The Structural Dependence of CRAZED Imaging

描述（由申请人提供）： 该提案的总体目标是进一步开发和了解可从基于在组织中的水中创建分子间多量子相干性（IMQC）的新型MR成像技术获得的信息，并评估这种新的成像技术和用于表征组织结构的对比机制的潜力。IMQC成像仅在六年前首次展示，它提供了与传统MR成像方法相比在概念上不同且可能更有价值的材料属性信息。然而，尽管在使用这种新的方法作为成像中的对比机制的广泛兴趣，很少的工作已经执行，以证明如何IMQC信号取决于生物学感兴趣的组织特性。因此，我们的目标是阐明IMQC-MRI的信号依赖于组织结构，弛豫时间，扩散，化学位移异质性，和脉冲序列定时。具体来说，我们将调查的CRAZED（COSY改造与非对称z梯度回波检测）成像序列的样本结构的依赖性，以及这种依赖性是如何影响的样本特性和脉冲序列参数。先前的工作已经证明，CRAZED信号可以被调谐为仅对由实验施加的场梯度的性质所确定的特定尺寸分离的那些自旋敏感。这种依赖性提供了独特的用户可控的对比度机制。然而，最近的研究结果提出了质疑，这种结构的敏感性在体内的弛豫时间和依赖于任何这样的影响的脉冲序列的定时。我们的目标是澄清影响这种依赖性的因素。

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.