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Ravenscroft L, Baker L. The influence of miscentering on radiation dose during computed tomography head examinations and the role of localiser orientation: A phantom study. Radiography (Lond) 2024; 30:1517-1523. [PMID: 39303328 DOI: 10.1016/j.radi.2024.09.051] [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: 06/05/2024] [Revised: 07/22/2024] [Accepted: 09/09/2024] [Indexed: 09/22/2024]
Abstract
INTRODUCTION Computed Tomography (CT) chest, abdomen and pelvis research demonstrates a relationship between vertical phantom positioning and radiation dose. Moving the phantom closer or further from the x-ray source results in magnification or minimisation of the localiser. As automatic tube current modulation (ATCM) algorithms use localisers to estimate patient size and calculate required tube current, magnification or minimisation results in the incorrect provision of radiation dose. Radiation dose changes also depend on localiser orientation, changes with anteroposterior (AP) and posteroanterior (PA) localisers demonstrating an inverse relationship. However, within CT head literature often attributes radiation dose changes on impaired function of the bow-tie filter instead. The current study investigated the role of miscentering on ATCM function within CT head, paying particular attention to localiser orientation. METHODS Head scanning was performed with an anthropomorphic phantom at the isocentre, alongside ten vertically miscentered positions. This was performed three times, with an AP, PA and lateral localiser. CT dose index values at each miscentered level were compared across conditions. RESULTS Vertical miscentering altered radiation dose in both AP and PA conditions, radiation dose linearly increasing (up to 17.05%) when positioning the phantom closer to the x-ray source and decreasing when positioning away (up to -13.13%). Changes across AP and PA conditions demonstrated an inverse relationship. Radiation dose was unaffected in the lateral condition. CONCLUSIONS Miscentering during CT head alters ATCM function due to magnification/minimisation of the localiser image, causing ATCM algorithms to misinterpret patient size and miscalculate required tube current. IMPLICATIONS FOR PRACTICE Radiographers should be accurate when centering for CT head, avoiding any potential radiation dose changes. Further research into vertical miscentering and image quality during CT head is recommended.
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Affiliation(s)
- L Ravenscroft
- University Hospitals of Derby and Burton NHS Foundation Trust, Staffordshire, UK.
| | - L Baker
- Research and Development Imaging Support Unit, Nottingham University Hospitals NHS Trust, Nottingham, UK.
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Agostini A, Borgheresi A, Mariotti F, Ottaviani L, Carotti M, Valenti M, Giovagnoni A. New frontiers in oncological imaging with Computed Tomography: from morphology to function. Semin Ultrasound CT MR 2023; 44:214-227. [PMID: 37245886 DOI: 10.1053/j.sult.2023.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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A Review of Deep Learning CT Reconstruction: Concepts, Limitations, and Promise in Clinical Practice. CURRENT RADIOLOGY REPORTS 2022. [DOI: 10.1007/s40134-022-00399-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Abstract
Purpose of Review
Deep Learning reconstruction (DLR) is the current state-of-the-art method for CT image formation. Comparisons to existing filter back-projection, iterative, and model-based reconstructions are now available in the literature. This review summarizes the prior reconstruction methods, introduces DLR, and then reviews recent findings from DLR from a physics and clinical perspective.
Recent Findings
DLR has been shown to allow for noise magnitude reductions relative to filtered back-projection without suffering from “plastic” or “blotchy” noise texture that was found objectionable with most iterative and model-based solutions. Clinically, early reader studies have reported increases in subjective quality scores and studies have successfully implemented DLR-enabled dose reductions.
Summary
The future of CT image reconstruction is bright; deep learning methods have only started to tackle problems in this space via addressing noise reduction. Artifact mitigation and spectral applications likely be future candidates for DLR applications.
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Anam C, Naufal A, Fujibuchi T, Matsubara K, Dougherty G. Automated development of the contrast-detail curve based on statistical low-contrast detectability in CT images. J Appl Clin Med Phys 2022; 23:e13719. [PMID: 35808971 PMCID: PMC9512356 DOI: 10.1002/acm2.13719] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 12/25/2022] Open
Abstract
Purpose We have developed a software to automatically find the contrast–detail (C–D) curve based on the statistical low‐contrast detectability (LCD) in images of computed tomography (CT) phantoms at multiple cell sizes and to generate minimum detectable contrast (MDC) characteristics. Methods A simple graphical user interface was developed to set the initial parameters needed to create multiple grid region of interest of various cell sizes with a 2‐pixel increment. For each cell in the grid, the average CT number was calculated to obtain the standard deviation (SD). Detectability was then calculated by multiplying the SD of the mean CT numbers by 3.29. This process was automatically repeated as many times as the cell size was set at initialization. Based on the obtained LCD, the C–D curve was obtained and the target size at an MDC of 0.6% (i.e., 6‐HU difference) was determined. We subsequently investigated the consistency of the target sizes for a 0.6% MDC at four locations within the homogeneous image. We applied the software to images with six noise levels, images of two modules of the American College of Radiology CT phantom, images of four different phantoms, and images of four different CT scanners. We compared the target sizes at a 0.6% MDC based on the statistical LCD and the results from a human observer. Results The developed system was able to measure C–D curves from different phantoms and scanners. We found that the C–D curves follow a power‐law fit. We found that higher noise levels resulted in a higher MDC for a target of the same size. The low‐contrast module image had a slightly higher MDC than the distance module image. The minimum size of an object detected by visual observation was slightly larger than the size using statistical LCD. Conclusions The statistical LCD measurement method can generate a C–D curve automatically, quickly, and objectively.
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Affiliation(s)
- Choirul Anam
- Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Semarang, Central Java, Indonesia
| | - Ariij Naufal
- Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Semarang, Central Java, Indonesia
| | - Toshioh Fujibuchi
- Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kosuke Matsubara
- Department of Quantum Medical Technology, Faculty of Health Sciences, Institute of Medical Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Geoff Dougherty
- Department of Applied Physics and Medical Imaging, California State University Channel Islands, Camarillo, California, USA
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In Vivo Comparison of Micro-Balloon Interventions (MBI) Advantage: A Retrospective Cohort Study of DEB-TACE Versus b-TACE and of SIRT Versus b-SIRT. Cardiovasc Intervent Radiol 2022; 45:306-314. [PMID: 35037086 DOI: 10.1007/s00270-021-03035-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 11/25/2021] [Indexed: 12/24/2022]
Abstract
PURPOSE The purpose of this study was to evaluate in vivo the role of the micro-balloon by comparing trans-arterial chemoembolization (DEB-TACE) and selective internal radiotherapy (SIRT) procedures performed with and without balloon micro-catheter (b-DEB-TACE and DEB-TACE/SIRT and b-SIRT) for the treatment of hepatocellular carcinoma (HCC). METHODS The impact of a balloon micro-catheter on trans-arterial loco-regional treatment was analyzed using non-enhanced post-procedural cone-beam CT (Ne-CBCT) by comparing the attenuation values in the embolized area and the surrounding liver tissue before and after DEB-TACE versus b-DEB-TACE and by comparing 2D/3D dosimetry in single-photon emission computed tomography after SIRT versus b-SIRT, and by comparing the histological count of the beads following orthotopic liver transplantation in the DEB-TACE versus b-DEB-TACE subgroup. RESULTS We treated 84 HCC patients using trans-arterial loco-regional therapy. Fifty-three patients (26 DEB-TACE and 27 b-DEB-TACE) were analyzed in the TACE group. Contrast, signal-to-noise ratio, and contrast-to-noise ratio were all significantly higher in b-DEB-TACE subgroup than DEB-TACE (182.33 HU [CI95% 160.3-273.5] vs. 124 HU [CI95% 80.6-163.6]; 8.3 [CI95% 5.7-10.1] vs. 4.5 [CI95% 3.7-6.0]; 6.9 [CI95% 4.3-7.8] vs. 3.1 [CI95% 2.2-5.0] p < 0.05). Thirty-one patients (24 SIRT and 7 b-SIRT) were analyzed in the SIRT group. 2D dosimetry profile evaluation showed an activity intensity peak significantly higher in the b-SIRT than in the SIRT subgroup (987.5 ± 393.8 vs. 567.7 ± 302.2, p = 0.005). Regarding 3D dose analysis, the mean dose administered to the treated lesions was significantly higher in the b-SIRT than in the SIRT group (151.6 Gy ± 53.2 vs. 100.1 Gy ± 43.4, p = 0.01). In histological explanted liver analysis, there was a trend for higher intra-tumoral localization of embolic microspheres for b-DEB-TACE in comparison with DEB-TACE. CONCLUSIONS Due to the use of three different methods, the results of this study demonstrate in vivo, a better embolization profile of oncological intra-arterial interventions performed with balloon micro-catheter regardless of the embolic agent employed.
