Theranostic systems, the fusion of diagnostic and therapeutic procedure in a single platform, have shown a great potential to improve the efficiency of cancer treatment. Particularly, nanotheranostics is an attractive theranostic approach which benefits of nanotechnology.
This paper describes the development of a novel theranostic system wherein a single coil was used to apply two different magnetic fields used for magnetic hyperthermia (therapy) and magnetomotive ultrasound imaging (diagnostics). This integrated system is proposed to address two of the main challenges that hinder magnetic hyperthermia to be translated into a clinical routine: localizing the magnetic nanoparticles (magnetomotive ultrasound) and real-time temperature monitoring (ultrasound thermometry). Both imaging techniques can be obtained using the same ultrasound imaging device. Since the spatial profiles of the magnetic fields are the same, it was verified that the temperature rise within the regions containing the magnetic nanoparticles was proportional to the induced displacements observed in the magnetomotive ultrasound images. Therefore, acquiring magnetomotive images prior to hyperthermia can be a useful tool to qualitatively predict the temperature distribution of the magnetic nanoparticle-laden regions. In addition, to our knowledge, this is the first study on the use of ultrasound thermometry as a non-invasive and real-time method during magnetic hyperthermia. Unlike other non-invasive methods which provide superficial temperature maps, this method can provide a two-dimensional temperature map during magnetic hyperthermia for any depth within the limitation of the ultrasound images.
Finally, the zinc substituted magnetite nanoparticle used in this study was effective as contrast agent for magnetomotive ultrasound and to generate heat during magnetic hyperthermia. Therefore, we believe this paper can open up a new horizon in magnetic hyperthermia, where planning, treating, and monitoring can be achieved through a single nanotheranostic agent and a cost-effective, portable, real-time and clinically available imaging device that uses non-ionizing radiation.