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McInnes-Dean H, Mellis R, Daniel M, Walton H, Baple EL, Bertoli M, Fisher J, Gajewska-Knapik K, Holder-Espinasse M, Lafarge C, Leeson-Beevers K, McEwan A, Pandya P, Parker M, Peet S, Roberts L, Sankaran S, Smith A, Tapon D, Wu WH, Wynn SL, Chitty LS, Hill M, Peter M. 'Something that helped the whole picture': Experiences of parents offered rapid prenatal exome sequencing in routine clinical care in the English National Health Service. Prenat Diagn 2024; 44:465-479. [PMID: 38441167 DOI: 10.1002/pd.6537] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 01/05/2024] [Accepted: 01/10/2024] [Indexed: 04/11/2024]
Abstract
OBJECTIVES In October 2020, rapid prenatal exome sequencing (pES) was introduced into routine National Health Service (NHS) care in England. This study aimed to explore parent experiences and their information and support needs from the perspective of parents offered pES and of health professionals involved in its delivery. METHODS In this qualitative study, semi-structured interviews were conducted with 42 women and 6 male partners and 63 fetal medicine and genetic health professionals. Interviews were transcribed verbatim and analysed using thematic analysis. RESULTS Overall views about pES were positive and parents were grateful to be offered the test. Highlighted benefits of pES included the value of the additional information for pregnancy management and planning for future pregnancies. An anxious wait for results was common, often associated with the need to make decisions near to 24 weeks in pregnancy when there are legal restrictions for late termination. Descriptions of dealing with uncertainty were also common, even when results had been returned. Many parents described pES results as informing decision-making around whether or not to terminate pregnancy. Some professionals were concerned that a non-informative result could be overly reassuring and highlighted that careful counselling was needed to ensure parents have a good understanding of what the result means for their pregnancy. Emotional support from professionals was valued; however, some parents felt that post-test support was lacking. CONCLUSION Parents and professionals welcomed the introduction of pES. Results inform parents' decision-making around the termination of pregnancy. When there are no diagnostic findings or uncertain findings from pES, personalised counselling that considers scans and other tests are crucial. Directing parents to reliable online sources of information and providing emotional support throughout could improve their experiences of care.
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Affiliation(s)
- Hannah McInnes-Dean
- Antenatal Results and Choices, London, UK
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Rhiannon Mellis
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Morgan Daniel
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Holly Walton
- Department of Applied Health Research, University College London, London, UK
| | - Emma L Baple
- RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon University Healthcare NHS Foundation Trust, Exeter, UK
- Peninsula Clinical Genetics Service, School, Royal Devon University Healthcare NHS Foundation Trust, Exeter, UK
| | | | | | - Katarzyna Gajewska-Knapik
- Department of Obstetrics and Gynaecology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Muriel Holder-Espinasse
- Clinical Genetics Department, Guy's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Caroline Lafarge
- School of Human and Social Sciences, University of West London, London, UK
| | | | - Alec McEwan
- Department of Obstetrics and Gynaecology, Nottingham University Hospitals, Nottingham, UK
| | - Pranav Pandya
- Elizabeth Garrett Anderson Institute for Women's Health, University College London, London, UK
- Fetal Medicine Unit, University College London Hospitals, London, UK
| | - Michael Parker
- The Ethox Centre, Nuffield Department of Population Health and Wellcome Centre for Ethics and Humanities, University of Oxford, Oxford, UK
| | | | | | - Srividhya Sankaran
- School of Life Course and Population Sciences, Kings College London, St Thomas' Hospital, London, UK
- Department of Women and Children Health, Evelina Women & Children's Hospital Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Audrey Smith
- Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester, UK
| | - Dagmar Tapon
- Queen Charlotte's & Chelsea Hospital, Imperial College Healthcare NHS Trust, London, UK
| | - Wing Han Wu
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Sarah L Wynn
- Unique - Rare Chromosome Disorder Support Group, Oxted, UK
| | - Lyn S Chitty
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Melissa Hill
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Michelle Peter
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
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Hill M, Ellard S, Fisher J, Fulop N, Knight M, Kroese M, Ledger J, Leeson-Beevers K, McEwan A, McMullan D, Mellis R, Morris S, Parker M, Tapon D, Baple E, Blackburn L, Choudry A, Lafarge C, McInnes-Dean H, Peter M, Ramakrishnan R, Roberts L, Searle B, Smith E, Walton H, Wynn SL, Han Wu W, Chitty LS. Optimising Exome Prenatal Sequencing Services (EXPRESS): a study protocol to evaluate rapid prenatal exome sequencing in the NHS Genomic Medicine Service. NIHR Open Res 2022; 2:10. [PMID: 35935673 PMCID: PMC7613246 DOI: 10.3310/nihropenres.13247.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 06/28/2022] [Indexed: 11/22/2022]
Abstract
Background Prenatal exome sequencing (ES) for the diagnosis of fetal anomalies was implemented nationally in England in October 2020 by the NHS Genomic Medicine Service (GMS). is the GMS is based around seven regional Genomic Laboratory Hubs (GLHs). Prenatal ES has the potential to significantly improve NHS prenatal diagnostic services by increasing genetic diagnoses and informing prenatal decision-making. Prenatal ES has not previously been offered routinely in a national healthcare system and there are gaps in knowledge and guidance. Methods Our mixed-methods evaluation commenced in October 2020, aligning with the start date of the NHS prenatal ES service . Study design draws on a framework developed in previous studies of major system innovation. There are five interrelated workstreams. Workstream-1 will use interviews and surveys with professionals, non-participant observations and documentary analysis to produce in-depth case studies across all GLHs. Data collection at multiple time points will track changes over time. In Workstream-2 qualitative interviews with parents offered prenatal ES will explore experiences and establish information and support needs. Workstream-3 will analyse data from all prenatal ES tests for nine-months to establish service outcomes (e.g. diagnostic yield, referral rates, referral sources). Comparisons between GLHs will identify factors (individual or service-related) associated with any variation in outcomes. Workstream-4 will identify and analyse practical ethical problems. Requirements for an effective ethics framework for an optimal and equitable service will be determined. Workstream-5 will assess costs and cost-effectiveness of prenatal ES versus standard tests and evaluate costs of implementing an optimal prenatal ES care pathway. Integration of findings will determine key features of an optimal care pathway from a service delivery, parent and professional perspective. Discussion The proposed formative and summative evaluation will inform the evolving prenatal ES service to ensure equity of access, high standards of care and benefits for parents across England.
