Improved Spoiling Efficiency in Dynamic RF-Spoiled Imaging by Ghost Phase Modulation and Temporal Filtering
Improved Spoiling Efficiency in Dynamic RF-Spoiled Imaging by Ghost Phase Modulation and Temporal Filtering
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DOI：
10.1002/mrm.25843
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发表时间：
2016-06-01
影响因子：
3.3
通讯作者：
Noll, Douglas C.
中科院分区：
文献类型：
--
作者：
Nielsen, Jon-Fredrik;Noll, Douglas C.
目的：射频扰频稳态序列提供T1或T2* 加权的快速数据采集。这些序列中的扰流梯度必须足够大以抑制重影伪影，并且根据经验选择。然而，某些因素，如需要最大限度地减少梯度的第一时刻或噪声可以限制扰流器的大小，因此，抑制重影的能力。我们提出了一种采集和预处理策略，以提高破坏效率，在传统的和回声移位动态radioffrequency-spoiled 3D imaging.Theory and Methods：通过要求每个时间帧中的动态成像序列包含一个特定的（有限的）数量的总射频射击，鬼信号可以交替的符号每隔一帧。然后通过沿时间维度进行沿着傅立叶变换并在预处理中去除奈奎斯特频率（类似于展开）来抑制重影。该方法适用于笛卡尔和非笛卡尔imaging.Results：我们证明了改进的鬼抑制与所提出的方法，为传统的和回波移位扰相梯度回波成像在固定phanteries和在体内。笛卡尔回波移位扰相梯度回波成像产生两个鬼在相反的方向上移动，这两个都被抑制与我们的method.Conclusion：对于一个给定的扰相梯度区，所提出的方法基本上抑制了鬼信号在常规和回波移位动态射频扰相成像。(C)2015 Wiley Periodicals，Inc.
Purpose: Radiofrequency-spoiled steady-state sequences offer rapid data acquisition with T1- or T2*-weighting. The spoiler gradients in these sequences must be large enough to suppress ghost artifacts, and are chosen empirically. However, certain factors such as the need to minimize gradient first moments or acoustic noise can limit the spoiler size and, hence, the ability to suppress ghosts. We present an acquisition and preprocessing strategy for improved spoiling efficiency in conventional and echo-shifted dynamic radiofrequency-spoiled 3D imaging.Theory and Methods: By requiring each time-frame in a dynamic imaging sequence to contain a particular (restricted) number of total radiofrequency shots, the ghost signal can be made to alternate in sign every other frame. The ghost is then suppressed by Fourier transforming along the temporal dimension, and removing the Nyquist frequency in preprocessing (similar to UNFOLD). The method works for both Cartesian and non-Cartesian imaging.Results: We demonstrate improved ghost suppression with the proposed approach, for both conventional and echo-shifted spoiled gradient echo imaging in stationary phantoms and in vivo. Cartesian echo-shifted spoiled gradient echo imaging produces two ghosts shifted in opposite directions, both of which are suppressed with our method.Conclusion: For a given spoiler gradient area, the proposed approach substantially suppresses the ghost signal in both conventional and echo-shifted dynamic radiofrequency-spoiled imaging. (C) 2015 Wiley Periodicals, Inc.