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Wang C, Jung H, Yang M, Shen C, Jia X. Simultaneous Image Reconstruction and Element Decomposition for Iodine Contrast Agent Visualization in Multienergy Element-Resolved Cone Beam CT. Front Oncol 2022; 12:827136. [PMID: 35178351 PMCID: PMC8843938 DOI: 10.3389/fonc.2022.827136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/10/2022] [Indexed: 12/04/2022] Open
Abstract
Iodine contrast agent is widely used in liver cancer radiotherapy at CT simulation stage to enhance detectability of tumor. However, its application in cone beam CT (CBCT) for image guidance before treatment delivery is still limited because of poor image quality and excessive dose of contrast agent during multiple treatment fractions. We previously developed a multienergy element-resolved (MEER) CBCT framework that included x-ray projection data acquisition on a conventional CBCT platform in a kVp-switching model and a dictionary-based image reconstruction algorithm that simultaneously reconstructed x-ray attenuation images at each kilovoltage peak (kVp), an electron density image, and elemental composition images. In this study, we investigated feasibility using MEER-CBCT for low-concentration iodine contrast agent visualization. We performed simulation and experimental studies using a phantom with inserts containing water and different concentrations of iodine solution and the MEER-CBCT scan with 600 projections in a full gantry rotation, in which the kVp level sequentially changed among 80, 100, and 120 kVps. We included iodine material in the dictionary of the reconstruction algorithm. We analyzed iodine detectability as quantified by contrast-to-noise ratio (CNR) and compared results with those of CBCT images reconstructed by the standard filter back projection (FBP) method with 600 projections. MEER-CBCT achieved similar contrast enhancement as FBP method but significantly higher CNR. At 2.5% iodine solution concentration, FBP method achieved 170 HU enhancement and CNR of 2.0, considered the standard CNR for successful tumor visualization. MEER-CBCT achieved the same CNR but at ~6.3 times lower iodine concentration of 0.4%.
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Affiliation(s)
- Chao Wang
- Innovative Technology of Radiotherapy Computation and Hardware (iTORCH) Laboratory, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Hyunuk Jung
- Innovative Technology of Radiotherapy Computation and Hardware (iTORCH) Laboratory, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Ming Yang
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Chenyang Shen
- Innovative Technology of Radiotherapy Computation and Hardware (iTORCH) Laboratory, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Xun Jia
- Innovative Technology of Radiotherapy Computation and Hardware (iTORCH) Laboratory, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States
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Sun J, Li H, Li H, Li M, Gao Y, Zhou Z, Peng Y. Application of deep learning image reconstruction algorithm to improve image quality in CT angiography of children with Takayasu arteritis. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2022; 30:177-184. [PMID: 34806646 DOI: 10.3233/xst-211033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
BACKGROUND The inflammatory indexes of children with Takayasu arteritis (TAK) usually tend to be normal immediately after treatment, therefore, CT angiography (CTA) has become an important method to evaluate the status of TAK and sometime is even more sensitive than laboratory test results. OBJECTIVE To evaluate image quality improvement in CTA of children diagnosed with TAK using a deep learning image reconstruction (DLIR) in comparison to other image reconstruction algorithms. METHODS hirty-two TAK patients (9.14±4.51 years old) underwent neck, chest and abdominal CTA using 100 kVp were enrolled. Images were reconstructed at 0.625 mm slice thickness using Filtered Back-Projection (FBP), 50%adaptive statistical iterative reconstruction-V (ASIR-V), 100%ASIR-V and DLIR with high setting (DLIR-H). CT number and standard deviation (SD) of the descending aorta and back muscle were measured and contrast-to-noise ratio (CNR) for aorta was calculated. The vessel visualization, overall image noise and diagnostic confidence were evaluated using a 5-point scale (5, excellent; 3, acceptable) by 2 observers. RESULTS There was no significant difference in CT number across images reconstructed using different algorithms. Image noise values (in HU) were 31.36±6.01, 24.96±4.69, 18.46±3.91 and 15.58±3.65, and CNR values for aorta were 11.93±2.12, 15.66±2.37, 22.54±3.34 and 24.02±4.55 using FBP, 50%ASIR-V, 100%ASIR-V and DLIR-H, respectively. The 100%ASIR-V and DLIR-H images had similar noise and CNR (all P > 0.05), and both had lower noise and higher CNR than FBP and 50%ASIR-V images (all P < 0.05). The subjective evaluation suggested that all images were diagnostic for large arteries, however, only 50%ASIR-V and DLIR-H met the diagnostic requirement for small arteries (3.03±0.18 and 3.53±0.51). CONCLUSION DLIR-H improves CTA image quality and diagnostic confidence for TAK patients compared with 50%ASIR-V, and best balances image noise and spatial resolution compared with 100%ASIR-V.
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Affiliation(s)
- Jihang Sun
- Department of Radiology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Haoyan Li
- Department of Radiology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Haiyun Li
- School of Biomedical Engineering, Capital Medical University, Fengtai District, Beijing, China
| | - Michelle Li
- Department of Human Biology, Stanford University, Stanford, CA, USA
| | - Yingzi Gao
- Department of Radiology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Zuofu Zhou
- Department of Radiology, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, Gulou District, Fujian, China
| | - Yun Peng
- Department of Radiology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
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Yoo J, Lee JM, Yoon JH, Joo I, Lee ES, Jeon SK, Jang S. Comparison of low kVp CT and dual-energy CT for the evaluation of hypervascular hepatocellular carcinoma. Abdom Radiol (NY) 2021; 46:3217-3226. [PMID: 33713160 DOI: 10.1007/s00261-020-02888-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 11/25/2020] [Accepted: 11/27/2020] [Indexed: 01/19/2023]
Abstract
PURPOSE To compare lesion conspicuity and image quality of arterial phase images obtained from low kVp (90-kVp) and dual-energy (DE) scans for the evaluation of hypervascular hepatocellular carcinoma (HCC). METHODS This retrospective study included 229 patients with HCC who underwent either 90 kVp (n = 106) or DE scan (80- and 150-kVp with a tin filter) (n = 123) during the arterial phase. DE scans were reconstructed into a linearly blended image with a mixed ratio of 0.6 (60% 80kVp and 40% 150 kVp) and post-processed for 40 keV and 50 keV images. The contrast-to-noise ratio (CNR) of HCC to the liver and image noise was measured. Lesion conspicuity, liver parenchymal image quality, and overall image preference were assessed qualitatively by three independent radiologists. RESULTS DE 40 keV images had the highest CNR of HCC, and DE blended images had the lowest image noise among four image sets (p = 0.01 and p < 0.001, respectively). There was no significant difference in mean volume CT dose index and dose-length product between DE and low kVp scan (ps > 0.05). For qualitative analyses, DE blended images had the highest scores for image quality and overall image preference (ps < 0.001). CONCLUSION At an equal radiation dose, DE 40 keV showed higher CNR of HCC and DE blended image showed higher image quality and image preference compared with low kVp CT.
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Affiliation(s)
- Jeongin Yoo
- Department of Radiology, Seoul National University Hospital, Seoul, Korea
| | - Jeong Min Lee
- Department of Radiology, Seoul National University Hospital, Seoul, Korea.
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.
- Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, Daehak-ro 101, Jongno-gu, Seoul, 03080, Korea.
| | - Jeong Hee Yoon
- Department of Radiology, Seoul National University Hospital, Seoul, Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea
| | - Ijin Joo
- Department of Radiology, Seoul National University Hospital, Seoul, Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea
| | - Eun Sun Lee
- Department of Radiology, Chung-Ang University Hospital, Seoul, Korea
| | - Sun Kyung Jeon
- Department of Radiology, Seoul National University Hospital, Seoul, Korea
| | - Siwon Jang
- Department of Radiology, Seoul National University Boramae Hospital, Seoul, Korea
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Sun J, Li H, Gao J, Li J, Li M, Zhou Z, Peng Y. Performance evaluation of a deep learning image reconstruction (DLIR) algorithm in "double low" chest CTA in children: a feasibility study. Radiol Med 2021; 126:1181-1188. [PMID: 34132926 DOI: 10.1007/s11547-021-01384-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/08/2021] [Indexed: 01/06/2023]
Abstract
BACKGROUND Chest CT angiography (CTA) is a convenient clinical examination for children with an increasing need to reduce both radiation and contrast medium doses. Iterative Reconstruction algorithms are often used to reduce image noise but encounter limitations under low radiation dose and conventional 100 kVp tube voltage may not provide adequate enhancement under low contrast dose. PURPOSE To evaluate the performance of a deep learning image reconstruction (DLIR) algorithm in conjunction with lower tube voltage in chest CTA in children under reduced radiation and contrast medium (CM) dose. MATERIALS AND METHODS 46 Children (age 5.9 ± 4.2 years) in the study group underwent chest CTA with 70 kVp and CM dose of 0.8-1.2 ml/kg. Images were reconstructed at 0.625 mm using a high setting DLIR (DLIR-H). The control group consisted of 46 age-matching children scanned with 100 kVp, CM dose of 1.3-1.8 ml/kg and images reconstructed with 50% and 100% adaptive statistical iterative reconstruction-V. Two radiologists evaluated images subjectively for overall image noise, vessel contrast and vessel margin clarity separately on a 5-point scale (5, excellent and 1, not acceptable). CT value and image noise of aorta and erector spinae muscle were measured. RESULTS Compared to the control group, the study group reduced the dose-length-product by 11.2% (p = 0.01) and CM dose by 24% (p < 0.001), improved the enhancement in aorta (416.5 ± 113.1HU vs. 342.0 ± 57.6HU, p < 0.001) and reduced noise (15.1 ± 3.5HU vs. 18.6 ± 4.4HU, p < 0.001). The DLIR-H images provided acceptable scores on all 3 aspects of the qualitative evaluation. CONCLUSION "Double low" chest CTA in children using 70 kVp and DLIR provides high image quality with reduced noise and improved vessel enhancement for diagnosis while further reduces radiation and CM dose.
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Affiliation(s)
- Jihang Sun
- Imaging Center, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, No. 56, Nanlishi Road, Xicheng District, Beijing, 100045, China
| | - Haoyan Li
- Imaging Center, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, No. 56, Nanlishi Road, Xicheng District, Beijing, 100045, China
| | - Jun Gao
- Imaging Center, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, No. 56, Nanlishi Road, Xicheng District, Beijing, 100045, China
| | | | | | - Zuofu Zhou
- Department of Radiology, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, No. 18 Daoshan Road, Gulou District, Fujian, 350000, China
| | - Yun Peng
- Imaging Center, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, No. 56, Nanlishi Road, Xicheng District, Beijing, 100045, China.
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A Universal Protocol for Abdominal CT Examinations Performed on a Photon-Counting Detector CT System: A Feasibility Study. Invest Radiol 2020; 55:226-232. [PMID: 32049691 DOI: 10.1097/rli.0000000000000634] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The aims of this study were to investigate the feasibility of using a universal abdominal acquisition protocol on a photon-counting detector computed tomography (PCD-CT) system and to compare its performance to that of single-energy (SE) and dual-energy (DE) CT using energy-integrating detectors (EIDs). METHODS Iodine inserts of various concentrations and sizes were embedded into different sizes of adult abdominal phantoms. Phantoms were scanned on a research PCD-CT and a clinical EID-CT with SE and DE modes. Virtual monoenergetic images (VMIs) were generated from PCD-CT and DE mode of EID-CT. For each image type and phantom size, contrast-to-noise ratio (CNR) was measured for each iodine insert and the area under the receiver operating characteristic curve (AUC) for iodine detectability was calculated using a channelized Hotelling observer. The optimal energy (in kiloelectrovolt) of VMIs was determined separately as the one with highest CNR and the one with the highest AUC. The PCD-CT VMIs at the optimal energy were then compared with DE VMIs and SE images in terms of CNR and AUC. RESULTS Virtual monoenergetic image at 50 keV had both the highest CNR and highest AUC for PCD-CT and DECT. For 1.0 mg I/mL iodine and 35 cm phantom, the CNRs of 50 keV VMIs from PCD-CT (2.01 ± 0.67) and DE (1.96 ± 0.52) were significantly higher (P < 0.001, Wilcoxon signed-rank test) than SE images (1.11 ± 0.35). The AUC of PCD-CT (0.98 ± 0.01) was comparable to SE (0.98 ± 0.01), and both were slightly lower than DE (0.99 ± 0.01, P < 0.01, Wilcoxon signed-rank test). A similar trend was observed for other phantom sizes and iodine concentrations. CONCLUSIONS Virtual monoenergetic images at a fixed energy from a universal acquisition protocol on PCD-CT demonstrated higher iodine CNR and comparable iodine detectability than SECT images, and similar performance compared with DE VMIs.
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Shaffiq Said Rahmat SM, Abdul Karim MK, Che Isa IN, Abd Rahman MA, Noor NM, Hoong NK. Effect of miscentering and low-dose protocols on contrast resolution in computed tomography head examination. Comput Biol Med 2020; 123:103840. [PMID: 32658782 DOI: 10.1016/j.compbiomed.2020.103840] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/28/2020] [Accepted: 05/28/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Unoptimized protocols, including a miscentered position, might affect the outcome of diagnostic in CT examinations. In this study, we investigate the effects of miscentering position during CT head examination on the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). METHOD We simulate the CT head examination using a water phantom with a standard protocol (120 kVp/180 mAs) and a low dose protocol (100 kVp/142 mAs). The table height was adjusted to simulate miscentering by 5 cm from the isocenter, where the height was miscentered superiorly (MCS) at 109, 114, 119, and 124 cm, and miscentered inferiorly (MCI) at 99, 94, 89, and 84 cm. Seven circular regions of interest were used, with one drawn at the center, four at the peripheral area of the phantom, and two at the background area of the image. RESULTS For the standard protocol, the mean CNR decreased uniformly as table height increased and significantly differed (p < 0.05) at +20 cm for MCS (435.70 ± 9.39) and -20 cm for MCI (438.91 ± 10.94) from the isocenter. Similarly, significant reductions (p < 0.05) were also noted for SNR for MCS (at +20 cm) and MCI (at -20 cm). For the low dose protocol, both CNR and SNR were significantly reduced (p < 0.05) at table heights of +20 and -20 cm from the isocenter. CONCLUSION Miscentering is proven to significantly affect the image quality in both low and standard dose protocols for head CT procedure. This study implies that accurate patient centering is one of the approaches that can improve CT optimization practice.
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Affiliation(s)
- Said Mohd Shaffiq Said Rahmat
- Department of Radiology, National Cancer Institute, 4, Jalan P7, Presint 7, 62250, Putrajaya, Wilayah Persekutuan Putrajaya, Malaysia
| | | | - Iza Nurzawani Che Isa
- Diagnostic Imaging and Radiotherapy Programme, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, 50300, Kuala Lumpur, Wilayah Persekutuan Kuala Lumpur, Malaysia
| | - Mohd Amiruddin Abd Rahman
- Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - Noramaliza Mohd Noor
- Department of Radiology, Faculty of Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - Ng Kwan Hoong
- Department of Biomedical Imaging, Universiti of Malaya Medical Centre, 50603, Kuala Lumpur, Malaysia
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Rampado O, Depaoli A, Marchisio F, Gatti M, Racine D, Ruggeri V, Ruggirello I, Darvizeh F, Fonio P, Ropolo R. Effects of different levels of CT iterative reconstruction on low-contrast detectability and radiation dose in patients of different sizes: an anthropomorphic phantom study. Radiol Med 2020; 126:55-62. [PMID: 32495272 DOI: 10.1007/s11547-020-01228-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 05/12/2020] [Indexed: 01/19/2023]
Abstract
PURPOSE The purpose of this study was to verify the maintenance of low-contrast detectability at different CT dose reduction levels, in patients of different sizes, as a consequence of the application of iterative reconstruction at different strengths combined with tube current modulation. METHODS Anthropomorphic abdominal phantoms of two sizes (small and large) were imaged at a fixed noise with iterative algorithm ASIR-V percentages in the range between 0 and 70% and corresponding dose reductions in the range of 0-83%. A total of 1400 images with and without liver low-contrast simulated lesions were evaluated by five radiologists, using the receiver operating characteristics (ROC) paradigm and evaluating the area under the ROC curve (AUC). The human observer results were then compared with AUC obtained with a channelized Hotelling observer (CHO). CNR values were also calculated. RESULTS For the small phantom, the AUC values lie between 0.90 and 0.93 for human evaluations of images acquired without iterative reconstruction, with 30% ASIR-V and with 50% ASIR-V. The AUC decreased significantly to 0.81 (p = 0.0001) at 70% ASIR-V. The CHO results were in coherence with human observer scores. Also, similar results were observed for the large size phantom. CNR values were stable for the different ASIR-V percentages. CONCLUSIONS The iterative algorithm maintained the low-contrast detectability up to a dose reduction of about 70%, following application of a 50% ASIR-V combined with automatic tube current modulation, regardless of the phantom size. At further dose reductions using greater iterative percentages, a significant decrease in detectability was observed.
