Magnetic Resonance Line Shape of Water as a Probe of the Structure of Biological Tissue

水在磁性非均匀组织中的NMR线形状已知偏离洛伦兹形状。最近提出了一种新的描述，使用有效介质理论，它最初是在凝聚态物理中发展起来的，用于描述无序介质中的输运。在这个描述中的中心量是介质平均传播子的自能部分。在本MRI上下文中，它可以被解释为取决于谱域中的频率的横向弛豫速率。这种相关性可以作为组织结构的探针，产生其特征相关长度和无序强度的度量。首次应用于血液水光谱证明了该方法的潜力。本项目的目的是利用这种潜力来开发和验证用于研究体内细胞相关的异质磁结构的方法。该方法将在血液中作为一个相对简单和充分研究的系统进行开发和优化。然后，该方法将扩展到其他细胞物种的悬浮液中的测量。该方法的第一个试点应用将是表征动物模型中的肿瘤细胞结构和检测正常人脑中铁蛋白分布的参数。这些应用的目的是利用方法的潜力和激励未来的研究。

The NMR line shape of water in magnetically heterogeneous tissues is known to deviate from the Lorentzian shape. A novel description was proposed recently using the effective medium theory, which has been originally developed within condensed matter physics to describe transport in disordered media. The central quantity in this description is the self-energy part of the medium- averaged propagator. In the present MRI context, it can be interpreted as a transverse relaxation rate that depends on the frequency in the spectral domain. This dependence can be used as a probe of tissue structure yielding its characteristic correlation length and a measure of the dis- order strength. The first application to blood water spectroscopy demonstrated the potential of the method. The present project aims at using this potential to develop and verify methods for investigating cell-related heterogeneous magnetic structure in vivo. The method will be developed and optimized in blood as a relative simple and well studied system. The method will then be extended for measurements in suspensions of other cell species. First pilot applications of the method would be characterisation of tumour cellular structure in animal model and detection of parameters of the ferritin distribution in the normal human brain. These applications are aimed at exploiting the method potential and motivating future studies.