Determination of the Optimum Permittivity of High-Permittivity Pads when Dipoles are Used as Transmit Coils for the Chest

High-Permittivity Materials are often used to manipulate the radiofrequency field B1. Optimization of the permittivity depends on the geometry of the pad, of the subject and of the coil. In this work we determine the permittivity of two pads positioned around the torso, having thickness 1.5 cm and 3 cm, when a dipole array is used to provide the highest transmit efficiency in the heart. The pads provide an improvement of the transmit efficiency of 9.5% and 7.6% for the 1.5 cm and 3cm case respectively, while providing a SAR reduction of 20.2% and 12.5%.