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Affiliation(s)
- Osvaldo Rampado
- Medical Physics Unit, S.C. Fisica Sanitaria, A.O.U. Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy.
| | - Alessandro Depaoli
- University Radiodiagnostic Unit, A.O.U. Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy
| | - Filippo Marchisio
- University Radiodiagnostic Unit, A.O.U. Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy
| | - Marco Gatti
- University Radiodiagnostic Unit, A.O.U. Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy
| | - Damien Racine
- Institute of Radiation Physics, Lausanne University Hospital, Rue du Grand-Pré 1, 1007, Lausanne, Switzerland
| | - Valeria Ruggeri
- University Radiodiagnostic Unit, A.O.U. Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy
| | - Irene Ruggirello
- University Radiodiagnostic Unit, A.O.U. Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy
| | - Fatemeh Darvizeh
- University Radiodiagnostic Unit, A.O.U. Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy
| | - Paolo Fonio
- University Radiodiagnostic Unit, A.O.U. Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy
| | - Roberto Ropolo
- Medical Physics Unit, S.C. Fisica Sanitaria, A.O.U. Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy
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Holmquist F, Söderberg M, Nyman U, Fält T, Siemund R, Geijer M. Can iterative reconstruction algorithms replace tube loading compensation in low kVp hepatic CT? Subjective versus objective image quality. Acta Radiol Open 2020; 9:2058460120910575. [PMID: 32206344 PMCID: PMC7076580 DOI: 10.1177/2058460120910575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 02/10/2020] [Indexed: 11/16/2022] Open
Abstract
Background Hepatic computed tomography (CT) with decreased peak kilovoltage (kVp) may be used to reduce contrast medium doses in patients at risk of contrast-induced acute kidney injury (CI-AKI); however, it increases image noise. To preserve image quality, noise has been controlled by X-ray tube loading (mAs) compensation (TLC), i.e. increased mAs. Another option to control image noise would be to use iterative reconstructions (IR) algorithms without TLC (No-TLC). It is unclear whether this may preserve image quality or only reduce image noise. Purpose To evaluate image quality of 80 kVp hepatic CT with TLC and filtered back projection (FBP) compared with 80 kVp with No-TLC and IR algorithms (SAFIRE 3 and 5) in patients with eGFR <45 mL/min. Material and Methods Forty patients (BMI 18–32 kg/m2) were examined with both protocols following injection of 300 mg I/kg. Hepatic attenuation, image noise, enhancement, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and subjective image quality were evaluated for each patient. Results Comparing TLC/FBP with No-TLC/IR-S5, there were no significant differences regarding hepatic attenuation, image noise, enhancement, SNR and CNR: 114 vs. 115 HU, 14 vs. 14 HU, 55 vs. 57 HU, 8.0 vs. 8.4, and 3.8 vs. 4.0 in median, respectively. No-TLC/IR-S3 resulted in higher image noise and lower SNR and CNR than TLC/FBP. Subjective image quality scoring with visual grading showed statistically significantly inferior scores for IR-S5 images. Conclusion CT of 80 kVp to reduce contrast medium dose in patients at risk of CI-AKI combined with IR algorithms with unchanged tube loading to control image noise does not provide sufficient diagnostic quality.
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Affiliation(s)
- Fredrik Holmquist
- Department of Medical Imaging and Physiology, Skåne University Hospital, Lund University, Lund, Sweden
| | - Marcus Söderberg
- Medical Radiation Physics, Department of Translational Medicine, Skåne University Hospital, Lund University, Malmö, Sweden.,Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Malmö, Sweden
| | - Ulf Nyman
- Department of Translational Medicine, Division of Medical Radiology, Skåne University Hospital, Lund University, Malmö, Sweden
| | - Tobias Fält
- Department of Translational Medicine, Division of Medical Radiology, Skåne University Hospital, Lund University, Malmö, Sweden
| | - Roger Siemund
- Department of Medical Imaging and Physiology, Skåne University Hospital, Lund University, Lund, Sweden
| | - Mats Geijer
- Department of Medical Imaging and Physiology, Skåne University Hospital, Lund University, Lund, Sweden.,Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Region Västra Götaland, Sahlgrenska University Hospital, Department of Radiology, Gothenburg, Sweden
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Mohammadinejad P, Ehman EC, Vasconcelos RN, Venkatesh SK, Hough DM, Lowe R, Lee YS, Nehra A, Dirks S, Holmes DR, Carter RE, Schmidt B, Halaweish AF, McCollough CH, Fletcher JG. Prior iterative reconstruction (PIR) to lower radiation dose and preserve radiologist performance for multiphase liver CT: a multi-reader pilot study. Abdom Radiol (NY) 2020; 45:45-54. [PMID: 31705250 DOI: 10.1007/s00261-019-02280-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE Prior iterative reconstruction (PIR) spatially registers CT image data from multiple phases of enhancement to reduce image noise. We evaluated PIR in contrast-enhanced multiphase liver CT. METHODS Patients with archived projection CT data with proven malignant or benign liver lesions, or without lesions, by reference criteria were included. Lower-dose PIR images were reconstructed using validated noise insertion from multiphase CT exams (50% dose in 2 phases, 25% dose in 1 phase). The phase of enhancement most relevant to the diagnostic task was selected for evaluation. Four radiologists reviewed routine-dose and lower-dose PIR images, circumscribing liver lesions and rating confidence for malignancy (0 to 100) and image quality. JAFROC Figures of Merit (FOM) were calculated. RESULTS 31 patients had 60 liver lesions (28 primary hepatic malignancies, 6 hepatic metastases, 26 benign lesions). Pooled JAFROC FOM for malignancy for routine-dose CT was 0.615 (95% CI 0.464, 0.767) compared to 0.662 for PIR (95% CI 0.527, 0.797). The estimated FOM difference between the routine-dose and lower-dose PIR images was + 0.047 (95% CI - 0.023, + 0.116). Pooled sensitivity/specificity for routine-dose images was 70%/68% compared to 73%/66% for lower-dose PIR. Lower-dose PIR had lower diagnostic image quality (mean 3.8 vs. 4.2, p = 0.0009) and sharpness (mean 2.3 vs. 2.0, p = 0.0071). CONCLUSIONS PIR is a promising method to reduce radiation dose for multiphase abdominal CT, preserving observer performance despite small reductions in image quality. Further work is warranted.
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Mileto A, Guimaraes LS, McCollough CH, Fletcher JG, Yu L. State of the Art in Abdominal CT: The Limits of Iterative Reconstruction Algorithms. Radiology 2019; 293:491-503. [DOI: 10.1148/radiol.2019191422] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Achille Mileto
- From the Department of Radiology, University of Washington School of Medicine, Seattle, Wash (A.M.); Joint Department of Medical Imaging, Sinai Health System, University of Toronto, Toronto, Ontario, Canada (L.S.G.); and Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (C.H.M., J.G.F., L.Y.)
| | - Luis S. Guimaraes
- From the Department of Radiology, University of Washington School of Medicine, Seattle, Wash (A.M.); Joint Department of Medical Imaging, Sinai Health System, University of Toronto, Toronto, Ontario, Canada (L.S.G.); and Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (C.H.M., J.G.F., L.Y.)
| | - Cynthia H. McCollough
- From the Department of Radiology, University of Washington School of Medicine, Seattle, Wash (A.M.); Joint Department of Medical Imaging, Sinai Health System, University of Toronto, Toronto, Ontario, Canada (L.S.G.); and Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (C.H.M., J.G.F., L.Y.)
| | - Joel G. Fletcher
- From the Department of Radiology, University of Washington School of Medicine, Seattle, Wash (A.M.); Joint Department of Medical Imaging, Sinai Health System, University of Toronto, Toronto, Ontario, Canada (L.S.G.); and Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (C.H.M., J.G.F., L.Y.)
| | - Lifeng Yu
- From the Department of Radiology, University of Washington School of Medicine, Seattle, Wash (A.M.); Joint Department of Medical Imaging, Sinai Health System, University of Toronto, Toronto, Ontario, Canada (L.S.G.); and Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (C.H.M., J.G.F., L.Y.)
