Chen Xi, Lin Meijin, Chen Zhong, Zhong Jianhui
Department of Physics and Magnetic Resonance Research Center, State Key Laboratory of Physical Chemistry of Solid Surface, Xiamen University, Xiamen, China.
Magn Reson Med. 2009 Apr;61(4):775-84. doi: 10.1002/mrm.21894.
Intermolecular multiple-quantum coherences (iMQCs) can refocus the phase dispersion caused by magnetic field inhomogeneities while preserving the chemical shift, so they have been applied to achieve high-resolution MR spectroscopy free of line broadening caused by susceptibility gradients. However, previous iMQC high-resolution methods all require two-dimensional spectra sampling of the full range of chemical shifts of solute evolutions in both F(1) and F(2) dimensions, resulting in a prolonged scanning time for data acquisition. In this work, sparse sampling in the t(1) dimension and subsequent fold-over correction are used to speed up the intermolecular zero-quantum coherence spectroscopy by up to 50 times on high-field MR systems. Furthermore, three types of spectra with homo-decoupling, original J-coupling constants, and doubled J-coupling constants respectively are obtained with manipulation of the t(1) period. The water suppression is also improved by the combined use of intermolecular double-quantum filter and excitation sculpting. The feasibilities of this group of new sequences are demonstrated by experiments using an agar gel phantom with an air bubble, in vitro pig brain tissues and an intact postmortem mudskipper.
分子间多量子相干（iMQCs）可以在保留化学位移的同时，重新聚焦由磁场不均匀性引起的相位色散，因此它们已被应用于实现高分辨率磁共振波谱，避免了由磁化率梯度导致的谱线展宽。然而，以往的iMQC高分辨率方法都需要在F(1)和F(2)维度上对溶质演化的全化学位移范围进行二维谱采样，这导致数据采集的扫描时间延长。在这项工作中，在t(1)维度上进行稀疏采样并随后进行折叠校正，可在高场磁共振系统上将分子间零量子相干谱学的速度提高多达50倍。此外，通过对t(1)周期的操控，分别获得了具有同核去耦、原始J耦合常数和加倍J耦合常数的三种类型的谱。通过分子间双量子滤波器和激发脉冲整形的联合使用，水抑制也得到了改善。使用带有气泡的琼脂凝胶模型、体外猪脑组织和完整的死后弹涂鱼进行的实验证明了这组新序列的可行性。
