Doty F D, Entzminger G, Hauck C D
Doty Scientific, Inc., Columbia, South Carolina 29229, USA.
J Magn Reson. 1999 Sep;140(1):17-31. doi: 10.1006/jmre.1999.1828.
A new class of NMR RF volume coils is being developed that permits improved tuning range, B(1) homogeneity, tuning stability, and sensitivity compared to birdcages over a wide range of practical conditions, especially for microscopy and wraparound flexible applications. They are denoted litz coils, as their flux transparency and current distribution is obtained from woven foil patterns with insulated crossovers. Contrary to the design criteria of phased arrays, the parallel routes in litz coils use high coupling coefficients to achieve optimal current distribution, which is highly independent of tuning, balancing, and matching adjustments and is compatible with multiple capacitive segmentation. Magnetic filling factors, loaded Q, and inhomogeneity measurements and calculations are presented for a variety of litz coils with frequency-diameter products from 7 to 20 MHz-m and are compared to similar birdcages.
正在开发一种新型的核磁共振射频体线圈，与鸟笼式线圈相比，在广泛的实际条件下，特别是在显微镜检查和环绕式柔性应用中，它具有更宽的调谐范围、更好的B(1)均匀性、调谐稳定性和灵敏度。它们被称为绞合线线圈，因为其磁通透明度和电流分布是通过具有绝缘交叉的编织箔图案获得的。与相控阵的设计标准相反，绞合线线圈中的平行路径使用高耦合系数来实现最佳电流分布，这种分布高度独立于调谐、平衡和匹配调整，并且与多个电容性分段兼容。给出了各种频率直径乘积从7到20 MHz-m的绞合线线圈的磁填充因子、加载品质因数以及不均匀性测量和计算结果，并与类似的鸟笼式线圈进行了比较。
