Dixon techniques in spiral trajectories with off resonance correction: A new approach for fat signal suppression without spatial-spectral RF pulses
Dixon techniques in spiral trajectories with off resonance correction: A new approach for fat signal suppression without spatial-spectral RF pulses
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DOI：
10.1002/mrm.10629
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发表时间：
2003-11-01
影响因子：
3.3
通讯作者：
Duerk, JL
中科院分区：
文献类型：
--
作者：
Moriguchi, H;Lewin, JS;Duerk, JL
螺旋成像最近在需要快速数据采集的MR应用中获得了认可。然而，螺旋成像的主要缺点之一是由非共振效应引起的模糊伪影。空间光谱（SPSP）脉冲通常用于抑制那些从水化学位移并导致非共振伪影的自旋。然而，当在存在B-0场不均匀性的情况下应用时，SPSP脉冲可能产生不均匀的脂肪信号抑制或不想要的水信号抑制。狄克逊技术已经被开发为用于直线采样方案中的水-脂肪信号分解的方法，因为它们即使在存在B-0不均匀性的情况下也可以产生明确的水-脂肪信号分解。本文证明了三点和两点狄克逊技术可以扩展到传统的螺旋和可变密度螺旋数据采集明确的水脂肪分解与非共振模糊校正。在螺旋三点狄克逊技术中，根据直接从采集图像中导出的频率图进行水脂信号分解和图像去模糊。在螺旋两点狄克逊技术中，测试几个预定频率以创建频率图。新提出的技术可以实现更有效和更均匀的脂肪信号抑制相比，传统的螺旋采集方法与SPSP脉冲。(C)2003 Wiley-Liss，Inc.
Spiral imaging has recently gained acceptance in MR applications requiring rapid data acquisition. One of the main disadvantages of spiral imaging, however, is blurring artifacts that result from off-resonance effects. Spatial-spectral (SPSP) pulses are commonly used to suppress those spins that are chemically shifted from water and lead to off-resonance artifacts. However, SPSP pulses may produce nonuniform fat signal suppression or unwanted water signal suppression when applied in the presence of B-0 field inhomogeneities. Dixon techniques have been developed as methods for water-fat signal decomposition in rectilinear sampling schemes since they can produce unequivocal water-fat signal decomposition even in the presence of B-0 inhomogeneities. This article demonstrates that three-point and two-point Dixon techniques can be extended to conventional spiral and variable-density spiral data acquisitions for unambiguous water-fat decomposition with off-resonance blurring correction. In the spiral three-point Dixon technique, water-fat signal decomposition and image deblurring are performed based on the frequency maps that are directly derived from the acquired images. In the spiral two-point Dixon technique, several predetermined frequencies are tested to create a frequency map. The newly proposed techniques can achieve more effective and more uniform fat signal suppression when compared to the conventional spiral acquisition method with SPSP pulses. (C) 2003 Wiley-Liss, Inc.