POLYMER-BASED, MR INVISIBLE, AND STRETCHABLE DIELECTRIC PADS FOR CLINICAL MRI AT 3 T

<p dir="ltr">The objective of the thesis is to develop new formulations for silicone-based MRI dielectric pads viable for in vivo use at 3 T. The purpose was to provide alternatives to current dielectric pads, resolving potential leakage issues and improving subject conformity. All dielectric pads in this study are silicone-based, as opposed to slurry- or aqueous-based pads. Dielectric pads containing CuSO₄ and BaTiO₃ are evaluated against SiC-based dielectric pads, silicone-only negative controls, and phantom only to assess imaging capabilities. Two types of tests were done to evaluate the performance of the dielectric pads, dielectric characterization and MRI experiments. Dielectric characterization was done to determine the dielectric constant for each pad. Phantom imaging quantified the effects on B₀ and B₁⁺ field homogeneity, T₁, T₂, T₂^* relaxation times, and SNR increases using GRE and SE scan sequences. In vivo imaging quantified the SNR improvements in tissue imaging. In phantom imaging, CuSO₄ with BaTiO₃ formulations had superior MR invisibility compared to other formulations tested but introduced B₀ field inhomogeneities. With higher BaTiO₃ concentrations in the formulation, better SNR increases were observed in silico, while in vivo imaging showed clear improvements for 10% BaTiO₃-containing dielectric pad. Further research into the effects of material-to-powder concentrations is needed to examine how MR invisibility is affected. However, paramagnetic and diamagnetic material inclusion into silicone-based dielectric pads improved MR invisibility, SNR and preserves stretchability of silicone.</p>