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Kim HJ, Kim HH, Eom HJ, Choi WJ, Chae EY, Shin HJ, Cha JH, Choi YW, Choi YJ, Kim KH, Min J, Shim WH, Lee S, Cho S. Optimizing angular range in digital breast tomosynthesis: A phantom study investigating lesion detection across varied breast density and thickness. Phys Med 2024; 124:103419. [PMID: 38986262 DOI: 10.1016/j.ejmp.2024.103419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 05/29/2024] [Accepted: 06/28/2024] [Indexed: 07/12/2024] Open
Abstract
PURPOSE To determine the optimal angular range (AR) for digital breast tomosynthesis (DBT) systems that provides highest lesion visibility across various breast densities and thicknesses. METHOD A modular DBT phantom, consisting of tissue-equivalent adipose and glandular modules, along with a module embedded with test objects (speckles, masses, fibers), was used to create combinations simulating different breast thicknesses, densities, and lesion locations. A prototype DBT system operated at four ARs (AR±7.5°, AR±12.5°, AR±19°, and AR±25°) to acquire 11 projection images for each combination, with separate fixed doses for thin and thick combinations. Three blinded radiologists independently assessed lesion visibility in reconstructed images; assessments were averaged and compared using linear mixed models. RESULTS Speckle visibility was highest with AR±7.5° or AR±12.5°, decreasing with wider ARs in all density and thickness combinations. The difference between AR±7.5° and AR±12.5° was not statistically significant, except for the tube-side speckles in thin-fatty combinations (5.83 [AR±7.5°] vs. 5.39 [AR±12.5°], P = 0.019). Mass visibility was not affected by AR in thick combinations, while AR±12.5° exhibited the highest mass visibility for both thin-fatty and thin-dense combinations (P = 0.032 and 0.007, respectively). Different ARs provided highest fiber visibility for different combinations; however, AR±12.5° consistently provided highest or comparable visibility. AR±12.5° showed highest overall lesion visibility for all density and thickness combinations. CONCLUSIONS AR±12.5° exhibited the highest overall lesion visibility across various phantom thicknesses and densities using a projection number of 11.
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Affiliation(s)
- Hee Jeong Kim
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, South Korea.
| | - Hak Hee Kim
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, South Korea.
| | - Hye Joung Eom
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, South Korea
| | - Woo Jung Choi
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, South Korea.
| | - Eun Young Chae
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, South Korea.
| | - Hee Jung Shin
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, South Korea.
| | - Joo Hee Cha
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, South Korea.
| | - Young Wook Choi
- Electro-Medical Equipment Research Division, Korea Electrotechnology Research Institute (KERI), 111, Hanggaul-ro, Sangrok-gu, Ansan-si, Gyeonggi-do 15588, South Korea.
| | - Young Jin Choi
- Electro-Medical Equipment Research Division, Korea Electrotechnology Research Institute (KERI), 111, Hanggaul-ro, Sangrok-gu, Ansan-si, Gyeonggi-do 15588, South Korea.
| | - Kee Hyun Kim
- Electro-Medical Equipment Research Division, Korea Electrotechnology Research Institute (KERI), 111, Hanggaul-ro, Sangrok-gu, Ansan-si, Gyeonggi-do 15588, South Korea.
| | - Joongkee Min
- Department of Medical Science, Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, South Korea.
| | - Woo Hyun Shim
- Department of Medical Science, Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, South Korea.
| | - Seoyoung Lee
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291, Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea.
| | - Seungryong Cho
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291, Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea.
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Quaia E, Kiyomi Lanza de Cristoforis E, Agostini E, Zanon C. Computed Tomography Effective Dose and Image Quality in Deep Learning Image Reconstruction in Intensive Care Patients Compared to Iterative Algorithms. Tomography 2024; 10:912-921. [PMID: 38921946 PMCID: PMC11209234 DOI: 10.3390/tomography10060069] [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: 05/06/2024] [Revised: 06/05/2024] [Accepted: 06/06/2024] [Indexed: 06/27/2024] Open
Abstract
Deep learning image reconstruction (DLIR) algorithms employ convolutional neural networks (CNNs) for CT image reconstruction to produce CT images with a very low noise level, even at a low radiation dose. The aim of this study was to assess whether the DLIR algorithm reduces the CT effective dose (ED) and improves CT image quality in comparison with filtered back projection (FBP) and iterative reconstruction (IR) algorithms in intensive care unit (ICU) patients. We identified all consecutive patients referred to the ICU of a single hospital who underwent at least two consecutive chest and/or abdominal contrast-enhanced CT scans within a time period of 30 days using DLIR and subsequently the FBP or IR algorithm (Advanced Modeled Iterative Reconstruction [ADMIRE] model-based algorithm or Adaptive Iterative Dose Reduction 3D [AIDR 3D] hybrid algorithm) for CT image reconstruction. The radiation ED, noise level, and signal-to-noise ratio (SNR) were compared between the different CT scanners. The non-parametric Wilcoxon test was used for statistical comparison. Statistical significance was set at p < 0.05. A total of 83 patients (mean age, 59 ± 15 years [standard deviation]; 56 men) were included. DLIR vs. FBP reduced the ED (18.45 ± 13.16 mSv vs. 22.06 ± 9.55 mSv, p < 0.05), while DLIR vs. FBP and vs. ADMIRE and AIDR 3D IR algorithms reduced image noise (8.45 ± 3.24 vs. 14.85 ± 2.73 vs. 14.77 ± 32.77 and 11.17 ± 32.77, p < 0.05) and increased the SNR (11.53 ± 9.28 vs. 3.99 ± 1.23 vs. 5.84 ± 2.74 and 3.58 ± 2.74, p < 0.05). CT scanners employing DLIR improved the SNR compared to CT scanners using FBP or IR algorithms in ICU patients despite maintaining a reduced ED.
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Affiliation(s)
- Emilio Quaia
- Department of Radiology, University of Padova, Via Giustiniani 2, 35128 Padova, Italy
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Balogh ZA, Barna Z, Majoros E. Comparison of iterative reconstruction implementations for multislice helical CT. Z Med Phys 2024:S0939-3889(24)00046-1. [PMID: 38679541 DOI: 10.1016/j.zemedi.2024.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 02/20/2024] [Accepted: 04/03/2024] [Indexed: 05/01/2024]
Abstract
The most mature image reconstruction algorithms in multislice helical computed tomography are based on analytical and iterative methods. Over the past decades, several methods have been developed for iterative reconstructions that improve image quality by reducing noise and artifacts. In the regularization step of iterative reconstruction, noise can be significantly reduced, thereby making low-dose CT. The quality of the reconstructed image can be further improved by using model-based reconstructions. In these reconstructions, the main focus is on modeling the data acquisition process, including the behavior of the photon beams, the geometry of the system, etc. In this article, we propose two model-based reconstruction algorithms using a virtual detector for multislice helical CT. The aim of this study is to compare the effect of using a virtual detector on image quality for the two proposed algorithms with a model-based iterative reconstruction using the original detector model. Since the algorithms are implemented using multiple GPUs, the merging of separately reconstructed volumes can significantly affect image quality. This issue is often referred to as the "long object" problem, for which we also present a solution that plays an important role in the proposed reconstruction processes. The algorithms were evaluated using mathematical and physical phantoms, as well as patient cases. The SSIM, MS-SSIM and L1 metrics were utilized to evaluate the image quality of the mathematical phantom case. To demonstrate the effectiveness of the algorithms, we used the CatPhan 600 phantom. Additionally, anonymized patient scans were used to showcase the improvements in image quality on real scan data.
