Calcium scoring using virtual non-contrast images from a dual-layer spectral detector CT: comparison to true non-contrast data and evaluation of proportionality factor in a large patient collective

Felix G Gassert,Florian T Gassert,Gregor Pahn,Karl-Ludwig Laugwitz,Christina Müller-Leisse,Jonathan Nadjiri,Claudio E Schacky,Marcus R Makowski

doi:10.1007/s00330-020-07677-w

Felix G Gassert, Florian T Gassert + Show 6 more

Open Access

https://doi.org/10.1007/s00330-020-07677-w

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Abstract

ObjectiveDetermination of coronary artery calcium scoring (CACS) in non-contrast computed tomography (CT) images has been shown to be an important prognostic factor in coronary artery disease (CAD). The objective of this study was to evaluate the accuracy of CACS from virtual non-contrast (VNC) imaging generated from spectral data in comparison to standard (true) non-contrast (TNC) imaging in a representative patient cohort with clinically approved software.MethodsOne hundred three patients referred to coronary CTA with suspicion of CAD were investigated on a dual-layer spectral detector CT (SDCT) scanner. CACS was calculated from both TNC and VNC images by software certified for medical use. Patients with a CACS of 0 were excluded from analysis.ResultsThe mean age of the study population was 61 ± 11 years with 48 male patients (67%). Inter-quartile range of clinical CACS was 22–282. Correlation of measured CACS from true- and VNC images was high (0.95); p < 0.001. The slope was 3.83, indicating an underestimation of VNC CACS compared to TNC CACS by that factor. Visual analysis of the Bland-Altman plot of CACS showed good accordance with both methods after correction of VNC CACS by the abovementioned factor.ConclusionsIn clinical diagnostics of CAD, the determination of CACS is feasible using VNC images generated from spectral data obtained on a dual-layer spectral detector CT. When multiplied by a correction factor, results were in good agreement with the standard technique. This could enable radiation dose reductions by obviating the need for native scans typically used for CACS.Key Points• Calcium scoring is feasible from contrast-enhanced CT images using a dual-layer spectral detector CT scanner.• When multiplied by a correction factor, calcium scoring from virtual non-contrast images shows good agreement with the standard technique.• Omitting native scans for calcium scoring could enable radiation dose reduction.

Highlights

Ischemic heart disease is the most common global cause of death, with high mortality reported in the developed countries [1]
When multiplied by a correction factor, calcium scoring from virtual non-contrast images shows good agreement with the standard technique
Besides contrast-enhanced imaging for the evaluation of vascular stenosis, several studies showed that the determination of coronary artery calcium scoring (CACS) is an essential prognostic factor and a strong and independent predictor of cardiovascular events, such as myocardial infarction and sudden cardiac death [3, 5, 6]

Summary

Introduction

Ischemic heart disease is the most common global cause of death, with high mortality reported in the developed countries [1]. The most commonly used method to evaluate patients’ burden of CAD is the Agatston score, which measures the amount of calcium present in each lesion scaled by an attenuation factor and summed over all lesions [7]. Whereas currently both contrast-enhanced CT imaging for stenosis determination and non-contrast images for CACS are widely established for the diagnosis of CAD, several methods using spectral imaging including the possibility to generate virtual non-contrast (VNC) images for calculation of CACS have previously been proposed in multiple studies [8,9,10]. The dual-layer method has been reported to be a reliable method of dual-energy imaging [13, 14]

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