Quantum-Enhanced Hyperpolarized Low Field MRI for Mapping Microwave Absorption in Biological Systems

Radiation from cell phones and cellular devices is ubiquitous and, in the microwave frequency bands used, human tissue is a highly absorbing complex electromagnetic material. Here, we present a method to directly image microwave electromagnetic fields from cellular devices in tissue mimics using hyperpolarized low-field Magnetic Resonance Imaging (MRI). Resonant absorption of microwave radiation in free radicals transfers polarization to the water proton system and, at cell phone power levels, can not only be detected, but can increase the signal over the native low-field MRI signal. Direct imaging and quantification provide a better understanding of how cellular radiation penetrates and is absorbed in complex materials, such as tissues, and allows validation of numerical models. We further demonstrate the use of this technique to image microwave field distortion and reradiation around implants and foreign objects as well as in complex dielectric structures such as cancellous bone. The current implementation uses polarization transfer through a 3-spin system. We evaluate the potential of quantum engineering to increase the sensitivity of this effect and predict more effective free radicals and spin-transfer chemistries.