Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
J Magn Reson. 2010 Mar;203(1):108-12. doi: 10.1016/j.jmr.2009.12.006. Epub 2009 Dec 29.
The double spin-echo point resolved spectroscopy sequence (PRESS) is a widely used method and standard in clinical MR spectroscopy. Existence of important J-modulations at constant echo times, depending on the temporal delays between the rf-pulses, have been demonstrated recently for strongly coupled spin systems and were exploited for difference editing, removing singlets from the spectrum (strong-coupling PRESS, S-PRESS). A drawback of this method for in vivo applications is that large signal modulations needed for difference editing occur only at relatively long echo times. In this work we demonstrate that, by simply adding a third refocusing pulse (3S-PRESS), difference editing becomes possible at substantially shorter echo times while, as applied to citrate, more favorable lineshapes can be obtained. For the example of an AB system an analytical description of the MR signal, obtained with this triple refocusing sequence (3S-PRESS), is provided.
双自旋回波点分辨波谱序列（PRESS）是一种广泛应用于临床磁共振波谱学的方法和标准。最近已经证明，在强耦合自旋系统中，在恒定回波时间存在重要的 J 调制，这取决于射频脉冲之间的时间延迟，并且已经被用于差异编辑，从谱中去除单峰（强耦合 PRESS，S-PRESS）。对于体内应用，该方法的一个缺点是，用于差异编辑的大信号调制仅在相对较长的回波时间发生。在这项工作中，我们证明，通过简单地添加第三个重聚焦脉冲（3S-PRESS），可以在更短的回波时间实现差异编辑，而应用于柠檬酸时，可以获得更有利的线宽形状。对于 AB 系统的示例，提供了使用这种三重聚焦序列（3S-PRESS）获得的磁共振信号的分析描述。
