X-ray CT in Phase Contrast Enhancement Geometry of Alginate Microbeads in a Whole-Animal Model.

Imaging soft biomaterials in vivo is a significant challenge, as most conventional techniques are limited by biomaterial contrast, penetration depth, or spatial resolution. Exogeneous contrast agents used to increase contrast may also alter material properties or exhibit local toxicity. The capability to observe biomaterial constructs in vivo without introducing exogenous contrast would improve preclinical testing and evaluation. Conventional X-ray Computed Tomography allows fast, high-resolution imaging at high penetration depth, but biomaterial contrast is low. Previous studies employing X-ray phase contrast (XPC) and utilizing a synchrotron source provided support for the significant potential of XPC in imaging biomaterials without contrast agents. In this study, XPC tomography was used to image alginate hydrogel microspheres within a small animal omental pouch model using a commercially available X-ray source. Multilayer microbeads could be identified in the XPC images with volumetric and structural information not possible in histological analysis. The number of microbeads present and microbead volume and diameter could be quantified from the images. The results of this study show that XPC tomography can be a useful tool for monitoring of implanted soft biomaterials in small animal models.