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- Title:
Prediction of bone strength by mu CT and MDCT-based finite-element-models: How much spatial resolution is needed?
- Document type:
- Article
- Author(s):
- Bauer, Jan S.; Sidorenko, Irina; Mueller, Dirk; Baum, Thomas; Issever, Ahi Sema; Eckstein, Felix; Rummeny, Ernst J.; Link, Thomas M.; Raeth, Christoph W.
- Abstract:
- Objectives: Finite-element-models (FEM) are a promising technology to predict bone strength and fracture risk. Usually, the highest spatial resolution technically available is used, but this requires excessive computation time and memory in numerical simulations of large volumes. Thus, FEM were compared at decreasing resolutions with respect to local strain distribution and prediction of failure load to (1) validate MDCT-based FEM and to (2) optimize spatial resolution to save computation time. Materials and methods: 20 cylindrical trabecular bone specimens (diameter 12 mm, length 15-20 mm) were harvested from elderly formalin-fixed human thoracic spines. All specimens were examined by micro-CT (isotropic resolution 30 pm) and whole-body multi-row-detector computed tomography (MDCT, 250 mu m x 250 mu m x 500 mu m). The resolution of all datasets was lowered in eight steps to similar to 2000 mu m x 2000 mu m x 500 mu m and FEM were calculated at all resolutions. Failure load was determined by biomechanical testing. Probability density functions of local micro-strains were compared in all datasets and correlations between FEM-based and biomechanically measured failure loads were determined. Results: The distribution of local micro-strains was similar for micro-CT and MDCT at comparable resolutions and showed a shift toward higher average values with decreasing resolution, corresponding to the increasing apparent trabecular thickness. Small micro-strains (epsilon(eff) < 0.005) could be calculated down to 250 mu m x 250 mu m x 500 mu m. Biomechanically determined failure load showed significant correlations with all FEM, up to r= 0.85 and did not significantly change with lower resolution but decreased with high thresholds, due to loss of trabecular connectivity. Conclusion: When choosing connectivity-preserving thresholds, both micro-CT- and MDCT-based finiteelement-models well predicted failure load and still accurately revealed the distribution of local microstrains in spatial resolutions, available in vivo (250 mu m x 250 mu m x 500 mu m), that thus seemed to be the optimal compromise between high accuracy and low computation time. (C) 2013 Elsevier Ireland Ltd. All rights reserved.
- Keywords:
- X-ray microtomography; Multidetector computed tomography; Finite element analysis; Bone; Spine; Osteoporosis
- Journal title:
- Eur. J. Radiol.
- Year:
- 2014
- Journal volume:
- 83
- Month:
- JAN
- Journal issue:
- 1
- Pages contribution:
- E36-E42
- Language:
- English
- Fulltext / DOI:
- doi:10.1016/j.ejrad.2013.10.024
- Publisher:
- ELSEVIER IRELAND LTD
- Print-ISSN:
- 0720-048X
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