Perfusion mapping with multiecho multishot parallel imaging EPI
Perfusion mapping with multiecho multishot parallel imaging EPI
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DOI：
10.1002/mrm.21255
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发表时间：
2007-07-01
影响因子：
3.3
通讯作者：
Bammer, Roland
中科院分区：
文献类型：
--
作者：
Newbould, Rexford D.;Skare, Stefan T.;Bammer, Roland
回声平面成像（EPI）是动态敏感性对比成像（DSC）灌注MRI的标准技术。然而，EPI存在众所周知的几何畸变，这可以通过增加k空间相速度来减小。此外，DSC中使用的长回波时间（TEs）导致动脉输入信号饱和，从而导致血流动力学信息的严重定量误差。在这里，通过使用交错镜头采集和并行成像（PI），使用伪单镜头（ss）EPI进行快速体积EPI，并具有多镜头EPI序列的有效T-2（*）模糊和敏感性扭曲。缩短的读出长度允许获得与单回波方法获得的时间分辨率和空间覆盖相似的多个回波。多回波读出允许无偏R-2（*）映射，以避免由于信号饱和或缩短效应对示踪剂浓度的不正确估计。多回波灌注测量还可以减轻由于使用PI导致的信噪比（SNR）降低。本文介绍了志愿者和临床脑卒中患者的结果。这种获取方案可以帮助大多数快速的时间序列获取。该方法在DSC中解决了信号饱和和T污染问题，同时提高了图像质量，是迈向更好定量MR PWI的合乎逻辑的一步。中华医学杂志，2006,38(5):771 - 781。(c) 2007 Wiley-Liss, Inc。
Echo-planar imaging (EPI) is the standard technique for dynamic susceptibility-contrast (DSC) perfusion MRI. However, EPI suffers from well-known geometric distortions, which can be reduced by increasing the k-space phase velocity. Moreover, the long echo times (TEs) used in DSC lead to signal saturation of the arterial input signal, and hence to severe quantitation errors in the hemodynamic information. Here, through the use of interleaved shot acquisition and parallel imaging (PI), rapid volumetric EPI is performed using pseudo-single-shot (ss)EPI with the effective T-2(*) blur and susceptibility distortions of a multishot EPI sequence. The reduced readout lengths permit multiple echoes to be acquired with temporal resolution and spatial coverage similar to those obtained with a single-echo method. Multiecho readouts allow for unbiased R-2(*) mapping to avoid incorrect estimation of tracer concentration due to signal saturation or T, shortening effects. Multiecho perfusion measurement also mitigates the signal-to-noise ratio (SNR) reduction that results from utilizing PI. Results from both volunteers and clinical stroke patients are presented. This acquisition scheme can aid most rapid time-series acquisitions. The use of this method for DSC addresses the problem of signal saturation and T, contamination while it improves image quality, and is a logical step toward better quantitative MR PWI. Magn Reson Med 58:70-81, 2007. (c) 2007 Wiley-Liss, Inc.