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Affiliation(s)
- Melissa Hill
- NHS North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Sian Ellard
- Institute of Biomedical and Clinical Science, College of Medicine and Health, University of Exeter, Exeter, UK
- Exeter Genomics Laboratory, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | | | - Naomi Fulop
- Department of Applied Health Research, University College London, London, UK
| | - Marian Knight
- National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK
| | - Mark Kroese
- PHG Foundation, University of Cambridge, Cambridge, UK
| | - Jean Ledger
- Department of Applied Health Research, University College London, London, UK
| | | | - Alec McEwan
- Department of Obstetrics and Gynaecology,, Nottingham University Hospitals NHS Trust, Nottingham, UK
| | - Dominic McMullan
- West Midlands Regional Genetics Service, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Rhiannon Mellis
- NHS North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Stephen Morris
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK
| | - Michael Parker
- The Ethox Centre, Nuffield Department of Population Health and Wellcome Centre for Ethics and Humanities, University of Oxford, Oxford, UK
| | - Dagmar Tapon
- Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, Imperial College Healthcare NHS Trust, London, UK
| | - Emma Baple
- Institute of Biomedical and Clinical Science, College of Medicine and Health, University of Exeter, Exeter, UK
- Peninsula Clinical Genetics Service, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | | | - Asya Choudry
- Manchester University NHS Foundation Trust, Manchester, UK
| | - Caroline Lafarge
- School of Human and Social Sciences, University of West London, London, UK
| | - Hannah McInnes-Dean
- NHS North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
- Antenatal Results and Choices, London, UK
| | - Michelle Peter
- NHS North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Rema Ramakrishnan
- National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK
| | | | - Beverly Searle
- Unique - Rare Chromosome Disorder Support Group, Oxted, UK
| | - Emma Smith
- NHS North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children, London, UK
| | - Holly Walton
- Department of Applied Health Research, University College London, London, UK
| | - Sarah L. Wynn
- Unique - Rare Chromosome Disorder Support Group, Oxted, UK
| | - Wing Han Wu
- NHS North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Lyn S. Chitty
- NHS North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children, London, UK
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
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Balaji P, Toan Tran V, Barry AM, Yang E, Lu J, Bandodkar S, Alvarez S, Ronquillo J, Varikatt W, McEwan A, Thiagalingam A, Thomas P, Qian C. Differential Biophysics of Heating, Efficacy and Durability of Renal Denervation for Microwave and Radiofrequency Ablation. Heart Lung Circ 2022. [DOI: 10.1016/j.hlc.2022.06.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Burne L, Sitaula C, Priyadarshi A, Tracy M, Kavehei O, Hinder M, Withana A, McEwan A, Marzbanrad F. Ensemble Approach on Deep and Handcrafted Features for Neonatal Bowel Sound Detection. IEEE J Biomed Health Inform 2022; PP. [DOI: 10.1109/jbhi.2022.3217559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- L. Burne
- Department of Electrical and Computer Systems Engineering, Monash University, Melbourne, VIC, Australia
| | - C. Sitaula
- Department of Electrical and Computer Systems Engineering, Monash University, Melbourne, VIC, Australia
| | - A. Priyadarshi
- Department of Paediatrics and Child Health, The University of Sydney and Westmead Hospital, Australia
| | - M. Tracy
- Department of Paediatrics and Child Health, The University of Sydney and Westmead Hospital, Australia
| | - O. Kavehei
- School of Biomedical Engineering, The University of Sydney, Australia
| | - M. Hinder
- Department of Paediatrics and Child Health, The University of Sydney and Westmead Hospital, Australia
| | - A. Withana
- School of Computer Science, The University of Sydney, Australia
| | - A. McEwan
- School of Biomedical Engineering, The University of Sydney, Australia
| | - F. Marzbanrad
- Department of Electrical and Computer Systems Engineering, Monash University, Melbourne, VIC, Australia
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Balaji P, Toan TV, Barry A, Yang E, Lu J, Bandodkar S, Alvarez S, Ronquillo J, Varikatt W, McEwan A, Thiagalingam A, P. Thomas S, C. Qian P. Long-Term Safety and Efficacy of Transcatheter Microwave Renal Denervation in an Ovine Model. Heart Lung Circ 2022. [DOI: 10.1016/j.hlc.2022.06.603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Yang E, Tran V, Barry T, McEwan A, Qian P. Monitoring Tissue Temperature Using Antenna Return Loss Spectrum. Heart Lung Circ 2021. [DOI: 10.1016/j.hlc.2021.06.360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Qian P, Barry MA, Lu J, Mina A, Ryan J, Bandodkar S, Alvarez S, James V, Ronquillo J, Varikatt W, Kovoor P, Pouliopoulos J, McEwan A, Thiagalingam A, Thomas S. 1197The development and validation of a novel transcatheter microwave renal denervation system. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz748.0027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Background
Clinical studies of transcatheter radiofrequency renal denervation for treating hypertension have been hampered by the lack of consistent denervation efficacy. Microwave energy is well suited to renal denervation due to its capacity to spare vascular structures due to cooling from adjacent blood flow while enabling deep perivascular heating.
