Summary

In vitro structure analysis of articular cartilage has recently been performed using diffusion tensor imaging (DTI) based on NMR imaging. We performed intravital imaging of human articular cartilage in vivo. Ultra-high-speed echo planar imaging (EPI) was optimized to provide images both in vivo and in vitro. While these images were obtained rapidly, and the resolution was lower than NMR, DTI of the structure of the articular cartilage was achieved. The structure was found to be different between images obtained in vivo vs. those obtained in vitro. The in vivo structural condition of the articular cartilage was elucidated. Purpose: The articular cartilage is a small tissue with matrix structure of three layers between which the orientation of collagen fiber differs. A diffusion weighted twice-refocused spin echo EPI sequence was optimized for the articular cartilage and the structure of the three layers of human articular cartilage was imaged in vivo from diffusion tensor images. Materials and Methods: The subjects imaged were 5 specimens of swine femur head after removal of the flesh around the knee joint, 5 specimens of swine articular cartilage with flesh present and the knee cartilage of five adult male volunteers. Based on diffusion-weighted image