Modeling and suppression of respiration-related physiological noise in echo-planar functional magnetic resonance imaging using global and one-dimensional navigator echo correction
Modeling and suppression of respiration-related physiological noise in echo-planar functional magnetic resonance imaging using global and one-dimensional navigator echo correction
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DOI：
10.1002/mrm.20591
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发表时间：
2005-08-01
影响因子：
3.3
通讯作者：
Menon, RS
中科院分区：
文献类型：
--
作者：
Barry, RL;Menon, RS
功能性磁共振成像（fMRI）的主要噪声源是由于受试者胸部在呼吸循环中运动而引起的头部局部磁场的调制，这种生理噪声可以抵消使用更高磁场进行fMRI所期望的统计功率增益。特别是，使用回波平面成像（EPI）获得的fMRI数据对这些空间和时间变化的呼吸引起的频率偏移非常敏感。在这项研究中，测量了头部精确的3D磁场图，并用于确定呼吸周期两个极端的频率偏移。从这些图中，通过呼吸周期在大脑中测量了大约-1.0 Hz到+1.5 Hz的空间依赖频率变化。在这种测量场变化的情况下，进行了典型轴向EPI fMRI实验的模拟，显示了单像素时间序列中区域图像强度变化在1%到5%之间。在fMRI时间序列中，无论是全局还是一维导航回波校正都不足以测量和抑制呼吸引起的噪声。观察到的空间变化的性质表明，应该考虑二维方法。
A major source of noise in functional magnetic resonance imaging (fMRI) arises from modulations in the local magnetic field in the head due to motion of the subject's chest through the respiratory cycle, and this physiologic noise can nullify the gains in statistical power expected by the use of higher magnetic fields for fMRI. In particular, fMRI data acquired using echo-planar imaging (EPI) are very sensitive to these spatially and temporally varying respiration-induced frequency offsets. In this study, accurate 3D magnetic field maps in the head were measured and used to determine the frequency offsets at the two extremes of the respiratory cycle. From these maps, spatially dependent frequency variations from about -1.0 Hz to +1.5 Hz were measured in the brain through the respiratory cycle. Simulations of a typical axial EPI fMRI experiment acquired in the presence of this measured field variation were performed, demonstrating regional image intensity variations between 1 and 5% in single pixel time series. The inadequacy of either global or 1 D navigator echo corrections to measure and suppress respiratory-induced noise in fMRI time series is demonstrated. The nature of the spatial variations observed suggests that 2D approaches should be considered.