de Visser S K, Crawford R W, Pope J M
School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia.
Osteoarthritis Cartilage. 2008 Jan;16(1):83-9. doi: 10.1016/j.joca.2007.05.013. Epub 2007 Jul 12.
To demonstrate the use of diffusion tensor magnetic resonance micro-imaging to observe adaptations of collagen fibres to mechanical compression in articular cartilage.
Spin-echo and diffusion tensor images (156x156microm in-plane resolution, 2mm slice thickness) of bovine cartilage were obtained at a magnetic field of 7.0T in relaxed and compressed states. The parameters determined were: T2, maximum and mean diffusivity, direction of the maximum diffusion eigenvector and fractional anisotropy of diffusion.
A correlation was found between the compressive strain applied to the cartilage and the change in both magnitude and direction of the maximum diffusivity. Compression resulted in a decrease in both the maximum and mean eigenvalues, particularly in the surface and transitional zones, while the change in orientation of the eigenvectors corresponding to maximum diffusion was greatest in the transitional region. In this region, the average orientation of the principal eigenvectors with respect to the normal to the articular surface increased by up to 40 degrees, indicating that the collagen fibre bundles were oriented more parallel to the surface when compressed.
Diffusion tensor imaging can be used to monitor the changes in the direction of the collagen fibres due to compression. It may form the basis of a new non-invasive approach to functional evaluation of cartilage, with potential applications in the diagnosis and treatment of osteoarthritis.
证明使用扩散张量磁共振显微成像观察关节软骨中胶原纤维对机械压缩的适应性。
在7.0T磁场下，获取处于松弛和压缩状态的牛软骨的自旋回波和扩散张量图像（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：T2、最大扩散率和平均扩散率、最大扩散特征向量的方向以及扩散分数各向异性。
发现施加于软骨的压缩应变与最大扩散率的大小和方向变化之间存在相关性。压缩导致最大和平均特征值均降低，尤其是在表面和过渡区，而对应于最大扩散的特征向量方向变化在过渡区最大。在该区域，主特征向量相对于关节表面法线的平均方向增加了多达40度，表明胶原纤维束在压缩时更平行于表面排列。
扩散张量成像可用于监测由于压缩导致的胶原纤维方向变化。它可能构成一种新的软骨功能评估非侵入性方法的基础，在骨关节炎的诊断和治疗中具有潜在应用价值。
