Inner-volume imaging in vivo using three-dimensional parallel spatially selective excitation
Inner-volume imaging in vivo using three-dimensional parallel spatially selective excitation
复制标题
DOI：
10.1002/mrm.24381
复制
发表时间：
2013-05-01
影响因子：
3.3
通讯作者：
Ullmann, Peter
中科院分区：
文献类型：
--
作者：
Schneider, Johannes T.;Kalayciyan, Raffi;Ullmann, Peter
这项工作描述了第一个实验实现的三维空间选择性激发使用并行传输在体内。为了设计具有短持续时间和高激励精度的三维并行激励脉冲，选择合适的发射k空间轨迹是至关重要的。为此，在最初的模拟研究中对螺旋叠层弹道和同心壳体弹道的特性进行了研究。它表明，特别是当欠采样的轨迹与并行传输相结合，实验参数，如发射线圈的几何形状和非谐振条件有一个重要的影响所选择的轨迹和欠采样方案的适用性。这两个轨迹被应用在MR内容积成像实验中，该实验表明，如果轨迹在时间上被优化并且其实际路径在脉冲计算期间被测量和考虑，则可以实现可接受的短且鲁棒的三维选择性脉冲。实现了短至3.2 ms的脉冲持续时间，并且这种脉冲适合于在玉米棒和大鼠体内精确地激发任意形状的体积。这些选择性激发的目标的视场成像减少允许高空间分辨率和显着减少的测量时间，并进一步证明了三维并行激励在现实的MRI应用在体内的可行性。Magn Reson Med，2013年。(c)2012 Wiley Periodicals，Inc.
This work describes the first experimental realization of three-dimensional spatially selective excitation using parallel transmission in vivo. For the design of three-dimensional parallel excitation pulses with short durations and high excitation accuracy, the choice of a suitable transmit k-space trajectory is crucial. For this reason, the characteristics of a stack-of-spirals trajectory and of a concentric-shells trajectory were examined in an initial simulation study. It showed that, especially when undersampling the trajectories in combination with parallel transmission, experimental parameters such as transmit-coil geometry and off-resonance conditions have an essential impact on the suitability of the selected trajectory and undersampling scheme. Both trajectories were applied in MR inner-volume imaging experiments which demonstrate that acceptably short and robust three-dimensional selective pulses can be achieved if the trajectory is temporally optimized and its actual path is measured and considered during pulse calculation. Pulse durations as short as 3.2 ms were realized and such pulses were appropriate to accurately excite arbitrarily shaped volumes in a corn cob and in a rat in vivo. Reduced field-of-view imaging of these selectively excited targets allowed high spatial resolution and significantly reduced measurement times and furthermore demonstrates the feasibility of three-dimensional parallel excitation in realistic MRI applications in vivo. Magn Reson Med, 2013. (c) 2012 Wiley Periodicals, Inc.