Charles-Edwards Geoffrey D, Payne Geoffrey S, Leach Martin O, Bifone Angelo
Cancer Research UK Clinical Magnetic Resonance Research Group, The Institute of Cancer Research and The Royal Marsden NHS Trust, Sutton, Surrey SM2 5PT, UK.
J Magn Reson. 2004 Feb;166(2):215-27. doi: 10.1016/j.jmr.2003.10.017.
Intermolecular multiple-quantum coherences (iMQCs) have been reported to offer a sensitivity to sample structure at a specific user-defined length scale down to the order of 10 microm. When assessing this novel contrast mechanism in controlled phantom experiments, we have observed three different mechanisms whereby residual single-quantum coherences (SQCs) arising from intense high spatial frequencies, stimulated echoes and strong spatially encoding gradients can produce significant changes in signal contrast at particular length scales. These changes which only appear when components arising from SQCs and iMQCs are both present in the detected signal, are similar to changes previously attributed to iMQCs alone. We demonstrate each mechanism by which these residual SQCs arise and describe methods for their suppression.
据报道，分子间多量子相干（iMQCs）能够在特定的用户定义长度尺度下对样品结构产生敏感性，低至10微米量级。在受控体模实验中评估这种新型对比机制时，我们观察到三种不同机制，即由强烈的高空间频率、受激回波和强空间编码梯度产生的残余单量子相干（SQCs），可在特定长度尺度下使信号对比度产生显著变化。这些变化仅在检测信号中同时存在由SQCs和iMQCs产生的成分时才会出现，类似于之前仅归因于iMQCs的变化。我们展示了这些残余SQCs产生的每种机制，并描述了抑制它们的方法。
