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

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

doi:10.1007/s00330-020-07677-w

Cited by 31 publications

(23 citation statements)

References 29 publications

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“…The impact of VMI on emphysema quantification has not yet been evaluated. The applicability of VNC imaging was already evaluated in the era of DE-CT 15,48–59 . For PCD-CT, there are hardly any studies dealing with the application of VNC images so far.…”

Section: Discussionmentioning

confidence: 99%

Impact of Contrast Enhancement and Virtual Monoenergetic Image Energy Levels on Emphysema Quantification

et al. 2022

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The aim of this study was to evaluate the impact of contrast enhancement and different virtual monoenergetic image energies on automatized emphysema quantification with photon-counting detector computed tomography (PCD-CT). Material and Methods: Sixty patients who underwent contrast-enhanced chest CT on a first-generation, clinical dual-source PCD-CT were retrospectively included. Scans were performed in the multienergy (QuantumPlus) mode at 120 kV with weight-adjusted intravenous contrast agent. Virtual noncontrast (VNC) images as well as virtual monoenergetic images (VMIs) from 40 to 80 keV obtained in 10-keV intervals were reconstructed. Computed tomography attenuation was measured in the aorta. Noise was measured in subcutaneous fat and defined as the standard deviation of attenuation. Contrast-to-noise with region of interest in the ascending aorta and signal-to-noise ratio in the subcutaneous fat were calculated. Subjective image quality (and emphysema assessment, lung parenchyma evaluation, and vessel evaluation) was rated by 2 blinded radiologists. Emphysema quantification (with a threshold of −950 HU) was performed by a commercially available software. Virtual noncontrast images served as reference standard for emphysema quantification. Results: Noise and contrast-to-noise ratio showed a strong negative correlation (r = −0.98; P < 0.01) to VMI energies. The score of subjective assessment was highest at 70 keV for lung parenchyma and 50 keV for pulmonary vessel evaluation ( P < 0.001). The best trade-off for the assessment of emphysema while maintaining reasonable contrast for pulmonary vessel evaluation was determined between 60 and 70 keV. Overall, contrast-enhanced imaging led to significant and systematic underestimation of emphysema as compared with VNC ( P < 0.001). This underestimation decreased with increasing VMI-energy (r = 0.98; P = 0.003). Emphysema quantification showed significantly ( P < 0.05) increased emphysema volumes with increasing VMI energies, except between 60-70 keV and 70-80 keV. The least difference in emphysema quantification between contrast-enhanced scans and VNC was found at 80 keV. Conclusion: Computed tomography emphysema quantification was significantly affected by intravenous contrast administration and VMI-energy level. Virtual monoenergetic image at 80 keV yielded most comparable results to VNC. The best trade-off in qualitative as well as in quantitative image quality evaluation was determined at 60/70 keV.

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Section: Discussionmentioning

confidence: 99%

Impact of Contrast Enhancement and Virtual Monoenergetic Image Energy Levels on Emphysema Quantification

et al. 2022

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“…Compared with other tube-based (rapid tube voltage switch or dual-source) dual-energy CT, it can provide exactly matched high-and low-energy X-ray attenuation, apply material decomposition algorithm in projection domain and not require pre-selection of the scan protocol (10). Some previous studies demonstrated that the VNC images derived from multi-phase contrast scan can replace the non-contrast scan (TNC) (11)(12)(13).…”

Section: Introductionmentioning

confidence: 99%

Feasibility and accuracy of coronary artery calcium score on virtual non-contrast images derived from a dual-layer spectral detector CT: A retrospective multicenter study

Yang

Zhao²,

Deng³

et al. 2023

Front. Cardiovasc. Med.

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Rationale and objectiveThis retrospective study was to evaluate the feasibility and accuracy of coronary artery calcium score (CACS) from virtual non-contrast (VNC) images in comparison with that from true non-contrast (TNC) images.Materials and methodsA total of 540 patients with suspected of coronary artery disease (CAD) who underwent a dual-layer spectral detector CT (SDCT) in three hospitals were eligible for this study and 233 patients were retrospectively enrolled for further analysis. The CACS was calculated from both TNC and VNC images and compared. Linear regression analysis of the CACS was performed between TNC and VNC images.ResultsThe correlation of overall CACS from VNC and TNC images was very strong (r = 0.923, p < 0.001). The CACS from VNC images were lower than that from TNC images (221 versus. 69, p < 0.001). When the regression equation of the overall coronary artery was applied, the mean calibrated CACS-VNC was 221 which had a significant difference from the CACS-TNC (p = 0.017). When the regression equation of each coronary branch artery was applied, the mean calibrated CACS-VNC was 221, which had a significant difference from the CACS-TNC (p = 0.003). But the mean difference between the CACS-TNC and the calibrated CACS-VNC in either way was less than 1. The agreement on risk stratification with CACS-TNC and CCACS-VNC was almost perfect.ConclusionThis multicenter study with dual-layer spectral detector CT showed that it was feasible to calculate CACS from the VNC images derived from the spectral coronary artery CT angiography scan, and the results were in good accordance with the TNC images after correction. Therefore, the TNC scan could be omitted, reducing the radiation dose to patients and saving examination time while using dual-layer spectral detector CT.

