Visualization of 3D osteon morphology by synchrotron radiation micro-CT

Area of Science:

• Biomedical Engineering
• Materials Science
• Orthopedics

Background:

• Cortical bone histology traditionally relies on 2D thin sections.
• Micro-computed tomography (micro-CT) is the gold standard for 3D trabecular bone analysis but struggles with 3D visualization of cortical secondary osteons using absorption contrast.
• Advancements in high-resolution X-ray imaging offer potential for visualizing smaller bone structures in 3D.

Purpose of the Study:

• To demonstrate the potential of synchrotron radiation micro-CT for non-destructive 3D visualization of secondary osteons in human cortical bone.
• To discuss how this approach can advance bone research by revealing detailed osteonal structures.

Main Methods:

• Human mid-femoral cortical bone specimens were imaged using synchrotron radiation micro-CT at the Advanced Photon Source.
• Propagation phase contrast with a 60-mm source-to-detector distance enhanced internal structure visualization.
• 1.4-μm nominal isotropic resolution and 1-hour scan times were utilized, followed by manual segmentation and 3D rendering.

Main Results:

• Secondary osteons were visualized in 3D, with hypomineralized osteons identified by X-ray attenuation differences.
• Osteon boundaries (cement lines) were delineated by phase contrast, which also detected soft tissue remnants within vascular pores.
• The 3D visualization revealed diverse secondary osteon morphologies and their superimposition on existing bone structures.

Conclusions:

• Synchrotron radiation micro-CT, particularly with phase contrast, overcomes limitations of conventional micro-CT for visualizing secondary osteons in 3D.
• This technique provides unprecedented detail on osteonal morphology, vascularity, and cellular porosity.
• Future improvements in resolution and phase contrast optimization promise even greater structural detail in bone research.