Understanding and manipulating the RF fields at high field MRI.
Understanding and manipulating the RF fields at high field MRI.
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DOI：
10.1002/nbm.1406
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发表时间：
2009-11
影响因子：
2.9
通讯作者：
Tang L
中科院分区：
文献类型：
--
作者：
Ibrahim TS;Hue YK;Tang L
本文介绍了一个完整的概述电磁（射频方面）的MRI在低场和高场。使用解析公式、数值建模（计算电磁学）和电磁场成像实验，分析了影响与MRI相关的电磁量的物理学，即（1）发射场，（2）接收场和（3）总电磁功率吸收。通过电磁理论研究上述量的物理解释，以理解“在不同的静态场强下工作时，在电磁学方面会发生什么？”使用实验研究和数值模拟，本文还探讨了物理和技术features的所有或任何这些指定的电磁量可以通过操作技术，如B1匀场（相控阵列激励）和信号组合使用接收阵列，以推进MRI在高场强。与此相关的主题和高度耦合的线圈在7 T下工作，本文还介绍了第一个幻影工作的B1匀场没有B1测量。
This paper presents a complete overview of the electromagnetics (radiofrequency aspect) of MRI at low and high fields. Using analytical formulations, numerical modeling (computational electromagnetics), and ultrahigh field imaging experiments, the physics that impacts the electromagnetic quantities associated with MRI, namely (1) the transmit field, (2) receive field, and (3) total electromagnetic power absorption, is analyzed. The physical interpretation of the above-mentioned quantities is investigated by electromagnetic theory, to understand ‘What happens, in terms of electromagnetics, when operating at different static field strengths?’ Using experimental studies and numerical simulations, this paper also examines the physical and technological feasibilities by which all or any of these specified electromagnetic quantities can be manipulated through techniques such as B1 shimming (phased array excitation) and signal combination using a receive array in order to advance MRI at high field strengths. Pertinent to this subject and with highly coupled coils operating at 7 T, this paper also presents the first phantom work on B1 shimming without B1 measurements.