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Affiliation(s)
- Zsolt Adam Balogh
- Department of Mathematical Sciences, United Arab Emirates University, Al Ain P.O.Box: 15551, United Arab Emirates.
| | | | - Eva Majoros
- Marton Varga Technical College, Budapest H-1149, Hungary
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Mese I, Altintas Mese C, Demirsoy U, Anik Y. Innovative advances in pediatric radiology: computed tomography reconstruction techniques, photon-counting detector computed tomography, and beyond. Pediatr Radiol 2024; 54:1-11. [PMID: 38041712 DOI: 10.1007/s00247-023-05823-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/17/2023] [Accepted: 11/20/2023] [Indexed: 12/03/2023]
Abstract
In pediatric radiology, balancing diagnostic accuracy with reduced radiation exposure is paramount due to the heightened vulnerability of younger patients to radiation. Technological advancements in computed tomography (CT) reconstruction techniques, especially model-based iterative reconstruction and deep learning image reconstruction, have enabled significant reductions in radiation doses without compromising image quality. Deep learning image reconstruction, powered by deep learning algorithms, has demonstrated superiority over traditional techniques like filtered back projection, providing enhanced image quality, especially in pediatric head and cardiac CT scans. Photon-counting detector CT has emerged as another groundbreaking technology, allowing for high-resolution images while substantially reducing radiation doses, proving highly beneficial for pediatric patients requiring frequent imaging. Furthermore, cloud-based dose tracking software focuses on monitoring radiation exposure, ensuring adherence to safety standards. However, the deployment of these technologies presents challenges, including the need for large datasets, computational demands, and potential data privacy issues. This article provides a comprehensive exploration of these technological advancements, their clinical implications, and the ongoing efforts to enhance pediatric radiology's safety and effectiveness.
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Affiliation(s)
- Ismail Mese
- Department of Radiology, Health Sciences University, Erenkoy Mental Health and Neurology Training and Research Hospital, 19 Mayis, Sinan Ercan Cd. No:23, Kadikoy, Istanbul, 34736, Turkey.
| | - Ceren Altintas Mese
- Department of Pediatrics, Haydarpasa Numune Training and Research Hospital, Istanbul, Turkey
| | - Ugur Demirsoy
- Department of Pediatric Oncology, Faculty of Medicine, Kocaeli University, Kocaeli, Turkey
| | - Yonca Anik
- Department of Pediatric Radiology, Faculty of Medicine, Kocaeli University, Kocaeli, Turkey
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Park MS, Ha HI, Ahn JH, Lee IJ, Lim HK. Reducing contrast-agent volume and radiation dose in CT with 90-kVp tube voltage, high tube current modulation, and advanced iteration algorithm. PLoS One 2023; 18:e0287214. [PMID: 37319309 PMCID: PMC10270572 DOI: 10.1371/journal.pone.0287214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 05/31/2023] [Indexed: 06/17/2023] Open
Abstract
Increasing utilization of computed tomography (CT) has raised concerns regarding CT radiation dose and technology has been developed to achieve an appropriate balance between image quality, radiation dose, and the amount of contrast material. This study was planned to evaluate the image quality and radiation dose in pancreatic dynamic computed tomography (PDCT) with 90-kVp tube voltage and reduction of the standard amount of contrast agent, compared with 100-kVp PDCT of the research hospital's convention. Total of 51 patients with both CT protocols were included. The average Hounsfield units (HU) values of the abdominal organs and image noise were measured for objective image quality analysis. Two radiologists evaluated five categories of image qualities such as subjective image noise, visibility of small structure, beam hardening or streak artifact, lesion conspicuity and overall diagnostic performance for subjective image quality analysis. The total amount of contrast agent, radiation dose, and image noise decreased in the low-kVp group, by 24.4%, 31.7%, and 20.6%, respectively (p < 0.001). The intraobserver and interobserver agreements were moderate to substantial (k = 0.4-0.8). The contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and figure of merit of the almost organs except psoas muscle in the low-kVp group were significantly higher (p < 0.001). Except for lesion conspicuity, both reviewers judged that subjective image quality of the 90-kVp group was better (p < 0.001). With 90-kVp tube voltage, 25% reduced contrast agent volume with advanced iteration algorithm and high tube current modulation achieved radiation dose reduction of 31.7%, as well as better image quality and diagnostic confidence.
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Affiliation(s)
- Min Su Park
- Department of Radiology, Hallym University Sacred Heart Hospital, Anyang-si, Gyeonggi-do, Republic of Korea
| | - Hong Il Ha
- Department of Radiology, Hallym University Sacred Heart Hospital, Anyang-si, Gyeonggi-do, Republic of Korea
| | - Jhii-Hyun Ahn
- Department of Radiology, Yonsei University Wonju College of Medicine, Wonju Severance Christian Hospital, Wonju, Gangwon-do, Republic of Korea
| | - In Jae Lee
- Department of Radiology, Hallym University Sacred Heart Hospital, Anyang-si, Gyeonggi-do, Republic of Korea
| | - Hyun Kyung Lim
- Department of Radiology, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea
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Masuda T, Funama Y, Nakaura T, Sato T, Urayama K, Kiguchi M, Oku T, Yoshida M, Arao S, Ono A, Hiratsuka J, Awai K. Usefulness of large beam-shaping filters at different tube voltages of newborn chest CT. Phys Eng Sci Med 2023; 46:289-293. [PMID: 36633769 DOI: 10.1007/s13246-023-01217-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/10/2022] [Accepted: 01/03/2023] [Indexed: 01/13/2023]
Abstract
BACKGROUND To investigate optimizing the use of different beam shaping filters (viz. small, medium and large) when using different tube voltages during the newborn chest computed tomography (CT) on a GE Lightspeed VCT scanner. METHODS We used pediatric anthropomorphic phantoms with a 64 detector-row CT scanner while scanning the chest. A real-time skin dosimeter (RD - 1000; Trek Corporation, Kanagawa, Japan) was positioned into the phantom center of the body, the surface of the body back, and the right and left mammary glands. We performed and compared six scan protocols using small, medium, and large beam shaping filters at 80 and 120 kVp protocols. RESULT There were no significant differences in the image noise for the chest scan among the different beam shaping filters. By using the large beam shaping filter at 80 kVp, it was possible to reduce the exposure dose by 5% in comparison with the small beam shaping filter, and by 10% in comparison with the medium beam shaping filter. By using the large beam shaping filter at 120 kVp, it was possible to reduce the exposure dose by 15% in comparison with the small beam shaping filter and by 20% in comparison with the medium beam shaping filter (p < 0.01). CONCLUSION The large beam shaping filter had the most dose reduction effect during newborn chest CT on a GE Lightspeed VCT scanner. The additional copper filtration being present in the large bowtie filter of the GE Lightspeed CT scanner when using different tube voltages is more effective in reducing radiation exposure in children.
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Affiliation(s)
- Takanori Masuda
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, 701-0193, Kurashiki-city, Okayama, Japan.
