A semi-automated method for hexahedral mesh construction of human vertebrae from CT scans

Abstract

Generation of finite element (FE) meshes of vertebrae from computed tomography (CT) scans is labour intensive due to their geometric complexity. As such, techniques that simplify creation of meshes of vertebrae are needed to make FE analysis feasible for large studies and clinical applications. Techniques to obtain a geometric representation of bone contours from CT scans of vertebrae and construct a hexahedral mesh from the contours were developed. An automated edge detection technique was developed to identify surface contours of the vertebrae, followed by atlas based B-spline curve fitting to construct curves from the edge points. The method was automatic and robust to missing data, with a controllable degree of smoothing and interpolation. Parametric mapping was then used to generate nodes for each CT slice, which were connected between slices to obtain a hexahedral mesh. This method could be adapted for modelling a variety of orthopaedic structures.

Keywords:

• finite element modelling
• computed tomography
• geometric modelling
• image segmentation
• spine

Acknowledgements

This study was supported by the US Centers for Disease Control (CDC CE000789) and the US National Institutes of Health (NIH AR052008). CTs scans were performed by Memorial Lighthouse Medical Imaging Center, Mishawaka, IN, USA.