NMR diffusion-encoding with axial symmetry and variable anisotropy: Distinguishing between prolate and oblate microscopic diffusion tensors with unknown orientation distribution
NMR diffusion-encoding with axial symmetry and variable anisotropy: Distinguishing between prolate and oblate microscopic diffusion tensors with unknown orientation distribution
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DOI：
10.1063/1.4913502
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发表时间：
2015-03-14
影响因子：
4.4
通讯作者：
Topgaard, Daniel
中科院分区：
文献类型：
--
作者：
Eriksson, Stefanie;Lasic, Samo;Topgaard, Daniel
我们引入了一种核磁共振方法，用于根据新的扩散各向异性度量 D-Delta 来量化轴对称微观扩散张量的形状，D-Delta 对于扁圆、球形和扁长张量形状具有唯一的值。脉冲序列包括一系列等幅磁场梯度脉冲对，其方向被定制以给出具有可变各向异性b(Delta)的轴对称扩散编码张量b。对张量 b 的对称轴的一系列方向获取的数据进行平均使得该方法对微观扩散张量的方向分布函数不敏感。对多域溶致液晶中的水进行原理验证实验，其几何形状可产生扁圆形、球形和长方形的微观扩散张量。该方法可用于表征多孔固体、软物质和生物组织中充满液体的隔室的几何形状。 (C) 2015 年作者。
We introduce a nuclear magnetic resonance method for quantifying the shape of axially symmetric microscopic diffusion tensors in terms of a new diffusion anisotropy metric, D-Delta, which has unique values for oblate, spherical, and prolate tensor shapes. The pulse sequence includes a series of equal-amplitude magnetic field gradient pulse pairs, the directions of which are tailored to give an axially symmetric diffusion-encoding tensor b with variable anisotropy b(Delta). Averaging of data acquired for a range of orientations of the symmetry axis of the tensor b renders the method insensitive to the orientation distribution function of the microscopic diffusion tensors. Proof-of-principle experiments are performed on water in polydomain lyotropic liquid crystals with geometries that give rise to microscopic diffusion tensors with oblate, spherical, and prolate shapes. The method could be useful for characterizing the geometry of fluid-filled compartments in porous solids, soft matter, and biological tissues. (C) 2015 Author(s).