Purpose
We aimed to: 1) develop a transcatheter microwave system capable of safely delivering deep and circumferential perivascular renal nerve ablation, and 2) demonstrate the feasibility, short-term efficacy and safety of transcatheter microwave renal denervation.
Method
A novel 7F transcatheter microwave denervation system was designed, built, and iteratively prototyped in vitro and in 15 sheep. A histological grading system for microwave induced renal arterial and renal nerve injury was devised. The microwave denervation system was validated in an additional 9 sheep, which underwent unilateral renal denervation. Up to 2 microwave ablations were delivered to each artery with maximum power at 100–110W for 480s. Sheep were euthanised at 2–3 weeks post procedure. Gross microscopic histological examination as well as renal tissue norepinephrine content was analysed.
Results
Catheter deployment and ablation was successful in all 19 targeted vessel segments and ablation produced substantial circumferential perivascular injury; median ablation lesion area >395 (IQR 251–437) mm2, depth 17.1 (IQR 15.8–18.4) mm, length 16 (IQR 12–20) mm, without collateral visceral injury. Limiting power to 100W minimised arterial injury, while maintaining a deep circumferential perivascular ablation. At microwave ablation sites, a total of 292 nerve fascicles were identified, median distance from the renal artery of 4.2mm (IQR 2.1–8.8mm), of which 249 (85%) had sustained thermal injury with 128/249 (51%) showing grade 3–4 (moderate to severe) injury. Microwave denervation reduced median functional sympathetic nerve surface area at the renal hilum on anti-tyrosine hydroxylase staining by 100% (IQR 87%-100%), p=0.0039, and median renal cortical norepinephrine content by 83% (IQR 76%–92%), p=0.0078, compared to the paired control kidney.
Conclusion
Transcatheter microwave ablation can produce deep circumferential perivascular ablations over a long segment of the renal artery without significant arterial or collateral visceral injury to provide effective renal denervation. Clinical translation may enable more consistent and complete transcatheter renal denervation and antihypertensive efficacy.
Acknowledgement/Funding
University of Sydney; Western Sydney Local health District; National Health and Medical Research Council of Australia; National Heart Foundation (Au)
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Affiliation(s)
- P Qian
- Westmead Hospital, Sydney, Australia
| | - M A Barry
- Westmead Hospital, Cardiology, Sydney, Australia
| | - J Lu
- Westmead Hospital, Cardiology, Sydney, Australia
| | - A Mina
- Westmead Hospital, Institute of Clinical Pathology and Medical Research, Sydney, Australia
| | - J Ryan
- Westmead Hospital, Institute of Clinical Pathology and Medical Research, Sydney, Australia
| | - S Bandodkar
- The Children's Hospital at Westmead, Biochemistry, Sydney, Australia
| | - S Alvarez
- The Children's Hospital at Westmead, Biochemistry, Sydney, Australia
| | - V James
- Westmead Institute for Medical Research, Histology, Sydney, Australia
| | - J Ronquillo
- Westmead Hospital, Institute of Clinical Pathology and Medical Research, Sydney, Australia
| | - W Varikatt
- Westmead Hospital, Institute of Clinical Pathology and Medical Research, Sydney, Australia
| | - P Kovoor
- Westmead Hospital, Cardiology, Sydney, Australia
| | | | - A McEwan
- Westmead Hospital, Sydney, Australia
| | | | - S Thomas
- Westmead Hospital, Sydney, Australia
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Saravana-Bawan B, Wieler M, McMullen T, McEwan A. Improved quality of life in patients with GEP-NETs treated with 177Lu-dotatate. Ann Oncol 2018. [DOI: 10.1093/annonc/mdy293.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Qian P, Barry M, Lu J, Al-Raisi S, Mina A, Ryan J, Bandodkar S, Alvarez S, James V, Ronquillo J, Varikatt W, Clayton Z, Chong J, Kovoor P, Pouliopoulos J, McEwan A, Thiagalingam A, Thomas S. Development and Validation of a Novel Microwave Transcatheter Renal Denervation System and an Intraprocedural Physiological End Point for Renal Sympathetic Denervation. Heart Lung Circ 2018. [DOI: 10.1016/j.hlc.2018.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Zhu D, Barry MA, Nguyen DM, Qian P, Thiagalingam A, McEwan A. Comparison of internal multi-electrode arrays for electrical impedance tomography. Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/3/1/015007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Chan B, Sim HW, Ravikumar A, Bailey D, Chan D, Lawrence B, McEwan A, Pavlakis N, Segelov E, Singh S, Roach P, Wyld D. 417P Availability and Utility of Functional Imaging (FI) and Peptide Receptor Radionuclide Therapy (PRRT) in the CommNETS Collaboration (Australia, Canada and New Zealand). Ann Oncol 2016. [DOI: 10.1016/s0923-7534(21)00575-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Gargiulo G, Bifulco P, Cesarelli M, McEwan A, OLoughlin A, Tapson J, Thiagalingam A. The Wilson's Central Terminal (WCT): A Systematic Error in ECG Recordings. Heart Lung Circ 2016. [DOI: 10.1016/j.hlc.2016.06.613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Chitty LS, Wright D, Hill M, Verhoef TI, Daley R, Lewis C, Mason S, McKay F, Jenkins L, Howarth A, Cameron L, McEwan A, Fisher J, Kroese M, Morris S. Uptake, outcomes, and costs of implementing non-invasive prenatal testing for Down's syndrome into NHS maternity care: prospective cohort study in eight diverse maternity units. BMJ 2016; 354:i3426. [PMID: 27378786 PMCID: PMC4933930 DOI: 10.1136/bmj.i3426] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To investigate the benefits and costs of implementing non-invasive prenatal testing (NIPT) for Down's syndrome into the NHS maternity care pathway. DESIGN Prospective cohort study. SETTING Eight maternity units across the United Kingdom between 1 November 2013 and 28 February 2015. PARTICIPANTS All pregnant women with a current Down's syndrome risk on screening of at least 1/1000. MAIN OUTCOME MEASURES Outcomes were uptake of NIPT, number of cases of Down's syndrome detected, invasive tests performed, and miscarriages avoided. Pregnancy outcomes and costs associated with implementation of NIPT, compared with current screening, were determined using study data on NIPT uptake and invasive testing in combination with national datasets. RESULTS NIPT was prospectively offered to 3175 pregnant women. In 934 women with a Down's syndrome risk greater than 1/150, 695 (74.4%) chose NIPT, 166 (17.8%) chose invasive testing, and 73 (7.8%) declined further testing. Of 2241 women with risks between 1/151 and 1/1000, 1799 (80.3%) chose NIPT. Of 71 pregnancies with a confirmed diagnosis of Down's syndrome, 13/42 (31%) with