuators that move the static magnets to adjust the position of the FFR in 3D space based on user input. Within the FFR, the nanoparticles generate hysteresis heating; however, outside the FFR where the static field is non-negligible, the nanoparticles are unable to generate hysteresis loss power.

Verification

We verified the performance of the HYPER to design specifications by independently heating two nanoparticle-rich areas of a phantom placed within the volume occupied by the AMF heating coil.

Keywords:

• Magnetic particle hyperthermia
• spatially confined heating
• design verification

Disclosure statement

P.G. is a stockholder and the CEO/CTO of Magnetic Insight, a company that develops and manufactures MPI scanners and MPI/MFH combination devices. R.I. is an inventor listed on several nanoparticle patents. All patents are assigned to either The Johns Hopkins University or Aduro Biosciences, Inc. R.I. is a member of the Scientific Advisory Board of Imagion Biosystems. All other authors report no other conflicts of interest.

Data availability statement

The data that support the findings of this study are available from the corresponding author, H.C., upon reasonable request.

Additional information

Funding

Funding for the experimental portion of this project was provided by the National Cancer Institute 1R01 CA257557, 1R01 CA247290, and 1R44 CA285064-01. The contents of this paper are solely the responsibility of the authors and do not necessarily represent the official view of Johns Hopkins University, or the NIH.