Three-dimensional characterization of the microstructure in rabbit patella–patellar tendon interface using propagation phase-contrast synchrotron radiation microtomography

Understanding the three-dimensional ultrastructure morphology of tendon-to-bone interface may allow the development of effective therapeutic interventions for enhanced interface healing. This study aims to assess the feasibility of propagation phase-contrast synchrotron radiation microtomography (PPC-SRµCT) for three-dimensional characterization of the microstructure in rabbit patella–patellar tendon interface (PPTI). Based on phase retrieval for PPC-SRµCT imaging, this technique is capable of visualizing the three-dimensional internal architecture of PPTI at a cellular high spatial resolution including bone and tendon, especially the chondrocytes lacuna at the fibrocartilage layer. The features on the PPC-SRµCT image of the PPTI are similar to those of a histological section using Safranin-O staining/fast green staining. The three-dimensional microstructure in the rabbit patella–patellar tendon interface and the spatial distributions of the chondrocytes lacuna and their quantification volumetric data are displayed. Furthermore, a color-coding map differentiating cell lacuna in terms of connecting beads is presented after the chondrocytes cell lacuna was extracted. This provides a more in-depth insight into the microstructure of the PPTI on a new scale, particularly the cell lacuna arrangement at the fibrocartilage layer. PPC-SRµCT techniques provide important complementary information to the conventional histological method for characterizing the microstructure of the PPTI, and may facilitate in investigations of the repair mechanism of the PPTI after injury and in evaluating the efficacy of a different therapy.

The 3D characteristics of post-traumatic syringomyelia in a rat model: a propagation-based synchrotron radiation microtomography study

Many published literature sources have described the histopathological characteristics of post-traumatic syringomyelia (PTS). However, three-dimensional (3D) visualization studies of PTS have been limited due to the lack of reliable 3D imaging techniques. In this study, the imaging efficiency of propagation-based synchrotron radiation microtomography (PB-SRµCT) was determined to detect the 3D morphology of the cavity and surrounding microvasculature network in a rat model of PTS. The rat model of PTS was established using the infinite horizon impactor to produce spinal cord injury (SCI), followed by a subarachnoid injection of kaolin to produce arachnoiditis. PB-SRµCT imaging and histological examination, as well as fluorescence staining, were conducted on the animals at the tenth week after SCI. The 3D morphology of the cystic cavity was vividly visualized using PB-SRµCT imaging. The quantitative parameters analyzed by PB-SRµCT, including the lesion and spared spinal cord tissue area, the minimum and maximum diameters in the cystic cavity, and cavity volume, were largely consistent with the results of the histological assessment. Moreover, the 3D morphology of the cavity and surrounding angioarchitecture could be simultaneously detected on the PB-SRµCT images. This study demonstrated that high-resolution PB-SRµCT could be used for the 3D visualization of trauma-induced spinal cord cavities and provides valuable quantitative data for cavity characterization. PB-SRµCT could be used as a reliable imaging technique and offers a novel platform for tracking cavity formation and morphological changes in an experimental animal model of PTS.