Radio Frequency Coil Design for Ultra High Field MRI

射频（RF）线圈是磁共振成像（MRI）系统的重要组成部分。由于在高磁场（>= 3t）下人体中的射频场/组织相互作用，头部大小的体积线圈的传输剖面显示出一种独特的模式，在大脑中心具有相对较强的射频磁场B(1+)，这种中心增亮效应可以影响图像或光谱的定量和定性方面。更令人不安的是，由于组织-B（1+）场相互作用带来的均匀性，在整个感兴趣的体积中发现了建设性和破坏性的B（1+）模式。我们研究计划的目标是设计射频线圈组件，以最大限度地减少人类受试者在7 T时的发射（B1+）和接收（B1-）场RF的均匀性。

Radio Frequency (RF) coils are an essential component of magnetic resonance imaging (MRI) systems. Due to RF field/tissue interactions in the human body at high magnetic fields (>= 3 T) the transmit profile from head-sized volume coils shows a distinctive pattern with a relatively strong RF magnetic field B(1+) in the center of the brain, This centre brightening effect can affect both quantitative and qualitative aspects of the image or spectrum. Even more troubling, constructive and destructive B(1+) patterns are found throughout the volume of interest due to the in homogeneities brought about by tissue-B(1+) field interaction The objective of our research program is to design RF coil assemblies that minimize the transmit (B1+) and receive (B1-) field RF in homogeneities at 7 T in human subjects. Our MRI system is probably the most advanced configuration of transmit and receive channels in the world which makes us we well positioned to continue the science and engineering for a new generation of RF array coils. Several MRI manufacturers are developing multiple-transmit RF capabilities on their systems to help overcome the RF in homogeneities that occur in human subjects in ultra-high field MRI scanners, and this is an area of intense development with over 50 instruments for MRI of humans at 7 T and higher worldwide and a growth rate of 5-10 units a year. RF inhomogeneity and power deposition are significant barriers for the adoption of these systems more broadly and our research has strong academic and industrial potential to alleviate these problems.