Torres Allan M, Dela Cruz Ruby, Price William S
Nanoscale Organisation and Dynamics Group, College of Health and Science, University of Western Sydney, Penrith South DC, NSW 1797, Australia.
J Magn Reson. 2008 Aug;193(2):311-6. doi: 10.1016/j.jmr.2008.05.006. Epub 2008 May 16.
Peak distortion caused by homonuclear J-coupling is a major problem that limits the utility of the pulsed-field gradient spin-echo (PGSE) method for studying translational diffusion. This unwanted effect can be removed by incorporation of anti-phase magnetization purging pulse elements at the end of the spin-echo sequence. Three methods, namely, trim-pulse, homospoil pulse gradient and chirp based z-filter were evaluated as potential candidates for an improved NMR diffusion method that is less sensitive to J-coupling peak distortion. The chirp based z-filter was found to be excellent in suppressing anti-phase magnetization while leaving the in-phase magnetization basically intact in spin-echo and stimulated-echo based experiments. The incorporation of chirp based z-filter into PGSE could allow diffusion analysis that would otherwise be impossible by conventional means.
由同核J耦合引起的峰失真，是限制脉冲场梯度自旋回波（PGSE）方法用于研究平移扩散的一个主要问题。这种不良效应可通过在自旋回波序列末尾加入反相磁化消除脉冲元件来消除。三种方法，即微调脉冲、同相破坏脉冲梯度和基于啁啾的z滤波器，被评估为改进的核磁共振扩散方法的潜在候选方法，该方法对J耦合峰失真不太敏感。发现在基于自旋回波和受激回波的实验中，基于啁啾的z滤波器在抑制反相磁化方面表现出色，同时使同相磁化基本保持不变。将基于啁啾的z滤波器并入PGSE中，可以进行常规方法无法实现的扩散分析。
