Functional Imaging of Tendon

Tendons are composed of cells, blood vessels and extracellular matrix, intricately woven together to form a vital musculoskeletal connective tissue. They act as a mechanical buffer for transmitting forces generated in muscles to bones, thus enabling movement. There is a growing need for functional imaging of tendon, for example to provide noninvasive biochemical and biomechanical insight into injured, diseased or repairing tendon. This study focuses on ex vivo imaging using a novel combination of state of the art imaging technology, specifically ultra-high field magnetic resonance imaging (MRI) and near infrared-multiphoton laser scanning microscopy (NIR-MPLSM). We show that both imaging modalities are able to distinguish between normal and damaged tendon. MR imaging revealed macroscopic changes and evidence of tissue disruption; high signal intensity corresponding to surrounding sheaths and some intra-tendinous regions. NIR-MPLSM demonstrated that local interactions between collagen and other matrix components are altered in enzyme-digested tendon. We propose a novel method for quantifying tendon disruption based on tendon crimp waveform parameterisation. Our findings suggest that MRI and NIR-MPLSM are useful technologies for extracting functional information from tendon. We provide insight into how biomechanical properties are related to biochemical parameters, and thus consider the future of in vivo functional MR imaging of tendon.