论文标题
简而言之
The localization regime in a nutshell
论文作者
论文摘要
如今，高扩散敏感的磁场梯度已经越来越多地应用以获得微观结构的更好表征。随着所得的自旋回波信号显着偏离常规高斯形式，已采用各种模型来解释这些偏差，并将它们与样品的微结构特性联系起来。在本文中，我们认为信号的非高斯行为是Bloch-Torrey方程的一般普遍特征。我们提供了一个简单而严格的描述，对在高扩展梯度下出现的本地化状态进行了简单的描述，并将其起源确定为在反射边界处的对称性破裂。我们将随之而来的非高斯信号衰减与其他扩散NMR状态（例如慢扩散，运动纳入和扩散 - 分化状态）进行了比较。我们强调传统扰动技术的局限性，并提倡非扰动方法的倡导者，这可能会为该领域的新成像方式铺平方法。
High diffusion-sensitizing magnetic field gradients have been more and more often applied nowadays to achieve a better characterization of the microstructure. As the resulting spin-echo signal significantly deviates from the conventional Gaussian form, various models have been employed to interpret these deviations and to relate them with the microstructural properties of a sample. In this paper, we argue that the non-Gaussian behavior of the signal is a generic universal feature of the Bloch-Torrey equation. We provide a simple yet rigorous description of the localization regime emerging at high extended gradients and identify its origin as a symmetry breaking at the reflecting boundary. We compare the consequent non-Gaussian signal decay to other diffusion NMR regimes such as slow-diffusion, motional-narrowing and diffusion-diffraction regimes. We emphasize limitations of conventional perturbative techniques and advocate for non-perturbative approaches which may pave a way to new imaging modalities in this field.
