结构特异性磁场不均匀性及其对相关时间的影响。

Structure-specific magnetic field inhomogeneities and its effect on the correlation time.

作者信息

Ziener Christian H, Bauer Wolfgang R, Melkus Gerd, Weber Thomas, Herold Volker, Jakob Peter M

机构信息

Bayerische Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, 97074 Würzburg, Germany.

出版信息

Magn Reson Imaging. 2006 Dec;24(10):1341-7. doi: 10.1016/j.mri.2006.08.005. Epub 2006 Oct 4.

DOI:10.1016/j.mri.2006.08.005

PMID:17145406

Abstract

We describe the relationship between the correlation time and microscopic spatial inhomogeneities in the static magnetic field. The theory takes into account diffusion of nuclear spins in the inhomogeneous field created by magnetized objects. A simple general expression for the correlation time is obtained. It is shown that the correlation time is dependent on a characteristic length, the diffusion coefficient of surrounding medium, the permeability of the surface and the volume fraction of the magnetized objects. For specific geometries (spheres and cylinders), exact analytical expressions for the correlation time are given. The theory can be applied to contrast agents (magnetically labeled cells), capillary network, BOLD effect and so forth.

摘要

我们描述了静态磁场中关联时间与微观空间不均匀性之间的关系。该理论考虑了核自旋在由磁化物体产生的非均匀场中的扩散。得到了关联时间的一个简单通用表达式。结果表明，关联时间取决于一个特征长度、周围介质的扩散系数、表面磁导率以及磁化物体的体积分数。对于特定的几何形状（球体和圆柱体），给出了关联时间的精确解析表达式。该理论可应用于造影剂（磁性标记细胞）、毛细血管网络、血氧水平依赖效应等。