Hinks R S, Derbyshire J A, LeRoux P L
Department of Medical Biophysics, University of Toronto, Sunnybrook Health Science Center, Ontario, Canada.
Magn Reson Med. 1998 Jun;39(6):1019-24. doi: 10.1002/mrm.1910390622.
Chemical shift artifacts and other off-resonance spatial shifts in 2DFT MRI arise from the linear time dependence in the k-space data in the readout direction. Introduction of a view-dependent time shift of the readout window adds a time dependence to the phase-encoding direction and results in a virtual frequency-encoding direction that is a linear combination of the phase-encode and readout axes. By this method, the readout and phase-encode directions can be made identical in their sensitivity to off-resonance effects and can be arbitrarily swapped with no change in chemical shift or inhomogeneity effects, improving previously reported methods that swap these axes for signal averaging or reduction of motion artifacts.
二维傅里叶变换磁共振成像（2DFT MRI）中的化学位移伪影和其他失谐空间移位源于读出方向上k空间数据的线性时间依赖性。引入读出窗口的视在时间偏移会给相位编码方向增加时间依赖性，并导致一个虚拟频率编码方向，该方向是相位编码轴和读出轴的线性组合。通过这种方法，读出方向和相位编码方向在对失谐效应的敏感性方面可以变得相同，并且可以任意交换，而不会改变化学位移或不均匀性效应，改进了先前报道的为信号平均或减少运动伪影而交换这些轴的方法。
