The Structural Dependence of CRAZED Imaging

描述(由申请人提供)： 这项建议的总体目标是进一步开发和理解从一种新的磁共振成像技术中获得的信息，该成像技术基于组织中水中分子间多量子相干(IMQC)的产生，并评估这种新的成像技术和对比机制在表征组织结构方面的潜力。IMQC成像在六年前才首次展示，它提供了与传统磁共振成像方法相比在概念上不同且潜在更有价值的材料特性信息。然而，尽管人们普遍对使用这种新方法作为成像中的对比机制感兴趣，但很少有人研究IMQC信号如何依赖于生物学上感兴趣的组织特性。因此，我们的目标是阐明IMQC-MRI中的信号依赖于组织结构、弛豫时间、扩散、化学位移异质性和脉冲序列时间。具体地说，我们将研究CRAZED(COSY REVERVIZED WITH AYMARY Z GRAPHER ECHO DISTING)成像序列对样品结构的依赖性，以及这种依赖性如何受样品特性和脉冲序列参数的影响。以前的工作已经证明，疯狂的信号可以被调谐为只对那些被特定维度分开的自旋敏感，该维度由实验施加的场梯度的性质决定。这种依赖提供了一种独特的用户可控的对比机制。然而，最近的结果质疑了体内松弛时间这种结构敏感性的存在，以及对脉冲序列计时的任何这种影响的依赖性。我们的目标是澄清影响这种依赖的因素。

DESCRIPTION (provided by applicant): The overall aims of this proposal are to further develop and understand the information obtainable from a novel MR imaging technique based on the creation of intermolecular multiple quantum coherences (IMQC) in water in tissues, and to evaluate the potential of this new imaging technique and contrast mechanism for characterizing tissue structure. IMQC imaging was first demonstrated only six years ago, and it provides information on material properties that are conceptually different and potentially more valuable compared to conventional MR imaging methods. However, despite the widespread interest in using this new approach as a contrast mechanism in imaging, little work has been performed to demonstrate how IMQC signals depend on tissue properties of biological interest. We therefore aim to elucidate the signal dependence in IMQC-MRI on tissue structure, relaxation times, diffusion, chemical shift heterogeneity, and pulse sequence timings. Specifically, we will investigate the dependence of the CRAZED (COSY revamped with asymmetric z gradient echo detection) imaging sequence on sample structure, and how this dependence is influenced by the sample characteristics and pulse sequence parameters. Previous work has demonstrated that the CRAZED signal can be tuned to be sensitive only to those spins that are separated by a specific dimension that is determined by the nature of a field gradient imposed by the experiment. Such a dependence offers a unique user-controllable contrast mechanism. However, recent results have called into question the existence of this structural sensitivity at in vivo relaxation times and the dependence on any such effect on the pulse sequence timings. We aim to clarify the factors that affect this dependence.