the diagnosis after NIPT and 2/29 (7%) after direct invasive testing continued, resulting in 12 live births. In an annual screening population of 698 500, offering NIPT as a contingent test to women with a Down's syndrome screening risk of at least 1/150 would increase detection by 195 (95% uncertainty interval -34 to 480) cases with 3368 (2279 to 4027) fewer invasive tests and 17 (7 to 30) fewer procedure related miscarriages, for a non-significant difference in total costs (£-46 000, £-1 802 000 to £2 661 000). The marginal cost of NIPT testing strategies versus current screening is very sensitive to NIPT costs; at a screening threshold of 1/150, NIPT would be cheaper than current screening if it cost less than £256. Lowering the risk threshold increases the number of Down's syndrome cases detected and overall costs, while maintaining the reduction in invasive tests and procedure related miscarriages. CONCLUSIONS Implementation of NIPT as a contingent test within a public sector Down's syndrome screening programme can improve quality of care, choices for women, and overall performance within the current budget. As some women use NIPT for information only, the Down's syndrome live birth rate may not change significantly. Future research should consider NIPT uptake and informed decision making outside of a research setting.
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Affiliation(s)
- Lyn S Chitty
- Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 3BH, UK Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - David Wright
- Department of Statistics, Plymouth University, Plymouth, UK
| | - Melissa Hill
- Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 3BH, UK
| | - Talitha I Verhoef
- Department of Applied Health Research, University College London, London, UK
| | - Rebecca Daley
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Celine Lewis
- Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 3BH, UK Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Sarah Mason
- North-East Thames Regional Genetics Laboratory, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Fiona McKay
- North-East Thames Regional Genetics Laboratory, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Lucy Jenkins
- North-East Thames Regional Genetics Laboratory, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Abigail Howarth
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | | | - Alec McEwan
- Department of Obstetrics and Gynaecology, Nottingham University Hospitals, Nottingham, UK
| | - Jane Fisher
- Antenatal Results and Choices (ARC), London, UK
| | | | - Stephen Morris
- Department of Applied Health Research, University College London, London, UK
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Nasehi Tehrani J, McEwan A, Wang J. TH-CD-207A-05: Lung Surface Deformation Vector Fields Prediction by Monitoring Respiratory Surrogate Signals. Med Phys 2016. [DOI: 10.1118/1.4958174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Prinable JB, Barry T, McEwan A, Jones P, Carter P. A cortical bone phantom with accurate permittivity at 100 kHz. Biomed Phys Eng Express 2016. [DOI: 10.1088/2057-1976/2/1/015004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Qian P, Barry T, Al-Raisi S, Kovoor P, McEwan A, Thiagalingam A, Thomas S. One-shot circumferential renal artery denervation with relative sparing of the arterial wall may be possible using a novel microwave catheter. Heart Lung Circ 2015. [DOI: 10.1016/j.hlc.2015.06.408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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18
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Gargiulo G, Thiagalingam A, McEwan A, Cesarelli M, Bifulco P, Tapson J, van Schaik A. True Unipolar ECG Leads Recording (Without the Use of WCT). Heart Lung Circ 2013. [DOI: 10.1016/j.hlc.2013.05.243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Nasehi Tehrani J, Oh TI, Jin C, Thiagalingam A, McEwan A. Evaluation of different stimulation and measurement patterns based on internal electrode: application in cardiac impedance tomography. Comput Biol Med 2012; 42:1122-32. [PMID: 23017828 DOI: 10.1016/j.compbiomed.2012.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 09/05/2012] [Accepted: 09/06/2012] [Indexed: 11/16/2022]
Abstract
The conductivity distribution around the thorax is altered during the cardiac cycle due to the blood perfusion, heart contraction and lung inflation. Previous studies showed that these bio-impedance changes are appropriate for non-invasive cardiac function imaging using Electrical Impedance Tomography (EIT) techniques. However, the spatial resolution is presently low. One of the main obstacles in cardiac imaging at the heart location is the large impedance variation of the lungs by respiration and muscles on the dorsal and posterior side of the body. In critical care units there is a potential to insert an internal electrode inside the esophagus directly behind the heart in the same plane of the external electrodes. The aim of the present study is to evaluate different current stimulation and measurement patterns with both external and internal electrodes. Analysis is performed with planar arrangement of 16 electrodes for a simulated 3D cylindrical tank and pig thorax model. In our study we evaluated current injection patterns consisting of adjacent, diagonal, trigonometric, and radial to the internal electrode. The performance of these arrangements was assessed using quantitative methods based on distinguishability, sensitivity and GREIT (Graz consensus Reconstruction algorithm for Electrical Impedance Tomography). Our evaluation shows that an internal electrode configuration based on the trigonometric injection patterns has better performance and improves pixel intensity of the small conductivity changes related to heart near 1.7 times in reconstructed images and also shows more stability with different levels of added noise. For the internal electrode, when we combined radial or adjacent injection with trigonometric injection pattern, we found an improvement in amplitude response. However, the combination of diagonal with trigonometric injection pattern deteriorated the shape deformation (correlation coefficient r=0.344) more than combination of radial and trigonometric injection (correlation coefficient r=0.836) for the perturbations in the area close to the center of the cylinder. We also find that trigonometric stimulation pattern performance is degraded in a realistic thorax model with anatomical asymmetry. For that reason we recommend using internal electrodes only for voltage measurements and as a reference electrode during trigonometric stimulation patterns in practical measurements.
