DXA-equivalent quantification of bone mineral density using dual-layer spectral CT scout scans

  • Alexis Laugerette
  • Benedikt J. Schwaiger
  • Kevin Brown
  • Lena C. Frerking
  • Felix K. Kopp
  • Kai Mei
  • Thorsten Sellerer
  • Jan Kirschke
  • Thomas Baum
  • Alexandra S. Gersing
  • Daniela Pfeiffer
  • Alexander A. Fingerle
  • Ernst J. Rummeny
  • Roland Proksa
  • Peter B. NoëlEmail author
  • Franz Pfeiffer
Computed Tomography



To develop and evaluate a method for areal bone mineral density (aBMD) measurement based on dual-layer spectral CT scout scans.


A post-processing algorithm using a pair of 2D virtual mono-energetic scout images (VMSIs) was established in order to semi-automatically compute the aBMD at the spine similarly to DXA, using manual soft tissue segmentation, semi-automatic segmentation for the vertebrae, and automatic segmentation for the background. The method was assessed based on repetitive measurements of the standardized European Spine Phantom (ESP) using the standard scout scan tube current (30 mA) and other tube currents (10 to 200 mA), as well as using fat-equivalent extension rings simulating different patient habitus, and was compared to dual-energy X-ray absorptiometry (DXA). Moreover, the feasibility of the method was assessed in vivo in female patients.


Derived from standard scout scans, aBMD values measured with the proposed method significantly correlated with DXA measurements (r = 0.9925, p < 0.001), and mean accuracy (DXA, 4.12%; scout, 1.60%) and precision (DXA, 2.64%; scout, 2.03%) were comparable between the two methods. Moreover, aBMD values assessed at different tube currents did not differ significantly (p ≥ 0.20 for all), suggesting that the presented method could be applied to scout scans with different settings. Finally, data derived from sample patients were concordant with BMD values from a reference age-matched population.


Based on dual-layer spectral scout scans, aBMD measurements were fast and reliable and significantly correlated with the according DXA measurements in phantoms. Considering the number of CT acquisitions performed worldwide, this method could allow truly opportunistic osteoporosis screening.

Key Points

• 2D scout scans (localizer radiographs) from a dual-layer spectral CT scanner, which are mandatory parts of a CT examination, can be used to automatically determine areal bone mineral density (aBMD) at the spine.

• The presented method allowed fast (< 25 s/patient), semi-automatic, and reliable DXA-equivalent aBMD measurements for state-of-the-art DXA phantoms at different tube settings and for various patient habitus, as well as for sample patients.

• Considering the number of CT scout scan acquisitions performed worldwide on a daily basis, the presented technique could enable truly opportunistic osteoporosis screening with DXA-equivalent metrics, without involving higher radiation exposure since it only processes existing data that is acquired during each CT scan.


Multidetector computed tomography Dual-energy X-ray absorptiometry Bone density Osteoporosis Spine 



Analysis of covariance (a statistical analysis technique)




Bone mineral content (g)


Bone mineral density (mg/mL), sometimes also used for areal bone mineral density (aBMD, g/cm2)


Coefficient of variation


Dual-energy X-ray absorptiometry


European Spine Phantom


Calcium-hydroxyapatite, the main mineral component of bone


Intravenous (contrast agent)


Quantitative computed tomography


Virtual mono-energetic scout image



We acknowledge support through QRM for providing the ESP phantom, the German Department of Education and Research (BMBF) under grant IMEDO (13GW0072C), the German Research Foundation (DFG - Gottfried Wilhelm Leibniz program), and the DFG within the Research Training Group GRK 2274.

K.B, L.C.F., and R.P. are employees of Philips. The remaining authors have no financial disclosures and had complete, unrestricted access to the study data at all stages of the study.

Compliance with ethical standards


The scientific guarantor of this publication is PD Dr. Peter B. Noël.

Conflict of interest

The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.

Statistics and biometry

One of the authors has significant statistical expertise. No complex statistical methods were necessary for this paper.

Informed consent

Written informed consent was waived by the Institutional Review Board.

Ethical approval

Institutional Review Board approval was obtained.


• prospective

• diagnostic study/experimental

• performed at one institution

Supplementary material

330_2019_6005_MOESM1_ESM.docx (25 kb)
ESM 1 (DOCX 24 kb)


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Copyright information

© European Society of Radiology 2019

Authors and Affiliations

  • Alexis Laugerette
    • 1
    • 2
  • Benedikt J. Schwaiger
    • 1
  • Kevin Brown
    • 3
  • Lena C. Frerking
    • 4
  • Felix K. Kopp
    • 1
  • Kai Mei
    • 1
  • Thorsten Sellerer
    • 2
  • Jan Kirschke
    • 5
  • Thomas Baum
    • 5
  • Alexandra S. Gersing
    • 1
  • Daniela Pfeiffer
    • 1
  • Alexander A. Fingerle
    • 1
  • Ernst J. Rummeny
    • 1
  • Roland Proksa
    • 4
  • Peter B. Noël
    • 1
    • 6
    Email author
  • Franz Pfeiffer
    • 1
    • 2
  1. 1.Department of Diagnostic and Interventional Radiology, Klinikum rechts der IsarTechnical University of MunichMunichGermany
  2. 2.Biomedical Physics & Munich School of BioEngineeringTechnical University of MunichGarchingGermany
  3. 3.Philips HealthcareClevelandUSA
  4. 4.Philips Research LaboratoriesHamburgGermany
  5. 5.Section of Diagnostic and Interventional NeuroradiologyTechnical University of MunichMunichGermany
  6. 6.Department of Radiology, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaUSA

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