Three-dimensional Imaging of Tongue Granulation Tissue Using Synchrotron- based Phase-contrast Techniques

X-ray phase-contrast imaging（PCI）is used to visualize phase shifts that occur when X-rays pass through a specimen, which enables ultra-sensitive imaging of soft tissues composed of light elements. PCI has been shown to be approximately 1000 times more sensitive to light elements than conventional absorption contrast. This makes it possible to distinguish between extremely small differences in density and to clearly visualize the fine structure of soft tissue. The aim of this study was to achieve high-resolution, three-dimensional reconstruction of tongue tissue and evaluate the effects of embedding materials（10 ％ neutral buffered formalin［formalin］, low-temperature polymerized acrylic resin［resin］, and 1％ agar［agar］）on the quality of PCI acquisition, using tongue granulation tissue as a sample. Absorption, refraction angle, and ultra-small-angle X-ray scattering images were extracted from the raw data and subjected to three-dimensional（3D）reconstruction. Sagittal images of the tongue showed that the refraction-angle image of samples embedded in acrylic resin provided the clearest visualization of granulation tissue structure. 3D reconstructed refraction-angle images of acrylic resin- and agarose-embedded samples captured the filiform papillae on the tongue tissue surface. Embedding materials thus significantly affects image quality in PCI analysis of soft tissues. Collectively, these findings suggest that high-clarity images and three-dimensional structural details obtained using PCI can provide valuable information for improving diagnostic imaging techniques and formulating treatment plans.