Magnetic nanoparticles that are responsive to clinically safe magnetic fields offer multi-modal nanomedicine capabilities. To succeed, complexities of physics and engineering must be addressed to match physical and magnetic properties of magnetic nanoparticles with devices used to activate them. This requires thoughtful design and fabrication of both nanoparticles and devices, with appropriate testing in relevant biological models that faithfully represent intended end use. Hyperthermia is a heat-based cancer therapy that improves treatment outcomes and patient survival when controlled energy delivery is combined with accurate thermometry. To date, few technologies have achieved the needed evolution for the demands of the clinic. Magnetic fluid hyperthermia (MFH) offers this potential, but to be successful it requires particle-imaging technology that provides real-time thermometry. Presently, the only technology having the potential to meet these requirements is magnetic particle imaging (MPI), for which a proof-of-principle demonstration with MFH has been achieved. Successful clinical translation and adoption of integrated MPI/MFH technology demands successful integration of imaging data processing with robust computational heat-transfer modeling and adaptive temperature control algorithms into a theranostic device platform.