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16
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A systematic review of incubator-based neonatal radiography - What does the evidence say? Radiography (Lond) 2019; 26:167-173. [PMID: 32052784 DOI: 10.1016/j.radi.2019.09.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 09/26/2019] [Accepted: 09/28/2019] [Indexed: 11/20/2022]
Abstract
OBJECTIVES This systematic review aimed to explore the impact of incubator design (canopy, mattress, and mattress support) on neonatal imaging in terms of imaging technique, radiation dose and image quality. KEY FINDINGS A systematic literature review was performed by searching multiple healthcare databases. Following study selection and extraction, 7 articles were deemed eligible and included within the study. Of these 7 studies, six were experimental phantom based with the remaining one being a retrospective analysis. Four studies reported a percentage reduction in beam attenuation for incubator components ranging from 12% to 72% with one other study reporting a reduction but with no numerical data. This wide variation in radiation beam attenuation from the incubator components was correlated with image quality within five studies, two suggesting reduced image quality when using the incubator tray under the mattress support whilst the other three found no significant difference. Although the seven studies reported that incubator components reduced X-ray beam intensity, there was limited evidence on whether this required an increase in exposure factors. Only one study suggested increasing exposure parameters to accommodate for the increase in beam attenuation when using an incubator tray. CONCLUSION The literature clearly demonstrates that with existing incubator designs, there is considerable beam attenuation between placing the image receptor directly behind the neonate as oppose to the incubator tray. However, this radiation beam attenuation is not well correlated to neonatal radiation dose or image quality effects and therefore is very confusing when considering clinical implementation. IMPLICATIONS FOR PRACTICE This review highlights the need for standardisation and further optimisation work to ensure best practice for this vulnerable patient group.
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Zhou W, Michalak G, Weaver J, Ferrero A, Gong H, Fetterly KA, McCollough CH, Leng S. Determination of iodine detectability in different types of multiple-energy images for a photon-counting detector computed tomography system. J Med Imaging (Bellingham) 2019; 6:043501. [PMID: 31620546 DOI: 10.1117/1.jmi.6.4.043501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 09/16/2019] [Indexed: 11/14/2022] Open
Abstract
In addition to low-energy-threshold images (TLIs), photon-counting detector (PCD) computed tomography (CT) can generate virtual monoenergetic images (VMIs) and iodine maps. Our study sought to determine the image type that maximizes iodine detectability. Adult abdominal phantoms with iodine inserts of various concentrations and lesion sizes were scanned on a PCD-CT system. TLIs, VMIs at 50 keV, and iodine maps were generated, and iodine contrast-to-noise ratio (CNR) was measured. A channelized Hotelling observer was used to determine the area under the receiver-operating-characteristic curve (AUC) for iodine detectability. Iodine map CNR ( 0.57 ± 0.42 ) was significantly higher ( P < 0.05 ) than for TLIs ( 0.46 ± 0.26 ) and lower ( P < 0.001 ) than for VMIs at 50 keV ( 0.74 ± 0.33 ) for 0.5 mgI/cc and a 35-cm phantom. For the same condition and an 8-mm lesion, iodine detectability from iodine maps ( AUC = 0.95 ± 0.01 ) was significantly lower ( P < 0.001 ) than both TLIs ( AUC = 0.99 ± 0.00 ) and VMIs ( AUC = 0.99 ± 0.01 ). VMIs at 50 keV had similar detectability to TLIs and both outperformed iodine maps. The lowest detectable iodine concentration was 0.5 mgI/cc for an 8-mm lesion and 1.0 mgI/cc for a 4-mm lesion.
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Affiliation(s)
- Wei Zhou
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Gregory Michalak
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Jayse Weaver
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Andrea Ferrero
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Hao Gong
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Kenneth A Fetterly
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States.,Mayo Clinic, Department of Cardiovascular Medicine, Rochester, Minnesota, United States
| | | | - Shuai Leng
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
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18
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Aortic CT angiography using the double region of interest timing bolus technique: feasibility of 80 kVp scanning in lean patients. Int J Cardiovasc Imaging 2019; 35:2113-2121. [DOI: 10.1007/s10554-019-01660-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 06/26/2019] [Indexed: 12/27/2022]
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19
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Simulated Dose Reduction for Abdominal CT With Filtered Back Projection Technique: Effect on Liver Lesion Detection and Characterization. AJR Am J Roentgenol 2019; 212:84-93. [DOI: 10.2214/ajr.17.19441] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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20
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Fletcher JG, Fidler JL, Venkatesh SK, Hough DM, Takahashi N, Yu L, Johnson M, Leng S, Holmes DR, Carter R, McCollough CH. Observer Performance with Varying Radiation Dose and Reconstruction Methods for Detection of Hepatic Metastases. Radiology 2018; 289:455-464. [PMID: 30204077 DOI: 10.1148/radiol.2018180125] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Purpose To estimate the ability of lower dose levels and iterative reconstruction (IR) to display hepatic metastases that can be detected by radiologists. Materials and Methods Projection data from 83 contrast agent-enhanced CT examinations were collected. Metastases were defined by histopathologic analysis or progression and regression. Lower radiation dose configurations were reconstructed at five dose levels with filtered back projection (FBP) and IR (automatic exposure control settings: 80, 100, 120, 160, and 200 quality reference mAs [QRM]). Three abdominal radiologists circumscribed metastases, indicating confidence (confidence range, 0-100) and image quality. Noninferiority was assessed by using jackknife alternative free-response receiver operating characteristic (JAFROC) analysis (noninferiority limit, -0.10) and reader agreement rules, which required identification of metastases identified at routine dose, and no nonlesion localizations in patients negative for metastases, in 71 or more patient CT examinations (of 83), for each configuration. Results There were 123 hepatic metastases (mean size, 1.4 cm; median volume CT dose index and size-specific dose estimate, 11.0 and 13.4 mGy, respectively). By using JAFROC figure of merit, 100 QRM FBP did not meet noninferiority criteria and had estimated performance difference from routine dose of -0.08 (95% confidence interval: -0.11, -0.04). Preset reader agreement rules were not met for 100 QRM IR or 80 QRM IR, but were met for doses 120 QRM or higher (ie, size-specific dose estimate ≥ 8.0 mGy). IR improved image quality (P < .05) but not reader performance. Other than 160 QRM IR, lower dose levels were associated with reduced confidence in metastasis detection (P < .001). Conclusion For detection of hepatic metastases by using contrast-enhanced CT, dose levels that corresponded to 120 quality reference mAs (size-specific dose estimate, 8.0 mGy) and higher performed similarly to 200 quality reference mAs with filtered back projection. © RSNA, 2018 Online supplemental material is available for this article.
