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Zhou Y, Eastman E, Lee C, Scott A. Optimal dose determination for coronary artery calcium scoring CT at standard tube voltage. Eur J Radiol 2023; 167:111029. [PMID: 37579562 DOI: 10.1016/j.ejrad.2023.111029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 05/31/2023] [Accepted: 08/08/2023] [Indexed: 08/16/2023]
Abstract
OBJECTIVES Coronary artery calcium scoring (CACs) at 120 kVp is the standard practice. It is an important tool for preventative management of asymptomatic patients. However, the current dose delivery, albeit patient-size dependent, does not connect the CACs specific noise requirement to the dose, causing significant dose variations. We propose a new approach for optimal dose determination by incorporating the patient-size dependent noise threshold. METHODS A polyethylene-based Mercury phantom of various diameters was scanned with a dual-source CT using CACs gating at different volume CT dose index (CTDIvol). The relationship of noise to the diameter and CTDIvol was obtained. The phantom diameter was then converted to the patient chest diameter through a retrospective analysis of a clinical cohort (N = 140). Finally, the patient-size dependent noise threshold was applied, and the optimal dose was derived. The prescribed doses were compared with those from a clinical CACs cohort (N = 262). RESULTS A power-exponential relationship was found for the noise versus CTDIvol and phantom diameter (R2 = 0.988). The phantom diameter versus the patient effective diameter was found to obey a linear relationship (R2 = 0.998). Two noise threshold settings were made for dose options: one for more dose saving, and another for tighter noise constraint. Retrospective comparisons with clinical CACs studies showed an average dose reduction of 23% in 80.5% of the cases with option 1. The average dose reduction is 23% in 77.9% of the cases with option 2. CONCLUSION A new optimal dose scheme dictated by the target noise was established for CACs at 120 kVp. The proposed dose modulation can serve as the baseline from which further dose reduction is possible.
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Affiliation(s)
- Yifang Zhou
- Department of Imaging, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA.
| | - Emi Eastman
- Department of Imaging, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA
| | - Christina Lee
- Department of Imaging, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA
| | - Alexander Scott
- Department of Imaging, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA
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Fink N, Zsarnoczay E, Schoepf UJ, O'Doherty J, Griffith JP, Pinos D, Tesche C, Ricke J, Willemink MJ, Varga-Szemes A, Emrich T. Radiation Dose Reduction for Coronary Artery Calcium Scoring Using a Virtual Noniodine Algorithm on Photon-Counting Detector Computed-Tomography Phantom Data. Diagnostics (Basel) 2023; 13:diagnostics13091540. [PMID: 37174932 PMCID: PMC10177425 DOI: 10.3390/diagnostics13091540] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/14/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023] Open
Abstract
Background: On the basis of the hypothesis that virtual noniodine (VNI)-based coronary artery calcium scoring (CACS) is feasible at reduced radiation doses, this study assesses the impact of radiation dose reduction on the accuracy of this VNI algorithm on a photon-counting detector (PCD)-CT. Methods: In a systematic in vitro setting, a phantom for CACS simulating three chest sizes was scanned on a clinical PCD-CT. The standard radiation dose was chosen at volumetric CT dose indices (CTDIVol) of 1.5, 3.3, 7.0 mGy for small, medium-sized, and large phantoms, and was gradually reduced by adjusting the tube current resulting in 100, 75, 50, and 25%, respectively. VNI images were reconstructed at 55 keV, quantum iterative reconstruction (QIR)1, and at 60 keV/QIR4, and evaluated regarding image quality (image noise (IN), contrast-to-noise ratio (CNR)), and CACS. All VNI results were compared to true noncontrast (TNC)-based CACS at 70 keV and standard radiation dose (reference). Results: INTNC was significantly higher than INVNI, and INVNI at 55 keV/QIR1 higher than at 60 keV/QIR4 (100% dose: 16.7 ± 1.9 vs. 12.8 ± 1.7 vs. 7.7 ± 0.9; p < 0.001 for every radiation dose). CNRTNC was higher than CNRVNI, but it was better to use 60 keV/QIR4 (p < 0.001). CACSVNI showed strong correlation and agreement at every radiation dose (p < 0.001, r > 0.9, intraclass correlation coefficient > 0.9). The coefficients of the variation in root-mean squared error were less than 10% and thus clinically nonrelevant for the CACSVNI of every radiation dose. Conclusion: This phantom study suggests that CACSVNI is feasible on PCD-CT, even at reduced radiation dose while maintaining image quality and CACS accuracy.
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Affiliation(s)
- Nicola Fink
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
- Department of Radiology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Emese Zsarnoczay
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
- Medical Imaging Center, Semmelweis University, Korányi Sándor utca 2, 1083 Budapest, Hungary
| | - U Joseph Schoepf
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
| | - Jim O'Doherty
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
- Siemens Medical Solutions, 40 Liberty Boulevard, Malvern, PA 19355, USA
| | - Joseph P Griffith
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
| | - Daniel Pinos
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
| | - Christian Tesche
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
- Department of Cardiology, Munich University Clinic, Ludwig-Maximilians-University, Marchioninistr. 15, 81377 Munich, Germany
| | - Jens Ricke
- Department of Radiology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Martin J Willemink
- Department of Radiology, Stanford University School of Medicine, 291 Campus Drive, Stanford, CA 94305, USA
| | - Akos Varga-Szemes
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
| | - Tilman Emrich
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
- Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes-Gutenberg-University, Langenbeckstr. 1, 55131 Mainz, Germany
- German Centre for Cardiovascular Research, Partner Site Rhine-Main, 55131 Mainz, Germany
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3
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van der Werf NR, Rodesch PA, Si-Mohamed S, van Hamersvelt RW, Greuter MJW, Leiner T, Boussel L, Willemink MJ, Douek P. Improved coronary calcium detection and quantification with low-dose full field-of-view photon-counting CT: a phantom study. Eur Radiol 2022; 32:3447-3457. [PMID: 34997284 DOI: 10.1007/s00330-021-08421-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 08/31/2021] [Accepted: 10/17/2021] [Indexed: 12/19/2022]
Abstract
OBJECTIVE The aim of the current study was to systematically assess coronary artery calcium (CAC) detection and quantification for spectral photon-counting CT (SPCCT) in comparison to conventional CT and, in addition, to evaluate the possibility of radiation dose reduction. METHODS Routine clinical CAC CT protocols were used for data acquisition and reconstruction of two CAC containing cylindrical inserts which were positioned within an anthropomorphic thorax phantom. In addition, data was acquired at 50% lower radiation dose by reducing tube current, and slice thickness was decreased. Calcifications were considered detectable when three adjacent voxels exceeded the CAC scoring threshold of 130 Hounsfield units (HU). Quantification of CAC (as volume and mass score) was assessed by comparison with known physical quantities. RESULTS In comparison with CT, SPCCT detected 33% and 7% more calcifications for the small and large phantoms, respectively. At reduced radiation dose and reduced slice thickness, small phantom CAC detection increased by 108% and 150% for CT and SPCCT, respectively. For the large phantom size, noise levels interfered with CAC detection. Although comparable between CT and SPCCT, routine protocols CAC quantification showed large deviations (up to 134%) from physical CAC volume. At reduced radiation dose and slice thickness, physical volume overestimations decreased to 96% and 72% for CT and SPCCT, respectively. In comparison with volume scores, mass score deviations from physical quantities were smaller. CONCLUSION CAC detection on SPCCT is superior to CT, and was even preserved at a reduced radiation dose. Furthermore, SPCCT allows for improved physical volume estimation. KEY POINTS • In comparison with conventional CT, increased coronary artery calcium detection (up to 156%) for spectral photon-counting CT was found, even at 50% radiation dose reduction. • Spectral photon-counting CT can more accurately measure physical volumes than conventional CT, especially at reduced slice thickness and for high-density coronary artery calcium. • For both conventional and spectral photon-counting CT, reduced slice thickness reconstructions result in more accurate physical mass approximation.
