Sources of error in bone mineral density estimates from quantitative CT

Published:October 15, 2021DOI:


      • Bone density estimates from CT are highly useful but can be highly variable.
      • Error can result from factors related to the scanner, acquisition, patient, and calibration.
      • Thorough understanding and management of error sources are essential.


      Bone mineral density (BMD) estimates from quantitative computed tomography (QCT) have proven useful for opportunistic screening of osteoporosis, treatment monitoring, and bone strength measurement. These estimates are subject to bias and variance from a variety of sources related to the imaging equipment, methods applied in the estimation procedure, and the patients themselves. In this article, we review the literature to describe the sources and sizes of error in spine and hip BMD estimates from single-energy QCT that can result from factors related to the scanner, imaging techniques, imaging subject, calibration phantom, and calibration approach. We also describe the baseline variance that can be expected based on repeatability and reproducibility studies. Though reproducible BMD estimates may be achievable with QCT, a thorough understanding of the potential sources of error and their size relative to the diagnostic task is essential to their appropriate and meaningful interpretation.



      BMD (Bone mineral density), CECT (Contrast-enhanced CT), CI (Confidence interval), CV (Coefficient of variation), CVRMS (Root mean square coefficient of variation), DECT (Dual-energy CT), DXA (Dual-energy x-ray absorptiometry), FOV (Field of view), HA (Hydroxyapatite), HU (Hounsfield units), IC (Internal calibration), IV (Intra-venous), kVp (Peak tube voltage), LSC (Least significant change), mAs (Current-time product), PV (Portal venous), ROI (Region of interest), SECT (Single-energy CT), QA (Quality assurance), QCT (Quantitative CT)
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