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Proceedings Paper

Analyzing µCT images of bone specimen with wavelets and scaling indices: Which texture measure does better to depict the trabecular bone structure?
Author(s): Christoph W. Raeth; Jan Bauer; Dirk Mueller; Ernst J. Rummeny; Thomas M. Link; Sharmila Majumdar; Felix Eckstein; Roberto Monetti
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Paper Abstract

The visualisation and subsequent quantification of the inner bone structure plays an important role for better understanding the disease- or drug-induced changes of the bone in the context of osteoporosis. Scaling indices (SIM) are well suited to quantify these structures on a local level, especially to discriminate between plate-like and rod-like structural elements. Local filters based on wavelets (WVL) are a standard technique in texture analysis. So far, they are mainly used for two-dimensional image data sets. Here we extend the formalism of the spherical Mexican hat wavelets to the analysis of three-dimensional tomographic images and evaluate its performance in comparison with scaling indices, histomorphometric measures and BMD. &mgr;CT images with isotropic resolution of 30 x 30 x 30 &mgr;m of a sample of 19 trabecular bone specimen of human thoracic vertebrae were acquired. In addition, the bone mineral density was measured by QCT. The maximum compressive strength (MCS) was determined in a biomechanical test. Some wavelet-based as well as all scaling index- based texture measures show a significantly higher correlation with MCS (WVL: &rgr;2=0.54, SIM: &rgr;2=0.53-0.56) than BMD (&rgr;2=0.46), where we find slightly better correlations for SIM than for WVL. The SIM and WVL results are comparable but not better to those obtained with histomorphometric measures (BV/TV: &rgr;2=0.45, Tr. N.: &rgr;2=0.67, Tr.Sp.: &rgr;2=0.67). In conclusion, WVL and SIM techniques can successfully be applied to &mgr;CT image data. Since the two measures characterize the image structures on a local scale, they offer the possibility to directly identify and discriminate rods and sheets of the trabecular structure. This property may give new insights about the bone constituents responsible for the mechanical strength.

Paper Details

Date Published: 26 March 2007
PDF: 8 pages
Proc. SPIE 6512, Medical Imaging 2007: Image Processing, 65124B (26 March 2007); doi: 10.1117/12.708980
Show Author Affiliations
Christoph W. Raeth, Max-Planck-Institut fuer extraterrestrische Physik (Germany)
Jan Bauer, Technische Univ. Muenchen (Germany)
Dirk Mueller, Technische Univ. Muenchen (Germany)
Ernst J. Rummeny, Technische Univ. Muenchen (Germany)
Thomas M. Link, Univ. of California/San Francisco (United States)
Sharmila Majumdar, Univ. of California/San Francisco (United States)
Felix Eckstein, Paracelsus Private Medical Univ. (Austria)
Roberto Monetti, Max-Planck-Institut fuer extraterrestrische Physik (Germany)

Published in SPIE Proceedings Vol. 6512:
Medical Imaging 2007: Image Processing
Josien P. W. Pluim; Joseph M. Reinhardt, Editor(s)

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