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Affiliation(s)
- N R van der Werf
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands. .,Department of Radiology & Nuclear Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
| | - P A Rodesch
- Louis Pradel Cardiology Hospital, Hospices Civils de Lyon, Lyon, France.,Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
| | - S Si-Mohamed
- Louis Pradel Cardiology Hospital, Hospices Civils de Lyon, Lyon, France.,Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
| | - R W van Hamersvelt
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - M J W Greuter
- Department of Radiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - T Leiner
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - L Boussel
- Louis Pradel Cardiology Hospital, Hospices Civils de Lyon, Lyon, France.,Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
| | - M J Willemink
- Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA
| | - P Douek
- Louis Pradel Cardiology Hospital, Hospices Civils de Lyon, Lyon, France.,Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
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4
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van Praagh GD, Wang J, van der Werf NR, Greuter MJW, Mastrodicasa D, Nieman K, van Hamersvelt RW, Oostveen LJ, de Lange F, Slart RHJA, Leiner T, Fleischmann D, Willemink MJ. Coronary Artery Calcium Scoring: Toward a New Standard. Invest Radiol 2022; 57:13-22. [PMID: 34261083 PMCID: PMC10072789 DOI: 10.1097/rli.0000000000000808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Although the Agatston score is a commonly used quantification method, rescan reproducibility is suboptimal, and different CT scanners result in different scores. In 2007, McCollough et al (Radiology 2007;243:527-538) proposed a standard for coronary artery calcium quantification. Advancements in CT technology over the last decade, however, allow for improved acquisition and reconstruction methods. This study aims to investigate the feasibility of a reproducible reduced dose alternative of the standardized approach for coronary artery calcium quantification on state-of-the-art CT systems from 4 major vendors. MATERIALS AND METHODS An anthropomorphic phantom containing 9 calcifications and 2 extension rings were used. Images were acquired with 4 state-of-the-art CT systems using routine protocols and a variety of tube voltages (80-120 kV), tube currents (100% to 25% dose levels), slice thicknesses (3/2.5 and 1/1.25 mm), and reconstruction techniques (filtered back projection and iterative reconstruction). Every protocol was scanned 5 times after repositioning the phantom to assess reproducibility. Calcifications were quantified as Agatston scores. RESULTS Reducing tube voltage to 100 kV, dose to 75%, and slice thickness to 1 or 1.25 mm combined with higher iterative reconstruction levels resulted in an on average 36% lower intrascanner variability (interquartile range) compared with the standard 120 kV protocol. Interscanner variability per phantom size decreased by 34% on average. With the standard protocol, on average, 6.2 ± 0.4 calcifications were detected, whereas 7.0 ± 0.4 were detected with the proposed protocol. Pairwise comparisons of Agatston scores between scanners within the same phantom size demonstrated 3 significantly different comparisons at the standard protocol (P < 0.05), whereas no significantly different comparisons arose at the proposed protocol (P > 0.05). CONCLUSIONS On state-of-the-art CT systems of 4 different vendors, a 25% reduced dose, thin-slice calcium scoring protocol led to improved intrascanner and interscanner reproducibility and increased detectability of small and low-density calcifications in this phantom. The protocol should be extensively validated before clinical use, but it could potentially improve clinical interscanner/interinstitutional reproducibility and enable more consistent risk assessment and treatment strategies.
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Affiliation(s)
| | - Jia Wang
- Department of Environmental Health and Safety, Stanford University, Stanford CA
| | | | | | | | | | | | - Luuk J Oostveen
- Department of Medical Imaging, Radboud University Medical Center, Nijmegen
| | - Frank de Lange
- Department of Medical Imaging, Radboud University Medical Center, Nijmegen
| | | | - Tim Leiner
- Department of Radiology, University Medical Center Utrecht, Utrecht
| | | | - Martin J Willemink
- From the Department of Radiology, Stanford University School of Medicine, Stanford, CA
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5
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Juntunen MAK, Kotiaho AO, Nieminen MT, Inkinen SI. Optimizing iterative reconstruction for quantification of calcium hydroxyapatite with photon counting flat-detector computed tomography: a cardiac phantom study. J Med Imaging (Bellingham) 2021; 8:052102. [PMID: 33718518 PMCID: PMC7946398 DOI: 10.1117/1.jmi.8.5.052102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 01/28/2021] [Indexed: 11/28/2022] Open
Abstract
Purpose: Coronary artery calcium (CAC) scoring with computed tomography (CT) has been proposed as a screening tool for coronary artery disease, but concerns remain regarding the radiation dose of CT CAC scoring. Photon counting detectors and iterative reconstruction (IR) are promising approaches for patient dose reduction, yet the preservation of CAC scores with IR has been questioned. The purpose of this study was to investigate the applicability of IR for quantification of CAC using a photon counting flat-detector. Approach: We imaged a cardiac rod phantom with calcium hydroxyapatite (CaHA) inserts with different noise levels using an experimental photon counting flat-detector CT setup to simulate the clinical CAC scoring protocol. We applied filtered back projection (FBP) and two IR algorithms with different regularization strengths. We compared the air kerma values, image quality parameters [noise magnitude, noise power spectrum, modulation transfer function (MTF), and contrast-to-noise ratio], and CaHA quantification accuracy between FBP and IR. Results: IR regularization strength influenced CAC scores significantly ( p < 0.05 ). The CAC volumes and scores between FBP and IRs were the most similar when the IR regularization strength was chosen to match the MTF of the FBP reconstruction. Conclusion: When the regularization strength is selected to produce comparable spatial resolution with FBP, IR can yield comparable CAC scores and volumes with FBP. Nonetheless, at the lowest radiation dose setting, FBP produced more accurate CAC volumes and scores compared to IR, and no improved CAC scoring accuracy at low dose was demonstrated with the utilized IR methods.
