Coronary artery calcium scoring with photon-counting CT: first in vivo human experience

  • Rolf Symons
  • Veit Sandfort
  • Marissa Mallek
  • Stefan Ulzheimer
  • Amir PourmortezaEmail author
Original Paper


To evaluate the performance of photon-counting detector (PCD) computed tomography (CT) for coronary artery calcium (CAC) score imaging at standard and reduced radiation doses compared to conventional energy-integrating detector (EID) CT. A dedicated cardiac CT phantom, ten ex vivo human hearts, and ten asymptomatic volunteers underwent matched EID and PCD CT scans at different dose settings without ECG gating. CAC score, contrast, and contrast-to-noise ratio (CNR) were calculated in the cardiac CT phantom. CAC score accuracy and reproducibility was assessed in the ex vivo hearts. Standard radiation dose (120 kVp, reference mAs = 80) in vivo CAC scans were compared against dose-reduced CAC scans (75% dose reduction; reference mAs = 20) for image quality and CAC score reproducibility. Interstudy agreement was assessed by using intraclass correlation (ICC), linear regression, and Bland–Altman analysis with 95% confidence interval limits of agreement (LOA). Calcium-soft tissue contrast and CNR were significantly higher for the PCD CAC scans in the cardiac CT phantom (all P < 0.01). Ex vivo hearts: CAC score reproducibility was significantly higher for the PCD scans at the lowest dose setting (50 mAs) (P = 0.002); score accuracy was similar for both detector systems at all dose settings. In vivo scans: the agreement between standard dose and low dose CAC score was significantly better for the PCD than for the EID with narrower LOA in Bland–Altman analysis, linear regression slopes closer to 1 (0.96 vs. 0.84), and higher ICC values (0.98 vs. 0.93, respectively). Phantom and in vivo human studies showed PCD may significantly improve CAC score image quality and/or reduce CAC score radiation dose while maintaining diagnostic image quality.


Coronary artery calcium score Photon-counting CT Radiation dose reduction 



This study was supported by the NIH intramural research program (ZIACL090019; ZIAEB000072), and a collaborative research agreement with Siemens Healthcare GmbH (Forchheim, Germany).

Compliance with ethical standards

Conflict of interest



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Copyright information

© This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright protection 2019

Authors and Affiliations

  1. 1.Radiology and Imaging Sciences - National Institutes of Health Clinical CenterBethesdaUSA
  2. 2.Department of Imaging & PathologyUniversity Hospitals LeuvenLeuvenBelgium
  3. 3.Siemens Healthcare GmbHForchheimGermany
  4. 4.Department of Radiology and Imaging SciencesEmory University School of MedicineAtlantaUSA
  5. 5.Department of Radiology and Imaging SciencesWinship Cancer Institute of Emory UniversityAtlantaUSA

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