Quantifying trabecular bone material anisotropy and orientation using low resolution clinical CT images: A...

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Orthopedics

Background:

• Accurate finite element (FE) modeling of bone requires accounting for trabecular material anisotropy and orientation.
• Clinical quantitative computed tomography (CT) has limitations in capturing these microstructural properties.

Purpose of the Study:

• To investigate the feasibility of quantifying trabecular bone material anisotropy and orientation using clinical CT.
• To assess the accuracy of derived stiffness properties and trabecular orientation compared to micro-FE analysis.

Main Methods:

• Micro-CT imaging and micro-FE modeling were used to obtain reference trabecular properties from human radius samples.
• Simulated clinical CT images were generated with varying voxel sizes and noise.
• A gray-level structure tensor was applied to simulated CT images to derive fabric eigenvalues and eigenvectors, representing anisotropy and orientation.

Main Results:

• The gray-level structure tensor method, combined with Cowin's equations, explained 94-97% of the variance in orthotropic stiffness entries.
• Zysset-Curnier equations explained 82-88% of the variance in stiffness.
• Image-derived orientation deviated by 4.4-10.8° from micro-FE derived orientation.

Conclusions:

• Clinical CT, using a gray-level structure tensor approach, shows potential for quantifying trabecular bone anisotropy and orientation.
• This method can improve subject-specific FE modeling of bone by incorporating spatial variations.
• The findings suggest a pathway towards more accurate bone mechanical assessments using standard clinical imaging.