Doty F D, Entzminger G, Hauck C D, Staab J P
Doty Scientific, Inc., Columbia, South Carolina 29229, USA.
J Magn Reson. 1999 May;138(1):144-54. doi: 10.1006/jmre.1998.1703.
Numerical modeling and experimental results are presented for a variety of birdcages for high-field MRI microscopy. The data include the first published numerical calculations and experimental measurements of magnetic filling factors of birdcages or other MRI coils. Fast, 3D calculations for shielded coils are demonstrated using the Biot-Savart law along with energy minimization. It is shown that the near-field, higher-order inhomogeneity effects remaining after a first-order, asymmetry correction may easily exceed 20% in situations where it is desirable to maximize filling factor. It is also found that an order-of-magnitude improvement in the accuracy of predicted capacitor values may be achieved by using a more detailed circuit model of the birdcage resonator.
本文给出了用于高场MRI显微镜的各种鸟笼式线圈的数值模拟和实验结果。数据包括首次发表的鸟笼式线圈或其他MRI线圈的磁填充因子的数值计算和实验测量。利用毕奥-萨伐尔定律和能量最小化方法，展示了对屏蔽线圈的快速三维计算。结果表明，在期望最大化填充因子的情况下，经过一阶不对称校正后残留的近场高阶不均匀性效应很容易超过20%。还发现，通过使用更详细的鸟笼式谐振器电路模型，可以使预测电容值的精度提高一个数量级。
