A novel method for flexible distributed capacitance coil simulation in MR imaging

Current radio frequency (RF) surface coils are made of rigid or semi-flexible materials with limited bending properties. Flexible RF coils are not only more ergonomic, but they also offer another opportunity to increase the signal-to-noise ratio, which is a fundamental limiting factor in magnetic resonance imaging (MRI) quality. Electromagnetic (EM) simulation is important for the design and performance evaluation of MR RF coils. However, EM simulation is often time-consuming due to the large number of mesh cells and complex calculations required for dimension modeling of the flexible distributed capacitance coils with lesser dielectric substrate thickness. To improve the simulation efficiency, a novel method was proposed whereby the dielectric thickness and dielectric constant were simultaneously increased, which allows to reduce the number of mesh cells while maintain the accuracy of the simulation. The performance was validated through a comparison with the actual dimension simulation approach. The results demonstrate that the proposed method saves approximately 78% on both one simulation time and the total simulation time, whereas the variations of simulation results of both EM fields and specific absorption rate (SAR) are less than 7%. The feasibility of the proposed novel method was validated through the performance of the distributed capacitance coil prototype in phantom studies.