Abstract
ObjectivesThe aim of this study was to determine mono-energetic (monoE) level–specific photon-counting CT (PCCT) Agatston thresholds, to yield monoE level independent Agatston scores validated with a dynamic cardiac phantom. Also, we examined the potential of dose reduction for PCCT coronary artery calcium (CAC) studies, when reconstructed at low monoE levels.MethodsTheoretical CAC monoE thresholds were calculated with data from the National Institute of Standards and Technology (NIST) database. Artificial CAC with three densities were moved in an anthropomorphic thorax phantom at 0 and 60–75 bpm, and scanned at full and 50% dose on a first-generation dual-source PCCT. For all densities, Agatston scores and maximum CT numbers were determined. Agatston scores were compared with the reference at full dose and 70 keV monoE level; deviations (95% confidence interval) < 10% were deemed to be clinically not-relevant.ResultsAveraged over all monoE levels, measured CT numbers deviated from theoretical CT numbers by 6%, 13%, and − 4% for low-, medium-, and high-density CAC, respectively. At 50% reduced dose and 60–75 bpm, Agatston score deviations were non-relevant for 60 to 100 keV and 60 to 120 keV for medium- and high-density CAC, respectively.ConclusionMonoE level–specific Agatston score thresholds resulted in similar scores as in standard reconstructions at 70 keV. PCCT allows for a potential dose reduction of 50% for CAC scoring using low monoE reconstructions for medium- and high-density CAC.Key Points• Mono-energy level–specific Agatston thresholds allow for reproducible coronary artery calcium quantification on mono-energetic images.• Increased calcium contrast-to-noise ratio at reduced mono-energy levels allows for coronary artery calcium quantification at 50% reduced radiation dose for medium- and high-density calcifications.
Highlights
Cardiovascular disease (CVD) is still the number one cause of death [1]
Mono-energy level–specific Agatston thresholds allow for reproducible coronary artery calcium quantification on monoenergetic images
At 50% radiation dose, non-relevant differences in Agatston score deviation with the reference were obtained for Whereas the mass attenuation coefficients of air, water, and pure hydroxyapatite at monoE levels of 130 keV and larger are very similar and in the range of 0.10 to 0.16 cm2/g, at lower monoE levels, the mass attenuation of HA strongly diverges from the mass attenuation of water and air (Supplemental Figure 1)
Summary
The amount of coronary artery calcium (CAC) is quantified according to the Agatston methodology, which was developed in the early 1990s on a obsolete electron beam tomography system [4]. With this method, a CT number specific threshold of 130 Hounsfield units (HU) at a 120-kVp acquisition is used to first discriminate CAC with a minimum density of 100 mg/cm hydroxyapatite (HA) from surrounding tissue [5]. Since the introduction of the Agatston scoring methodology, CT scanners have evolved rapidly, with improvements in spatial resolution, temporal resolution, longitudinal coverage, and required radiation dose. While the temporal resolution in the isocenter of a single-source CT is half the rotation time, the temporal resolution of a dual-source CT is reduced to only a quarter of the rotation time
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
