CSI-EPT: A novel contrast source approach to MRI based electric properties tomography and patient-specific SAR

In this paper, we present a novel method (Contrast Source Inversion - Electric Properties Tomography or CSI-EPT) to dielectric imaging of biological tissue using so-called B₁⁺ data measurable by Magnetic Resonance Imaging (MRI) systems. Integral representations for the electromagnetic field quantities are taken as a starting point and we follow an iterative contrast source inversion approach to retrieve the dielectric tissue parameters from measured field data. Numerical results illustrate the performance of the method and show that reliable results are produced near tissue boundaries as opposed to the currently used methods. Fine structures can be resolved as well and since CSI-EPT reconstructs the electric field strength inside a scanning region of interest, it is also a promising candidate to determine the patient-specific SAR deposition during an MRI scan.