Optimized outer volume suppression for single-shot fast spin-echo cardiac imaging
Optimized outer volume suppression for single-shot fast spin-echo cardiac imaging
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DOI：
10.1002/jmri.1880080505
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发表时间：
1998-09-01
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影响因子：
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通讯作者：
Carlier, PG
中科院分区：
文献类型：
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作者：
Le Roux, P;Gilles, RJ;Carlier, PG
在超快MRI技术中，单次激发快速自旋回波序列提供了回波平面成像的稳健替代方案，主要是因为对B-o不均匀性的灵敏度大大降低。在B不均匀性可能严重且难以校正的情况下，例如在心脏成像中，该性质特别有吸引力。然而，对于单次激发心脏成像，在不引入后折叠伪影的情况下在必要的大视场上实现高分辨率是有问题的。一个选项是使用多点序列。然而，随后出现了与心脏门控相关的问题。另一种解决方案是使用具有由Shinnar-LeRoux算法生成的二次相位脉冲的优化的预饱和板。这些可以被设置为减少相位编码方向上的视场，从而减少相位编码步骤的数量。例如，对于1 x 2 mm的空间分辨率，在250 x 125 mm的矩形视野内，并使用半傅立叶采集，仅需要40的回波链长度。当回波间隔为4.5毫秒时，总成像时间约为180毫秒。证明了该溶液对幻影和志愿者的有效性。整个心脏的多层短轴检查，在一个单一的短屏气约10秒内实现，显示。研究的可能性不仅心脏解剖，但也收缩和心肌灌注进行了讨论。
Among the ultrafast MRI techniques, the single-shot fast spin-echo sequence offers a robust alternative to echo planar imaging, essentially because of a much reduced sensitivity to B-o inhomogeneity. This property is particularly appealing in situations in which B, inhomogeneities can be severe and difficult to correct, such as in cardiac imaging. With single-shot cardiac imaging, however, achieving high resolution over the necessarily large field of views without introducing back-folding artifacts is problematic. One option is to use multishot sequences. However, then issues related to cardiac gating arise. Another solution is to use, optimized presaturation slabs with quadratic phase pulses generated by the Shinnar-LeRoux algorithm. These can be set to reduce the field of view in the phase-encoding direction, resulting in a reduction in the number of phase-encoding steps. For instance, for a 1 x 2-mm spatial resolution, over a rectangular, 250 x 125-mm held of view, and using a half Fourier acquisition, an echo-train length of only 40 is required. With a 4,5-msec echo spacing, the total imaging time is approximate to 180 msec, The efficacy of this solution on phantoms and volunteers is demonstrated. Multislice short-axis examinations of the whole heart, realized within a single short breath-hold of approximate to 10 seconds, are shown. The possibility of investigating not only cardiac anatomy but also both contractility and myocardial perfusion is discussed.