| | - Yoshinori Funama
- Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, 860-8556, Kumamoto, Japan
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, 860-8556, Kumamoto, Japan
| | - Tomoyasu Sato
- Department of Diagnostic Radiology, Tsuchiya General Hospital, Nakajima-cho 3-30, Naka-ku, 730-8655, Hiroshima, Japan
| | - Kotaro Urayama
- Department of Pediatric cardiology, Tsuchiya General Hospital, Nakajima-cho 3-30, Naka-ku, 730-8655, Hiroshima, Japan
| | - Masao Kiguchi
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, 734-8551, Hiroshima, Japan
| | - Takayuki Oku
- Department of Radiological technologist, Tsuchiya General Hospital, Nakajima-cho 3-30, Naka-ku, 730-8655, Hiroshima, Japan
| | - Masato Yoshida
- Department of Radiological technologist, Tsuchiya General Hospital, Nakajima-cho 3-30, Naka-ku, 730-8655, Hiroshima, Japan
| | - Shinichi Arao
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, 701-0193, Kurashiki-city, Okayama, Japan
| | - Atsushi Ono
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, 701-0193, Kurashiki-city, Okayama, Japan
| | - Junichi Hiratsuka
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, 701-0193, Kurashiki-city, Okayama, Japan
| | - Kazuo Awai
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, 734-8551, Hiroshima, Japan
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Dissaux B, Cheddad El Aouni M, Ognard J, Gentric JC. Model-Based Iterative Reconstruction (MBIR) for ASPECT Scoring in Acute Stroke Patients Selection: Comparison to rCBV and Follow-Up Imaging. Tomography 2022; 8:1260-1269. [PMID: 35645390 PMCID: PMC9149901 DOI: 10.3390/tomography8030104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND To compare a model-based iterative reconstruction (MBIR) versus a hybrid iterative reconstruction (HIR) for initial and final Alberta Stroke Program Early Ct Score (ASPECT) scoring in acute ischemic stroke (AIS). We hypothesized that MBIR designed for brain computed tomography (CT) could perform better than HIR for ASPECT scoring. METHODS Among patients who had undergone CT perfusion for AIS between April 2018 and October 2019 with a follow-up imaging within 7 days, we designed a cohort of representative ASPECTS. Two readers assessed regional-cerebral-blood-volume-ASPECT (rCBV-ASPECTS) on the initial exam and final-ASPECTS on the follow-up non-contrast-CT (NCCT) in consensus. Four readers performed independently MBIR and HIR ASPECT scoring on baseline NCCT. RESULTS In total, 294 hemispheres from 147 participants (average age of 69.59 ± 15.63 SD) were analyzed. Overall raters' agreement between rCBV-map and MBIR and HIR ranged from moderate to moderate (κ = 0.54 to κ = 0.57) with HIR and moderate to substantial (κ = 0.52 to κ = 0.74) with MBIR. Overall raters' agreement between follow-up imaging and HIR/MBIR ranged from moderate to moderate (κ = 0.55 to κ = 0.59) with HIR and moderate to almost perfect (κ = 0.48 to κ = 0.82) with MBIR. CONCLUSIONS ASPECT scoring with MBIR more closely matched with initial and final infarct extent than classical HIR NCCT reconstruction.
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Affiliation(s)
- Brieg Dissaux
- Service d’Imagerie Médicale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France; (M.C.E.A.); (J.O.)
- Groupe d’Étude de la Thrombose Occidentale GETBO (Inserm UMR 1304), Université de Bretagne Occidentale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France
| | - Mourad Cheddad El Aouni
- Service d’Imagerie Médicale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France; (M.C.E.A.); (J.O.)
| | - Julien Ognard
- Service d’Imagerie Médicale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France; (M.C.E.A.); (J.O.)
- Laboratoire de Traitement de l’Information médicale—LaTIM (Inserm UMR 1101), Université de Bretagne Occidentale, 5 Avenue Foch, CEDEX, 29200 Brest, France
| | - Jean-Christophe Gentric
- Service d’Imagerie Médicale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France; (M.C.E.A.); (J.O.)
- Groupe d’Étude de la Thrombose Occidentale GETBO (Inserm UMR 1304), Université de Bretagne Occidentale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France
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Zhang Q, Sheng J, Chen B. Image Quality Assessment of Low-Dose CT using Hybrid Iterative Reconstruction. J Imaging Sci Technol 2021. [DOI: 10.2352/j.imagingsci.technol.2021.65.6.060501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Abstract Background: X-ray computed tomography is the first imaging technology that supports accurate nondestructive interior image reconstruction of an object from sufficient projection data. Low-dose computed tomography (LDCT) has been considered to relieve the harm
to patients caused by X-ray radiation. However, LDCT images can be degraded by quantum noise and streak artifacts.Methods: The objective of the authors’ study is to evaluate the optimal level of the hybrid iterative reconstruction (HIR) that generates images with the best
diagnostic quality on different dose and noise levels. HIR with optimizations is proposed to reduce image noise and provide better performance at a low dose. The Catphan®504 phantom is employed to assess various image qualities (IQ).Results: For any given scanning
protocols, there is linear noise reduction and linear increase of contrast-to-noise ratio (CNR) using optimal HIR. The evidence from various module tests demonstrates that the shape of the noise power spectrum is continuously shifted to low frequency with increasing HIR levels compared with
that of filtered-back-projection (FBP). This may describe the difference between the human observer performance and features of the ideal low-contrast objects.Conclusion: Optimal HIR is clearly demonstrated to be a superior method for reducing image noise and improving CNR compared
to FBP. Optimal HIR also inhibits texture change or spectrum shift compared with the pure IR method. Even though there are continuous noise reduction and CNR increase with HIR at increasing levels, the human observer performance does not seem to improve simultaneously due to coarser noise
(low-frequency noise). HIR level 3 to 5 is optimal for their study. It is possible for the optimal HIR to offer equivalent diagnostic IQ at a lower dose compared with FBP at a routine dose.
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Affiliation(s)
- Qiao Zhang
- Beijing Hospital, Beijing, 100730, China
| | - Jinhua Sheng
- College of Computer Science, Hangzhou Dianzi University, Hangzhou, Zhejiang, 310018, China
| | - Bin Chen
- College of Computer Science, Hangzhou Dianzi University, Hangzhou, Zhejiang, 310018, China
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Yamasaki Y, Kamitani T, Sagiyama K, Matsuura Y, Hida T, Nagata H. Model-based iterative reconstruction for 320-detector row CT angiography reduces radiation exposure in infants with complex congenital heart disease. ACTA ACUST UNITED AC 2021; 27:42-49. [PMID: 33290239 DOI: 10.5152/dir.2020.19633] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE We investigated the impact of model-based iterative reconstruction (MBIR) on 320-detector row computed tomography angiography (CTA) in infants with complex congenital heart disease (CHD). METHODS Seventy infants with complex CHD who underwent 320-detector row CTA (40 boys and 30 girls; age range, 0-22 months; median age, 60 days) were retrospectively evaluated. First, the images were reconstructed by filtered back projection (FBP), hybrid iterative reconstruction (HIR), or MBIR in 20 cases, and variables were compared among the three iterative reconstruction methods (IR test). Second, the variables were compared between 25 cases scanned using HIR and 25 cases scanned using MBIR, with a 20 standard deviation noise level for both. Attenuation values and contrast-to-noise ratios (CNRs) of the great vessels and heart chambers were calculated. Total dose-length products were recorded for all patients (radiation dose: RD test). RESULTS In the IR test, the mean CNR values were 4.8±1.3 for FBP, 6.9±1.4 for HIR, and 8.2±1.7 for MBIR (P < 0.0001). The best subjective image qualities in the great vessels and heart chambers were obtained with MBIR. In RD testing, no significant differences between HIR and MBIR in image quality (CNR: HIR, 8.4±2.4; MBIR, 8.3±2.4) were observed. The effective dose was significantly lower for MBIR than for HIR (0.7±0.2 vs. 1.1±0.3 mSv; P < 0.001). CONCLUSION The MBIR algorithm significantly improved image quality and decreased radiation exposure in 320-row CTA of infants with complex CHD, providing an alternative to FBP or HIR that is both safer and produces better results.
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Affiliation(s)
- Yuzo Yamasaki
- Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Takeshi Kamitani
- Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Koji Sagiyama
- Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Yuko Matsuura
- Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Tomoyuki Hida
- Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Hazumu Nagata
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Effect of New Model-Based Iterative Reconstruction on Quantitative Analysis of Airway Tree by Computer-Aided Detection Software in Chest Computed Tomography. J Comput Assist Tomogr 2021; 45:166-170. [PMID: 31929380 DOI: 10.1097/rct.0000000000000975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Compared the performance of computer-aided detection (CAD) software for quantitative analysis of airway using computed tomography (CT) images reconstructed with versions of model-based iterative reconstruction (MBIR) that either balances spatial and density resolution (MBIRSTND) or prefers spatial resolution (MBIRRP20), and adaptive statistical iterative reconstruction (ASIR) with lung kernel. METHODS Thirty patients were included who were scanned for pulmonary disease using a routine dose multidetector CT system. Data were reconstructed with ASIR, MBIRSTND, and MBIRRP20. Airway dimensions from the 3 reconstructions were measured using an automated, quantitative CAD software designed to segment and quantify the bronchial tree automatically using a skeletonization algorithm. For each patient and reconstruction algorithm, the right middle lobe bronchus was selected as a representative for measuring the bronchial length of the matched airways. Two radiologists used a semiquantitative 5-point scale to rate the subjective image quality of MBIRSTND and MBIRRP20 reconstructions on airway trees analysis. RESULTS Algorithm impacts the measurement variability of bronchus length in chest CT, MBIRRP20 were the best, whereas ASIR were the worst (P < 0.05). In addition, the optimal reconstruction algorithm was found to be MBIRSTND for the airway trees being assessed about subjective noise and MBIRRP20 about bronchial end shows, and there were no significant differences in the continuity and completeness of bronchial wall, whereas ASIR performed inferiorly compared with them (P < 0.05). CONCLUSIONS Compared with ASIR, MBIRSTND, and MBIRRP20 from MBIRn algorithm potentially allow the desired airway quantification accuracy to be achieved on the performance of CAD, especially for MBIRRP20.
