NEW METHOD FOR MRI BASED ON DETECTION OF INTERMOLECULAR ZERO QUANTUM COHERENCES

MRI中的对比度很大程度上基于自旋密度的变化， 弛豫时间，有时通过注射造影剂增强， 作为钆化合物。 这些参数之间的关系 并且组织形态并不总是唯一的。 因此， 在某些应用中，这些参数的组合不能给出 足够的对比度。 即使有脑成像，特别是在 随着功能性磁共振成像领域的迅速扩大， 限制因素。 因此，增强对比度的新方法可以 改善软组织表征，特别是如果它们相关 具有重要的生理特征。 在这里，我们展示了一个 一种基于“不可能”分子间检测的新型MRI 多量子相干（iMQCs），特别是零量子相干 相干性（iZQC），对应于同时翻转两个 水分子在10毫米到1毫米的距离内以相反的方向旋转 毫米 iZQC线宽（因此图像对比度）由下式确定： 局部磁化率变化 这些变化是生理上的 重要（例如，它们受组织氧梯度的影响 体内），但不能通过其它成像方法直接测量。 我们 已经获得了幻影图像，并在扩展这项工作的过程中， 人类研究。 我们预计iZQC生成的对比度可能是 由于敏感性与肿瘤的大小和大小相关， 氧气浓度。

Contrast in MRI is largely based on variations in spin density or relaxation times, sometimes enhanced by injected contrast agents such as gadolinium compounds. The relationship between these parameters and tissue morphology is not always unique. Thus it is not surprising that in some applications no combination of these parameters gives sufficient useful contrast. Even with brain imaging, particularly in the rapidly expanding field of functional MRI, contrast is frequently the limiting factor. New methods for contrast enhancement could thus improve soft tissue characterization, particularly if they correlate with physiologically important characteristics. Here we demonstrate a new type of MRI based on detection of "impossible" intermolecular multiple-quantum coherences (iMQCs), specifically the zero-quantum coherences (iZQCs) which correspond to simultaneously flipping two water spins in opposite directions on molecules separated by 10mm to1 mm. The iZQC linewidth (hence the image contrast) is determined by local susceptibility variations. These variations are physiologically important (for example, they are affected by tissue oxygen gradients in vivo) but are not directly measured by other imaging methods. We have obtained phantom images and in the process of extending this work to human studies. We expect that contrast generated by iZQC might be useful in the detection of small tumor since susceptibility correlates with oxygen concentration.