Correction of physiologically induced global off resonance effects in dynamic echo-planar and spiral functional imaging
Correction of physiologically induced global off resonance effects in dynamic echo-planar and spiral functional imaging
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DOI：
10.1002/mrm.10065
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发表时间：
2002-02-01
影响因子：
3.3
通讯作者：
Glover, GH
中科院分区：
文献类型：
--
作者：
Pfeuffer, J;Van de Moortele, PF;Glover, GH
在功能磁共振成像中，使用诸如回波平面（EPI）或螺旋的快速方法来收集动态系列图像。这些技术对可能由呼吸引起的共振频率的变化敏感，并且在高磁场下更显着。为了减少呼吸引起的相位和频率波动的噪声，开发了“k空间中的动态非共振”（DORK）的简单校正。校正使用来自k空间中心的相位信息和导航回波，并通过单次激发和分段EPI的动态扫描以及首次在7 T下对人脑的螺旋成像进行说明。用边缘算子测量呼吸频谱中的图像噪声。DORK校正显著降低了呼吸引起的噪声（EPI的图像偏移、螺旋的模糊、分段采集的重影）。虽然发现螺旋成像在校正前比EPI表现出更少的噪声，但DORK校正后的残留噪声是相当的。该校正应用简单，并且可以校正动态成像中的频率漂移和波动的其他来源。Magn Reson Med 47：344-353，2002。(C)2002 Wiley-Liss，Inc.
In functional magnetic resonance imaging, a rapid method such as echo-planar (EPI) or spiral is used to collect a dynamic series of images. These techniques are sensitive to changes in resonance frequency which can arise from respiration and are more significant at high magnetic fields. To decrease the noise from respiration-induced phase and frequency fluctuations, a simple correction of the "dynamic off-resonance in k-space" (DORK) was developed. The correction uses phase information from the center of k-space and a navigator echo and is illustrated with dynamic scans of single-shot and segmented EPI and, for the first time, spiral imaging of the human brain at 7 T. Image noise in the respiratory spectrum was measured with an edge operator. The DORK correction significantly reduced respiration-induced noise (image shift for EPI, blurring for spiral, ghosting for segmented acquisition). While spiral imaging was found to exhibit less noise than EPI before correction, the residual noise after the DORK correction was comparable. The correction is simple to apply and can correct for other sources of frequency drift and fluctuations in dynamic imaging. Magn Reson Med 47:344-353, 2002. (C) 2002 Wiley-Liss, Inc.