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Affiliation(s)
- Joel G Fletcher
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - Jeff L Fidler
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - Sudhakar K Venkatesh
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - David M Hough
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - Naoki Takahashi
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - Lifeng Yu
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - Matthew Johnson
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - Shuai Leng
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - David R Holmes
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - Rickey Carter
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - Cynthia H McCollough
- From the Departments of Radiology (J.G.F., J.L.F., S.K.V., D.M.H., N.T., L.Y., S.L., C.H.M.), Health Sciences Research (M.J., R.C.), and Physiology and Biomedical Research (D.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905
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Nagayama Y, Oda S, Nakaura T, Tsuji A, Urata J, Furusawa M, Utsunomiya D, Funama Y, Kidoh M, Yamashita Y. Radiation Dose Reduction at Pediatric CT: Use of Low Tube Voltage and Iterative Reconstruction. Radiographics 2018; 38:1421-1440. [DOI: 10.1148/rg.2018180041] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Yasunori Nagayama
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Seitaro Oda
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Takeshi Nakaura
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Akinori Tsuji
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Joji Urata
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Mitsuhiro Furusawa
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Daisuke Utsunomiya
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Yoshinori Funama
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Masafumi Kidoh
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Yasuyuki Yamashita
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
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Mileto A, Zamora DA, Alessio AM, Pereira C, Liu J, Bhargava P, Carnell J, Cowan SM, Dighe MK, Gunn ML, Kim S, Kolokythas O, Lee JH, Maki JH, Moshiri M, Nasrullah A, O'Malley RB, Schmiedl UP, Soloff EV, Toia GV, Wang CL, Kanal KM. CT Detectability of Small Low-Contrast Hypoattenuating Focal Lesions: Iterative Reconstructions versus Filtered Back Projection. Radiology 2018; 289:443-454. [PMID: 30015591 DOI: 10.1148/radiol.2018180137] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Purpose To investigate performance in detectability of small (≤1 cm) low-contrast hypoattenuating focal lesions by using filtered back projection (FBP) and iterative reconstruction (IR) algorithms from two major CT vendors across a range of 11 radiation exposures. Materials and Methods A low-contrast detectability phantom consisting of 21 low-contrast hypoattenuating focal objects (seven sizes between 2.4 and 10.0 mm, three contrast levels) embedded into a liver-equivalent background was scanned at 11 radiation exposures (volume CT dose index range, 0.5-18.0 mGy; size-specific dose estimate [SSDE] range, 0.8-30.6 mGy) with four high-end CT platforms. Data sets were reconstructed by using FBP and varied strengths of image-based, model-based, and hybrid IRs. Sixteen observers evaluated all data sets for lesion detectability by using a two-alternative-forced-choice (2AFC) paradigm. Diagnostic performances were evaluated by calculating area under the receiver operating characteristic curve (AUC) and by performing noninferiority analyses. Results At benchmark exposure, FBP yielded a mean AUC of 0.79 ± 0.09 (standard deviation) across all platforms which, on average, was approximately 2% lower than that observed with the different IR algorithms, which showed an average AUC of 0.81 ± 0.09 (P = .12). Radiation decreases of 30%, 50%, and 80% resulted in similar declines of observer detectability with FBP (mean AUC decrease, -0.02 ± 0.05, -0.03 ± 0.05, and -0.05 ± 0.05, respectively) and all IR methods investigated (mean AUC decrease, -0.00 ± 0.05, -0.04 ± 0.05, and -0.04 ± 0.05, respectively). For each radiation level and CT platform, variance in performance across observers was greater than that across reconstruction algorithms (P = .03). Conclusion Iterative reconstruction algorithms have limited radiation optimization potential in detectability of small low-contrast hypoattenuating focal lesions. This task may be further complicated by a high degree of variation in radiologists' performances, seemingly exceeding real performance differences among reconstruction algorithms. © RSNA, 2018 Online supplemental material is available for this article.
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Affiliation(s)
- Achille Mileto
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - David A Zamora
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Adam M Alessio
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Carina Pereira
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Jin Liu
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Puneet Bhargava
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Jonathan Carnell
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Sophie M Cowan
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Manjiri K Dighe
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Martin L Gunn
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Sooah Kim
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Orpheus Kolokythas
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Jean H Lee
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Jeffrey H Maki
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Mariam Moshiri
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Ayesha Nasrullah
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Ryan B O'Malley
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Udo P Schmiedl
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Erik V Soloff
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Giuseppe V Toia
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Carolyn L Wang
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
| | - Kalpana M Kanal
- From the Departments of Radiology (A.M., D.A.Z., A.M.A., P.B., J.C., S.M.C., M.K.D., M.L.G., S.K., O.K., J.H.L., M.M., A.N., R.B.O., U.P.S., E.V.S., G.V.T., C.L.W., K.M.K.) and Bioengineering (C.P., J.L.), University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195; and Department of Radiology, University of Colorado-Denver, Aurora, Colo (J.H.M.)
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23
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Hammond E, Chan KS, Ames JC, Stoyles N, Sloan CM, Guo J, Newell JD, Hoffman EA, Sieren JC. Impact of advanced detector technology and iterative reconstruction on low-dose quantitative assessment of lung computed tomography density in a biological lung model. Med Phys 2018; 45:10.1002/mp.13057. [PMID: 29926932 PMCID: PMC6309498 DOI: 10.1002/mp.13057] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 06/13/2018] [Accepted: 06/13/2018] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Quantitative computed tomography (QCT)-derived measures of lung density are valued methods for objectively characterizing lung parenchymal and peripheral airways disease and are being used in a growing number of lung disease focused trials. Detector and reconstruction improvements in CT technology have allowed for significant radiation dose reduction in image acquisition with comparable qualitative image quality. We report the impact of detector type and reconstruction type on QCT lung density measures in relation to decreasing dose indices. METHODS Two sets of studies were completed in an in vivo pig model with a SOMATOM Definition Flash CT system: (a) prior to system upgrade with conventional detectors (UFC) and filtered back projection (FBP), and (b) post system upgrade with integrated electronic detectors (STELLAR) and iterative reconstruction (SAFIRE). CT data were acquired across estimated CT volume dose indices (CTDIvol ) ranging from 0.75 to 15 mGy at both inspiratory and expiratory breath holds. Semiautomated lung segmentations allowed calculation of histogram median, kurtosis, and 15th percentile. Percentage of voxels below -910 HU and -950 HU (inspiratory), and -856 HU (expiratory) were also examined. The changes in these QCT metrics from dose reduction (15 mGy down to 0.75 mGy) were calculated relative to paired reference values (15 mGy). Results were compared based on detector and reconstruction type. RESULTS In this study, STELLAR detectors improved concordance with 15 mGy values down to 3 mGy for inspiratory scans and 6 mGy for expiratory scans. The addition of SAFIRE reconstruction in all acquired measurements resulted in minimal deviation from reference values at 0.75 mGy. CONCLUSION The use of STELLAR integrated electronic detectors and SAFIRE iterative reconstruction may allow for comparable lung density measures with CT dose indices down to 0.75 mGy.
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Affiliation(s)
- E. Hammond
- Department of Radiology, University of Iowa, Iowa City, IA, 52242, USA
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA
| | - K. S. Chan
- Statistics and Actuarial Science, University of Iowa, Iowa City, IA, 52242, USA
| | - J. C. Ames
- Department of Radiology, University of Iowa, Iowa City, IA, 52242, USA
| | - N. Stoyles
- Department of Radiology, University of Iowa, Iowa City, IA, 52242, USA
| | - C. M. Sloan
- Department of Radiology, University of Iowa, Iowa City, IA, 52242, USA
| | - J. Guo
- Department of Radiology, University of Iowa, Iowa City, IA, 52242, USA
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA
| | - J. D. Newell
- Department of Radiology, University of Iowa, Iowa City, IA, 52242, USA
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA
| | - E. A. Hoffman
- Department of Radiology, University of Iowa, Iowa City, IA, 52242, USA
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA
| | - J. C. Sieren
- Department of Radiology, University of Iowa, Iowa City, IA, 52242, USA
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA
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Effects of various generations of iterative CT reconstruction algorithms on low-contrast detectability as a function of the effective abdominal diameter: A quantitative task-based phantom study. Phys Med 2018; 48:111-118. [DOI: 10.1016/j.ejmp.2018.04.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 04/05/2018] [Accepted: 04/07/2018] [Indexed: 11/24/2022] Open
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Jensen K, Andersen HK, Smedby Ö, Østerås BH, Aarsnes A, Tingberg A, Fosse E, Martinsen AC. Quantitative Measurements Versus Receiver Operating Characteristics and Visual Grading Regression in CT Images Reconstructed with Iterative Reconstruction: A Phantom Study. Acad Radiol 2018; 25:509-518. [PMID: 29198945 DOI: 10.1016/j.acra.2017.10.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/16/2017] [Accepted: 10/26/2017] [Indexed: 01/11/2023]
Abstract
RATIONALE AND OBJECTIVES This study aimed to evaluate the correlation of quantitative measurements with visual grading regression (VGR) and receiver operating characteristics (ROC) analysis in computed tomography (CT) images reconstructed with iterative reconstruction. MATERIALS AND METHODS CT scans on a liver phantom were performed on CT scanners from GE, Philips, and Toshiba at three dose levels. Images were reconstructed with filtered back projection (FBP) and hybrid iterative techniques (ASiR, iDose, and AIDR 3D of different strengths). Images were visually assessed by five readers using a four- and five-grade ordinal scale for liver low contrast lesions and for 10 image quality criteria. The results were analyzed with ROC and VGR. Standard deviation, signal-to-noise ratios, and contrast-to-noise ratios were measured in the images. RESULTS All data were compared to FBP. The results of the quantitative measurements were improved for all algorithms. ROC analysis showed improved lesion detection with ASiR and AIDR and decreased lesion detection with iDose. VGR found improved noise properties for all algorithms, increased sharpness with iDose and AIDR, and decreased artifacts from the spine with AIDR, whereas iDose increased the artifacts from the spine. The contrast in the spine decreased with ASiR and iDose. CONCLUSIONS Improved quantitative measurements in images reconstructed with iterative reconstruction compared to FBP are not equivalent to improved diagnostic image accuracy.
