Rourke David E, Bretschneider Christian O
Sir Peter Mansfield Magnetic Resonance Centre, Nottingham University, Nottingham, NG7 2RD, UK.
J Magn Reson. 2007 May;186(1):123-30. doi: 10.1016/j.jmr.2007.02.002. Epub 2007 Feb 4.
Selective rotation pulses cause magnetization within a given frequency range (or slice) to undergo a specified rotation, about a specified axis. Magnetization outside this slice remains unaffected if it is initially along the z axis. It has previously been shown that the design of such pulses can be reduced to the design of selective "point-to-point" pulses, which rotate magnetization within the slice from the y axis. By decomposing the point-to-point pulses into two sub-pulses, it is shown that an inverse scattering algorithm for selective pulse design can be used to calculate selective rotation pulses with any desired spinor response, subject to the constraint that the second spinor component have constant phase across the slice. The design of selective refocusing pulses can be treated specially, requiring the calculation, by the same inverse scattering algorithm, of a single sub-pulse.
选择性旋转脉冲使给定频率范围（或切片）内的磁化强度绕指定轴进行特定的旋转。如果该切片外的磁化强度最初沿z轴，则其不受影响。先前已经表明，此类脉冲的设计可以简化为选择性“点对点”脉冲的设计，这种脉冲可使切片内的磁化强度从y轴开始旋转。通过将点对点脉冲分解为两个子脉冲，可以证明用于选择性脉冲设计的逆散射算法可用于计算具有任何所需旋量响应的选择性旋转脉冲，但前提是第二个旋量分量在整个切片上具有恒定相位。选择性重聚焦脉冲的设计可以特殊处理，需要通过相同的逆散射算法计算单个子脉冲。