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“…In clinical routine, both scans are implemented as complementary acquisitions that increase scan time and radiation dose. With the advent of dual-energy and spectral imaging techniques, several studies have evaluated algorithms that allow the estimation of CACS from virtual noncontrast (VNC) images derived from CCTA datasets using material decomposition into 2 materials (soft tissue and iodine) 4–6 . As calcium is represented neither by iodine nor by soft tissue, all of the aforementioned approaches using dual-energy techniques demonstrated a high correlation, but a relevant underestimation of coronary artery calcium (CAC) scores derived from virtual unenhanced images.…”

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confidence: 99%

Coronary Computed Tomography Angiography-Based Calcium Scoring

et al. 2022

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PurposeThe aim of this study was to evaluate coronary computed tomography angiography (CCTA)-based in vitro and in vivo coronary artery calcium scoring (CACS) using a novel virtual noniodine reconstruction (PureCalcium) on a clinical first-generation photon-counting detector–computed tomography system compared with virtual noncontrast (VNC) reconstructions and true noncontrast (TNC) acquisitions.Materials and MethodsAlthough CACS and CCTA are well-established techniques for the assessment of coronary artery disease, they are complementary acquisitions, translating into increased scan time and patient radiation dose. Hence, accurate CACS derived from a single CCTA acquisition would be highly desirable. In this study, CACS based on PureCalcium, VNC, and TNC, reconstructions was evaluated in a CACS phantom and in 67 patients (70 [59/80] years, 58.2% male) undergoing CCTA on a first-generation photon counting detector–computed tomography system. Coronary artery calcium scores were quantified for the 3 reconstructions and compared using Wilcoxon test. Agreement was evaluated by Pearson and Spearman correlation and Bland-Altman analysis. Classification of coronary artery calcium score categories (0, 1–10, 11–100, 101–400, and >400) was compared using Cohen κ.ResultsPhantom studies demonstrated strong agreement between CACSPureCalcium and CACSTNC (60.7 ± 90.6 vs 67.3 ± 88.3, P = 0.01, r = 0.98, intraclass correlation [ICC] = 0.98; mean bias, 6.6; limits of agreement [LoA], −39.8/26.6), whereas CACSVNC showed a significant underestimation (42.4 ± 75.3 vs 67.3 ± 88.3, P < 0.001, r = 0.94, ICC = 0.89; mean bias, 24.9; LoA, −87.1/37.2). In vivo comparison confirmed a high correlation but revealed an underestimation of CACSPureCalcium (169.3 [0.7/969.4] vs 232.2 [26.5/1112.2], P < 0.001, r = 0.97, ICC = 0.98; mean bias, −113.5; LoA, −470.2/243.2). In comparison, CACSVNC showed a similarly high correlation, but a substantially larger underestimation (24.3 [0/272.3] vs 232.2 [26.5/1112.2], P < 0.001, r = 0.97, ICC = 0.54; mean bias, −551.6; LoA, −2037.5/934.4). CACSPureCalcium showed superior agreement of CACS classification (κ = 0.88) than CACSVNC (κ = 0.60).ConclusionsThe accuracy of CACS quantification and classification based on PureCalcium reconstructions of CCTA outperforms CACS derived from VNC reconstructions.

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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

Cited by 31 publications

References 29 publications

Impact of Contrast Enhancement and Virtual Monoenergetic Image Energy Levels on Emphysema Quantification

Impact of Contrast Enhancement and Virtual Monoenergetic Image Energy Levels on Emphysema Quantification

Feasibility and accuracy of coronary artery calcium score on virtual non-contrast images derived from a dual-layer spectral detector CT: A retrospective multicenter study

Coronary Computed Tomography Angiography-Based Calcium Scoring

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