Bauer W R, Schulten K
Beckman Institute, University of Illinois, Urbana 61801.
Magn Reson Med. 1992 Jul;26(1):16-39. doi: 10.1002/mrm.1910260104.
The role of diffusive transport on the enhancement of nuclear spin relaxation through NMR contrast agents is described by means of diffusion-Bloch equations. These equations are solved in the mean relaxation time approximation [W. Nadler and K. Schulten, J. Chem. Phys. 82, 151-160 (1985)]. A model presented considers relaxation enhancement in tissue in which contrast agents confined to intravascular spaces affect nuclear spin in the extravascular volume. We show how the mean relaxation time depends on capillary density, on permeability, and on diffusion. A second model describes enhanced phase relaxation of liver tissue in the presence of magnetic particles in Kupffer cells. The relationship between relaxation rate and density of Kupffer cells is investigated. The diagnostic value of enhanced nuclear relaxation in the presence of contrast agents is discussed on the basis of the systematic mathematical results obtained.
通过扩散 - 布洛赫方程描述了扩散输运在通过核磁共振造影剂增强核自旋弛豫方面的作用。这些方程是在平均弛豫时间近似下求解的[W. 纳德勒和K. 舒尔滕，《化学物理杂志》82, 151 - 160 (1985)]。所提出的一个模型考虑了组织中的弛豫增强，其中局限于血管内空间的造影剂会影响血管外体积中的核自旋。我们展示了平均弛豫时间如何取决于毛细血管密度、渗透率和扩散。第二个模型描述了在枯否细胞中存在磁性颗粒时肝脏组织增强的相位弛豫。研究了弛豫率与枯否细胞密度之间的关系。基于所获得的系统数学结果，讨论了在存在造影剂的情况下增强核弛豫的诊断价值。
