Abstract
Introduction
Bone densitometry is one of the main pillars in the assessment of osteoporosis. The most important modalities are dual x-ray absorptiometry (DXA), quantitative computed tomography (QCT), and quantitative ultrasound (QUS).
Materials and methods
For each modality a variety of technical solutions and numerous commercial devices are available and widely used for patient measurements. While the field of bone densitometry may be considered mature, new modalities and devices are being introduced. Consequently, there is a constant need to assess and compare the quality of bone densitometry approaches and devices in a rigorous way.
Results
The International Commission on Radiation Units has commissioned a report on bone densitometry to address some of these issues, in particular to provide clear definitions of quantities and units used and to describe parameters and methods that can be used to compare and standardize densitometric equipment and measurements. One of the core chapters of the report summarizes quality and performance measures in bone densitometry. It is divided into four sections: physical performance measures, diagnosis, fracture risk, and monitoring. Here we publish part 1 of this chapter containing the first two sections: physical performance measures and issues in diagnosing osteoporosis.
Conclusion
Following the international standard (ISO 5725-1), trueness, bias, repeatability, and reproducibility are defined along with terms common to osteoporosis research, such as accuracy and precision. Building on the conceptual definition of osteoporosis, diagnostic criteria are defined and discussed including criteria for reference data. Based on this, clinical performance measures commonly used for the diagnosis of osteoporosis are reviewed and discussed.
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Notes
Formerly, trueness was denoted as accuracy that now encompasses trueness and precision.
Formerly, bias was often denoted as accuracy error.
In the literature, the term “precision error” is often used for imprecision.
The ICRU report will endorse the use of BMDa to distinguish areal from volumetric BMD measurements. BMD only refers to volumetric density as measured by QCT; BMDa denotes areal BMD as measured by DXA.
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Acknowledgements
This study was supported by travel grants of the International Commission on Radiation Units (ICRU).We thank the ICRU for the possibility to separately publish a part of the forthcoming report on bone densitometry. Members of the report committee are W. Kalender, Institute of Medical Physics, University of Erlangen (head); P. Laugier, Laboratoire d’Imagérie Paramétrique, Université Paris IV; J. Shepherd, Department of Radiology, University of California at San Francisco; T. Fuerst, Synarc, San Francisco, and the authors of this article. We also thank Y. Lu, Department of Radiology, University of California at San Francisco, for his valuable comments on the manuscript.
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Engelke, K., Glüer, CC. Quality and performance measures in bone densitometry. Osteoporos Int 17, 1283–1292 (2006). https://doi.org/10.1007/s00198-005-0039-0
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DOI: https://doi.org/10.1007/s00198-005-0039-0