RF coil element with longitudinal and transversal two-peak field distribution for low SAR 7-Tesla magnetic resonance imaging
RF coil element with longitudinal and transversal two-peak field distribution for low SAR 7-Tesla magnetic resonance imaging
复制标题
用于低SAR 7特斯拉磁共振成像的具有纵向和横向双峰场分布的射频线圈元件
DOI：
10.1109/mwsym.2013.6697434
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
A. Rennings
中科院分区：
文献类型：
--
作者：
Zhichao Chen;K. Solbach;D. Erni;A. Rennings
在超高场MRI（B 0 ≥ 7 T）中，允许的局部SAR限制了可施加到RF线圈的功率。在本文中，我们提出了一种方法，可以更好地分配身体吸收的功率，从而产生较低的SARmax值，因此可以使用更高的功率水平来喂养。优化的SAR分布是由一个扩展偶极子（41厘米长），这是比普通的半波长之一，和本征共振金属板用于屏蔽目的。在300 MHz时，激励偶极子的电长度约为3λ/2，最大电流位于远离馈电点的位置，激发出纵向双峰SAR分布，而无源屏蔽板呈现半波长本征共振，产生横向双峰SAR分布。与已建立的带状线单元（25 cm长）相比，基于仿真获得了29%的品质因数（Hmean/SARmax）的改善。
In ultra high field MRI (B0 ≥ 7 T) the allowed local SAR restricts the power that can be applied to the RF coil. Here in this paper we propose an approach where the power that is absorbed by the body is better distributed, yielding a lower SARmax value, hence higher power level can be used for feeding. The optimized SAR distribution is excited by an extended dipole (41 cm-long), which is longer than the ordinary half-wavelength one, and an eigen-resoanant metal plate used for shielding purpose. At 300 MHz, the excited dipole has an approximate 3λ/2 electrical length where the maximum of current is located away from the feeding position, exciting a longitudinal two-peak SAR distribution, whereas the passive shielding plate exhibits a half-wavelength eigen-resonance, which yields a transveral two-peak SAR distribution. Compared to an established strip line element (25 cm-long), a 29% improvement of figure of merit (Hmean/√SARmax) is obtained based on simulation.