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Affiliation(s)
- J Nasehi Tehrani
- School of Electrical and Information Engineering, CARLAB, The University of Sydney, NSW, Australia.
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Roa WH, Yaremko B, McEwan A, Amanie J, Yee D, Cho J, McQuarrie S, Riauka T, Sloboda R, Wiebe L, Loebenberg R, Janicki C. Dosimetry study of [I-131] and [I-125]- meta-iodobenz guanidine in a simulating model for neuroblastoma metastasis. Technol Cancer Res Treat 2012; 12:79-90. [PMID: 22974332 DOI: 10.7785/tcrt.2012.500301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The physical properties of I-131 may be suboptimal for the delivery of therapeutic radiation to bone marrow metastases, which are common in the natural history of neuroblastoma. In vitro and preliminary clinical studies have implied improved efficacy of I-125 relative to I-131 in certain clinical situations, although areas of uncertainty remain regarding intratumoral dosimetry. This prompted our study using human neuroblastoma multicellular spheroids as a model of metastasis. 3D dose calculations were made using voxel-based Medical Internal Radiation Dosimetry (MIRD) and dose-point-kernel (DPK) techniques. Dose distributions for I-131 and I-125 labeled mIBG were calculated for spheroids (metastases) of various sizes from 0.01 cm to 3 cm diameter, and the relative dose delivered to the tumors was compared for the same limiting dose to the bone marrow. Based on the same data, arguments were advanced based upon the principles of tumor control probability (TCP) to emphasize the potential theoretical utility of I-125 over I-131 in specific clinical situations. I-125-mIBG can deliver a higher and more uniform dose to tumors compared to I-131 mIBG without increasing the dose to the bone marrow. Depending on the tumor size and biological half-life, the relative dose to tumors of less than 1 mm diameter can increase several-fold. TCP calculations indicate that tumor control increases with increasing administered activity, and that I-125 is more effective than I-131 for tumor diameters of 0.01 cm or less. This study suggests that I-125-mIBG is dosimetrically superior to I-131-mIBG therapy for small bone marrow metastases from neuroblastoma. It is logical to consider adding I-125-mIBG to I-131-mIBG in multi-modality therapy as these two isotopes could be complementary in terms of their cumulative dosimetry.
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Affiliation(s)
- W H Roa
- Divisions of Radiation Oncology, University of Alberta/Cross Cancer Institute, Edmonton, Alberta, Canada.
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Abstract
The diagnosis and management of a heterokaryotypic monochorionic pregnancy, in which one of twins had trisomy 13, is presented. Monozygosity and discordant karyotypes were confirmed by amniocentesis of both the sacs. Radiofrequency ablation of the trisomic twin was successfully performed at 18-weeks gestation and the pregnancy ended at term with the birth of a healthy girl who remains well on follow-up at 12 months of age. We reiterate the importance of early amniocentesis of both the sacs in the presence of discordant fetal abnormalities and consideration of selective fetal termination to optimise the outcome of heterokaryotypic monochorionic twin pregnancies.
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Affiliation(s)
- A Dixit
- Department of Clinical Genetics, Nottingham City Hospital, Nottingham, UK
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Packham B, Koo H, Romsauerova A, Ahn S, McEwan A, Jun SC, Holder DS. Comparison of frequency difference reconstruction algorithms for the detection of acute stroke using EIT in a realistic head-shaped tank. Physiol Meas 2012; 33:767-86. [PMID: 22531059 DOI: 10.1088/0967-3334/33/5/767] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Imaging of acute stroke might be possible using multi-frequency electrical impedance tomography (MFEIT) but requires absolute or frequency difference imaging. Simple linear frequency difference reconstruction has been shown to be ineffective in imaging with a frequency-dependant background conductivity; this has been overcome with a weighted frequency difference approach with correction for the background but this has only been validated for a cylindrical and hemispherical tank. The feasibility of MFEIT for imaging of acute stroke in a realistic head geometry was examined by imaging a potato perturbation against a saline background and a carrot-saline frequency-dependant background conductivity, in a head-shaped tank with the UCLH Mk2.5 MFEIT system. Reconstruction was performed with time difference (TD), frequency difference (FD), FD adjacent (FDA), weighted FD (WFD) and weighted FDA (WFDA) linear algorithms. The perturbation in reconstructed images corresponded to the true position to <9.5% of image diameter with an image SNR of >5.4 for all algorithms in saline but only for TD, WFDA and WFD in the carrot-saline background. No reliable imaging was possible with FD and FDA. This indicates that the WFD approach is also effective for a realistic head geometry and supports its use for human imaging in the future.
