In vivo monitoring of bone microstructure by propagation-based phase-contrast computed tomography using monochromatic synchrotron light

Abstract

Hard X-ray phase-contrast imaging is sensitive to density variation in objects and shows a dose advantage for in vivo observation over absorption-contrast imaging. We examined the capability of propagation-based phase-contrast tomography (PB-PCT) with single-distance phase retrieval for tracking of bone structure and mineral changes using monochromatic synchrotron light. Female mice underwent ovariectomy and drill-hole surgery in the right tibial diaphysis and were divided into two groups: OVX and OVX-E (n = 6 each); the latter group was treated with intraperitoneal administration of 14,15epoxyeicosatrienoic acid (14,15-EET) for promoting bone repair. Age-matched mice subjected to sham ovariectomy and drill-hole surgery (Sham) were also prepared (n = 6). In vivo CT scans of the drilled defect were acquired 3, 7, and 11 days after surgery, and tomographic images were matched by three-dimensional registration between successive time points for monitoring the process of defect filling. In addition, using absorption-contrast CT as the reference method, the validity of PB-PCT was evaluated in one mouse by comparing images of tibial metaphyseal bone between the two methods in terms of bone geometry as well as the measure of mineralization. Although phase retrieval is strictly valid only for single-material objects, PB-PCT, with its lower radiation dose, could provide a depiction of bone structure similar to that from absorptioncontrast CT. There was a significant correlation of linear absorption coefficients between the two methods, indicating the possibility of a rough estimate of the measure of mineralization by PB-PCT. Indeed, delayed bone regeneration (OVX vs. Sham) and the efficacy of 14,15-EET for improving osteoporotic bone repair (OVX-E vs. OVX) could be detected in both bone volume and mineralization by PB-PCT. Thus, in combination with single-distance phase retrieval, PB-PCT would have great potential for providing a valuable tool to track changes in bone structure and mineralization, and for evaluating the effects of therapeutic interventions as well.

Computed Tomography as a Characterization Tool for Engineered Scaffolds with Biomedical Applications

“…Additionally, to obtain optimal results in terms of both 3D reconstructed images and data sets to be used for quantitative measurements, phase contrast performed using conventional CT scanners [44][45][46] or synchrotron radiation sources [47][48][49][50][51] have been largely exploited. While the working principle of CT scanning is based on different X-ray absorbencies within the tested specimen, phase contrast scanning relies on the shift of the X-ray after passing through the scanned object [52].…”

MRI overestimates articular cartilage thickness and volume compared to synchrotron radiation phase-contrast imaging

“…One unique imaging method is synchrotron radiation phase-contrast imaging computed tomography (SR-PCI). In a synchrotron, high-energy electromagnetic radiation is emitted by electrons moving at speeds close to that of light [ 32 , 33 ]. SR enables high-resolution imaging because it has high photon flux, stable sources, and an energy density 1000 times higher than conventional X-ray absorption imaging [ 34 , 35 ].…”

Characterize the microstructure change after tendon enthesis injury using synchrotron radiation μCT

“…In the research field, the application of SRμCT has shown superior 3D visualization capacity of cartilage, bone, and cartilage interface 15–19 . Aiming for better image quality, Matsumoto et al compared the imaging capacity between phase retrieval imaging versus conventional absorption imaging, and they confirmed that the phase contrast method did acquire considerably higher SNR and minimized edge‐enhancement effect 20 . Here in this study, SR‐based phase‐contrast μCT may provide us with a promising method to visualize the tissue components across BTI, at both native and injured status.…”