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Affiliation(s)
- Mikael A. K. Juntunen
- University of Oulu, Research Unit of Medical Imaging, Physics, and Technology, Oulu, Finland
- Oulu University Hospital, Department of Diagnostic Radiology, Oulu, Finland
| | - Antti O. Kotiaho
- Oulu University Hospital, Department of Diagnostic Radiology, Oulu, Finland
| | - Miika T. Nieminen
- University of Oulu, Research Unit of Medical Imaging, Physics, and Technology, Oulu, Finland
- Oulu University Hospital, Department of Diagnostic Radiology, Oulu, Finland
- Medical Research Center, University of Oulu, Oulu University Hospital, Oulu, Finland
| | - Satu I. Inkinen
- University of Oulu, Research Unit of Medical Imaging, Physics, and Technology, Oulu, Finland
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Coronary artery calcium scoring at lower tube voltages - Dose determination and scoring mechanism. Eur J Radiol 2021; 139:109680. [PMID: 33848779 DOI: 10.1016/j.ejrad.2021.109680] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 03/19/2021] [Accepted: 03/23/2021] [Indexed: 11/22/2022]
Abstract
PURPOSE Population dose has been a concern with coronary artery calcium scoring CT since it is performed in adults with borderline risk. Lower tube voltage acquisitions are appealing but there are no agreed schemes for reduced dose determination. Moreover, conventional scoring cannot be used without changing the multiple Agatston thresholds. METHODS By applying consistent calcium contrast-to-noise ratio to two anthropomorphic heart phantoms (medium and large) with 3-cm hydroxyapatite (HA) inserts, scanned using a dual-source CT, the relationship was derived between the volume CT dose index (CTDIvol) at lower tube voltages and the baseline CTDIvol at 120 kVp. The baseline CTDIvol was obtained using the noise thresholds from the images acquired at 120 kVp. To preserve the conventional Agatston thresholds, down-scaling with the found factors was applied to images acquired at lower voltages with a dynamic heart module and 1.2-5 mm inserts (50-400 mg/cc) on the coronary tracks. Scores were evaluated on the scaled images by six readers. RESULTS The CTDIvol at lower voltages was related to the baseline CTDIvol following a power form of the voltage (index 1.246), regardless of the phantom size. The baseline CTDIvol was 1.5 and 4.5 mGy, for the medium and large phantoms, respectively. Correspondingly, the reduced CTDIvol at 100-70 kVp were 1.28-0.76 mGy, and 3.57-2.32 mGy. The downscaling factors were 0.88-0.63. The calcium scores at lower voltages were found within 12 % of the ground-truths. CONCLUSION A vendor-independent approach was established to obtain the reduced dose and correct coronary calcium scores at lower tube voltages.
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Pan YK, Sun MH, Wang JJ, Chen XB, Kan XJ, Ge YH, Guo ZP. Effect of different reconstruction algorithms on coronary artery calcium scores using the reduced radiation dose protocol: a clinical and phantom study. Quant Imaging Med Surg 2021; 11:1504-1517. [PMID: 33816187 DOI: 10.21037/qims-20-437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Background This study aimed to evaluate the effects of different iterative reconstruction (IR) algorithms on coronary artery calcium (CAC) score quantification using the reduced radiation dose (RRD) protocol in an anthropomorphic phantom and in patients. Methods A thorax phantom, containing 9 calcification inserts with varying hydroxyapatite (HA) densities, was scanned with the reference protocol [120 kv, 80 mAs, filtered back projection (FBP)] and RRD protocol (120 kV, 20-80 mAs, 5 mAs interval) using a 256-slice computed tomography (CT) scanner. Raw data were reconstructed with different reconstruction algorithms [iDose4 levels 1-7 and iterative model reconstruction (IMR) levels 1-3]. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and Agatston score (AS) were calculated for each image series. The correction factor was derived from linear regression analysis between the reference image series and other image series with different parameters. Additionally, 40 patients were scanned with the RRD protocol (50 mAs) and reconstructed with FBP, iDose4 level 4, and IMR level 2. AS was calculated for the 3-group image series, and was corrected by applying a correction factor for the IMR group. The agreement of risk stratification with different reconstruction algorithms was also analyzed. Results For the phantom study, the iDose4 and IMR groups had significantly higher SNR and CNR than the FBP group (all P<0.05). There were no significant differences in the total AS after comparing image series reconstructed with iDose4 (level 1-7) and FBP (all P>0.05), while AS from the IMR (level 1-3) image series were lower than the FBP group (all P<0.05). The tube current of 50 mAs was determined for the clinical study, and the correction factor was 1.14. For the clinical study, the median AS from the iDose4 and IMR groups were both significantly lower compared to the FBP image series [(112.89 (63.01, 314.09), 113.22 (64.78, 364.95) vs. 118.59 (65.05, 374.48), both P<0.05]. After applying the correction factor, the adjusted AS from the IMR group was not significantly different from that of the FBP group [126.48 (69.62, 355.85) vs. 118.59 (65.05, 374.48), P=0.145]. Moreover, the agreement in risk stratification between FBP and IMR improved from 0.81 to 0.85. Conclusions The RRD CAC scoring scan using the IMR reconstruction algorithm is clinically feasible, and a correction factor can help reduce the AS underestimation effect.
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Affiliation(s)
- Yu-Kun Pan
- Department of Radiology, Central China Fuwai Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Ming-Hua Sun
- Department of Radiology, Henan Provincial People's Hospital, Department of Radiology of Central China Fuwai Hospital, Central China Fuwai Hospital of Zhengzhou University, Zhengzhou, China
| | - Jia-Jia Wang
- Department of Radiology, Central China Fuwai Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | | | - Xiao-Jing Kan
- Department of Radiology, Henan Provincial People's Hospital, Department of Radiology of Central China Fuwai Hospital, Central China Fuwai Hospital of Zhengzhou University, Zhengzhou, China
| | - Ying-Hui Ge
- Department of Radiology, Henan Provincial People's Hospital, Department of Radiology of Central China Fuwai Hospital, Central China Fuwai Hospital of Zhengzhou University, Zhengzhou, China
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Tao S, Sheedy E, Bruesewitz M, Weber N, Williams K, Halaweish A, Schmidt B, Williamson E, McCollough C, Leng S. Technical Note: kV-independent coronary calcium scoring: A phantom evaluation of score accuracy and potential radiation dose reduction. Med Phys 2021; 48:1307-1314. [PMID: 33332626 DOI: 10.1002/mp.14663] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/04/2020] [Accepted: 12/08/2020] [Indexed: 11/10/2022] Open
Abstract
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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Affiliation(s)
- Shengzhen Tao
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
| | - Emily Sheedy
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - Nikkole Weber
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | - Kyle Williams
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - Bernhard Schmidt
- Siemens Healthineers, Siemensstraße 1, Forchheim, 91301, Germany
| | | | | | - Shuai Leng
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
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Toia P, La Grutta L, Sollami G, Clemente A, Gagliardo C, Galia M, Maffei E, Midiri M, Cademartiri F. Technical development in cardiac CT: current standards and future improvements-a narrative review. Cardiovasc Diagn Ther 2020; 10:2018-2035. [PMID: 33381441 DOI: 10.21037/cdt-20-527] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Non-invasive depiction of coronary arteries has been a great challenge for imaging specialists since the introduction of computed tomography (CT). Technological development together with improvements in spatial, temporal, and contrast resolution, progressively allowed implementation of the current clinical role of the CT assessment of coronary arteries. Several technological evolutions including hardware and software solutions of CT scanners have been developed to improve spatial and temporal resolution. The main challenges of cardiac computed tomography (CCT) are currently plaque characterization, functional assessment of stenosis and radiation dose reduction. In this review, we will discuss current standards and future improvements in CCT.
