更高的频率和更短的波长在超高场提出了重要的设计问题,使多通道阵列设置超高场MR成像的关键组件。多通道阵列的要求,以及不断努力增加阵列中的通道数量,总是受到称为元件间耦合的主要问题的限制。这种耦合影响电流和磁场分布,信道之间的噪声相关性,和数组元素的频率,降低成像质量和性能。为了实现UHFMRI的全部潜力,我们必须确保阵列元件之间的耦合保持在最低限度。高阻抗线圈允许阵列系统通过提供最佳隔离来完全实现其潜力,同时需要最少的设计修改。这些微小的设计变化,这要求在常规环路上使用低电容来引起升高的阻抗,导致不可忽视的重大安全隐患。在这些低电容集总元件上形成高电场,这可能会导致成像对象中更高的SAR值,沉积更多的能量,最终,提供了对人体样品的组织加热相关损伤的更大风险。我们提出了一种创新的方法,利用高介电材料有效地降低成像样品中的电场和SAR值,同时保持B1效率和阵列元件之间的元件间去耦,以解决这一重要的安全问题,而对包括高阻抗线圈的现有阵列设计进行最小的改变。
Higher frequencies and shorter wavelengths present significant design issues at ultra-high fields, making multi-channel array setup a critical component for ultra-high field MR imaging. The requirement for multi-channel arrays, as well as ongoing efforts to increase the number of channels in an array, are always limited by the major issue known as inter-element coupling. This coupling affects the current and field distribution, noise correlation between channels, and frequency of array elements, lowering imaging quality and performance. To realize the full potential of UHF MRI, we must ensure that the coupling between array elements is kept to a minimum. High-impedance coils allow array systems to completely realize their potential by providing optimal isolation while requiring minimal design modifications. These minor design changes, which demand the use of low capacitance on the conventional loop to induce elevated impedance, result in a significant safety hazard that cannot be overlooked. High electric fields are formed across these low capacitance lumped elements, which may result in higher SAR values in the imaging subject, depositing more power and, ultimately, providing a greater risk of tissue heating-related injury to the human sample. We propose an innovative method of utilizing high-dielectric material to effectively reduce electric fields and SAR values in the imaging sample while preserving the B1 efficiency and inter-element decoupling between the array elements to address this important safety concern with minimal changes to the existing array design comprising high-impedance coils.