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Nagayama Y, Tanoue S, Tsuji A, Urata J, Furusawa M, Oda S, Nakaura T, Utsunomiya D, Yoshida E, Yoshida M, Kidoh M, Tateishi M, Yamashita Y. Application of 80-kVp scan and raw data-based iterative reconstruction for reduced iodine load abdominal-pelvic CT in patients at risk of contrast-induced nephropathy referred for oncological assessment: effects on radiation dose, image quality and renal function. Br J Radiol 2018; 91:20170632. [PMID: 29470108 DOI: 10.1259/bjr.20170632] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVE To evaluate the image quality, radiation dose, and renal safety of contrast medium (CM)-reduced abdominal-pelvic CT combining 80-kVp and sinogram-affirmed iterative reconstruction (SAFIRE) in patients with renal dysfunction for oncological assessment. METHODS We included 45 patients with renal dysfunction (estimated glomerular filtration rate <45 ml per min per 1.73 m2) who underwent reduced-CM abdominal-pelvic CT (360 mgI kg-1, 80-kVp, SAFIRE) for oncological assessment. Another 45 patients without renal dysfunction (estimated glomerular filtration rate >60 ml per lmin per 1.73 m2) who underwent standard oncological abdominal-pelvic CT (600 mgI kg-1, 120-kVp, filtered-back projection) were included as controls. CT attenuation, image noise, and contrast-to-noise ratio (CNR) were compared. Two observers performed subjective image analysis on a 4-point scale. Size-specific dose estimate and renal function 1-3 months after CT were measured. RESULTS The size-specific dose estimate and iodine load of 80-kVp protocol were 32 and 41%,, respectively, lower than of 120-kVp protocol (p < 0.01). CT attenuation and contrast-to-noise ratio of parenchymal organs and vessels in 80-kVp images were significantly better than those of 120-kVp images (p < 0.05). There were no significant differences in quantitative or qualitative image noise or subjective overall quality (p > 0.05). No significant kidney injury associated with CM administration was observed. CONCLUSION 80-kVp abdominal-pelvic CT with SAFIRE yields diagnostic image quality in oncology patients with renal dysfunction under substantially reduced iodine and radiation dose without renal safety concerns. Advances in knowledge: Using 80-kVp and SAFIRE allows for 40% iodine load and 32% radiation dose reduction for abdominal-pelvic CT without compromising image quality and renal function in oncology patients at risk of contrast-induced nephropathy.
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Affiliation(s)
- Yasunori Nagayama
- 1 Department of Radiology, Kumamoto City Hospital , Kumamoto , Japan.,2 Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
| | - Shota Tanoue
- 1 Department of Radiology, Kumamoto City Hospital , Kumamoto , Japan.,2 Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
| | - Akinori Tsuji
- 1 Department of Radiology, Kumamoto City Hospital , Kumamoto , Japan
| | - Joji Urata
- 1 Department of Radiology, Kumamoto City Hospital , Kumamoto , Japan
| | | | - Seitaro Oda
- 2 Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
| | - Takeshi Nakaura
- 2 Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
| | - Daisuke Utsunomiya
- 2 Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
| | - Eri Yoshida
- 1 Department of Radiology, Kumamoto City Hospital , Kumamoto , Japan.,2 Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
| | - Morikatsu Yoshida
- 2 Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
| | - Masafumi Kidoh
- 2 Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
| | - Machiko Tateishi
- 1 Department of Radiology, Kumamoto City Hospital , Kumamoto , Japan.,2 Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
| | - Yasuyuki Yamashita
- 2 Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
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Suther KR, Hopp E, Smevik B, Fiane AE, Lindberg HL, Larsen S, de Lange C. Can visual analogue scale be used in radiologic subjective image quality assessment? Pediatr Radiol 2018; 48:1567-1575. [PMID: 29974179 PMCID: PMC6153875 DOI: 10.1007/s00247-018-4187-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 05/14/2018] [Accepted: 06/13/2018] [Indexed: 12/01/2022]
Abstract
BACKGROUND Assessment of qualitative or subjective image quality in radiology is traditionally performed using a fixed-point scale even though reproducibility has proved challenging. OBJECTIVE Image quality of 3-T coronary magnetic resonance (MR) angiography was evaluated using three scoring methods, hypothesizing that a continuous scoring scale like visual analogue scale would improve the assessment. MATERIALS AND METHODS Adolescents corrected for transposition of the great arteries with arterial switch operation, ages 9-15 years (n=12), and healthy, age-matched controls (n=12), were examined with 3-D steady-state free precession magnetic resonance imaging. Image quality of the coronary artery origin was evaluated by using a fixed-point scale (1-4), visual analogue scale of 10 cm and a visual analogue scale with reference points (figurative visual analogue scale). Satisfactory image quality was set to a fixed-point scale 3=visual analogue scale/figurative visual analogue scale 6.6 cm. Statistical analysis was performed using Cohen kappa coefficient and agreement index. RESULTS The mean interobserver scores for the fixed-point scale, visual analogue scale and figurative visual analogue scale were, respectively, in the left main stem 2.8, 5.7, 7.0; left anterior descending artery 2.8, 4.7, 6.6; circumflex artery 2.5, 4.5, 6.2, and right coronary artery 3.2, 6.3, 7.7. Scoring with a fixed-point scale gave an intraobserver κ of 0.52-0.77 while interobserver κ was lacking. For visual analogue scale and figurative visual analogue scale, intraobserver agreement indices were, respectively, 0.08-0.58 and 0.43-0.71 and interobserver agreement indices were up to 0.5 and 0.65, respectively. CONCLUSION Qualitative image quality evaluation with coronary 3-D steady-state free precession MR angiography, using a visual analogue scale with reference points, had better reproducibility compared to a fixed-point scale and visual analogue scale. Image quality, being a continuum, may be better determined by this method.
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Affiliation(s)
- Kathrine Rydén Suther
- Division of Radiology and Nuclear Medicine, Oslo University Hospital, Rikshospitalet, P.O. Box 4950, Nydalen, 0424, Oslo, Norway.
| | - Einar Hopp
- Division of Radiology and Nuclear Medicine, Oslo University Hospital, Rikshospitalet, P.O. Box 4950, Nydalen, 0424, Oslo, Norway
| | - Bjarne Smevik
- Division of Radiology and Nuclear Medicine, Oslo University Hospital, Rikshospitalet, P.O. Box 4950, Nydalen, 0424, Oslo, Norway
| | - Arnt Eltvedt Fiane
- Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Cardiothoracic Surgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Harald Lauritz Lindberg
- Department of Cardiothoracic Surgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Stig Larsen
- Faculty of Veterinary Medicine, Centre for Epidemiology and Biostatistics, Norwegian University of Life Sciences, Oslo, Norway
| | - Charlotte de Lange
- Division of Radiology and Nuclear Medicine, Oslo University Hospital, Rikshospitalet, P.O. Box 4950, Nydalen, 0424, Oslo, Norway
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Choi YJ, Lee JH, Yoon DH, Kim HJ, Seo KJ, Do KH, Baek JH. Effect of an Arm Traction Device on Image Quality and Radiation Exposure during Neck CT: A Prospective Study. AJNR Am J Neuroradiol 2018; 39:151-155. [PMID: 29122761 DOI: 10.3174/ajnr.a5418] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/14/2017] [Indexed: 12/22/2022]
Abstract
BACKGROUND AND PURPOSE The image quality of neck CT is frequently disturbed by streak artifact from the shoulder girdles. Our aim was to determine the effects of an arm traction device on image quality and radiation exposure in neck CT. MATERIALS AND METHODS Patients with lymphoma with complete remission who were scheduled to undergo 2 consecutive follow-up neck CT scans for surveillance within a 1-year interval were enrolled in this prospective study. They underwent 2 consecutive neck CT scans (intervention protocol: patients with an arm traction device; standard protocol: no positioning optimization) on the same CT system. The primary outcome measures were image noise in the lower neck and dose-length product. Secondary outcomes were streak artifacts in the supraclavicular fossa, volume CT dose index, and the extent of the biacromial line shift. RESULTS Seventy-three patients were enrolled and underwent 2 consecutive CT scans with a mean interval of 155 days. In the intervention protocol, a mean noise reduction in the lower neck of 25.2%-28.5% (P < .001) was achieved, and a significant decrease in dose-length product (413 versus 397, P < .001) was observed. The intervention protocol significantly decreased streak artifacts (P < .001) and volume CT dose index (13.9 versus 13.4, P < .001) and could lower the biacromial line an average of 2.1 cm. CONCLUSIONS An arm traction device can improve image quality and reduce radiation exposure during neck CT. The device can be simply applied in cooperative patients with suspected lower neck lesions, and the approach offers distinct advantages over the conventional imaging protocol.