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Affiliation(s)
- B Packham
- Department of Medical Physics and Bioengineering, UCL, London, UK.
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Khamis H, Mohamed A, Simpson S, McEwan A. Detection of temporal lobe seizures and identification of lateralisation from audified EEG. Clin Neurophysiol 2012; 123:1714-20. [PMID: 22418593 DOI: 10.1016/j.clinph.2012.02.073] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 02/06/2012] [Accepted: 02/17/2012] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To investigate the accuracy of human listeners in identifying epileptic seizures and seizure lateralisation from audified EEG signals. METHODS EEG data from 17 temporal lobe epilepsy patients (9 male, 8 female; aged 23-55) was converted to audio format by 60× time compression. Using a subset of 19% of the data, five auditory participants (2 female, 3 male; aged 23-58) were trained to identify seizures and their lateralisation by listening to audified EEG signals from difference electrodes P3-T5 and P4-T6. Following training, seizure detection performance of the auditory participants was tested using the remaining data. RESULTS Allowing a 5s auditory time margin for successful detection, the mean sensitivity of the five auditory participants was 89.6% (SD 8.3%) with a false detection rate of only 0.0068/h (SD 0.0077/h). The mean accuracy of seizure lateralisation identification was 77.6% (SD 7.1%). CONCLUSIONS With a limited amount of training, humans can detect seizures and seizure lateralisation from audified EEG signals of electrodes P3-T5 and P4-T6 with accuracy comparable to visual assessment of full EEG traces (21 electrodes) by an expert encephalographer. SIGNIFICANCE A more efficient and accurate clinical tool for assessing EEG data based on audification may be developed, which will improve diagnosis and treatment of epilepsy.
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Affiliation(s)
- H Khamis
- Comprehensive Epilepsy Service, Royal Prince Alfred Hospital, Sydney, NSW 2050, Australia.
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Chen N, Couñago RM, Chen N, Djoko K, McEwan A, Kobe B. The structure of a bacterial esterase essential for NO-stress response. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311088143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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25
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Kerhet A, Small C, Quon H, Riauka T, Schrader L, Greiner R, Yee D, McEwan A, Roa W. Application of machine learning methodology for PET-based definition of lung cancer. ACTA ACUST UNITED AC 2011; 17:41-7. [PMID: 20179802 PMCID: PMC2826776 DOI: 10.3747/co.v17i1.394] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We applied a learning methodology framework to assist in the threshold-based segmentation of non-small-cell lung cancer (nsclc) tumours in positron-emission tomography–computed tomography (pet–ct) imaging for use in radiotherapy planning. Gated and standard free-breathing studies of two patients were independently analysed (four studies in total). Each study had a pet–ct and a treatment-planning ct image. The reference gross tumour volume (gtv) was identified by two experienced radiation oncologists who also determined reference standardized uptake value (suv) thresholds that most closely approximated the gtv contour on each slice. A set of uptake distribution-related attributes was calculated for each pet slice. A machine learning algorithm was trained on a subset of the pet slices to cope with slice-to-slice variation in the optimal suv threshold: that is, to predict the most appropriate suv threshold from the calculated attributes for each slice. The algorithm’s performance was evaluated using the remainder of the pet slices. A high degree of geometric similarity was achieved between the areas outlined by the predicted and the reference suv thresholds (Jaccard index exceeding 0.82). No significant difference was found between the gated and the free-breathing results in the same patient. In this preliminary work, we demonstrated the potential applicability of a machine learning methodology as an auxiliary tool for radiation treatment planning in nsclc.
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Affiliation(s)
- A Kerhet
- Department of Oncology, University of Alberta, Edmonton, AB.
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Lee D, McEwan A, Robinson D, Jans H, Martin W, Wieler M, Riauka T. SU-E-I-173: Factor Analysis with Prior Information Using Projected Gradient Method - Application to 11C-DTBZ Dynamic PET Dataset for Early Detection of Parkinsonˈs Disease. Med Phys 2011. [DOI: 10.1118/1.3611747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Jha N, Harris J, Seikaly H, Jacobs J, McEwan A, Robbins K, Grecula J, Sharma A, Ang K. A Phase II Study of Submandibular Salivary Gland Transfer to the Submental Space Prior to Start of Radiation Treatment for Prevention of Radiation-induced Xerostomia in Head and Neck Cancer Patients: Initial Report of RTOG – 0244. Int J Radiat Oncol Biol Phys 2010. [DOI: 10.1016/j.ijrobp.2010.07.219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lochard J, Bogdevitch I, Gallego E, Hedemann-Jensen P, McEwan A, Nisbet A, Oudiz A, Oudiz T, Strand P, Janssens A, Lazo T, Carr Z, Sugier A, Burns P, Carboneras P, Cool D, Cooper J, Kai M, Lecomte JF, Liu H, Massera G, McGarry A, Mrabit K, Mrabit M, Sjöblom KL, Tsela A, Weiss W. ICRP Publication 111 - Application of the Commission's recommendations to the protection of people living in long-term contaminated areas after a nuclear accident or a radiation emergency. Ann ICRP 2010; 39:1-4, 7-62. [PMID: 20472181 DOI: 10.1016/j.icrp.2009.09.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In this report, the Commission provides guidance for the protection of people living in long-term contaminated areas resulting from either a nuclear accident or a radiation emergency. The report considers the effects of such events on the affected population. This includes the pathways of human exposure, the types of exposed populations, and the characteristics of exposures. Although the focus is on radiation protection considerations, the report also recognises the complexity of post-accident situations, which cannot be managed without addressing all the affected domains of daily life, i.e. environmental, health, economic, social, psychological, cultural, ethical, political, etc. The report explains how the 2007 Recommendations apply to this type of existing exposure situation, including consideration of the justification and optimisation of protection strategies, and the introduction and application of a reference level to drive the optimisation process. The report also considers practical aspects of the implementation of protection strategies, both by authorities and the affected population. It emphasises the effectiveness of directly involving the affected population and local professionals in the management of the situation, and the responsibility of authorities at both national and local levels to create the conditions and provide the means favouring the involvement and empowerment of the population. The role of radiation monitoring, health surveillance, and the management of contaminated foodstuffs and other commodities is described in this perspective. The Annex summarises past experience of longterm contaminated areas resulting from radiation emergencies and nuclear accidents, including radiological criteria followed in carrying out remediation measures.
