A Novel Theranostic Platform: Integration of Magnetomotive and Thermal Ultrasound Imaging With Magnetic Hyperthermia.

OBJECTIVE

Nanotheranostic systems integrate therapeutic and diagnostic procedures using nanotechnology. This type of approach has enabled the development of methods for early detection and treatment of different pathologies. Magnetic hyperthermia (MH) has been proposed as an alternative or complementary method of cancer therapy. However, challenges such as delivering and localizing the magnetic nanoparticles (MNPs) within tissues and monitoring the temperature during the treatment hinder this technique to be effectively translated into a clinical routine. Therefore, in this study a theranostic platform has been proposed and examined to address two main issues, localizing MNPs and real-time temperature monitoring, for preclinical MH.

METHODS

The system integrates magnetomotive (MMUS) and thermal ultrasound imaging with MH. An ultrasound device was used to acquire MMUS images to detect MNPs, and ultrasound thermometry to monitor the temperature. This platform was designed such that a single coil generated the magnetic field for MMUS and MH. The feasibility of the system was examined using a tissue mimicking phantom containing an inclusion filled with zinc substituted magnetite NPs.

RESULTS

These MNPs were effectively used as contrast agent for MMUS and to generate heat during MH. In addition to localizing MNPs, real-time two-dimensional temperature maps were obtained with substantial concordance (ρ > 0.97) with invasive measurements using fiber optic thermometer. The heating rate was proportional to the displacements in MMUS (r = 0.92).

CONCLUSION

Ultrasound thermometry was successfully used to monitor the temperature during MH. In addition, it was shown that acquiring MMUS images prior to MH can qualitatively predict the temperature distribution of the MNP-laden regions.