Long-lived spin states as a source of contrast in magnetic resonance spectroscopy and imaging
Long-lived spin states as a source of contrast in magnetic resonance spectroscopy and imaging
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DOI：
10.1016/j.jmr.2015.10.004
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发表时间：
2015-12-01
影响因子：
2.2
通讯作者：
Ivanov, Konstantin L.
中科院分区：
文献类型：
--
作者：
Kiryutin, Alexey S.;Zimmermann, Herbert;Ivanov, Konstantin L.
提出了一种利用纵向自旋磁化产生长寿命自旋态的方法，该方法基于射频场在适当频率下的绝热开关。该技术易于使用标准核磁共振（NMR）设备实现，提供了从三重态T+（或T-）状态到一对自旋的单重态和反向的良好转换。该方法已被测试的氨基酸酪氨酸和其部分氘代同位素异构体的氘代化合物，我们已经实现了LLS寿命，超过纵向弛豫时间的21倍。此外，通过稍微修改该方法，实现了相对于NMR谱中的LLS的增强对比度;超过1200的对比度增强是可行的。这使得能够有效抑制NMR中的纵向自旋磁化，从而允许选择性地查看LLS。使用这种方法，我们已经证明，不仅光谱，而且空间对比度可以实现：我们已经获得了空间NMR图像与强烈改善的对比度起源于LLS寿命在样品中的不同位置的差异。(C)2015 Elsevier Inc. All rights reserved.
A method is proposed to create Long-Lived spin States (LLSs) from longitudinal spin magnetization, which is based on adiabatic switching of a Radio-Frequency (RF) field with proper frequency. The technique is simple to implement with standard Nuclear Magnetic Resonance (NMR) equipment, providing an excellent conversion of population from the triplet T+ (or T-) state to the singlet state of a pair of spins and back. The method has been tested for the amino acid tyrosine and its partially deuterated isotopomer; for the deuterated compound, we have achieved a LLS lifetime, which exceeds the longitudinal relaxation time by a factor of 21. Furthermore, by slightly modifying the method, an enhanced contrast with respect to LLSs in NMR spectra is achieved; contrast enhancements of more than 1200 are feasible. This enables efficient suppression of longitudinal spin magnetization in NMR allowing one to look selectively at LLSs. Using this method we have demonstrated that not only spectral but also spatial contrast can be achieved: we have obtained spatial NMR images with strongly improved contrast originating from the difference of LLS lifetimes at different positions in the sample. (C) 2015 Elsevier Inc. All rights reserved.