1.5 T下高介电材料几何结构对发射场影响的仿真研究

A Simulation Study on the Effect of the High Permittivity Materials Geometrical Structure on the Transmit Field B^(+)_(1) at 1.5 T

近年来研究发现,在高场及超高场磁共振成像(MRI)中,高介电材料在提高磁共振射频线圈性能,以及增强图像信噪比方面具有极大的应用潜力.当前高介电材料研究主要集中于其对磁共振图像信噪比的改善,但对于高介电材料几何结构,以及其对发射场分布均匀度影响的研究不多.本研究利用电磁仿真的方法定量分析了1.5 T下,高介电材料几何结构对水模感兴趣区内发射效率均值和发射场B^(+)_(1)均匀度的影响.结果表明,高介电材料的几何结构对B^(+)_(1)均匀度会产生较大影响;比较了不同几何结构的高介电衬垫之后发现,加入四等分圆筒状高介电衬垫后,感兴趣区内发射效率提升最高,同时B^(+)_(1)均匀度也保持良好.该结果对高介电材料应用于MRI具有重要的参考价值.

Recent studies show that high permittivity materials(HPMs)have great application prospects in improving the performance of RF coils and enhancing magnetic resonance image signal to noise ratio(SNR)in high and ultra-high field magnetic resonance imaging(MRI).So far the research about HPMs mainly focuses on its benefit for MRI image SNR,while investigation on how its geometrical structure affects the homogeneity of transmit field(B^(+)_(1))is insufficient.In this study the effect of the geometrical structure of HPMs on the average transmit efficiency and B^(+)_(1) inhomogeneity at 1.5 T was quantitatively analyzed through electromagnetic simulation.The results indicated that for the four investigated geometrical structures of HPMs the quartered cylinder is the optimum solution,which would be valuable for the application of HPMs in MRI.