RELAXATION OF SOLVENT PROTONS BY PARAMAGNETIC-IONS AND ITS DEPENDENCE ON MAGNETIC-FIELD AND CHEMICAL ENVIRONMENT - IMPLICATIONS FOR NMR IMAGING
RELAXATION OF SOLVENT PROTONS BY PARAMAGNETIC-IONS AND ITS DEPENDENCE ON MAGNETIC-FIELD AND CHEMICAL ENVIRONMENT - IMPLICATIONS FOR NMR IMAGING
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DOI：
10.1002/mrm.1910010407
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发表时间：
1984-01-01
影响因子：
3.3
通讯作者：
BROWN, RD
中科院分区：
文献类型：
--
作者：
KOENIG, SH;BROWN, RD
自近40年前首次观测到质子共振信号以来，顺磁离子已被用于改变溶剂水质子的磁弛豫率1/ t1和1/ t2。最早的弛豫理论表明，溶质顺磁离子对溶剂质子弛豫速率的影响既取决于溶质离子的化学环境，也取决于磁场强度。从那以后，关于水合离子（aquoions）溶液中的弛豫效应以及这些离子与大分子（主要是蛋白质）的复合物的弛豫效应，已经积累了大量的实验和理论知识。在这一点上，这种现象得到了很好的理解，尽管这种理解更多的是回顾性的，而不是对离子蛋白复合物的预测。尽管如此，从目前对均相溶液的了解，以及目前关于将顺磁性离子引入组织中，通过影响弛豫率来改变核磁共振图像对比度的报道来看，很明显，溶液的结果与组织研究特别相关，并且可转移。本文介绍了溶质顺磁离子（如水合离子和与蛋白质络合的顺磁离子）存在时溶剂质子弛豫的主要特征，重点介绍了与体内研究最相关的那些离子，并强调了磁场和这些离子的化学环境对溶剂质子弛豫速率的影响。
Paramagnetic ions have been used to alter the magnetic relaxation rates 1/T1and 1/T2of solvent water protons since the first observations of a proton resonance signal almost four decades ago. The earliest theories of relaxation indicated that the influence of solute paramagnetic ions on relaxation rates of solvent protons should depend both on the chemical environment of the solute ions and on the magnetic field strength. Much knowledge, both experimental and theoretical, has since been amassed regarding relaxation effects in solutions of hydrated ions (aquoions) and of complexes of these ions with macromolecules, mainly proteins. The phenomena are well understood at this point, though the understanding is more retrospective than predictive for ion‐protein complexes. Nonetheless, from what is now known about homogeneous solutions, and from current reports on the introduction of paramagnetic ions into tissue to alter contrast in NMR images by affecting relaxation rates, it is clear that the solution results are particularly germane, and transferable, to tissue investigations. The main features of relaxation of solvent protons in the presence of solute paramagnetic ions, as hydrated aquoions and complexed with protein, are presented here, with attention to those ions most relevant to in vivo studies, and with emphasis on the influence of the magnetic field and the chemical environment of these ions on solvent proton relaxation rates.