Calibration of coronary calcium scores determined using iterative image reconstruction (AIDR 3D) at 120, 100, and 80 kVp

Blobel, Joerg; Mews, Jürgen; Goatman, Keith A; Schuijf, Joanne D.; Overlaet, Willem

doi:10.1118/1.4942484

Cited by 13 publications

(14 citation statements)

References 22 publications

(30 reference statements)

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“…Regarding calcifications with HA density of 400 mg/cm 3 , it is suspected that the influences of low intensity (small w i ) and more pixels (large A i ) owing to partial volume effect on Agatston score cancelled each other out, so changing SD value or body size did not cause obvious variation in AS 400HA . By definition, reducing CT number threshold would increase the Agatston score, and vice versa . This phenomenon was also observed in our results, which was adapted to determine the optimal HU threshold for CAC scans undergoing various imaging conditions to ensure the quantification accuracy of calcium scoring from CAC scans reconstructed at 0.5‐mm slice thickness using IR relative to the conventional protocol.…”

Section: Relationship Between Image Quality and Agatston Scoressupporting

confidence: 76%

“…As seen in Fig. , the Agatston scores from 108 IR measurements increased as decreasing kVp, which can be explained by the increase in CT number of calcifications at lower tube voltage . This phenomenon was observed in all calcification densities and was most obvious in the Agatston score of calcifications with HA density of 200 mg/cm 3 .…”

Section: Relationship Between Image Quality and Agatston Scoresmentioning

confidence: 68%

“…Kurata et al demonstrated a systematic decrease between 8% and 48% in Agatston score when using 10–50% of Sinogram‐affirmed Iterative Reconstruction (SAFIRE; Siemens Medical Solutions, Malvern, USA) blending . On the other hand, Rodrigues et al and Blobel et al showed good agreement in calcium scores between FBP and AIDR 3D protocols. Consistency in Agatston score between FBP and AIDR 3D was observed in our results acquired with 120 kVp and SD = 55 for QRM small , but not in those acquired with low‐dose protocols or larger phantoms.…”

Section: Discussionmentioning

confidence: 99%

“…Calcified lesions are excluded from the Agatston score if they have an axial area less than 1 mm 2 or a CT number less than the predefined CT number threshold, that is, 130 HU at 120 kVp. It has been reported that lower kVp settings would increase the CT number of calcifications, and thus may result in overestimation of Agatston score . In this study, the CAC scans were acquired not at 120 kVp but also at 100 and 80 kVp.…”

Section: Cac Scoringmentioning

confidence: 99%

“…It has been reported that lower kVp settings would increase the CT number of calcifications, and thus may result in overestimation of Agatston score. 23,24 In this study, the CAC scans were acquired not at 120 kVp but also at 100 and 80 kVp. Hence, three different HU thresholds were applied to detect calcification for each CAC scan listed in Table 1, including 130, 150, and 170 HU.…”

Section: Cac Scoringmentioning

confidence: 99%

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Optimization of HU threshold for coronary artery calcium scans reconstructed at 0.5‐mm slice thickness using iterative reconstruction

Hou

Tsujioka

Yang

2019

J Applied Clin Med Phys

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Purpose This work investigated the simultaneous influence of tube voltage, tube current, body size, and HU threshold on calcium scoring reconstructed at 0.5‐mm slice thickness using iterative reconstruction (IR) through multivariate analysis. Regression results were used to optimize the HU threshold to calibrate the resulting Agatston scores to be consistent with those obtained from the conventional protocol. Methods A thorax phantom set simulating three different body sizes was used in this study. A total of 14 coronary artery calcium (CAC) protocols were studied, including 1 conventional protocol reconstructed at 3‐mm slice thickness, 1 FBP protocol, and 12 statistical IR protocols (3 kVp values*4 SD values) reconstructed at 0.5‐mm slice thickness. Three HU thresholds were applied for calcium identification, including 130, 150, and 170 HU. A multiple linear regression method was used to analyze the impact of kVp, SD, body size, and HU threshold on the Agatston scores of three calcification densities for IR‐reconstructed CAC scans acquired with 0.5‐mm slice thickness. Results Each regression relationship has R2 larger than 0.80, indicating a good fit to the data. Based on the regression models, the HU thresholds as a function of SD estimated to ensure the quantification accuracy of calcium scores for 120‐, 100‐, and 80‐kVp CAC scans reconstructed at 0.5‐mm slice thickness using IR for three different body sizes were proposed. Our results indicate that the HU threshold should be adjusted according to the imaging condition, whereas a 130‐HU threshold is appropriate for 120‐kVp CAC scans acquired with SD = 55 for body size of 24.5 cm. Conclusion The optimized HU thresholds were proposed for CAC scans reconstructed at 0.5‐mm slice thickness using IR. Our study results may provide a potential strategy to improve the reliability of calcium scoring by reducing partial volume effect while keeping radiation dose as low as reasonably achievable.

