Uniformity Using Segmented Dielectric Pads

INTRODUCTION: It has been shown that high-permittivity dielectric pads can be used to efficiently improve the field homogeneity in the region of interest (ROI) in high-field MRI [1-8]. Recent studies focused on the design of these pads by controlling parameters such as size, position and permittivity, using simple patient specific parameter sweeping to improve the transmit field in a small region. In most cases, two pads with identical permittivities are placed on the opposite sides of the ROI (left/right for brain imaging, front/back for chest imaging). In these cases, the dimensions of the pads are similar to that of the ROI [1-4]. In this study, we analyse the fundamental behaviour of the dielectric pads and demonstrate how segmenting bigger pads into smaller ones with different permittivities can significantly improve the dielectric shimming.