Meder R, de Visser S K, Bowden J C, Bostrom T, Pope J M
School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, Australia.
Osteoarthritis Cartilage. 2006 Sep;14(9):875-81. doi: 10.1016/j.joca.2006.03.002. Epub 2006 Apr 24.
To use diffusion tensor MR micro-imaging to observe differences in magnitude and anisotropy of water diffusion between 'healthy' cartilage and cartilage enzymatically degraded to simulate arthritic damage.
Diffusion tensor images (156 x 156 microm in-plane resolution, 2mm slice thickness) of bovine cartilage were obtained at either 4.7 or 7.0 T using pulsed field gradient spin echo sequences. The parameters determined were: maximum and mean diffusivity, direction of the maximum diffusion eigenvector with respect to the normal to the articular surface and fractional anisotropy (FA) of diffusion.
Both maximum and mean diffusion eigenvalues were found to decrease, respectively, from approximately 1.95 x 10(-9) and 1.80 x 10(-9) m2 s(-1) at the articular surface to approximately 1.08 x 10(-9) and 0.79 x 10(-9) m2 s(-1) in the deep zone. A systematic change was observed in the direction of the eigenvector corresponding to maximum diffusivity, reflecting the expected change in orientation of the collagen macrofibrillar bundles. Degradation with trypsin to remove proteoglycans resulted in a 10-15% increase in apparent diffusion coefficient of water in the cartilage, with no apparent change in FA.
These methods have the potential to be used to probe local changes in tissue microstructure and the hydrodynamic status of cartilage during development of osteoarthritis.
运用扩散张量磁共振显微成像技术，观察“健康”软骨与经酶降解模拟关节炎损伤的软骨之间水扩散的大小和各向异性差异。
使用脉冲场梯度自旋回波序列，在4.7或7.0T场强下获取牛软骨的扩散张量图像（平面分辨率为156×156微米，切片厚度为2毫米）。测定的参数包括：最大扩散率和平均扩散率、最大扩散特征向量相对于关节表面法线的方向以及扩散的分数各向异性（FA）。
发现最大和平均扩散特征值分别从关节表面的约1.95×10⁻⁹和1.80×10⁻⁹平方米每秒降至深层区域的约1.08×10⁻⁹和0.79×10⁻⁹平方米每秒。观察到对应最大扩散率的特征向量方向有系统性变化，反映了胶原大纤维束方向的预期变化。用胰蛋白酶降解以去除蛋白聚糖导致软骨中水的表观扩散系数增加10 - 15%，FA无明显变化。
这些方法有潜力用于探究骨关节炎发展过程中软骨组织微观结构和流体动力学状态的局部变化。