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Section: Relationship Between Image Quality and Agatston Scoressupporting

confidence: 76%

Section: Relationship Between Image Quality and Agatston Scoresmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Section: Cac Scoringmentioning

confidence: 99%

Section: Cac Scoringmentioning

confidence: 99%

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Optimization of HU threshold for coronary artery calcium scans reconstructed at 0.5‐mm slice thickness using iterative reconstruction

Hou

Tsujioka

Yang

2019

J Applied Clin Med Phys

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Fully automated quantification method (FQM) of coronary calcium in an anthropomorphic phantom

et al. 2021

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ObjectiveCoronary artery calcium (CAC) score is a strong predictor for future adverse cardiovascular events.Anthropomorphic phantoms are often used for CAC studies on computed tomography (CT) to allow for evaluation or variation of scanning or reconstruction parameters within or across scanners against a reference standard. This often results in large number of datasets. Manual assessment of these large datasets is time consuming and cumbersome. Therefore, this study aimed to develop and validate a fully automated, open-source quantification method (FQM) for coronary calcium in a standardized phantom. Materials and MethodsA standard, commercially available anthropomorphic thorax phantom was used with an insert containing nine calcifications with different sizes and densities. To simulate two different patient sizes, an extension ring was used. Image data was acquired with four state-of-the-art CT systems using routine CAC scoring acquisition protocols. For inter-scan variability, each acquisition was repeated five times with small translations and/or rotations. Vendor-specific CAC scores (Agatston, volume, and mass) were calculated as reference scores using vendor-specific software. Both the international standard CAC quantification methods as well as vendorspecific adjustments were implemented in FQM. Reference and FQM scores were compared using Bland-Altman analysis, intraclass correlation coefficients, risk reclassifications, and Cohen's kappa. Also, robustness of FQM was assessed using varied acquisitions and reconstruction settings and validation on a dynamic phantom. Further, image quality metrics were implemented: noise power spectrum, task transfer function, and contrast-and signal-to-noise ratio among others. Results were validated using imQuest software. ResultsThree parameters in CAC scoring methods varied among the different vendor-specific software packages: the Hounsfield unit (HU) threshold, the minimum area used to designate a group of voxels as calcium, and the usage of isotropic voxels for the volume score. The FQM was in high agreement with vendor-specific scores and ICC's (median [95% CI]) were excellent (1.

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2022 ASNC/AAPM/SCCT/SNMMI guideline for the use of CT in hybrid nuclear/CT cardiac imaging

Al‐Mallah

Bateman

Branch

et al. 2022

Journal of Nuclear Cardiology

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Calibration of coronary calcium scores determined using iterative image reconstruction (AIDR 3D) at 120, 100, and 80 kVp

Cited by 13 publications

References 22 publications

Optimization of HU threshold for coronary artery calcium scans reconstructed at 0.5‐mm slice thickness using iterative reconstruction

Optimization of HU threshold for coronary artery calcium scans reconstructed at 0.5‐mm slice thickness using iterative reconstruction

Fully automated quantification method (FQM) of coronary calcium in an anthropomorphic phantom

2022 ASNC/AAPM/SCCT/SNMMI guideline for the use of CT in hybrid nuclear/CT cardiac imaging

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