Diffusion coefficients of articular cartilage for different CT and MRI contrast agents
Diffusion coefficients of articular cartilage for different CT and MRI contrast agents
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DOI：
10.1016/j.medengphy.2010.06.002
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发表时间：
2010-10-01
影响因子：
2.2
通讯作者：
Toyras, J.
中科院分区：
文献类型：
--
作者：
Kulmala, K. A. M.;Korhonen, R. K.;Toyras, J.
在对比增强磁共振成像（MRI）和计算机断层扫描（CT）中，阴离子造影剂的平衡分布有望反映关节软骨的固定电荷密度（FCD）。扩散主要负责将造影剂输送到软骨中。在骨关节炎中，软骨成分在疾病的早期阶段发生变化，并且溶质扩散最有可能受到影响。因此，造影剂扩散的研究可以使软骨成分成像的新方法成为可能。本研究的目的是确定四种造影剂（碘克沙酸盐、钆喷酸盐、碘化物、钆双胺）在牛关节软骨中的扩散系数。造影剂的分子大小和电荷不同。在外周定量CT实验中，允许造影剂通过关节面或深层软骨渗透到组织中。为了确定扩散系数，根据菲克定律的有限元模型拟合实验数据。每种造影剂通过关节面的扩散均快于通过深层软骨。对于任一运输方向，原子大小的碘化物比其他三种造影剂显著更快（q < 0.05）地扩散到软骨中。所有临床造影剂（碘克酸盐、钆喷酸盐和钆双胺）的扩散系数相对较低（142.8-253.7 μ m（2）/s）。在临床诊断中，这种缓慢的扩散可能无法达到平衡，这会危及通过标准方法测定FCD。然而，通过关节面和深层软骨的扩散之间的差异，其特征在于不同的组织组成，表明扩散系数可能与软骨组成。因此，本方法可以通过确定软骨组织内的扩散系数来实现软骨组成的基于图像的评估。(c)2010年，妇女平等问题国际研究所。由爱思唯尔有限公司出版。保留所有权利。
In contrast enhanced magnetic resonance imaging (MRI) and computed tomography (CT), the equilibrium distribution of anionic contrast agent is expected to reflect the fixed charged density (FCD) of articular cartilage. Diffusion is mainly responsible for the transport of contrast agents into cartilage. In osteoarthritis, cartilage composition changes at early stages of disease, and solute diffusion is most likely affected. Thus, investigation of contrast agent diffusion could enable new methods for imaging of cartilage composition. The aim of this study was to determine the diffusion coefficient of four contrast agents (ioxaglate, gadopentetate, iodide, gadodiamide) in bovine articular cartilage. The contrast agents were different in molecular size and charge. In peripheral quantitative CT experiments, penetration of contrast agent into the tissue was allowed either through the articular surface or through deep cartilage. To determine diffusion coefficients, a finite element model based on Fick's law was fitted to experimental data. Diffusion through articular surface was faster than through deep cartilage with every contrast agent. Iodide, being of atomic size, diffused into the cartilage significantly faster (q < 0.05) than the other three contrast agents, for either transport direction. The diffusion coefficients of all clinical contrast agents (ioxaglate, gadopentetate and gadodiamide) were relatively low (142.8-253.7 mu m(2)/s). In clinical diagnostics, such slow diffusion may not reach equilibrium and this jeopardizes the determination of FCD by standard methods. However, differences between diffusion through articular surface and deep cartilage, that are characterized by different tissue composition, suggest that diffusion coefficients may correlate with cartilage composition. Present method could therefore enable image-based assessment of cartilage composition by determination of diffusion coefficients within cartilage tissue. (c) 2010 IPEM. Published by Elsevier Ltd. All rights reserved.