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Affiliation(s)
- Patrizia Toia
- Department of Biomedicine, Neurosciences and Advanced Diagnostic (BiND), University of Palermo, Palermo, Italy
| | - Ludovico La Grutta
- Department of Health Promotion Sciences Maternal and Infantile Care, Internal Medicine and Medical Specialities (ProMISE), University of Palermo, Palermo, Italy
| | - Giulia Sollami
- Department of Biomedicine, Neurosciences and Advanced Diagnostic (BiND), University of Palermo, Palermo, Italy
| | - Alberto Clemente
- Fondazione Toscana G. Monasterio CNR - Regione Toscana, Pisa and Massa, Italy
| | - Cesare Gagliardo
- Department of Biomedicine, Neurosciences and Advanced Diagnostic (BiND), University of Palermo, Palermo, Italy
| | - Massimo Galia
- Department of Biomedicine, Neurosciences and Advanced Diagnostic (BiND), University of Palermo, Palermo, Italy
| | - Erica Maffei
- Department of Radiology, Area Vasta 1, ASUR Marche, Urbino (PU), Italy
| | - Massimo Midiri
- Department of Biomedicine, Neurosciences and Advanced Diagnostic (BiND), University of Palermo, Palermo, Italy
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Sinogram-Affirmed Iterative Reconstruction Negatively Impacts the Risk Category Based on Agatston Score: A Study Combining Coronary Calcium Score Measurement and Coronary CT Angiography. BIOMED RESEARCH INTERNATIONAL 2020; 2020:6909130. [PMID: 32733949 PMCID: PMC7376420 DOI: 10.1155/2020/6909130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 04/13/2020] [Accepted: 05/19/2020] [Indexed: 11/23/2022]
Abstract
Purpose To assess the impact of sinogram-affirmed iterative reconstruction (SAFIRE) on risk category for coronary artery disease by combining coronary calcium score measurement and coronary CT angiography (CCTA). Materials and Methods Eighty-nine patients (64.0% male) older than 18 years (64.4 ± 10.3 years) underwent coronary artery calcium scanning and prospectively ECG-triggered sequential CCTA examination. All raw data acquired in coronary artery calcium scanning were reconstructed by both filtered back projection (FBP) and SAFIRE algorithms with 5 different levels. Objective image quality and calcium quantification were evaluated and compared between FBP and all SAFIRE levels by the Sphericity Assumed test or Greenhouse-Geisser ε correction coefficient. Coronary artery stenosis was assessed in CCTA. Risk categories of all patients and of the patients with coronary artery stenosis in CCTA were compared between FBP and all SAFIRE levels by the Friedman test. Results The reconstruction protocol from traditional FBP to SAFIRE 5 was associated with a gradual reduction in CT value and image noise (P < 0.001) but associated with a gradual improvement in the signal-to-noise ratio (P < 0.001). There was a gradual reduction in coronary calcification quantification (Agatston score: from 73.5 in FBP to 38.1 in SAFIRE 5, P < 0.001) from traditional FBP to SAFIRE 5. There was a significant difference for the risk category between FBP and all levels of SAFIRE in all patients (from 3.5 in FBP to 3.2 in SAFIRE 5, P < 0.001) and in the patients with coronary artery stenosis in CCTA (from 4.0 in FBP to 3.6 in SAFIRE 5, P < 0.001). Conclusions SAFIRE significantly reduces coronary calcification quantification compared to FBP, resulting in the reduction of risk categories based on the Agatston score. The risk categories of the patients with coronary artery stenosis in CCTA may also decline. Thus, SAFIRE may lead risk categories to underestimate the existence of significant coronary artery stenosis.
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Affiliation(s)
| | - Christina Stewart
- Department of Medical Physics, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - Nicholas W Weir
- Department of Medical Physics, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - David E Newby
- Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh, UK
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Vonder M, van der Werf NR, Leiner T, Greuter MJ, Fleischmann D, Vliegenthart R, Oudkerk M, Willemink MJ. The impact of dose reduction on the quantification of coronary artery calcifications and risk categorization: A systematic review. J Cardiovasc Comput Tomogr 2018; 12:352-363. [DOI: 10.1016/j.jcct.2018.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 05/18/2018] [Accepted: 06/11/2018] [Indexed: 11/29/2022]
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Fraser AG. A manifesto for cardiovascular imaging: addressing the human factor. Eur Heart J Cardiovasc Imaging 2018; 18:1311-1321. [PMID: 29029029 PMCID: PMC5837338 DOI: 10.1093/ehjci/jex216] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 09/11/2017] [Indexed: 12/22/2022] Open
Abstract
Our use of modern cardiovascular imaging tools has not kept pace with their technological development. Diagnostic errors are common but seldom investigated systematically. Rather than more impressive pictures, our main goal should be more precise tests of function which we select because their appropriate use has therapeutic implications which in turn have a beneficial impact on morbidity or mortality. We should practise analytical thinking, use checklists to avoid diagnostic pitfalls, and apply strategies that will reduce biases and avoid overdiagnosis. We should develop normative databases, so that we can apply diagnostic algorithms that take account of variations with age and risk factors and that allow us to calculate pre-test probability and report the post-test probability of disease. We should report the imprecision of a test, or its confidence limits, so that reference change values can be considered in daily clinical practice. We should develop decision support tools to improve the quality and interpretation of diagnostic imaging, so that we choose the single best test irrespective of modality. New imaging tools should be evaluated rigorously, so that their diagnostic performance is established before they are widely disseminated; this should be a shared responsibility of manufacturers with clinicians, leading to cost-effective implementation. Trials should evaluate diagnostic strategies against independent reference criteria. We should exploit advances in machine learning to analyse digital data sets and identify those features that best predict prognosis or responses to treatment. Addressing these human factors will reap benefit for patients, while technological advances continue unpredictably.
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Affiliation(s)
- Alan G Fraser
- School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.,Department of Cardiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, UK.,Division of Cardiovascular Imaging and Dynamics, Department of Cardiovascular Sciences, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
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Blaha MJ, Mortensen MB, Kianoush S, Tota-Maharaj R, Cainzos-Achirica M. Coronary Artery Calcium Scoring: Is It Time for a Change in Methodology? JACC Cardiovasc Imaging 2018; 10:923-937. [PMID: 28797416 DOI: 10.1016/j.jcmg.2017.05.007] [Citation(s) in RCA: 154] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 05/06/2017] [Accepted: 05/11/2017] [Indexed: 02/07/2023]
Abstract
Quantification of coronary artery calcium (CAC) has been shown to be reliable, reproducible, and predictive of cardiovascular risk. Formal CAC scoring was introduced in 1990, with early scoring algorithms notable for their simplicity and elegance. Yet, with little evidence available on how to best build a score, and without a conceptual model guiding score development, these scores were, to a large degree, arbitrary. In this review, we describe the traditional approaches for clinical CAC scoring, noting their strengths, weaknesses, and limitations. We then discuss a conceptual model for developing an improved CAC score, reviewing the evidence supporting approaches most likely to lead to meaningful score improvement (for example, accounting for CAC density and regional distribution). After discussing the potential implementation of an improved score in clinical practice, we follow with a discussion of the future of CAC scoring, asking the central question: do we really need a new CAC score?
