Imaging the Depth-Dependent Anisotropies in Articular Cartilage by Multidisciplinary Microscopies (μMRI, PLM, FTIRI)

The purpose of this study is to correlate the depth-dependent anisotropic information in articular cartilage from multidisciplinary high-resolution imaging techniques, including microscopic MRI (μMRI), polarized light microscopy (PLM) and Fourier-transform infrared imaging (FTIRI). Each imaging technique can produce an anisotropy map of the tissue based on a unique physical mechanism: nuclear dipole interaction in magnetic resonance, molecular bond orientation in infrared, and optical birefringence in polarized light. We show that the standard deviation profiles for both IR and T₂ anisotropics in articular cartilage have several distinct features that are common to the retardation profiles from PLM, all of them characterize the randomness of the collagen fibril network, which is a key parameter for the healthy status of the tissue.