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Fabrizi L, Yerworth R, McEwan A, Gilad O, Bayford R, Holder DS. A method for removing artefacts from continuous EEG recordings during functional electrical impedance tomography for the detection of epileptic seizures. Physiol Meas 2010; 31:S57-72. [DOI: 10.1088/0967-3334/31/8/s05] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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McEwan A, Tapson J, van Schaik A, Holder DS. Code-division-multiplexed electrical impedance tomography spectroscopy. IEEE Trans Biomed Circuits Syst 2009; 3:332-338. [PMID: 23853272 DOI: 10.1109/tbcas.2009.2032159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Electrical impedance tomography uses multiple impedance measurements to image the internal conductivity of an object, such as the human body. Code-division multiplexing is proposed as a new method that can provide simultaneous impedance measurements of the multiple channels. Code division provides clear advantages of a wide frequency range at reduced cost and reduced complexity of sources. A potential drawback is the lack of perfectly orthogonal code sets. This caused an increase of 0.62% in root-mean-square spectral error when two codes were used to record two impedance channels simultaneously on a low-pass filter network. The method described provides images and spectra which are equivalent to the conventional time-multiplexed method, with increases in frequency resolution and measurement speed which may be of benefit in some applications of electrical impedance tomography spectroscopy.
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Kerhet A, Small C, Quon H, Riauka T, Schrader L, Greiner R, Yee D, McEwan A, Roa W. 186 APPLICATION OF MACHINE LEARNING METHODOLOGY FOR PETBASED DEFINITION OF LUNG CANCER. Radiother Oncol 2009. [DOI: 10.1016/s0167-8140(12)72573-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Small C, McEwan A, Kerhet A, Riauka T, Postema E, Roa W. 157 THE ROLE OF 18F-FAZA COMBINED WITH 18F-FDG IN ASSESSING RESPONSE IN PATIENTS WITH INOPERABLE NON-SMALL CELL LUNG CANCER UNDERGOING RADIOTHERAPY OR CHEMORADIOTHERAPY. Radiother Oncol 2009. [DOI: 10.1016/s0167-8140(12)72544-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Fabrizi L, McEwan A, Oh T, Woo EJ, Holder DS. A comparison of two EIT systems suitable for imaging impedance changes in epilepsy. Physiol Meas 2009; 30:S103-20. [PMID: 19491447 DOI: 10.1088/0967-3334/30/6/s07] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Fabrizi L, McEwan A, Oh T, Woo EJ, Holder DS. An electrode addressing protocol for imaging brain function with electrical impedance tomography using a 16-channel semi-parallel system. Physiol Meas 2009; 30:S85-101. [PMID: 19491446 DOI: 10.1088/0967-3334/30/6/s06] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Electrical impedance tomography of brain function poses special problems because applied current is diverted by the resistive skull. In the past, image resolution was maximized with the use of an electrode addressing protocol with widely spaced drive electrode pairs and use of a multiplexer so that many electrode pairs could be flexibly addressed. The purpose of this study was to develop and test an electrode protocol for a 16-channel semi-parallel system which uses parallel recording channels with fixed wiring, the Kyung Hee University (KHU) Mk1. Ten protocols were tested, all addressing pairs of electrodes for recording or current drive, based on recording with a spiral, spiral with suboccipital electrodes (spiral s-o) and zig-zag configurations, and combinations of current injection from electrode pairs at 180 degrees , 120 degrees and 60 degrees . These were compared by assessing the image reconstruction quality of five simulated perturbations in a homogenous model of the human head and of four epileptic foci in an anatomically realistic model in the presence of realistic noise, in terms of localization error, resolution, image distortion and sensitivity in the region of interest. The spiral s-o with current injection at 180 degrees + 120 degrees + 60 degrees gave the best image quality and permitted reconstruction with a localization error of less than 10% of the head diameter. This encourages the view that it might be possible to obtain satisfactory images of focal abnormalities in the human brain with 16 scalp electrodes and improved instrumentation avoiding multiplexers on recording circuits.
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Affiliation(s)
- L Fabrizi
- Department of Medical Physics and Bioengineering, Malet Place Engineering Building, Gower Street, University College London, London WC1E 6BT, UK.
