Electrical properties tomography using contrast source inversion techniques

In this paper, we present an Electrical Properties Tomography (EPT) methodology based on integral (Green's tensor) representations for the electromagnetic field. Inhomogeneous tissue profiles can easily be incorporated in such an approach and the reconstruction method is less sensitive to noise compared with more standard differential based EPT methods since smoothing integral operators act on measured field data. To keep the computational bookkeeping to a minimum, we derive our basic EPT field representations for two-dimensional E-polarized radio frequency fields, which is a valid assumption in the midplane of a loaded birdcage coil. The extension to the fully three-dimensional case is briefly discussed and some initial 3D reconstructions are presented as well. Possible extensions and practical implementation issues are also discussed.