Individualized coronary calcium scoring at any tube voltage using a kV-independent reconstruction algorithm

Vingiani, Vincenzo; Abadia, Andres F.; Schoepf, U. Joseph; Fischer, Andreas; Varga-Szemes, Ákos; Sahbaee, Pooyan; Allmendinger, Thomas; Giovagnoli, Dante A; Hudson, H. Todd; Marano, Riccardo; Tinnefeld, F.; Martin, Simon S.

doi:10.1007/s00330-020-06951-1

Cited by 11 publications

(20 citation statements)

References 22 publications

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“…Comparison of results is hampered by the fact that for their first study, 100 kVp with tin filtration was applied, whereas in our study a tube voltage of 150 kVp with tin filtration was manually selected for the phantom [22]. In the other study by Vingiani et al, forty-three patients were imaged with both 120 kVp and an individualized tube voltage [23]. A high concordance in Agatston scores between both scans was found.…”

Section: Discussionmentioning

confidence: 68%

“…In addition, two patient studies have been carried out by Vingiani et al [22,23]. Both studies showed the feasibility of the Ca-aware reconstruction kernel, in combination with patient-specific tube voltages, where one study considered spectral beam shaping with tin filtration.…”

Section: Discussionmentioning

confidence: 99%

“…Motion artifacts can increase or decrease CAC scores, depending on the density of the calcification [20]. While recent studies have assessed the influence of the novel Ca-aware reconstruction technique on both stationary calcifications and in patients, the effect of this reconstruction technique on CAC scores of moving calcifications of different densities at varying heart rates remains unknown [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

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Evaluating a calcium-aware kernel for CT CAC scoring with varying surrounding materials and heart rates: a dynamic phantom study

et al. 2021

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Objectives The purpose of this study was twofold. First, the influence of a novel calcium-aware (Ca-aware) computed tomography (CT) reconstruction technique on coronary artery calcium (CAC) scores surrounded by a variety of tissues was assessed. Second, the performance of the Ca-aware reconstruction technique on moving CAC was evaluated with a dynamic phantom. Methods An artificial coronary artery, containing two CAC of equal size and different densities (196 ± 3, 380 ± 2 mg hydroxyapatite cm−3), was moved in the center compartment of an anthropomorphic thorax phantom at different heart rates. The center compartment was filled with mixtures, which resembled fat, water, and soft tissue equivalent CT numbers. Raw data was acquired with a routine clinical CAC protocol, at 120 peak kilovolt (kVp). Subsequently, reduced tube voltage (100 kVp) and tin-filtration (150Sn kVp) acquisitions were performed. Raw data was reconstructed with a standard and a novel Ca-aware reconstruction technique. Agatston scores of all reconstructions were compared with the reference (120 kVp) and standard reconstruction technique, with relevant deviations defined as > 10%. Results For all heart rates, Agatston scores for CAC submerged in fat were comparable to the reference, for the reduced-kVp acquisition with Ca-aware reconstruction kernel. For water and soft tissue, medium-density Agatston scores were again comparable to the reference for all heart rates. Low-density Agatston scores showed relevant deviations, up to 15% and 23% for water and soft tissue, respectively. Conclusion CT CAC scoring with varying surrounding materials and heart rates is feasible at patient-specific tube voltages with the novel Ca-aware reconstruction technique. Key Points • A dedicated calcium-aware reconstruction kernel results in similar Agatston scores for CAC surrounded by fatty materials regardless of CAC density and heart rate. • Application of a dedicated calcium-aware reconstruction kernel allows for radiation dose reduction. • Mass scores determined with CT underestimated physical mass.

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Section: Discussionmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluating a calcium-aware kernel for CT CAC scoring with varying surrounding materials and heart rates: a dynamic phantom study

et al. 2021

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“…Therefore, it is expected that the results shown in static phantoms can be readily extended to clinical examinations with motion. Recently, an independent study was conducted in which a group of patients who were scanned twice, one with 120 kV and the other using the kV‐independent technique, 25 and its results showed agreement of calcium scores between the two scans. Results from that work were consistent with our phantom study and the two studies provide complimentary information to each other.…”

