Simultaneous Multislice Excitation by Parallel Transmission
Simultaneous Multislice Excitation by Parallel Transmission
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DOI：
10.1002/mrm.24791
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发表时间：
2014-04-01
影响因子：
3.3
通讯作者：
Stenger, V. Andrew
中科院分区：
文献类型：
--
作者：
Poser, Benedikt A.;Anderson, Robert James;Stenger, V. Andrew
PurposeA技术描述了使用射频（RF）并行传输（pTX）的同时多切片（SMS）激励。MethodsSpatially不同的切片同时通过施加不同的RF频率上的多通道发射阵列的元素组来激励。线圈几何结构的局部发射灵敏度由此被利用以减少RF功率。该方法能够使用单片RF脉冲或多频带脉冲实现SMS激励。SMS-pTX在3 T下使用双环pTX线圈上的八通道并行RF传输进行演示。通过实验和模拟评估了对B-1（+）均匀性和比吸收率（SAR）的影响。切片-GRAPPA重建用于分离的崩溃切片signals.ResultsPhantom和在体内的大脑数据与快速低角度拍摄（FLASH）和闪烁控制的混叠结果在更高的加速度（CAIPIRINHA）回波平面成像提出了在SMS激励因素的两个，四个和六个。我们还表明，与我们的pTX线圈设计，切片放置，和二进制划分的发射机，SMS-pTX激励可以实现相同的平均翻转角激励在约30%的RF功率比传统的SMS方法与多频带RF pulses.ConclusionThe建议的SMS-pTX允许SMS激励在降低RF功率通过利用本地B-1（+）的灵敏度合适的多元pTX阵列。Magn Reson Med 71：1416-1427，2014。(c)2013 Wiley Periodicals，Inc.
PurposeA technique is described for simultaneous multislice (SMS) excitation using radiofrequency (RF) parallel transmission (pTX).MethodsSpatially distinct slices are simultaneously excited by applying different RF frequencies on groups of elements of a multichannel transmit array. The localized transmit sensitivities of the coil geometry are thereby exploited to reduce RF power. The method is capable of achieving SMS-excitation using single-slice RF pulses, or multiband pulses. SMS-pTX is demonstrated using eight-channel parallel RF transmission on a dual-ring pTX coil at 3 T. The effect on B-1(+) homogeneity and specific absorption rate (SAR) is evaluated experimentally and by simulations. Slice-GRAPPA reconstruction was used for separation of the collapsed slice signals.ResultsPhantom and in vivo brain data acquired with fast low-angle shot (FLASH) and blipped-controlled aliasing results in higher acceleration (CAIPIRINHA) echo-planar imaging are presented at SMS excitation factors of two, four, and six. We also show that with our pTX coil design, slice placement, and binary division of transmitters, SMS-pTX excitations can achieve the same mean flip angles excitations at approximate to 30% lower RF power than a conventional SMS approach with multiband RF pulses.ConclusionThe proposed SMS-pTX allows SMS excitations at reduced RF power by exploiting the local B-1(+) sensitivities of suitable multielement pTX arrays. Magn Reson Med 71:1416-1427, 2014. (c) 2013 Wiley Periodicals, Inc.