Improved Visualization of Polymer Foams using Talbot-Lau Grating Interferometry to Reduce Metal Artifacts

The sufficiency of bone fixation via ceramic or metallic implants largely depends on the osseointegration at the bone-implant interface and is of major importance in trauma, orthopedic, and maxillofacial surgery. Preclinical imaging via micro computed tomography (XCT) is the state-of-the-art solution to study the ingrowth of mineralized tissue at the bone-implant interface and to investigate the influence of innovative materials on the regeneration of bone tissue. However, a major challenge in XCT imaging is impaired image quality due to metallic objects such as implants and orthopedic screws as they can cause severe image artefacts characterized by bright and dark streaks due to scattering and beam hardening effects. These artefacts can severely reduce image quality, impeding the quantification of trabecular structures and therefore reducing the diagnostic value of the data. In this paper we present multi-modal image data acquired using Talbot-Lau grating interferometer (TLGI) XCT visualizing the interface between surgical screws and artificial trabecular bone. Our findings reveal that differential phase contrast (DPC) is less prone to metal artefacts improving the visualization of microstructure in bone adjacent to metal components. For this purpose, we produced polymeric foam structures imitating the microstructure of human bone to systematically investigate the advantages of DPC imaging for multi-component applications. We created a realistic set-up of four synthetic foam cylinders produced with different filler materials representing artificial bone. Two to four titanium screws (thread diameter 2 mm, length 20 mm) were applied into the artificial bone parallel to each other. The specimens were investigated using a TLGI-XCT system (SkyScan 1294) to extract information in relation to absorption contrast (AC), DPC, and dark-field contrast (DFC). In AC, metal streaking artefacts are severe, covering microstructure between the screws completely. DPC images in return show almost no streaking artefacts, which enhances image segmentation and volume rendering between the screws and close to the screw surface.