Advancing three-dimensional tendon imaging using laboratory X-ray phase contrast techniques and refined sample preparation

Abstract Tendinopathy is of great socio-economic importance, with high rates of prevalance in both athletic and non-athletic populations. Despite this, there remains limited understanding of the three-dimensional macro and microscopic anatomy and its significance in health, clinical and sub-clinical disease due to difficulties in gaining three-dimensional images of tissue volumes. Although histology is considered the gold standard for pre-clinical tendon imaging, the tissue is notoriously difficult to process and section, leading to a high incidence of artefacts. X-ray phase contrast imaging (XPCi) is becoming increasingly important with regards to three-dimensional imaging of biological tissues, and has shown promise in tendon imaging with synchrotron radiation, however laboratory based imaging and associated sample preparation protocols have yet to be validated. samples in this work, equine superficial digital flexor tendons were prepared using various combinations of PBS, 10% neutral buffered formalin, 70% and 100% ethanol and imaged using a laboratory based edge illumination XPCi system in a custom made 3D printed container. Consistent with other findings for tissue, contrast for tendon tissue was found to be maximised when dehydrated in ethanol, while the fixation medium has no notable affect on contrast.