Coronary calcium test phantom containing true CaHA microspheres for evaluation of advanced CT calcium scoring methods

Arnold, Ben; Budoff, Matthew J.; Child, Janis; Xiang, Ping; Mao, Song

doi:10.1016/j.jcct.2010.08.004

Cited by 6 publications

(5 citation statements)

References 28 publications

(31 reference statements)

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“…A microsphere CCS test phantom was constructed with simulated lung, spine and heart regions as described elsewhere [21]. The phantom contains simulated calcifications manufactured from pure CaHA with microsphere volumes ranging from 0.054 to 3.05 mm 3 and was used to establish ground truth (Fig.…”

Section: Caha Microsphere Phantom Scansmentioning

confidence: 99%

Very small calcifications are detected and scored in the coronary arteries from small voxel MDCT images using a new automated/calibrated scoring method with statistical and patient specific plaque definitions

Arnold¹,

Xiang²,

Budoff

et al. 2011

Int J Cardiovasc Imaging

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A negative (zero) Agatston coronary calcium score (CCS) by current methods confers a very low risk for hard coronary events during the next years. However, controversy remains on how to use a negative score since some hard events still occur. We report on a new method with improved detection sensitivity for very small calcifications with the potential to more confidently rule out early atherosclerotic disease. Seventy-eight (78) patients with negative Agatston scores by conventional methods with 2.5 mm slices were selected from routine GE 64 MDCT scans. Each scan was reconstructed a second time from the same data to create 0.625 mm isotropic voxels. The 2.5 mm images were manually scored by the usual Agatston method using the GE SmartScore™ software. Both the 2.5 and 0.625 mm image sets were scored with a new automated and calibrated method (N-vivo™, Image Analysis). The software automatically computes dual scoring thresholds that are statistically defined and specific for each patient, scanner, and scan. The images were hybrid calibrated by simultaneous scanned phantoms in combination with in vivo blood/muscle references. The output reported the calibrated mass scores along with the number of plaques using 18 pt, 3-D connectivity criteria. A CCS Test phantom with known CaHA microspheres was used to validate the method. Twenty-three percent (18 of 78) of the patients with negative Agatston scores by the conventional method scored positive for coronary calcifications by the N-vivo method. The number of small plaques scored per patient varied from 1 to 4. One patient with a single small calcification suffered a hard coronary event during the CT scan. All of the detected plaques were located in the proximal heart. The conventional CCS method misclassified 23% of these patients as having negative coronary calcium scores. The N-vivo automated scoring method with small voxel CT images increased the detection sensitivity of small calcifications with no increase in radiation dose. Detection of small coronary calcified plaques occult to conventional scoring methods may increase the negative predictive power of calcium scoring and may improve plaque composition analysis.

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Section: Caha Microsphere Phantom Scansmentioning

confidence: 99%

Very small calcifications are detected and scored in the coronary arteries from small voxel MDCT images using a new automated/calibrated scoring method with statistical and patient specific plaque definitions

Arnold¹,

Xiang²,

Budoff

et al. 2011

Int J Cardiovasc Imaging

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“…It is, thus, important to investigate the exact influence of these parameters on CAC scores and the impact of scoring method standardization on differences in CAC scores between scanners. Besides that, the need of an improved CAC scoring method is high 28,30,31 . Both Agatston and volume scores show high variability in scores within and between CT systems 11,12 .…”

Section: Discussionmentioning

confidence: 99%

“…Besides that, the need of an improved CAC scoring method is high. 28 , 30 , 31 Both Agatston and volume scores show high variability in scores within and between CT systems. 11 , 12 The mass score is a more reliable score in terms of variability, although small differences still exist.…”

Section: Discussionmentioning

confidence: 99%

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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“…A microsphere coronary calcium scoring ͑CCS͒ test phantom was constructed with simulated lung, spine, and heart regions as described elsewhere. 31 The phantom contains simulated calcifications manufactured from CaHA with physical density 2.31 g / cm 3 and with microsphere volumes ranging from 0.054 to 3.05 mm 3 . The CCS phantom contains two additional rings to simulate patient sizes as shown in Fig.…”

Section: Iic1 Caha Microsphere Phantom Scansmentioning

confidence: 99%

Peak SNR in automated coronary calcium scoring: Selecting CT scan parameters and statistically defined scoring thresholdsa)

Arnold¹,

Xiang²,

Mao³

et al. 2010

Medical Physics

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The SNR(P) equation can be used to model and optimize calcium scoring and CT scan parameters. The common assumptions that noise is too high in thin slice CT or requires high radiation dose for CAC scoring are shown to be misleading. The N-vivo method showed higher detection sensitivity for small microspheres and more consistent mass scores at different beam energies than the conventional Agatston method. Advanced calcium scoring methods with higher sensitivity may allow improved monitoring of plaque changes and provide earlier detection of atherosclerosis.

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Coronary calcium test phantom containing true CaHA microspheres for evaluation of advanced CT calcium scoring methods

Cited by 6 publications

References 28 publications

Very small calcifications are detected and scored in the coronary arteries from small voxel MDCT images using a new automated/calibrated scoring method with statistical and patient specific plaque definitions

Very small calcifications are detected and scored in the coronary arteries from small voxel MDCT images using a new automated/calibrated scoring method with statistical and patient specific plaque definitions

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

Peak SNR in automated coronary calcium scoring: Selecting CT scan parameters and statistically defined scoring thresholdsa)

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