Mass diffusion coefficient measurement for vitreous humor using FEM and MRI.
Mass diffusion coefficient measurement for vitreous humor using FEM and MRI.
复制标题
使用 FEM 和 MRI 测量玻璃体液的质量扩散系数。
DOI：
10.1088/1757-899x/297/1/012024
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Sadhal,SatwindarS
中科院分区：
文献类型：
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作者：
Rattanakijsuntorn,Komsan;Penkova,Anita;Sadhal,SatwindarS
在早期的研究中，发展了确定玻璃体扩散系数的“轮廓法”。该技术依赖于将MRI造影剂（替代药物）小心地注射到新鲜牛眼的玻璃体中，并及时跟踪造影剂的轮廓。此外，还建立了基于点源模型的替代药物注射理论轮廓的解析解。将理论轮廓与实验轮廓以最小二乘拟合的方式匹配，同时浮动扩散系数，得到扩散系数的值。由于分析结果是基于点源模型的，因此该方法存在替代剂初始进样必须为球形或椭球体的局限性。本研究采用了一种新的有限元模型进行分析，该技术的限制大大减少，并且可以处理初始丸的不规则形状。采用新鲜牛眼进行药物在玻璃体中的扩散研究，并采用三种不同分子质量的造影剂：钆-二乙烯三胺五乙酸（Gd-DTPA, 938 Da）、非离子型加多啶醇（Prohance, 559 Da）和牛白蛋白偶联钆（Galbumin, 74 kDa）作为药物替代品，通过MRI观察药物的扩散过程。建立了三维有限元模型来确定这些替代物与MRI图像的扩散系数。该方法可用于其他类型的生物多孔介质，只要浓度分布可以可视化（通过MRI或荧光等方法）。
In early studies, the'contour method'for determining the diffusion coefficient of the vitreous humor was developed. This technique relied on careful injection of an MRI contrast agent (surrogate drug) into the vitreous humor of fresh bovine eyes, and tracking the contours of the contrast agent in time. In addition, an analytical solution was developed for the theoretical contours built on point source model for the injected surrogate drug. The match between theoretical and experimental contours as a least square fit, while floating the diffusion coefficient, led to the value of the diffusion coefficient. This method had its limitation that the initial injection of the surrogate had to be spherical or ellipsoidal because of the analytical result based on the point-source model. With a new finite element model for the analysis in this study, the technique is much less restrictive and handles irregular shapes of the initial bolus. The fresh bovine eyes were used for drug diffusion study in the vitreous and three contrast agents of different molecular masses: gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA, 938 Da), non-ionic gadoteridol (Prohance, 559 Da), and bovine albumin conjugated with gadolinium (Galbumin, 74 kDa) were used as drug surrogates to visualize the diffusion process by MRI. The 3D finite element model was developed to determine the diffusion coefficients of these surrogates with the images from MRI. This method can be used for other types of bioporous media provided the concentration profile can be visualized (by methods such as MRI or fluorescence).