Alumina as a Computed Tomography Soft Material and Tissue Fiducial Marker.

Background: The use of 3D imaging is becoming increasingly common, so too is the use of fiducial markers to identify/track regions of interest and assess material deformation. While many different materials have been used as fiducials, they are often used in isolation, with little comparison to one another. Objective: In the current study, we aim to directly compare different Computed Tomography (CT and µCT) fiducial materials, both metallic and nonmetallic. Methods: µCT imaging was performed on a soft-tissue structure, in this case heart valve tissue, with various markers attached. Additionally, we evaluated the same markers with DiceCT stained tissue in a fluid medium. Eight marker materials were tested in all. Results: All of the metallic markers generated significant artifacts and were found unsuitable for soft-tissue µCT imaging, whereas alumina markers were found to perform the best, with excellent contrast and consistency. Conclusions: These findings support the further use of alumina as fiducial markers for soft material and tissue studies that utilize CT and µCT imaging.

MicroCT Imaging of Heart Valve Tissue in Fluid.

BACKGROUND: Heart valve computational models require high quality geometric input data, commonly obtained using micro-computed tomography. Whether in the open or closed configuration, most studies utilize dry valves, which poses significant challenges including gravitational and surface tension effects along with desiccation induced mechanical changes. OBJECTIVE: These challenges are overcome by scanning in a stress-free configuration in fluid. Utilizing fluid backgrounds however reduces overall contrast due to the similar density of fluid and tissue. METHODS: The work presented here demonstrates imaging of the mitral valve by utilizing an iodine-based staining solution to improve the contrast of valve tissue against a fluid background and investigates the role of stain time and concentration. RESULTS: It is determined that an Olea europaea oil bath with a relatively high concentration, short stain time approach produces high quality imagery suitable for creating accurate 3D renderings. CONCLUSIONS: Micro-CT scanning of heart valves in fluid is shown to be feasible using iodine staining techniques.