同步辐射显微CT的人关节软骨三维成像研究

目的:探讨同步辐射显微CT(SR-μCT)相位对比技术成像研究人软骨细微组织结构的可行性。方法:3例直径约1mm,高度约4mm的圆柱状离体人软骨(正常1例,轻度损伤1例,重度损伤1例)样本,经4%甲醛溶液固定后行SR-μCT扫描,扫描后将原始投影图像相位恢复,切片重构及三维重建,而后与病理图片对照,对比分析SR-μCT图像的细胞形态,大小及排列方式;比较正常标本与软骨损伤标本的胶原原纤维网的改变。结果:SR-μCT重建图像可以清楚显示软骨细胞、软骨陷窝及排列方式,与病理切片高度吻合。经MIP重建,可以显示软骨基质内的胶原原纤维网,正常软骨呈垂直于软骨下骨面的平行排列,其横截面呈拱形网状,轻度软骨损伤标本纵向呈弯曲状排列,其横截面可见轻度塌陷,重度软骨损伤表现为横截面明显塌陷,纵切面纤维排列紊乱。结论:SR-μCT可实现软骨细胞水平的成像,经合适阈值处理,可以显示胶原原纤维网三维结构。

Three-dimensional Imaging of Articular Cartilage in Human Using Synchrotron Radiation Micro-computer Tomography

Objective: To investigate the feasibility of detecting microstructure in human articular cartilage with Synchrotron Radiation Micro-Computer Tomography. Methods: Three cylindrical cartilage-bone plugs with approximate 1mm in diameters and 4mm in heights were harvested from the joint of human knee. The three specimens were performed by SR-μCT after being soaked in 4% formalin solution. The original projection images of SR-μCT were processed by phase retrieval, slice and 3D reconstruction. Then we compared the size, shape, orientation of chondrocytes with pathologic pictures and analyzed the differences of orientation of collagen framework between normal and damaged cartilage. Results: The size, shape, distribution of chondrocytes and lacunas can be clearly demonstrated on reconstructed images of SR-μCT. The results were in accordance with pathological pictures. On Maximum intensity projection(MIP) images the orientation of collagen framework was revealed. Collagen fiber structure was in a vertical direction through the cartilage with arcade structure on surface in normal cartilage. And the collagen fibrils were deformed in the vertical direction with their axial low-grade collapse in mild cartilage damage. As to severe cartilage damage, the collagen framework was disordered and there was a severe collapse in axial direction. Conclusion: SR-μCT can demonstrate a true cellular resolution for human articular cartilage and clearly show the three-dimensional structure of collagen framework by selecting appropriate threshold value.