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Affiliation(s)
- Michael J Blaha
- Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Baltimore, Maryland.
| | - Martin Bødtker Mortensen
- Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Baltimore, Maryland; Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
| | - Sina Kianoush
- Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Baltimore, Maryland
| | - Rajesh Tota-Maharaj
- Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Baltimore, Maryland; Florida Heart and Vascular Multi-Specialty Group, Leesburg, Florida
| | - Miguel Cainzos-Achirica
- Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Baltimore, Maryland; IDIBELL-Bellvitge Biomedical Research Institute, Barcelona, Spain; RTI Health Solutions, Barcelona, Spain
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Luhur R, Schuijf JD, Mews J, Blobel J, Hamm B, Lembcke A. Accuracy of coronary artery calcium scoring with tube current reduction by 75%, using an adaptive iterative reconstruction algorithm. Br J Radiol 2018; 91:20170678. [PMID: 29260893 DOI: 10.1259/bjr.20170678] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE To assess the accuracy of an iterative reconstruction (IR) technique for coronary artery calcium scoring with reduced radiation dose. METHODS 163 consecutive patients underwent twofold scanning by 320-row detector CT at 120 kVp. A low-dose scan at 25% tube current but with standard scan length (14 cm) was followed by a standard dose scan with routine tube current but reduced scan length (10 cm). Reduced dose images were constructed using filtered back-projection (FBP) and IR (adaptive iterative dose reduction in three dimensions). The standard dose scan reconstructed with FBP served as the gold standard for comparisons. Image noise and Agatston coronary calcium scores were determined and compared between the groups. RESULTS Compared with FBP at standard dose, noise at reduced dose increased markedly with FBP but remained low with IR. Mean Agatston score with FBP at reduced dose showed a significant increase as compared with FBP at standard dose. No significant difference was observed when applying IR at reduced dose. At reduced dose, 38 (23.3%) patients were reassigned to a different cardiovascular risk category with FBP but only 8 (4.9%) with IR. Out of 47 patients with a zero Agatston score, 15 patients (31.9%) were false-positive with FBP at reduced dose, but no false positives were found with IR. CONCLUSION IR allows accurate coronary artery calcium scoring with a radiation dose reduced by 75%. Advances in knowledge: The application of adaptive iterative dose reduction in three dimensions allows the maintenance of accurate Agatston scores and risk stratification at significantly reduced tube current, thus reducing the patient's exposure to ionizing radiation.
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Affiliation(s)
- Reny Luhur
- 1 Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Charité Mitte , Charité - Universitätsmedizin Berlin, Campus Charité Mitte , Berlin , Germany
| | - Joanne D Schuijf
- 2 Center for Medical Research & Development Europe,Toshiba Medical Systems Europe BV , Toshiba Medical Systems Europe BV , Zoetermeer , Netherlands
| | - Jürgen Mews
- 2 Center for Medical Research & Development Europe,Toshiba Medical Systems Europe BV , Toshiba Medical Systems Europe BV , Zoetermeer , Netherlands
| | - Jörg Blobel
- 2 Center for Medical Research & Development Europe,Toshiba Medical Systems Europe BV , Toshiba Medical Systems Europe BV , Zoetermeer , Netherlands
| | - Bernd Hamm
- 1 Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Charité Mitte , Charité - Universitätsmedizin Berlin, Campus Charité Mitte , Berlin , Germany
| | - Alexander Lembcke
- 1 Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Charité Mitte , Charité - Universitätsmedizin Berlin, Campus Charité Mitte , Berlin , Germany
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Vonder M, van der Aalst CM, Vliegenthart R, van Ooijen PMA, Kuijpers D, Gratama JW, de Koning HJ, Oudkerk M. Coronary Artery Calcium Imaging in the ROBINSCA Trial: Rationale, Design, and Technical Background. Acad Radiol 2018; 25:118-128. [PMID: 28843465 DOI: 10.1016/j.acra.2017.07.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/18/2017] [Accepted: 07/20/2017] [Indexed: 01/20/2023]
Abstract
RATIONALE AND OBJECTIVES To describe the rationale, design, and technical background of coronary artery calcium (CAC) imaging in the large-scale population-based cardiovascular disease screening trial (Risk Or Benefit IN Screening for CArdiovascular Diseases [ROBINSCA]). MATERIALS AND METHODS First, literature search was performed to review the logistics, setup, and settings of previously performed CAC imaging studies, and current clinical CAC imaging protocols of participating centers in the ROBINSCA trial were evaluated. A second literature search was performed to evaluate the impact of computed tomography parameter settings on CAC score. RESULTS Based on literature reviews and experts opinion an imaging protocol accompanied by data management protocol was created for ROBINSCA. The imaging protocol should consist of a fixed tube voltage, individually tailored tube current setting, mid-diastolic electrocardiography-triggering, fixed field-of-view, fixed reconstruction kernel, fixed slice thickness, overlapping reconstruction and without iterative reconstruction. The analysis of scans is performed with one type and version of CAC scoring software, by two dedicated and experienced researchers. The data management protocol describes the organization of data handling between the coordinating center, participating centers, and core analysis center. CONCLUSION In this paper we describe the rationale and technical considerations to be taken in developing CAC imaging protocol, and we present a detailed protocol that can be implemented for CAC screening purposes.
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Affiliation(s)
- Marleen Vonder
- University of Groningen, University Medical Center Groningen, Center for Medical Imaging North-East Netherlands (CMI-NEN), Groningen, The Netherlands
| | - Carlijn M van der Aalst
- Erasmus MC-University Medical Centre, Department of Public Health, Rotterdam, The Netherlands
| | - Rozemarijn Vliegenthart
- University of Groningen, University Medical Center Groningen, Center for Medical Imaging North-East Netherlands (CMI-NEN), Groningen, The Netherlands
| | - Peter M A van Ooijen
- University of Groningen, University Medical Center Groningen, Center for Medical Imaging North-East Netherlands (CMI-NEN), Groningen, The Netherlands; University of Groningen, University Medical Center Groningen, Department of Radiology, Groningen, The Netherlands
| | - Dirkjan Kuijpers
- University of Groningen, University Medical Center Groningen, Center for Medical Imaging North-East Netherlands (CMI-NEN), Groningen, The Netherlands; Department of Radiology, Haaglanden Medical Center Bronovo, The Hague, The Netherlands
| | - Jan Willem Gratama
- University of Groningen, University Medical Center Groningen, Center for Medical Imaging North-East Netherlands (CMI-NEN), Groningen, The Netherlands; Department of Radiology, Gelre Hospital, Apeldoorn, The Netherlands
| | - Harry J de Koning
- Erasmus MC-University Medical Centre, Department of Public Health, Rotterdam, The Netherlands
| | - Matthijs Oudkerk
- University of Groningen, University Medical Center Groningen, Center for Medical Imaging North-East Netherlands (CMI-NEN), Groningen, The Netherlands.
