ANALYSIS OF EDDY CURRENTS IN NUCLEAR-MAGNETIC-RESONANCE IMAGING
ANALYSIS OF EDDY CURRENTS IN NUCLEAR-MAGNETIC-RESONANCE IMAGING
复制标题
DOI：
10.1002/mrm.1910170119
复制
发表时间：
1991-01-01
影响因子：
3.3
通讯作者：
CHO, ZH
中科院分区：
文献类型：
--
作者：
AHN, CB;CHO, ZH
从麦克斯韦方程组的解中分析了核磁共振（NMR）成像中的涡流，并在从全身诊断成像到最近开发的NMR显微镜的各种实验条件下检查了它们的影响。分析主要集中在涡流感应场的频率特性和强度变化上，这取决于整个系统尺寸、梯度线圈尺寸与磁体孔径的比率以及脉冲序列相关参数，例如输入电流波形和重复时间。根据分析，涡流感应场的频率响应是高通滤波器的频率响应，其截止频率与整个系统尺寸的平方成反比。产生的磁场与感应磁场的强度比不受整个系统尺寸的影响，但与梯度线圈尺寸与磁体孔直径的比值敏感相关。出版社：Academic Press，Inc.
The eddy currents in nuclear magnetic resonance (NMR) imaging are analyzed from the solutions of Maxwell's equations and their effects are examined over various experimental conditions from whole‐body diagnostic imaging to recently developed NMR microscopy. The analysis is focused mainly on the frequency characteristics and intensity variations of the eddy‐current‐induced field which depends on the overall system size, ratio of the gradient coil size to the magnet bore diameter, and the pulse‐sequence‐dependent parameters such as input current waveform and repetition time. From the analysis, the frequency response of the eddy‐current‐induced field is that of a high‐pass filter whose cutoff frequency is inversely proportional to the square of the overall system size. The intensity ratio of the generated field to the induced field is not affected by the overall system size, but is sensitively related to the ratio of the gradient coil size to the magnet bore diameter. © 1991 Academic Press, Inc.