Quantitative Ultrasound and Trabecular Architecture in the Human Calcaneus*

Authors

  • P. H. F. Nicholson,

    1. Orthopedic Biomechanics Laboratory, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
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  • R. Müller,

    1. Orthopedic Biomechanics Laboratory, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
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  • X. G. Cheng,

    1. Osteoporosis and Arthritis Research Group, University of California San Francisco, San Francisco, California, USA
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  • P. Rüegsegger,

    1. Institute for Biomedical Engineering, University of Zürich and Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
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  • G. Van Der Perre,

    1. Division of Biomechanics and Engineering Design, Katholieke Universiteit Leuven, Leuven, Belgium
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  • J. Dequeker,

    1. Arthritis and Metabolic Bone Disease Research Unit, Katholieke Universiteit Leuven, Leuven, Belgium
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  • S. Boonen

    Corresponding author
    1. Leuven University Center for Metabolic Bone Diseases, Katholieke Universiteit Leuven, Leuven, Belgium
    2. Division of Geriatric Medicine, Katholieke Universiteit Leuven, Leuven, Belgium
    • Address reprint requests to: Steven Boonen, M.D., Ph.D., Leuven University Center for Metabolic Bone Diseases, University Hospitals K.U. Leuven, Brusselsestraat 69, B-3000 Leuven, Belgium
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  • *

    Presented in part, and winner of the Quantitative Ultrasound Research Award at the Joint Meeting of the International Bone and Mineral Society and the American Society for Bone and Mineral Research, San Francisco, California, USA, 1998

Abstract

Relationships between quantitative ultrasound (QUS), density (bone volume density [BV/TV]), and trabecular architecture were investigated in 69 calcaneal cancellous bone cubes. Ultrasound signal velocity, phase velocity, attenuation, and broadband ultrasonic attenuation (BUA) measurements were made along the mediolateral axis. Density and architectural parameters were measured using microcomputed tomography (μCT). Density yielded the best correlations with QUS (r2 = 73–77%). Of the individual architectural parameters, correlations with QUS were highest for the Structure Model Index (SMI), a parameter quantifying the relative proportion of rods and plates (r2 = 57–63%). After adjustment for density, significant associations with QUS remained for SMI, trabecular spacing (Tb.Sp), and trabecular number (Tb.N), although the variance in QUS attributable uniquely to individual architectural parameters was at best 4%. In multivariate regression models, combinations of density and architectural parameters explained 76–82% of the variance in QUS, representing an r2 increase of, at most, 8% compared with using density alone. However, multivariate models using combinations of architectural parameters alone (i.e., density excluded) also had a good predictive ability for QUS (r2 = 73–81%). Thus, although these data show modest but significant density-independent relationships between QUS and trabecular architecture in the human calcaneus for the first time, the causal relationships behind the variation in acoustic properties remain obscure. Given the relative weakness and complexity of the emerging associations between QUS and architecture, it is prudent to regard QUS measurements in calcaneal bone primarily as an indicator of bone density.

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