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Halliburton SS, Tanabe Y, Partovi S, Rajiah P. The role of advanced reconstruction algorithms in cardiac CT. Cardiovasc Diagn Ther 2017; 7:527-538. [PMID: 29255694 DOI: 10.21037/cdt.2017.08.12] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Non-linear iterative reconstruction (IR) algorithms have been increasingly incorporated into clinical cardiac CT protocols at institutions around the world. Multiple IR algorithms are available commercially from various vendors. IR algorithms decrease image noise and are primarily used to enable lower radiation dose protocols. IR can also be used to improve image quality for imaging of obese patients, coronary atherosclerotic plaques, coronary stents, and myocardial perfusion. In this article, we will review the various applications of IR algorithms in cardiac imaging and evaluate how they have changed practice.
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Affiliation(s)
| | - Yuki Tanabe
- Cardiothoracic Imaging, Radiology Department, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sasan Partovi
- University Hospitals Cleveland Medical Center, Cleveland, OH, USA
| | - Prabhakar Rajiah
- Cardiothoracic Imaging, Radiology Department, UT Southwestern Medical Center, Dallas, TX, USA
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Dose reduction techniques in coronary calcium scoring: The effect of iterative reconstruction combined with low tube voltage on calcium scores in a thoracic phantom. Eur J Radiol 2017; 93:229-235. [PMID: 28668419 DOI: 10.1016/j.ejrad.2017.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 01/13/2017] [Accepted: 06/01/2017] [Indexed: 11/20/2022]
Abstract
OBJECTIVES To define a dose-reduced coronary calcium CT protocol that provides similar calcium score values as a conventional 120kVp protocol. METHODS A thorax phantom containing 100 calcifications was scanned with the reference protocol (120kVp, 90 ref mAs, FBP) and 30 dose-reduced protocols (70-110kVp, 90 ref mAs, FBP and iterative reconstruction (IR) levels 1-5) with 3rd generation dual-source CT. For protocols that yielded similar detectability and calcium scores as the reference protocol, additional scans were acquired at reduced ref mAs. Kendall's τb and independent-samples-median test were used to determine trends and differences in contrast/signal-to-noise ratio (CNR and SNR), dose and calcium scores. RESULTS The detectability and calcium scores decreased at increasing IR levels (τb<-0.825, p<0.001) and increasing tube voltage (τb<-0.679, p<0.001). For 90kVp-IR3 and 100kVp-IR1, similar detectability and calcium score was found compared to the reference protocol (p>0.206). For these protocols, lower tube currents did not affect the detectability and Agatston score (p>0.206), while CNR and SNR were similar/higher compared to the reference protocol (0.008<p<0.206). Dose reduction was 60.6% (90kVp-IR3) and 43.6% (100kVp-IR1). CONCLUSIONS The protocol of 90kVp-IR3 and 100kVp-IR1 yielded similar calcium detectability, Agatston score and image quality as the reference protocol, with dose reduction up to 60.6%.
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Gassenmaier T, Allmendinger T, Kunz AS, Veyhl-Wichmann M, Ergün S, Bley TA, Petritsch B. In vitro evaluation of a new iterative reconstruction algorithm for dose reduction in coronary artery calcium scoring. Acta Radiol Open 2017; 6:2058460117710682. [PMID: 28607763 PMCID: PMC5453409 DOI: 10.1177/2058460117710682] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 04/27/2017] [Indexed: 11/17/2022] Open
Abstract
Background Coronary artery calcium (CAC) scoring is a widespread tool for cardiac risk assessment in asymptomatic patients and accompanying possible adverse effects, i.e. radiation exposure, should be as low as reasonably achievable. Purpose To evaluate a new iterative reconstruction (IR) algorithm for dose reduction of in vitro coronary artery calcium scoring at different tube currents. Material and Methods An anthropomorphic calcium scoring phantom was scanned in different configurations simulating slim, average-sized, and large patients. A standard calcium scoring protocol was performed on a third-generation dual-source CT at 120 kVp tube voltage. Reference tube current was 80 mAs as standard and stepwise reduced to 60, 40, 20, and 10 mAs. Images were reconstructed with weighted filtered back projection (wFBP) and a new version of an established IR kernel at different strength levels. Calcifications were quantified calculating Agatston and volume scores. Subjective image quality was visualized with scans of an ex vivo human heart. Results In general, Agatston and volume scores remained relatively stable between 80 and 40 mAs and increased at lower tube currents, particularly in the medium and large phantom. IR reduced this effect, as both Agatston and volume scores decreased with increasing levels of IR compared to wFBP (P < 0.001). Depending on selected parameters, radiation dose could be lowered by up to 86% in the large size phantom when selecting a reference tube current of 10 mAs with resulting Agatston levels close to the reference settings. Conclusion New iterative reconstruction kernels may allow for reduction in tube current for established Agatston scoring protocols and consequently for substantial reduction in radiation exposure.
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Affiliation(s)
- Tobias Gassenmaier
- Department of Diagnostic and Interventional Radiology, University Hospital of Würzburg, Würzburg, Germany
| | | | - Andreas S Kunz
- Department of Diagnostic and Interventional Radiology, University Hospital of Würzburg, Würzburg, Germany
| | - Maike Veyhl-Wichmann
- Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany
| | - Süleyman Ergün
- Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany
| | - Thorsten A Bley
- Department of Diagnostic and Interventional Radiology, University Hospital of Würzburg, Würzburg, Germany
| | - Bernhard Petritsch
- Department of Diagnostic and Interventional Radiology, University Hospital of Würzburg, Würzburg, Germany
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Fuchs A, Groen JM, Arnold BA, Nikolovski S, Knudsen AD, Kühl JT, Nordestgaard BG, Greuter MJ, Kofoed KF. Assessment of coronary calcification using calibrated mass score with two different multidetector computed tomography scanners in the Copenhagen General Population Study. Eur J Radiol 2017; 88:21-25. [DOI: 10.1016/j.ejrad.2016.12.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 11/16/2016] [Accepted: 12/28/2016] [Indexed: 01/07/2023]
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Influence of dose reduction and iterative reconstruction on CT calcium scores: a multi-manufacturer dynamic phantom study. Int J Cardiovasc Imaging 2017; 33:899-914. [PMID: 28102510 PMCID: PMC5406488 DOI: 10.1007/s10554-017-1061-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 01/02/2017] [Indexed: 11/13/2022]
Abstract
To evaluate the influence of dose reduction in combination with iterative reconstruction (IR) on coronary calcium scores (CCS) in a dynamic phantom on state-of-the-art CT systems from different manufacturers. Calcified inserts in an anthropomorphic chest phantom were translated at 20 mm/s corresponding to heart rates between 60 and 75 bpm. The inserts were scanned five times with routinely used CCS protocols at reference dose and 40 and 80% dose reduction on four high-end CT systems. Filtered back projection (FBP) and increasing levels of IR were applied. Noise levels were determined. CCS, quantified as Agatston and mass scores, were compared to physical mass and scores at FBP reference dose. For the reference dose in combination with FBP, noise level variation between CT systems was less than 18%. Decreasing dose almost always resulted in increased CCS, while at increased levels of IR, CCS decreased again. The influence of IR on CCS was smaller than the influence of dose reduction. At reference dose, physical mass was underestimated 3–30%. All CT systems showed similar CCS at 40% dose reduction in combinations with specific reconstructions. For some CT systems CCS was not affected at 80% dose reduction, in combination with IR. This multivendor study showed that radiation dose reductions of 40% did not influence CCS in a dynamic phantom using state-of-the-art CT systems in combination with specific reconstruction settings. Dose reduction resulted in increased noise and consequently increased CCS, whereas increased IR resulted in decreased CCS.
