High-order multibland encoding in the heart
High-order multibland encoding in the heart
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DOI：
10.1002/mrm.10277
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发表时间：
2002-10-01
影响因子：
3.3
通讯作者：
Wood, ML
中科院分区：
文献类型：
--
作者：
Cunningham, CH;Wright, GA;Wood, ML
具有多频带选择性激励的空间编码（例如，Hadamard编码）已经被限制到少量的切片，因为当多于大约八个切片被编码时，RF脉冲变得不可接受地长。在这项工作中，技术，以缩短多波段射频脉冲，从而允许更大数量的切片，进行了调查。一种方法应用的技术，同时保留自适应切片厚度的能力进行了概述。示出了切片厚度和脉冲持续时间之间的折衷。仿真和实验结果表明，缩短的脉冲减少了运动诱导的激发轮廓模糊和相位累积。梯度硬件限制、切片厚度和流量灵敏度之间的联系如图所示。激励配置文件编码32个连续切片的1毫米厚度进行了实验测量，并从RF脉冲相对于梯度的定时误差所产生的伪影进行了研究。一个多波段技术成像32个连续的2毫米切片，自适应切片厚度，并证明了健康受试者的冠状动脉成像。由于能够使用相对较短（1-2 ms）的RF脉冲对大量连续切片成像，多频带编码已经进一步向实际应用发展。(C)2002 Wiley-Liss，Inc.
Spatial encoding with multiband selective excitation (e.g., Hadamard encoding) has been restricted to a small number of slices because the RF pulse becomes unacceptably long when more than about eight slices are encoded. In this work, techniques to shorten multiband RF pulses, and thus allow larger numbers of slices, are investigated. A method for applying the techniques while retaining the capability of adaptive slice thickness is outlined. A tradeoff between slice thickness and pulse duration is shown. Simulations and experiments with the shortened pulses confirmed that motion-induced excitation profile blurring and phase accrual were reduced. The connection between gradient hardware limitations, slice thickness, and flow sensitivity is shown. Excitation profiles for encoding 32 contiguous slices of 1-mm thickness were measured experimentally, and the artifact resulting from errors in timing of RF pulse relative to gradient was investigated. A multiband technique for imaging 32 contiguous 2-mm slices, with adaptive slice thickness, was developed and demonstrated for coronary artery imaging in healthy subjects. With the ability to image high numbers of contiguous slices, using relatively short (1-2 ms) RF pulses, multiband encoding has been advanced further toward practical application. (C) 2002 Wiley-Liss, Inc.