Multiscale and multimodality computed tomography for cortical bone analysis

Area of Science:

• Bone biology and imaging
• Biomaterials science
• Medical imaging physics

Background:

• High-resolution peripheral quantitative computed tomography (HR-pQCT) is clinically used to assess cortical and trabecular bone parameters.
• Micro-computed tomography (micro-CT), especially with synchrotron radiation (SR), is considered the gold standard for in vitro bone microstructure analysis.
• Understanding modality-specific measurement differences is crucial for accurate bone health assessment.

Purpose of the Study:

• To compare cortical bone parameter measurements between HR-pQCT and conventional micro-CT.
• To evaluate the impact of different micro-CT resolutions and SR on bone microstructure analysis.
• To identify potential artifacts and limitations of each imaging modality.

Main Methods:

• HR-pQCT and conventional micro-CT were used to measure cortical bone parameters in human tibias and femurs.
• Synchrotron radiation micro-CT (SR micro-CT) was employed at various voxel sizes (7.5 µm³, 2.8 µm³) to assess resolution effects.
• Statistical analysis, including correlation and bias assessment, was performed to compare measurements.

Main Results:

• HR-pQCT measurements of cortical density (D.comp) and thickness (Ct.Th) strongly correlated with micro-CT findings.
• Conventional micro-CT underestimated porosity (Po.V/TV) and pore diameter, while overestimating pore number (Po.N) and separation (Po.Sp) compared to SR micro-CT.
• Higher resolution SR micro-CT (2.8 µm³) revealed more accurate porosity and pore characteristics than lower resolution (7.5 µm³).

Conclusions:

• HR-pQCT offers consistent and reliable cortical bone density and thickness measurements, comparable to conventional micro-CT.
• Conventional micro-CT may introduce artifacts affecting porosity quantification, particularly for smaller pores.
• SR micro-CT at higher resolutions provides more accurate microstructural bone analysis, but its application is limited to in vitro studies.