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Li Q, Liu S, Myers KJ, Gavrielides MA, Zeng R, Sahiner B, Petrick N. Impact of Reconstruction Algorithms and Gender-Associated Anatomy on Coronary Calcium Scoring with CT: An Anthropomorphic Phantom Study. Acad Radiol 2016; 23:1470-1479. [PMID: 27665673 PMCID: PMC5567798 DOI: 10.1016/j.acra.2016.08.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 07/20/2016] [Accepted: 08/01/2016] [Indexed: 10/21/2022]
Abstract
RATIONALE AND OBJECTIVES Different computed tomography imaging protocols and patient characteristics can impact the accuracy and precision of the calcium score and may lead to inconsistent patient treatment recommendations. The aim of this work was to determine the impact of reconstruction algorithm and gender characteristics on coronary artery calcium scoring based on a phantom study using computed tomography. MATERIALS AND METHODS Four synthetic heart vessels with vessel diameters corresponding to female and male left main and left circumflex arteries containing calcification-mimicking materials (200-1000 HU) were inserted into a thorax phantom and were scanned with and without female breast plates (male and female phantoms, respectively). Ten scans were acquired and were reconstructed at 3-mm slices using filtered-back projection (FBP) and iterative reconstruction with medium and strong denoising (IR3 and IR5) algorithms. Agatston and calcium volume scores were estimated for each vessel. Calcium scores for each vessel and the total calcium score (summation of all four vessels) were compared between the two phantoms to quantify the impact of the breast plates and reconstruction parameters. Calcium scores were also compared among vessels of different diameters to investigate the impact of the vessel size. RESULTS The calcium scores were significantly larger for FBP reconstruction (FBP > IR3>IR5). Agatston scores (calcium volume score) for vessels in the male phantom scans were on average 4.8% (2.9%), 8.2% (7.1%), and 10.5% (9.4%) higher compared to those in the female phantom with FBP, IR3, and IR5, respectively, when exposure was conserved across phantoms. The total calcium scores from the male phantom were significantly larger than those from the female phantom (P <0.05). In general, calcium volume scores were underestimated (up to about 50%) for smaller vessels, especially when scanned in the female phantom. CONCLUSIONS Calcium scores significantly decreased with iterative reconstruction and tended to be underestimated for female anatomy (smaller vessels and presence of breast plates).
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Affiliation(s)
- Qin Li
- U.S. Food and Drug Administration, CDRH/OSEL/DIDSR, 10903 New Hampshire Ave., Bldg. 62 Rm. 4110, Silver Spring, MD 20993.
| | - Songtao Liu
- U.S. Food and Drug Administration, CDRH/OIR/DRH, Silver Spring, Maryland
| | - Kyle J Myers
- U.S. Food and Drug Administration, CDRH/OSEL/DIDSR, 10903 New Hampshire Ave., Bldg. 62 Rm. 4110, Silver Spring, MD 20993
| | - Marios A Gavrielides
- U.S. Food and Drug Administration, CDRH/OSEL/DIDSR, 10903 New Hampshire Ave., Bldg. 62 Rm. 4110, Silver Spring, MD 20993
| | - Rongping Zeng
- U.S. Food and Drug Administration, CDRH/OSEL/DIDSR, 10903 New Hampshire Ave., Bldg. 62 Rm. 4110, Silver Spring, MD 20993
| | - Berkman Sahiner
- U.S. Food and Drug Administration, CDRH/OSEL/DIDSR, 10903 New Hampshire Ave., Bldg. 62 Rm. 4110, Silver Spring, MD 20993
| | - Nicholas Petrick
- U.S. Food and Drug Administration, CDRH/OSEL/DIDSR, 10903 New Hampshire Ave., Bldg. 62 Rm. 4110, Silver Spring, MD 20993
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den Harder AM, Wolterink JM, Willemink MJ, Schilham AM, de Jong PA, Budde RP, Nathoe HM, Išgum I, Leiner T. Submillisievert coronary calcium quantification using model-based iterative reconstruction: A within-patient analysis. Eur J Radiol 2016; 85:2152-2159. [DOI: 10.1016/j.ejrad.2016.09.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 09/26/2016] [Accepted: 09/29/2016] [Indexed: 11/16/2022]
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Schaller F, Sedlmair M, Raupach R, Uder M, Lell M. Noise Reduction in Abdominal Computed Tomography Applying Iterative Reconstruction (ADMIRE). Acad Radiol 2016; 23:1230-8. [PMID: 27318787 DOI: 10.1016/j.acra.2016.05.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 05/24/2016] [Accepted: 05/27/2016] [Indexed: 12/11/2022]
Abstract
RATIONALE AND OBJECTIVES The study aimed to compare image quality of filtered back projection (FBP) and iterative reconstruction (advanced modeled iterative reconstruction, ADMIRE) in contrast-enhanced computed tomography (CT) of the abdomen, and to assess the differences of reconstructions according to these methods. It also aimed to investigate the potential for noise reduction of ADMIRE for different reconstructed slice thicknesses. MATERIALS AND METHODS CT data of the abdomen and pelvis were acquired using a 128-slice single-source CT system using automated kV selection and tube current adaption based on patients' anatomy. Raw data sets from patients scanned at 100 kV were selected, and images were reconstructed with slice thicknesses of 1 mm, 3 mm, and 5 mm, both with FBP and ADMIRE. Filter strength F1, F3, and F5 of the ADMIRE algorithm and the corresponding reconstruction kernels were used. In total, 58 raw data sets from 17 patients were used to reconstruct from the same raw data FBP and ADMIRE images, representing identical body regions. Identical regions of interest were placed at the same position of up to four images and image noise was measured. Differences of reconstructed images and detail preservation were tested using an image subtraction technique, and subjective image quality was assessed using a 5-point Likert scale. RESULTS On average, for 1-mm slice thickness, noise reduction was 9.15% ± 2.4% with filter strength level F1, 30.2% ± 3.4% with F3, and 54.4% ± 7.0% with F5 as compared to FBP. For a slice thickness of 3 mm, noise reduction was 8.5% ± 3.7% with F1, 28.6% ± 3.9% with F3, and 52.2% ± 9.1% with F5. For 5 mm, the corresponding values are 8.9% ± 2.7%, 31.4% ± 2.8%, and 52.7% ± 7.7%. On subtraction images, edge information of tissue classes with a high attenuation gradient was found, but structures with small differences in attenuation were not detectable on subtraction images, confirming that no relevant details were lost in the iterative reconstruction process. CONCLUSIONS ADMIRE is able to reduce image noise considerably (up to 50%) without any obvious negative impact on lesion depiction as assessed visually. Noise reduction of ADMIRE seems to be independent of slice thickness.