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Kim H, Hong J, Lee T, Choi YW, Kim HH, Chae EY, Choi WJ, Cho S. A synthesizing method for signal-enhanced and artifact-reduced mammogram from digital breast tomosynthesis. Phys Med Biol 2020; 65:215026. [PMID: 33151909 DOI: 10.1088/1361-6560/abb31e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this paper, we propose a method for compositing a synthetic mammogram (SM) from digital breast tomosynthesis (DBT) slice images. The method consists of four parts. The first part is image reconstruction of DBT from the acquired projection data by use of backprojection-filtration (BPF) algorithm with a low-frequency boosting scheme and a high-density object reduction technique embedded. Also, a few expectation-maximization (EM) iterations have been additively implemented on top of the BPF algorithm to prepare a separate volume image. The second is generating three kinds of intermediate SMs. A forward projection image and a linear structure weighted forward projection image were computed. A maximum intensity projection of the BPF reconstructed volume image was also generated. The third part is integrating three intermediate SMs. The last is the post-processing of the SM. We scanned two physical phantoms in a prototype DBT scanner, and we have evaluated the performance of the proposed method. We also performed a clinical data study by use of 30 patient data who went through both DBT and digital mammography (DM) scans. Three experienced radiologists have read the SMs generated by several component techniques and also read the DM of each patient, and evaluated the generated SMs. The experimental phantom study and the clinical reader study consistently demonstrated the usefulness of the proposed method.
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Affiliation(s)
- Hyeongseok Kim
- Department of Nuclear and Quantum Engineering, KAIST, Daejeon 34141, Republic of Korea. KAIST Institute for Artificial Intelligence, KAIST, Daejeon 34141, Republic of Korea
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Zhang Z, Seeram E. The use of artificial intelligence in computed tomography image reconstruction - A literature review. J Med Imaging Radiat Sci 2020; 51:671-677. [PMID: 32981888 DOI: 10.1016/j.jmir.2020.09.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 08/28/2020] [Accepted: 09/02/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND AND PURPOSE The use of AI in the process of CT image reconstruction may improve image quality of resultant images and therefore facilitate low-dose CT examinations. METHODS Articles in this review were gathered from multiple databases (Google Scholar, Ovid and Monash University Library Database). A total of 17 articles regarding AI use in CT image reconstruction was reviewed, including 1 white paper from GE Healthcare. RESULTS DLR algorithms performed better in terms of noise reduction abilities, and image quality preservation at low doses when compared to other reconstruction techniques. CONCLUSION Further research is required to discuss clinical application and diagnostic accuracy of DLR algorithms, but AI is a promising dose-reduction technique with future computational advances.
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Affiliation(s)
- Ziyu Zhang
- Radiography and Medical Imaging, Monash University, Clayton, Victoria, Australia.
| | - Euclid Seeram
- Department of Medical Imaging and Radiation Sciences, Monash University, Australia
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Assessment of computed tomography radiation doses for paediatric head and chest examinations using paediatric phantoms of three different ages. Radiography (Lond) 2020; 27:332-339. [PMID: 32972850 DOI: 10.1016/j.radi.2020.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 09/04/2020] [Accepted: 09/06/2020] [Indexed: 11/20/2022]
Abstract
INTRODUCTION With the rapid development of computed tomography (CT) scanners, the assessment of the radiation dose received by the patient has become a heavily researched topic and may result in a reduction in radiation exposure risk. In this study, radiation doses were measured using three paediatric phantoms for head and chest CT examinations in Najran, Saudi Arabia. METHODS Thirteen scanners were included in the study to estimate the CT radiation doses using three phantoms representing three age groups (1-, 5-, and 10-year-old patients). RESULTS The volume CT dose index (CTDIvol) estimated for each phantom ranged from 6.56 to 41.12 mGy and 0.292 to 11.10 mGy for the head and chest examinations, respectively. The estimation of lifetime attributable risk (LAR) indicated that the cancer risk could reach approximately 0.02-0.16% per 500 children undergoing head and chest CT examinations. CONCLUSION The comparison with the published data of the European Commission (EC) and countries reported in this study revealed that the mean CTDIvol for the head examinations was within the recommended dose reference levels (DRLs). Meanwhile, chest results exceeded the international DRLs for the one-year-old phantoms, suggesting that optimisation work is required at a number of sites. IMPLICATIONS FOR PRACTICE The variation among CT doses reported in this study showed that substantial standardisation is needed.
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Warin Fresse K, Isorni MA, Dacher JN, Pontana F, Gorincour G, Boddaert N, Jacquier A, Raimondi F. Cardiac computed tomography angiography in the paediatric population: Expert consensus from the Filiale de cardiologie pédiatrique et congénitale (FCPC) and the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV). Arch Cardiovasc Dis 2020; 113:579-586. [PMID: 32522436 DOI: 10.1016/j.acvd.2020.03.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 12/30/2022]
Abstract
This paper aims to provide a paediatric cardiac computed tomography angiography expert panel consensus based on the opinions of experts from the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV) and the Filiale de cardiologie pédiatrique congénitale (FCPC). This expert panel consensus includes recommendations for indications, patient preparation, computed tomography angiography radiation dose reduction techniques and postprocessing techniques. We think that to realize its full potential and to avoid pitfalls, cardiac computed tomography angiography in children with congenital heart disease requires training and experience. Moreover, paediatric cardiac computed tomography angiography protocols should be standardized to acquire optimal images in this population with the lowest radiation dose possible, to prevent unnecessary radiation exposure. We also provide a suggested structured report and a list of acquisition protocols and technical parameters in relation to specific vendors.
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Affiliation(s)
- Karine Warin Fresse
- Imagerie cardiovasculaire fédération des cardiopathies congénitales, CHU de Nantes HGRL, 44093 Nantes, France
| | - Marc Antoine Isorni
- Unité de radiologie diagnostique et thérapeutique, hôpital Marie-Lannelongue, 92350 Le Plessis Robinson, France
| | - Jean Nicolas Dacher
- Cardiac MR/CT Unit, University Hospital, 76031 Rouen, France; Inserm U1096, UFR Médecine-Pharmacie, 76183 Rouen, France
| | - François Pontana
- Inserm UMR 1011, Department of Cardiovascular Radiology, EGID (European Genomic Institute for Diabetes), université de Lille, Institut Cœur-Poumon, Institut Pasteur de Lille, CHU de Lille, FR3508, 59000 Lille, France
| | - Guillaume Gorincour
- Image(2), institut méditerranéen d'imagerie médicale appliquée à la gynecologie, grossesse et enfance, 13008 Marseille, France
| | - Nathalie Boddaert
- Paediatric Radiology Unit, Hôpital Universitaire Necker-Enfants Malades, 75743 Paris, France
| | - Alexis Jacquier
- Department of Radiology, University of Marseille Méditerranée, CHU La Timone, Marseille, France
| | - Francesca Raimondi
- Unité médicochirurgicale de cardiologie congénitale et pédiatrique, centre de référence des maladies cardiaques congénitales complexes (M3C), hôpital universitaire Necker-Enfants-Malades, 149, rue de Sèvres, 75743 Paris cedex 15, France.