Section: Discussionmentioning

confidence: 99%

Technical Note: kV‐independent coronary calcium scoring: A phantom evaluation of score accuracy and potential radiation dose reduction

et al. 2021

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Purpose To determine the accuracy of CT number and calcium score of a kV‐independent technique based on an artificial 120 kV reconstruction, and its potential to reduce radiation dose. Methods Anthropomorphic chest phantoms were scanned on a third‐generation dual‐source CT system equipped with the artificial 120 kV reconstruction. First, a phantom module containing a 20‐mm diameter hydroxyapatite (HA) insert was scanned inside the chest phantoms at different tube potentials (70–140 kV) to evaluate calcium CT number accuracy. Next, three small HA inserts (diameter/length = 5 mm) were inserted into a pork steak and scanned inside the phantoms to evaluate calcium score accuracy at different kVs. Finally, the same setup was scanned using automatic exposure control (AEC) at 120 kV, and then with automatic kV selection (auto‐kV). Phantoms were also scanned at 120 kV using a size‐dependent mA chart. CT numbers of soft tissue and calcium were measured from different kV images. Calcium score of each small HA insert was measured using commercial software. Results The CT number difference from 120 kV was small with tube potentials from 90 to 140 kV for both soft tissue and calcium (maximal difference of 4/5 HU, respectively). Consistent calcium scores were obtained from images of different kVs compared to 120 kV, with a relative difference <8%. Auto‐kV provided a 25–34% dose reduction compared to AEC alone. Conclusion A kV‐independent calcium scoring technique can produce artificial 120 kV images with consistent soft tissue and calcium CT numbers compared to standard 120 kV examinations. When coupled with auto‐kV, this technique can reduce radiation by 25–34% compared to that with AEC alone, while providing consistent calcium scores as that of standard 120 kV examinations.

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“…This technique was originally designed for coronary calcium scoring 17–21 . Studies have demonstrated the efficacy of this technique and its potential for dose reduction 22–24 . Additionally, another technique utilizing deep learning techniques to generate artificial 120 kV images from MV images has also been reported 25 .…”

Section: Introductionmentioning

confidence: 99%

Technical note: Evaluation of artificial 120‐kilovolt computed tomography images for radiation therapy applications

et al. 2022

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Purpose The purpose of this work is to evaluate the scaled computed tomography (CT) number accuracy of an artificial 120 kV reconstruction technique based on phantom experiments in the context of radiation therapy planning. Methods An abdomen‐shaped electron density phantom was scanned on a clinical CT scanner capable of artificial 120 kV reconstruction using different tube potentials from 70 to 150 kV. A series of tissue‐equivalent phantom inserts (lung, adipose, breast, solid water, liver, inner bone, 30%/50% CaCO3, cortical bone) were placed inside the phantom. Images were reconstructed using a conventional quantitative reconstruction kernel as well as the artificial 120 kV reconstruction kernel. Scaled CT numbers of inserts were measured from images acquired at different kVs and compared with those acquired at 120 kV, which were deemed as the ground truth. The relative error was quantified as the percentage deviation of scaled CT numbers acquired at different tube potentials from their ground truth values acquired at 120 kV. Results Scaled CT numbers measured from images reconstructed using the conventional reconstruction demonstrated a strong kV‐dependence. The relative error in scaled CT numbers ranged from 0.6% (liver insert) to 31.1% (cortical bone insert). The artificial 120 kV reconstruction reduced the kV dependence, especially for bone tissues. The relative error in scaled CT number was reduced to 0.4% (liver insert) and 2.6% (30% CaCO3 insert) using this technique. When tube potential selection was limited to the range of 90 to 150 kV, the relative error was further restrained to <1.2% for all tissue types. Conclusion Phantom results demonstrated that using the artificial 120 kV technique, it was feasible to acquire raw projection data at the desired tube potential and then reconstruct images with scaled CT numbers comparable to those obtained directly at 120 kV. In radiotherapy applications, this technique may allow optimization of tube potential without complicating clinical workflow by eliminating the necessity of maintaining multiple sets of CT calibration curves.

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Individualized coronary calcium scoring at any tube voltage using a kV-independent reconstruction algorithm

Cited by 11 publications

References 22 publications

Evaluating a calcium-aware kernel for CT CAC scoring with varying surrounding materials and heart rates: a dynamic phantom study

Evaluating a calcium-aware kernel for CT CAC scoring with varying surrounding materials and heart rates: a dynamic phantom study

Technical Note: kV‐independent coronary calcium scoring: A phantom evaluation of score accuracy and potential radiation dose reduction

Technical note: Evaluation of artificial 120‐kilovolt computed tomography images for radiation therapy applications

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