Evaluation of High Impedance Surfaces for MRI RF Coil Applications ­ Simulations of RF Field and Specific Absorption Rate

This paper investigates the use of High Impedance Surfaces (HIS) to enhance the magnetic near-field within a dielectric phantom stimulated by a surface coil antenna resonating at 63.8 MHz for use in Magnetic Resonance Imaging (MRI) systems. Specifically, the optimization of the space between the surface of the coil and the HIS is presented here. The HIS incorporates interdigitated capacitive elements that produce an electrically small unit cell size. The magnetic field strength is shown to be improved by 42% as compared to a system which uses only an RF shield The associated Specific Absorption Rate (SAR) for the optimum design is simulated and compared to international standards. The work is aimed at 1.5T MRI applications.