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Abstract
OBJECTIVE. Pediatric CT angiography (CTA) presents unique challenges compared with adult CTA. Because of the ionizing radiation exposure, CTA should be used judiciously in children. The pearls offered here are observations gleaned from the authors' experience in the use of pediatric CTA. We also present some potential follies to be avoided. CONCLUSION. Understanding the underlying principles and paying meticulous attention to detail can substantially optimize dose and improve the diagnostic quality of pediatric CTA.
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Warin-Fresse K, Isornii MA, Dacher JN, Pontana F, Gorincour G, Boddaert N, Jacquier A, Raimondi F. Pediatric cardiac computed tomography angiography: Expert consensus from the Filiale de Cardiologie Pédiatrique et Congénitale (FCPC) and the Société Française d'Imagerie Cardiaque et Vasculaire diagnostique et interventionnelle (SFICV). Diagn Interv Imaging 2020; 101:335-345. [PMID: 32029386 DOI: 10.1016/j.diii.2020.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/11/2020] [Accepted: 01/15/2020] [Indexed: 02/06/2023]
Abstract
This article was designed to provide a pediatric cardiac computed tomography angiography (CCTA) expert panel consensus based on opinions of experts of the Société Française d'Imagerie Cardiaque et Vasculaire diagnostique et interventionnelle (SFICV) and of the Filiale de Cardiologie Pédiatrique Congénitale (FCPC). This expert panel consensus includes recommendations for indications, patient preparation, CTA radiation dose reduction techniques, and post-processing techniques. The consensus was based on data from available literature (original papers, reviews and guidelines) and on opinions of a group of specialists with extensive experience in the use of CT imaging in congenital heart disease. In order to reach high potential and avoid pitfalls, CCTA in children with congenital heart disease requires training and experience. Moreover, pediatric cardiac CCTA protocols should be standardized to acquire optimal images in this population with the lowest radiation dose possible to prevent unnecessary radiation exposure. We also provided a suggested structured report and a list of acquisition protocols and technical parameters in relation to specific vendors.
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Affiliation(s)
- K Warin-Fresse
- Department of Cardiovascular Imaging, CHU Nantes HGRL, 44093 Nantes, France
| | - M-A Isornii
- Department of Radiology, Hôpital Marie Lannelongue, 92350 Le Plessis-Robinson, France
| | - J-N Dacher
- Department of Radiology, Rouen University Hospital, 76031 Rouen, France; Inserm U1096, UFR Médecine-Pharmacie, University of Rouen, 76000 Rouen, France
| | - F Pontana
- Department of Cardiovascular Radiology, Institut Cœur-Poumon, CHU Lille, INSERM UMR 1011, Institut Pasteur de Lille, EGID, FR3508, Univ Lille, 59000 Lille, France
| | - G Gorincour
- Image2, Mediterranean Institute of Medical Imaging, 13008 Marseille, France
| | - N Boddaert
- Pediatric Radiology Unit, Hôpital Universitaire Necker Enfants-Malades, 75015 Paris, France; Université de Paris, Descartes-Paris 5, 75006 Paris, France
| | - A Jacquier
- Department of Radiology, University of Marseille Méditerranée, CHU la Timone, 13000 Marseille, France
| | - F Raimondi
- Unité Médicochirurgicale de Cardiologie Congénitale et Pédiatrique, Centre de Référence des Maladies Cardiaques Congénitales Complexes - M3C, Hôpital Universitaire Necker Enfants-Malades, 75015 Paris, France.
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Abstract
CLINICAL/METHODICAL ISSUE Computed tomography (CT) acquisition should be performed following the ALARA principle: keeping patient radiation exposure as low as reasonably achievable. STANDARD RADIOLOGICAL METHODS Reconstruction with filtered backprojection is still the standard in CT. METHODICAL INNOVATIONS Recently, iterative reconstruction techniques have become available, using a different approach for image reconstruction. A similar approach is used for iterative metal artifact reduction. PERFORMANCE Compared to filtered backprojection, iterative reconstruction yields improvements in image quality and reduces image noise. ACHIEVEMENTS Using iterative reconstruction allows the reduction of patient radiation exposure by up to 80%, depending on the used algorithm and the clinical task at hand. With the help of iterative metal artifact reduction, images of diagnostic quality can be acquired despite metal implants. PRACTICAL RECOMMENDATIONS Iterative reconstruction should be used to reduce patient radiation exposure in accordance with the clinical requirements. The use of iterative metal artifact reduction is recommended.
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Southard RN, Bardo DME, Temkit MH, Thorkelson MA, Augustyn RA, Martinot CA. Comparison of Iterative Model Reconstruction versus Filtered Back-Projection in Pediatric Emergency Head CT: Dose, Image Quality, and Image-Reconstruction Times. AJNR Am J Neuroradiol 2019; 40:866-871. [PMID: 30975652 DOI: 10.3174/ajnr.a6034] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 02/27/2019] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Noncontrast CT of the head is the initial imaging test for traumatic brain injury, stroke, or suspected nonaccidental trauma. Low-dose head CT protocols using filtered back-projection are susceptible to increased noise and decreased image quality. Iterative reconstruction noise suppression allows the use of lower-dose techniques with maintained image quality. We review our experience with children undergoing emergency head CT examinations reconstructed using knowledge-based iterative model reconstruction versus standard filtered back-projection, comparing reconstruction times, radiation dose, and objective and subjective image quality. MATERIALS AND METHODS This was a retrospective study comparing 173 children scanned using standard age-based noncontrast head CT protocols reconstructed with filtered back-projection with 190 children scanned using low-dose protocols reconstructed with iterative model reconstruction. ROIs placed on the frontal white matter and thalamus yielded signal-to-noise and contrast-to-noise ratios. Volume CT dose index and study reconstruction times were recorded. Random subgroups of patients were selected for subjective image-quality review. RESULTS The volume CT dose index was significantly reduced in studies reconstructed with iterative model reconstruction compared with filtered back-projection, (mean, 24.4 ± 3.1 mGy versus 31.1 ± 6.0 mGy, P < .001), while the SNR and contrast-to-noise ratios improved 2-fold (P < .001). Radiologists graded iterative model reconstruction images as superior to filtered back-projection images for gray-white matter differentiation and anatomic detail (P < .001). The average reconstruction time of the filtered back-projection studies was 101 seconds, and with iterative model reconstruction, it was 147 seconds (P < .001), without a practical effect on work flow. CONCLUSIONS In children referred for emergency noncontrast head CT, optimized low-dose protocols with iterative model reconstruction allowed us to significantly reduce the relative dose, on average, 22% compared with filtered back-projection, with significantly improved objective and subjective image quality.
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Affiliation(s)
- R N Southard
- From the Departments of Medical Imaging (R.N.S., D.M.E.B., M.A.T., R.A.A., C.A.M.)
| | - D M E Bardo
- From the Departments of Medical Imaging (R.N.S., D.M.E.B., M.A.T., R.A.A., C.A.M.)
| | - M H Temkit
- Clinical Research (M.H.T.), Phoenix Children's Hospital, Phoenix Arizona
| | - M A Thorkelson
- From the Departments of Medical Imaging (R.N.S., D.M.E.B., M.A.T., R.A.A., C.A.M.)
| | - R A Augustyn
- From the Departments of Medical Imaging (R.N.S., D.M.E.B., M.A.T., R.A.A., C.A.M.)
| | - C A Martinot
- From the Departments of Medical Imaging (R.N.S., D.M.E.B., M.A.T., R.A.A., C.A.M.)