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Affiliation(s)
- Y J Choi
- From the Departments of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., K.J.S., K.-H.D., J.H.B.)
| | - J H Lee
- From the Departments of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., K.J.S., K.-H.D., J.H.B.)
| | | | - H J Kim
- Clinical Epidemiology and Biostatistics (H.J.K.), University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - K J Seo
- From the Departments of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., K.J.S., K.-H.D., J.H.B.)
| | - K-H Do
- From the Departments of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., K.J.S., K.-H.D., J.H.B.)
| | - J H Baek
- From the Departments of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., K.J.S., K.-H.D., J.H.B.)
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29
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Dose Reduction With Dedicated CT Metal Artifact Reduction Algorithm: CT Phantom Study. AJR Am J Roentgenol 2017; 210:593-600. [PMID: 29231758 DOI: 10.2214/ajr.17.18544] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE The objective of this study was to compare reader accuracy detecting lesions near hardware in a CT phantom model at different radiation exposures using an advanced metal artifact reduction (MAR) algorithm and standard filtered back projection (FBP) techniques and to determine if radiation exposure could be decreased using MAR without compromising lesion detectability. MATERIALS AND METHODS A CT phantom manufactured with spherical lesions of various sizes (10-20 mm) and attenuations (20-50 HU) embedded around cobalt-chromium spheres attached to titanium rods, simulating an arthroplasty, was scanned on a single CT scanner (FLASH, Siemens Healthcare) at 140 kVp and 0.6-mm collimation using clinical-dose (300 Quality Reference mAs [Siemens Healthcare]), low-dose (150 Quality Reference mAs), and high-dose (600 Quality Reference mAs) protocols. Images reconstructed with iterative MAR, advanced modeled iterative reconstruction (ADMIRE), and FBP with identical parameters were anonymized and independently reviewed by three radiologists. Accuracies for detecting lesions, measured as AUC, sensitivity, and specificity, were compared. RESULTS Accuracy using MAR was significantly higher than that using FBP at all exposures (p values ranged from < 0.001 to 0.021). Sensitivity was also higher for MAR than for FBP at all exposures. Specificity was very high for both reconstruction techniques at all exposures with no significant differences. Accuracy of low-dose MAR was higher than and not inferior to standard-dose and high-dose FBP. MAR was significantly more sensitive than FBP in detecting smaller lesions (p = 0.021) and lesions near high streak artifact (p < 0.001). CONCLUSION MAR improves reader accuracy to detect lesions near hardware and allows significant reductions in radiation exposure without compromising accuracy compared with FBP in a CT phantom model.
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30
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Nagayama Y, Nakaura T, Oda S, Tsuji A, Urata J, Furusawa M, Tanoue S, Utsunomiya D, Yamashita Y. Value of 100 kVp scan with sinogram-affirmed iterative reconstruction algorithm on a single-source CT system during whole-body CT for radiation and contrast medium dose reduction: an intra-individual feasibility study. Clin Radiol 2017; 73:217.e7-217.e16. [PMID: 29029768 DOI: 10.1016/j.crad.2017.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 07/04/2017] [Accepted: 09/12/2017] [Indexed: 01/28/2023]
Abstract
AIM To perform an intra-individual investigation of the usefulness of a contrast medium (CM) and radiation dose-reduction protocol using single-source computed tomography (CT) combined with 100 kVp and sinogram-affirmed iterative reconstruction (SAFIRE) for whole-body CT (WBCT; chest-abdomen-pelvis CT) in oncology patients. MATERIALS AND METHODS Forty-three oncology patients who had undergone WBCT under both 120 and 100 kVp protocols at different time points (mean interscan intervals: 98 days) were included retrospectively. The CM doses for the 120 and 100 kVp protocols were 600 and 480 mg iodine/kg, respectively; 120 kVp images were reconstructed with filtered back-projection (FBP), whereas 100 kVp images were reconstructed with FBP (100 kVp-F) and the SAFIRE (100 kVp-S). The size-specific dose estimate (SSDE), iodine load and image quality of each protocol were compared. RESULTS The SSDE and iodine load of 100 kVp protocol were 34% and 21%, respectively, lower than of 120 kVp protocol (SSDE: 10.6±1.1 versus 16.1±1.8 mGy; iodine load: 24.8±4versus 31.5±5.5 g iodine, p<0.01). Contrast enhancement, objective image noise, contrast-to-noise-ratio, and visual score of 100 kVp-S were similar to or better than of 120 kVp protocol. CONCLUSION Compared with the 120 kVp protocol, the combined use of 100 kVp and SAFIRE in WBCT for oncology assessment with an SSCT facilitated substantial reduction in the CM and radiation dose while maintaining image quality.
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Affiliation(s)
- Y Nagayama
- Department of Radiology, Kumamoto City Hospital 1-1-60, Koto, Higashi-ku, Kumamoto City, 862-0909, Japan; Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan.
| | - T Nakaura
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan
| | - S Oda
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan
| | - A Tsuji
- Department of Radiology, Kumamoto City Hospital 1-1-60, Koto, Higashi-ku, Kumamoto City, 862-0909, Japan
| | - J Urata
- Department of Radiology, Kumamoto City Hospital 1-1-60, Koto, Higashi-ku, Kumamoto City, 862-0909, Japan
| | - M Furusawa
- Department of Radiology, Kumamoto City Hospital 1-1-60, Koto, Higashi-ku, Kumamoto City, 862-0909, Japan
| | - S Tanoue
- Department of Radiology, Kumamoto City Hospital 1-1-60, Koto, Higashi-ku, Kumamoto City, 862-0909, Japan; Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan
| | - D Utsunomiya
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan
| | - Y Yamashita
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan
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31
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Fletcher JG, Yu L, Fidler JL, Levin DL, DeLone DR, Hough DM, Takahashi N, Venkatesh SK, Sykes AMG, White D, Lindell RM, Kotsenas AL, Campeau NG, Lehman VT, Bartley AC, Leng S, Holmes DR, Toledano AY, Carter RE, McCollough CH. Estimation of Observer Performance for Reduced Radiation Dose Levels in CT: Eliminating Reduced Dose Levels That Are Too Low Is the First Step. Acad Radiol 2017; 24:876-890. [PMID: 28262519 PMCID: PMC6481673 DOI: 10.1016/j.acra.2016.12.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 12/23/2016] [Accepted: 12/26/2016] [Indexed: 12/20/2022]
Abstract
RATIONALE AND OBJECTIVES This study aims to estimate observer performance for a range of dose levels for common computed tomography (CT) examinations (detection of liver metastases or pulmonary nodules, and cause of neurologic deficit) to prioritize noninferior dose levels for further analysis. MATERIALS AND METHODS Using CT data from 131 examinations (abdominal CT, 44; chest CT, 44; head CT, 43), CT images corresponding to 4%-100% of the routine clinical dose were reconstructed with filtered back projection or iterative reconstruction. Radiologists evaluated CT images, marking specified targets, providing confidence scores, and grading image quality. Noninferiority was assessed using reference standards, reader agreement rules, and jackknife alternative free-response receiver operating characteristic figures of merit. Reader agreement required that a majority of readers at lower dose identify target lesions seen by the majority of readers at routine dose. RESULTS Reader agreement identified dose levels lower than 50% and 4% to have inadequate performance for detection of hepatic metastases and pulmonary nodules, respectively, but could not exclude any low dose levels for head CT. Estimated differences in jackknife alternative free-response receiver operating characteristic figures of merit between routine and lower dose configurations found that only the lowest dose configurations tested (ie, 30%, 4%, and 10% of routine dose levels for abdominal, chest, and head CT examinations, respectively) did not meet criteria for noninferiority. At lower doses, subjective image quality declined before observer performance. Iterative reconstruction was only beneficial when filtered back projection did not result in noninferior performance. CONCLUSION Opportunity exists for substantial radiation dose reduction using existing CT technology for common diagnostic tasks.
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Affiliation(s)
- Joel G Fletcher
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905.
| | - Lifeng Yu
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - Jeff L Fidler
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - David L Levin
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - David R DeLone
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - David M Hough
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - Naoki Takahashi
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | | | - Anne-Marie G Sykes
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - Darin White
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - Rebecca M Lindell
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - Amy L Kotsenas
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - Norbert G Campeau
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - Vance T Lehman
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - Adam C Bartley
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Shuai Leng
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
| | - David R Holmes
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | | | - Rickey E Carter
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
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