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Aortic Valve and Thoracic Aortic Calcification Measurements: How Low Can We Go in Radiation Dose? J Comput Assist Tomogr 2016; 41:148-155. [PMID: 27560017 DOI: 10.1097/rct.0000000000000477] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE This study aimed to determine the lowest radiation dose and iterative reconstruction level(s) at which computed tomography (CT)-based quantification of aortic valve calcification (AVC) and thoracic aortic calcification (TAC) is still feasible. METHODS Twenty-eight patients underwent a cardiac CT and 20 patients a chest CT at 4 different dose levels (routine dose and approximately 40%, 60%, and 80% reduced dose). Data were reconstructed with filtered back projection, 3 iDose levels, and 3 iterative model-based reconstruction levels. Two observers scored subjective image quality. The AVC and TAC were quantified using mass and compared to the reference scan (routine dose reconstructed with filtered back projection). RESULTS In cardiac CT at 0.35 mSv (60% reduced), all scans reconstructed with iDose (all levels) were diagnostic, calcification detection errors occurred in only 1 patient, and there were no significant differences in mass scores compared to the reference scan. Similar results were found for chest CT at 0.48 mSv (75% reduced) with iDose levels 4 and 6 and iterative model reconstruction levels 1 and 2. CONCLUSIONS Iterative reconstruction enables AVC and TAC quantification on CT at submillisievert dose.
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Rodrigues MA, Williams MC, Fitzgerald T, Connell M, Weir NW, Newby DE, van Beek EJR, Mirsadraee S. Iterative reconstruction can permit the use of lower X-ray tube current in CT coronary artery calcium scoring. Br J Radiol 2016; 89:20150780. [PMID: 27266373 DOI: 10.1259/bjr.20150780] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
OBJECTIVE: CT coronary artery calcium scoring (CACS) is additive to traditional risk factors for predicting future cardiac events but is associated with relatively high radiation doses. We assessed the feasibility of CACS radiation dose reduction using a lower tube current and iterative reconstruction (IR). METHODS: Artificial noise was added to the raw data from 27 CACS studies from patients who were symptomatic to simulate lower tube current scanning (75, 50 and 25% original current). All studies were performed on the same CT scanner at 120 kVp. Data were reconstructed using filtered back projection [Quantum Denoising Software (QDS+)] and IR [adaptive iterative dose reduction three dimensional mild, standard and strong]. Agatston scores were independently measured by two readers. CACS percentile risk scores were calculated. RESULTS: At 75, 50 and 25% tube currents, all adaptive iterative dose reduction (AIDR) reconstructions decreased image noise relative to QDS+ (p < 0.05). All AIDR reconstructions resulted in small reductions in Agatston score relative to QDS+ at the standard tube current (p < 0.05). Agatston scores increased with QDS+ at 75, 50 and 25% tube current (p < 0.05), whereas no significant change was observed with AIDR mild at any tested tube current. No difference in the percentile risk score with AIDR mild at any tube current occurred compared with QDS+ at standard tube current (p > 0.05). Interobserver agreement for AIDR mild remained excellent even at 25% tube current (intraclass correlation coefficient 0.997). CONCLUSION: Up to 75% reduction in CACS tube current is feasible using AIDR mild. ADVANCES IN KNOWLEDGE: AIDR mild IR permits low tube current CACS whilst maintaining excellent intraobserver and interobserver variability and without altering risk classification.
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Affiliation(s)
- Mark A Rodrigues
- 1 Department of Radiology, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - Michelle C Williams
- 2 British Heart Foundation/University of Edinburgh Centre for Cardiovascular Science, Queen's Medical Research Institute, Edinburgh, UK
| | - Thomas Fitzgerald
- 1 Department of Radiology, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - Martin Connell
- 3 Clinical Research Imaging Centre, University of Edinburgh, Edinburgh, UK
| | - Nicholas W Weir
- 3 Clinical Research Imaging Centre, University of Edinburgh, Edinburgh, UK.,4 Department of Medical Physics, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - David E Newby
- 2 British Heart Foundation/University of Edinburgh Centre for Cardiovascular Science, Queen's Medical Research Institute, Edinburgh, UK
| | - Edwin J R van Beek
- 3 Clinical Research Imaging Centre, University of Edinburgh, Edinburgh, UK
| | - Saeed Mirsadraee
- 3 Clinical Research Imaging Centre, University of Edinburgh, Edinburgh, UK
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Abstract
Coronary computed tomography (CT) allows for the acquisition of thin slices of the heart and coronary arteries, which can be used to detect and quantify coronary artery calcium (CAC), a marker of atherosclerotic cardiovascular disease. Despite the proven clinical value in cardiac risk prognostication, there remain concerns regarding radiation exposure from CAC CT scans. There have been several recent technical advancements that allow for significant radiation dose reduction in CAC scoring. This paper reviews the clinical utility and recent literature in low radiation dose CAC scoring.
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Willemink MJ, den Harder AM, Foppen W, Schilham AM, Rienks R, Laufer EM, Nieman K, de Jong PA, Budde RP, Nathoe HM, Leiner T. Finding the optimal dose reduction and iterative reconstruction level for coronary calcium scoring. J Cardiovasc Comput Tomogr 2016; 10:69-75. [DOI: 10.1016/j.jcct.2015.08.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 08/01/2015] [Accepted: 08/18/2015] [Indexed: 01/07/2023]
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Coronary calcium scores are systematically underestimated at a large chest size: A multivendor phantom study. J Cardiovasc Comput Tomogr 2015; 9:415-21. [DOI: 10.1016/j.jcct.2015.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 03/11/2015] [Accepted: 03/30/2015] [Indexed: 11/21/2022]
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Szilveszter B, Elzomor H, Károlyi M, Kolossváry M, Raaijmakers R, Benke K, Celeng C, Bartykowszki A, Bagyura Z, Lux Á, Merkely B, Maurovich-Horvat P. The effect of iterative model reconstruction on coronary artery calcium quantification. Int J Cardiovasc Imaging 2015; 32:153-60. [DOI: 10.1007/s10554-015-0740-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 08/11/2015] [Indexed: 01/07/2023]
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Iterative reconstruction in cardiac CT. J Cardiovasc Comput Tomogr 2015; 9:255-63. [PMID: 26088375 DOI: 10.1016/j.jcct.2015.04.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 04/15/2015] [Accepted: 04/15/2015] [Indexed: 12/29/2022]
Abstract
Iterative reconstruction (IR) has the ability to reduce image noise in CT without compromising diagnostic quality, which permits a significant reduction in effective radiation dose. This been increasingly integrated into clinical CT practice over the past 7 years and has been particularly important in the field of cardiac CT with multiple vendors introducing cardiac CT-compatible IR algorithms. The following review will summarize the principles of IR algorithms, studies validating their noise- and dose-reducing abilities, and the specific applications of IR in cardiac CT.
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Leng S, Hruska CB, McCollough CH. Use of ionizing radiation in screening examinations for coronary artery calcium and cancers of the lung, colon, and breast. Semin Roentgenol 2015; 50:148-60. [PMID: 25770345 DOI: 10.1053/j.ro.2014.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shuai Leng
- Department of Radiology, Mayo Clinic, Rochester, MN.
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