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Extent of tube-current reduction using sinogram affirmed iterative reconstruction in pediatric computed tomography: phantom study. Pediatr Radiol 2019; 49:51-56. [PMID: 30259068 DOI: 10.1007/s00247-018-4260-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 08/12/2018] [Accepted: 09/05/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND Iterative image reconstruction techniques can produce diagnostic-quality computed tomography (CT) images with lower radiation dose. OBJECTIVE To quantify the reduction in x-ray tube-current setting and optimize pediatric CT scans using different strengths of an iterative reconstruction technique. MATERIALS AND METHODS The head, chest and abdomen regions of an anthropomorphic phantom representing a 5-year-old patient were scanned using standard CT protocols. Images were reconstructed using filtered back projection and different strengths of a sinogram affirmed iterative reconstruction technique. Repeated measurements of contrast-to-noise ratios in the lungs, bone and soft-tissue regions of the phantom were carried out. Maximum increase in contrast-to-noise ratio with iterative reconstruction strength was identified and a tube-current reduction factor was calculated. Head scans were repeated with reduced tube current and compared to filtered back projection images. RESULTS Iterative reconstruction strength of 3 for head and chest images and 4 for abdomen images were optimum, resulting in contrast-to-noise ratio increase of about 50%. A tube-current reduction factor of 1.2 for head images was calculated. Images of the head acquired using reduced tube-current showed similar contrast-to-noise ratio as images form filtered back projection with full tube current. CONCLUSION Optimum strength of iterative reconstruction technique has been identified for head, chest and abdomen images. Reductions in tube current of 20%, resulting in similar radiation dose reduction, have been established.
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20
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Jia Y, Ji X, He T, Yu Y, Yu N, Duan H, Guo Y. Quantitative Analysis of Airway Tree in Low-dose Chest CT with a New Model-based Iterative Reconstruction Algorithm: Comparison to Adaptive Statistical Iterative Reconstruction in Routine-dose CT. Acad Radiol 2018; 25:1526-1532. [PMID: 30017502 DOI: 10.1016/j.acra.2018.03.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 01/12/2018] [Accepted: 03/19/2018] [Indexed: 11/30/2022]
Abstract
OBJECTIVE We aimed to evaluate a new model-based iterative reconstruction (MBIRn) algorithm either with spatial resolution and noise reduction balance (MBIRSTND) or spatial resolution preference (MBIRRP20) for quantitative analysis of airway in low-dose chest computed tomography (CT) with a computer-aided detection (CAD) software, in comparison to adaptive statistical iterative reconstruction (ASIR) in routine-dose CT. METHODS Thirty patients who underwent both the routine-dose (noise index [NI] = 14 HU) and low-dose (at 30% level with NI = 28 HU) CT examination for pulmonary disease were included. Image acquisition was performed with 120 kVp tube voltage and automatic tube current modulation. Routine-dose scans were reconstructed with ASIR, whereas low-dose scans were reconstructed with ASIR, MBIRSTND, and MBIRRP20. Airway dimensions of the right middle lobe bronchus from the four reconstructions were measured using CAD software. Two radiologists used a semiquantitative 5 scoring criteria (-2, inferior to; +2, superior to; -1 slightly inferior to; +1, slightly superior to; and 0, equal to ASIR in routine-dose CT) to rate the subjective image quality of MBIRSTND and MBIRRP20 of airway trees. The paired t test and Wilcoxon signed-rank test were used for statistical comparison. RESULTS The low-dose CT provided 70.76% dose reduction compared to the routine-dose CT (0.88 ± 0.83 mSv vs 3.01 ± 1.89 mSv). MBIRSTND and MBIRRP20 with low-dose CT provided longer bronchial length measurements and were better in measurement variability and continuity and completeness of bronchial walls than ASIR in routine-dose CT (P < .05). MBIRSTND was better for subjective noise and MBIRRP20 for showing distal branches. CONCLUSIONS: MBIRSTND and MBIRRP20 algorithms provide better airway quantification at 30% of the radiation dose, compared to ASIR at routine-dose CT.
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Affiliation(s)
- Yongjun Jia
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Yanta Western Road, Xi'an, Shannxi 710061, China; Department of Radiology, Affiliated Hospital of Shaanxi Chinese Medicine University, Xianyang 712000, China
| | - Xing Ji
- Department of Radiology, Affiliated Hospital of Yan'an University, Yan'an 716000, China
| | - Taiping He
- Department of Radiology, Affiliated Hospital of Shaanxi Chinese Medicine University, Xianyang 712000, China
| | - Yong Yu
- Department of Radiology, Affiliated Hospital of Shaanxi Chinese Medicine University, Xianyang 712000, China
| | - Nan Yu
- Department of Radiology, Affiliated Hospital of Shaanxi Chinese Medicine University, Xianyang 712000, China
| | - Haifeng Duan
- Department of Radiology, Affiliated Hospital of Shaanxi Chinese Medicine University, Xianyang 712000, China
| | - Youmin Guo
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Yanta Western Road, Xi'an, Shannxi 710061, China.
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den Harder AM, Willemink MJ, van Doormaal PJ, Wessels FJ, Lock MTWT, Schilham AMR, Budde RPJ, Leiner T, de Jong PA. Radiation dose reduction for CT assessment of urolithiasis using iterative reconstruction: A prospective intra-individual study. Eur Radiol 2018; 28:143-150. [PMID: 28695359 PMCID: PMC5717126 DOI: 10.1007/s00330-017-4929-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 06/05/2017] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To assess the performance of hybrid (HIR) and model-based iterative reconstruction (MIR) in patients with urolithiasis at reduced-dose computed tomography (CT). METHODS Twenty patients scheduled for unenhanced abdominal CT for follow-up of urolithiasis were prospectively included. Routine dose acquisition was followed by three low-dose acquisitions at 40%, 60% and 80% reduced doses. All images were reconstructed with filtered back projection (FBP), HIR and MIR. Urolithiasis detection rates, gall bladder, appendix and rectosigmoid evaluation and overall subjective image quality were evaluated by two observers. RESULTS 74 stones were present in 17 patients. Half the stones were not detected on FBP at the lowest dose level, but this improved with MIR to a sensitivity of 100%. HIR resulted in a slight decrease in sensitivity at the lowest dose to 72%, but outperformed FBP. Evaluation of other structures with HIR at 40% and with MIR at 60% dose reductions was comparable to FBP at routine dose, but 80% dose reduction resulted in non-evaluable images. CONCLUSIONS CT radiation dose for urolithiasis detection can be safely reduced by 40 (HIR)-60 (MIR) % without affecting assessment of urolithiasis, possible extra-urinary tract pathology or overall image quality. KEY POINTS • Iterative reconstruction can be used to substantially lower the radiation dose. • This allows for radiation reduction without affecting sensitivity of stone detection. • Possible extra-urinary tract pathology evaluation is feasible at 40-60% reduced dose.
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Affiliation(s)
- Annemarie M den Harder
- Department of Radiology, Utrecht University Medical Center, P.O. Box 85500, E01.132, 3508GA, Utrecht, The Netherlands.
