Parallel transmit capability of various RF transmit elements and arrays at 7T MRI
Parallel transmit capability of various RF transmit elements and arrays at 7T MRI
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DOI：
10.1002/mrm.26704
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发表时间：
2018-02-01
影响因子：
3.3
通讯作者：
Quick, Harald H.
中科院分区：
文献类型：
--
作者：
Rietsch, Stefan H. G.;Orzada, Stephan;Quick, Harald H.
PurposeIn这项工作中，22个配置的远程射频（RF）线圈阵列组成的不同发射元件设计7特斯拉（T）超高场MRI.MethodsInvestigated发射RF元件类型是矩形回路，微带线，微带线与曲折，250毫米屏蔽偶极子与曲折，和λ在两个偶极子与屏蔽和不屏蔽。这些元件被组合在四种不同配置的圆周RF体阵列中，每个阵列具有四个或八个发射元件。比较包括耦合行为，自由度所提供的个人传输模式，和度量，如功率和特定的吸收率efficiency. ResultsCoupled相邻的RF元件之间的升高（高达-7 dB）的所有阵列与8个元素，而它是低于-25 dB的阵列，只有4个元素。奇异值的累积和指出了中央横断面的最高自由度、中央冠状面的减小值和矢状面的最小值。关于功率和SAR效率，八个λ在两个偶极子是最有利的。ConclusionsAmong的调查远程阵列和参数，八个偶极子的组合似乎是最有利的潜在用途在7 T的身体MRI。Magn Reson Med 79：1116-1126，2018。(c)2017年国际医学磁共振学会。
PurposeIn this work, 22 configurations for remote radiofrequency (RF) coil arrays consisting of different transmit element designs for 7 Tesla (T) ultrahigh-field MRI are compared by numerical simulations.MethodsInvestigated transmit RF element types are rectangular loops, micro striplines, micro striplines with meanders, 250-mm shielded dipoles with meanders, and lambda over two dipoles with and without shield. These elements are combined in four different configurations of circumferential RF body arrays with four or eight transmit elements each. Comparisons included coupling behavior, degrees of freedom offered by the individual transmit patterns, and metrics like power and specific absorption rate efficiency.ResultsCoupling between neighboring RF elements is elevated (up to -7 dB) for all arrays with eight elements, whereas it is below -25 dB for arrays with only four elements. The cumulative sum of singular values points out highest degrees of freedom for the central transversal, reduced values in the central coronal, and minimum values in the sagittal slice. Concerning power and SAR efficiency, eight lambda over two dipoles are most advantageous.ConclusionsAmong the investigated remote arrays and parameters, a combination of eight dipoles appears to be most favorable for potential use in 7T body MRI. Magn Reson Med 79:1116-1126, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.