| | - Martin J Willemink
- Department of Radiology, Utrecht University Medical Center, P.O. Box 85500, E01.132, 3508GA, Utrecht, The Netherlands
| | - Pieter J van Doormaal
- Department of Radiology, Erasmus Medical Center, P.O. Box 2040, 3000CA, Rotterdam, The Netherlands
| | - Frank J Wessels
- Department of Radiology, Utrecht University Medical Center, P.O. Box 85500, E01.132, 3508GA, Utrecht, The Netherlands
| | - M T W T Lock
- Department of Urology, University Medical Center, P.O. Box 85500, 3508GA, Utrecht, The Netherlands
| | - Arnold M R Schilham
- Department of Radiology, Utrecht University Medical Center, P.O. Box 85500, E01.132, 3508GA, Utrecht, The Netherlands
| | - Ricardo P J Budde
- Department of Radiology, Erasmus Medical Center, P.O. Box 2040, 3000CA, Rotterdam, The Netherlands
| | - Tim Leiner
- Department of Radiology, Utrecht University Medical Center, P.O. Box 85500, E01.132, 3508GA, Utrecht, The Netherlands
| | - Pim A de Jong
- Department of Radiology, Utrecht University Medical Center, P.O. Box 85500, E01.132, 3508GA, Utrecht, The Netherlands
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den Harder AM, Suchá D, van Doormaal PJ, Budde RPJ, de Jong PA, Schilham AMR, Breur JMPJ, Leiner T. Radiation dose reduction in pediatric great vessel stent computed tomography using iterative reconstruction: A phantom study. PLoS One 2017; 12:e0175714. [PMID: 28410386 PMCID: PMC5391930 DOI: 10.1371/journal.pone.0175714] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 03/30/2017] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND To study dose reduction using iterative reconstruction (IR) for pediatric great vessel stent computed tomography (CT). METHODS Five different great vessel stents were separately placed in a gel-containing plastic holder within an anthropomorphic chest phantom. The stent lumen was filled with diluted contrast gel. CT acquisitions were performed at routine dose, 52% and 81% reduced dose and reconstructed with filtered back projection (FBP) and IR. Objective image quality in terms of noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as well as subjective image quality were evaluated. RESULTS Noise, SNR and CNR were improved with IR at routine and 52% reduced dose, compared to FBP at routine dose. The lowest dose level resulted in decreased objective image quality with both FBP and IR. Subjective image quality was excellent at all dose levels. CONCLUSION IR resulted in improved objective image quality at routine dose and 52% reduced dose, while objective image quality deteriorated at 81% reduced dose. Subjective image quality was not affected by dose reduction.
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Affiliation(s)
- Annemarie M. den Harder
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
- * E-mail:
| | - Dominika Suchá
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
| | | | | | - Pim A. de Jong
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
| | - Arnold M. R. Schilham
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
| | - Johannes M. P. J. Breur
- Department of Pediatric Cardiology, Utrecht University Medical Center, Utrecht, The Netherlands
| | - Tim Leiner
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
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den Harder AM, Suchá D, van Hamersvelt RW, Budde RPJ, de Jong PA, Schilham AMR, Bos C, Breur JMPJ, Leiner T. Imaging of pediatric great vessel stents: Computed tomography or magnetic resonance imaging? PLoS One 2017; 12:e0171138. [PMID: 28141852 PMCID: PMC5283725 DOI: 10.1371/journal.pone.0171138] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/16/2017] [Indexed: 11/28/2022] Open
Abstract
Background Complications might occur after great vessel stent implantation in children. Therefore follow-up using imaging is warranted. Purpose To determine the optimal imaging modality for the assessment of stents used to treat great vessel obstructions in children. Material and methods Five different large vessel stents were evaluated in an in-vitro setting. All stents were expanded to the maximal vendor recommended diameter (20mm; n = 4 or 10mm; n = 1), placed in an anthropomorphic chest phantom and imaged with a 256-slice CT-scanner. MRI images were acquired at 1.5T using a multi-slice T2-weighted turbo spin echo, an RF-spoiled three-dimensional T1-weighted Fast Field Echo and a balanced turbo field echo 3D sequence. Two blinded observers assessed stent lumen visibility (measured diameter/true diameter *100%) in the center and at the outlets of the stent. Reproducibility of diameter measurements was evaluated using the intraclass correlation coefficient for reliability and 95% limits of agreement for agreement analysis. Results Median stent lumen visibility was 88 (IQR 86–90)% with CT for all stents at both the center and outlets. With MRI, the T2-weighted turbo spin echo sequence was preferred which resulted in 82 (78–84%) stent lumen visibility. Interobserver reliability and agreement was good for both CT (ICC 0.997, mean difference -0.51 [-1.07–0.05] mm) and MRI measurements (ICC 0.951, mean difference -0.05 [-2.52 –-2.41] mm). Conclusion Good in-stent lumen visibility was achievable in this in-vitro study with both CT and MRI in different great vessel stents. Overall reliability was good with clinical acceptable limits of agreement for both CT and MRI. However, common conditions such as in-stent stenosis and associated aneurysms were not tested in this in-vitro study, limiting the value of the in-vitro study.
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Affiliation(s)
- A. M. den Harder
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
- * E-mail:
| | - D. Suchá
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
| | - R. W. van Hamersvelt
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
| | - R. P. J. Budde
- Department of Radiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - P. A. de Jong
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
| | - A. M. R. Schilham
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
| | - C. Bos
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
| | - J. M. P. J. Breur
- Department of Pediatric Cardiology, Utrecht University Medical Center, Utrecht, The Netherlands
| | - T. Leiner
- Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands
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Contrast-Enhanced High-Pitch Computed Tomography in Pediatric Patients Without Electrocardiography Triggering and Sedation. J Comput Assist Tomogr 2017; 41:165-171. [DOI: 10.1097/rct.0000000000000482] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Shirota G, Maeda E, Namiki Y, Bari R, Ino K, Torigoe R, Abe O. Pediatric 320-row cardiac computed tomography using electrocardiogram-gated model-based full iterative reconstruction. Pediatr Radiol 2017; 47:1463-1470. [PMID: 28667349 PMCID: PMC5608791 DOI: 10.1007/s00247-017-3901-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 04/05/2017] [Accepted: 05/09/2017] [Indexed: 12/03/2022]
Abstract
BACKGROUND Full iterative reconstruction algorithm is available, but its diagnostic quality in pediatric cardiac CT is unknown. OBJECTIVE To compare the imaging quality of two algorithms, full and hybrid iterative reconstruction, in pediatric cardiac CT. MATERIALS AND METHODS We included 49 children with congenital cardiac anomalies who underwent cardiac CT. We compared quality of images reconstructed using the two algorithms (full and hybrid iterative reconstruction) based on a 3-point scale for the delineation of the following anatomical structures: atrial septum, ventricular septum, right atrium, right ventricle, left atrium, left ventricle, main pulmonary artery, ascending aorta, aortic arch including the patent ductus arteriosus, descending aorta, right coronary artery and left main trunk. We evaluated beam-hardening artifacts from contrast-enhancement material using a 3-point scale, and we evaluated the overall image quality using a 5-point scale. We also compared image noise, signal-to-noise ratio and contrast-to-noise ratio between the algorithms. RESULTS The overall image quality was significantly higher with full iterative reconstruction than with hybrid iterative reconstruction (3.67±0.79 vs. 3.31±0.89, P=0.0072). The evaluation scores for most of the gross structures were higher with full iterative reconstruction than with hybrid iterative reconstruction. There was no significant difference between full and hybrid iterative reconstruction for the presence of beam-hardening artifacts. Image noise was significantly lower in full iterative reconstruction, while signal-to-noise ratio and contrast-to-noise ratio were significantly higher in full iterative reconstruction. CONCLUSION The diagnostic quality was superior in images with cardiac CT reconstructed with electrocardiogram-gated full iterative reconstruction.
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Affiliation(s)
- Go Shirota
- Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
| | - Eriko Maeda
- Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655 Japan
| | - Yoko Namiki
- Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655 Japan
| | - Razibul Bari
- Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655 Japan
| | - Kenji Ino
- Imaging Center, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655 Japan
| | - Rumiko Torigoe
- Toshiba Medical Systems, 2-1-6, Tsukuda, Chuo-ku, Tokyo, 104-0051 Japan
| | - Osamu Abe
- Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655 Japan
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Kubo T, Ohno Y, Seo JB, Yamashiro T, Kalender WA, Lee CH, Lynch DA, Kauczor HU, Hatabu H. Securing safe and informative thoracic CT examinations—Progress of radiation dose reduction techniques. Eur J Radiol 2017; 86:313-319. [DOI: 10.1016/j.ejrad.2016.10.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 10/08/2016] [Accepted: 10/12/2016] [Indexed: 12/16/2022]
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Takagi S, Koyama M, Hayashi K, Kawauchi T. Image Quality Required for the Diagnosis of Skull Fractures Using Head CT: A Comparison of Conventional and Improved Reconstruction Kernels. AJNR Am J Neuroradiol 2016; 37:1992-1995. [PMID: 27418472 DOI: 10.3174/ajnr.a4861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 05/05/2016] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Although skull fractures are generally assessed on bone images obtained by using head CT, the combined multikernel technique that enables evaluation of both brain and bone through a change in the window settings of an image set has been reported. The purpose of this retrospective study was to determine the image quality required for the accurate assessment of skull fractures by using head CT. MATERIALS AND METHODS A random sample of 50 patients (25 nonfracture and 25 simple nondisplaced skull fractures) was selected, and sets of conventional brain and bone images and improved combined multikernel images were reconstructed (4614 images). Three radiologists indicated their confidence levels regarding the presence of skull fractures by marking on a continuous scale for each image set. The mean area under the receiver operating characteristic curve was calculated for each kernel, and the statistical significance of differences was tested by using the Dorfman-Berbaum-Metz method. RESULTS Although a difference in the diagnostic performance of the 3 radiologists was suggested, the mean area under the curve value showed no significant differences among the 3 reconstruction kernels (P = .95 [bone versus combined]), P = .91 [bone versus brain]), and P = .88 [brain versus combined]). However, the quality of brain images was distinctly poorer than the quality of the other 2 images. CONCLUSIONS There was no significant difference in the diagnostic performance of brain, bone, and combined multikernel images for skull fractures. Skull fracture diagnosis is made possible by brain image assessments. Combined multikernel images offer the advantage of high-quality brain and bone images.
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Affiliation(s)
- S Takagi
- From the Faculty of Health Sciences (S.T.), Hokkaido University, Hokkaido, Japan
| | - M Koyama
- Radiological Center (M.K.), National Defense Medical College Hospital, Saitama, Japan
| | - K Hayashi
- Department of Radiology (K.H., T.K.), National Defense Medical College, Saitama, Japan
| | - T Kawauchi
- Department of Radiology (K.H., T.K.), National Defense Medical College, Saitama, Japan
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Jia Q, Zhuang J, Jiang J, Li J, Huang M, Liang C. Image quality of ct angiography using model-based iterative reconstruction in infants with congenital heart disease: Comparison with filtered back projection and hybrid iterative reconstruction. Eur J Radiol 2016; 86:190-197. [PMID: 28027746 DOI: 10.1016/j.ejrad.2016.10.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/02/2016] [Accepted: 10/15/2016] [Indexed: 10/20/2022]
Abstract
PURPOSE To compare the image quality, rate of coronary artery visualization and diagnostic accuracy of 256-slice multi-detector computed tomography angiography (CTA) with prospective electrocardiographic (ECG) triggering at a tube voltage of 80kVp between 3 reconstruction algorithms (filtered back projection (FBP), hybrid iterative reconstruction (iDose4) and iterative model reconstruction (IMR)) in infants with congenital heart disease (CHD). METHODS Fifty-one infants with CHD who underwent cardiac CTA in our institution between December 2014 and March 2015 were included. The effective radiation doses were calculated. Imaging data were reconstructed using the FBP, iDose4 and IMR algorithms. Parameters of objective image quality (noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR)); subjective image quality (overall image quality, image noise and margin sharpness); coronary artery visibility; and diagnostic accuracy for the three algorithms were measured and compared. RESULTS The mean effective radiation dose was 0.61±0.32 mSv. Compared to FBP and iDose4, IMR yielded significantly lower noise (P<0.01), higher SNR and CNR values (P<0.01), and a greater subjective image quality score (P<0.01). The total number of coronary segments visualized was significantly higher for both iDose4 and IMR than for FBP (P=0.002 and P=0.025, respectively), but there was no significant difference in this parameter between iDose4 and IMR (P=0.397). There was no significant difference in the diagnostic accuracy between the FBP, iDose4 and IMR algorithms (χ2=0.343, P=0.842). CONCLUSIONS For infants with CHD undergoing cardiac CTA, the IMR reconstruction algorithm provided significantly increased objective and subjective image quality compared with the FBP and iDose4 algorithms. However, IMR did not improve the diagnostic accuracy or coronary artery visualization compared with iDose4.
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Affiliation(s)
- Qianjun Jia
- Southern Medical University, Guangzhou, Guangdong, China; Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China; Department of Catheterization Lab, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of South China Structural Heart Disease, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China.
| | - Jian Zhuang
- Department of Cardiac Surgery, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of South China Structural Heart Disease, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China.
| | - Jun Jiang
- Department of Radiology, Shenzhen Second People's Hospital, Shenzhen, Guangdong, China.
| | - Jiahua Li
- Department of Catheterization Lab, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of South China Structural Heart Disease, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China.
| | - Meiping Huang
- Department of Catheterization Lab, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of South China Structural Heart Disease, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China; Southern Medical University, Guangzhou, Guangdong, China.
| | - Changhong Liang
- Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China; Southern Medical University, Guangzhou, Guangdong, China.
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Results from a phantom based multi-centre paediatric computed tomography dose survey. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2016; 39:885-893. [PMID: 27730457 DOI: 10.1007/s13246-016-0488-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 09/26/2016] [Indexed: 10/20/2022]
Abstract
A computed tomography radiation dose survey was performed within our enterprise using three age-based paediatric phantoms representing a 1, 5 and 10 years old. Twenty-seven scanners were surveyed with volume computed tomography dose index and dose length product data collected for head, chest and abdomen-pelvis protocols at each age. Reconstruction method e.g. filtered back projection (FBP) or iterative (IR) was also recorded. About two-thirds of the 1 year old FBP chest scans exceeded the national Baby diagnostic reference level (DRL). A small number of scanners also exceeded the national Child DRL for the 1 and 5 years old phantoms. Only about half of the phantom protocols showed a difference of statistical significance between FBP and IR scanners. The results suggested the need for optimisation work at a number of sites. It was determined that the proposed local (i.e. enterprise-wide) DRLs are presented best in terms of weight or girth rather than age.
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Effect of radiation dose reduction and iterative reconstruction on computer-aided detection of pulmonary nodules: Intra-individual comparison. Eur J Radiol 2015; 85:346-51. [PMID: 26781139 DOI: 10.1016/j.ejrad.2015.12.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/30/2015] [Accepted: 12/05/2015] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate the effect of radiation dose reduction and iterative reconstruction (IR) on the performance of computer-aided detection (CAD) for pulmonary nodules. METHODS In this prospective study twenty-five patients were included who were scanned for pulmonary nodule follow-up. Image acquisition was performed at routine dose and three reduced dose levels in a single session by decreasing mAs-values with 45%, 60% and 75%. Tube voltage was fixed at 120 kVp for patients ≥ 80 kg and 100 kVp for patients < 80 kg. Data were reconstructed with filtered back projection (FBP), iDose(4) (levels 1,4,6) and IMR (levels 1-3). All noncalcified solid pulmonary nodules ≥ 4 mm identified by two radiologists in consensus served as the reference standard. Subsequently, nodule volume was measured with CAD software and compared to the reference consensus. The numbers of true-positives, false-positives and missed pulmonary nodules were evaluated as well as the sensitivity. RESULTS Median effective radiation dose was 2.2 mSv at routine dose and 1.2, 0.9 and 0.6 mSv at respectively 45%, 60% and 75% reduced dose. A total of 28 pulmonary nodules were included. With FBP at routine dose, 89% (25/28) of the nodules were correctly identified by CAD. This was similar at reduced dose levels with FBP, iDose(4) and IMR. CAD resulted in a median number of false-positives findings of 11 per scan with FBP at routine dose (93% of the CAD marks) increasing to 15 per scan with iDose(4) (95% of the CAD marks) and 26 per scan (96% of the CAD marks) with IMR at the lowest dose level. CONCLUSION CAD can identify pulmonary nodules at submillisievert dose levels with FBP, hybrid and model-based IR. However, the number of false-positive findings increased using hybrid and especially model-based IR at submillisievert dose while dose reduction did not affect the number of false-positives with FBP.
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