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Kumar P, Emami S, Kresolek Z, Yang J, McEwan A, Wiebe L. Synthesis and Hypoxia Selective Radiosensitization Potential of β-2-FAZA and β-3-FAZL: Fluorinated Azomycin β-Nucleosides. Med Chem 2009; 5:118-29. [DOI: 10.2174/157340609787582945] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Kumar P, Emami S, McEwan A, Wiebe L. Development of an Economical, Single Step Synthesis of FAZA, a Clinical Hypoxia Marker, and Potential Synthons to Prepare its Positional Analogs. LETT DRUG DES DISCOV 2009. [DOI: 10.2174/157018009787158616] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Abstract
Multi-frequency electrical impedance tomography (MFEIT) was proposed over 10 years ago as a potential spectroscopic impedance imaging method. At least seven systems have been developed for imaging the lung, heart, breast and brain, yet none has yet achieved clinical acceptance. While the absolute impedance varies considerably between different tissues, the changes in the spectrum due to physiological changes are expected to be quite small, especially when measured through a volume. This places substantial requirements on the MFEIT instrumentation to maintain a flat system frequency response over a broad frequency range (dc-MHz). In this work, the EIT measurement problem is described from a multi-frequency perspective. Solutions to the common problems are considered from recent MFEIT systems, and the debate over four-terminal or two-terminal (multiple source) architecture is revisited. An analysis of the sources of MFEIT errors identifies the major sources of error as stray capacitance and common-mode voltages which lead to a load dependence in the frequency response of MFEIT systems. A system that employs active electrodes appears to be the most able to cope with these errors (Li et al 1996). A distributed system with digitization at the electrode is suggested as a next step in MFEIT system development.
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Affiliation(s)
- A McEwan
- Department of Medical Physics and Bioengineering, UCL, London, UK.
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Fabrizi L, McEwan A, Woo E, Holder DS. Analysis of resting noise characteristics of three EIT systems in order to compare suitability for time difference imaging with scalp electrodes during epileptic seizures. Physiol Meas 2007; 28:S217-36. [PMID: 17664637 DOI: 10.1088/0967-3334/28/7/s16] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Electrical impedance tomography measurements in clinical applications are limited by an undesired noise component. We have investigated the noise in three systems suitable for imaging epileptic seizures, the UCH Mark1b, UCH Mark2.5 and KHU Mark1 16 channel, at applied frequencies in three steps from 1 to 100 kHz, by varying load impedance, single terminal or multiplexed measurements, and in test objects of increasing complexity from a resistor to a saline filled tank and human volunteer. The noise was white, and increased from about 0.03% rms on the resistor to 0.08% on the human; it increased with load but was independent of use of the multiplexer. The KHU Mark1 delivered the best performance with noise spectra of about 0.02%, which could be further reduced by averaging to a level where reliable imaging of changes of about 0.1% estimated during epileptic seizures appears plausible.
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Affiliation(s)
- L Fabrizi
- Department of Medical Physics and Bioengineering, UCL, London, UK.
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Taylor CJ, Derrick G, McEwan A, Haworth SG, Sury MRJ. Risk of cardiac catheterization under anaesthesia in children with pulmonary hypertension. Br J Anaesth 2007; 98:657-61. [PMID: 17401143 DOI: 10.1093/bja/aem059] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Children with primary pulmonary hypertension (PHT) are a high-risk group who require assessment by cardiac catheterization under anaesthesia. Complications, including death, have occurred during anaesthesia in these patients, but the true risk has not been quantified. METHODS The clinical records of children with PHT undergoing general anaesthesia for pulmonary vascular resistance studies were reviewed retrospectively. Data collected included pre-catheter measures of severity of disease, details of clinical management, and complications occurring within 24 h of the start of anaesthesia. RESULTS During the past 5 yr, 75 consecutive patients were catheterized and usable records were available in 70. The age range was 0.1-18 yr (mean 7.1). Four children required external cardiac massage [6% (95% confident limits 1-11%)] and one of these died. Of the four, two had an arrhythmia related to the mechanical effects of catheterization, one was hypotensive during anaesthesia and the other had fatal cardiac failure in recovery. All four had severe PHT as judged by echocardiographic estimation of tricuspid regurgitant jet velocity>4 m s-1. CONCLUSIONS Resuscitation or death occurred in 6% of cases. Any associated risk factors could not be determined because the number of complications was too small. Risks may be highest in children with severe idiopathic PHT and symptoms of chest pain, syncope, or dizziness.
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Affiliation(s)
- C J Taylor
- Department of Anaesthesia, Great Ormond Street Hospital for Children NHS Trust, London, UK
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Alexander A, Murtha A, Abdulkarim B, Mehta V, Wheatley M, Murray B, Riauka T, Hanson J, Fulton D, McEwan A, Roa W. Prognostic significance of serial magnetic resonance spectroscopies over the course of radiation therapy for patients with malignant glioma. CLIN INVEST MED 2006; 29:301-11. [PMID: 17144440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
BACKGROUND The standard treatment of high grade gliomas (HGG) involves maximal neuro-surgical debulking, followed by post-operative radiotherapy, with or without concurrent chemotherapy, depending on histologic grade. Despite this aggressive strategy, there are few long-term survivors. Proton magnetic resonance spectroscopy (MRS) is a non-invasive imaging method that can monitor metabolic changes in brain tumours. To date there is little data concerning the prognostic significance of the evolving spectral alterations during a course of radiotherapy. MATERIALS We report herein a prospective study of patients with HGGs undergoing post-operative radiotherapy. Fourteen consecutively eligible patients with a confirmed histologic diagnosis of malignant glioma and completion of all required MRS imaging were included in this study. All patients had MRS imaging prior to radiotherapy, at week 4 of radiotherapy, and 2 months post-treatment. T1 and T2 weighted images as well as post-gadolinium multi-voxel proton MRS images were obtained. Normalized (tumour metabolite/normal brain metabolite) levels of choline, NAA, creatine, lipid and lactate were calculated. Kaplan-Meier (KM) curves of progression-free and overall survival were constructed based on the evolving patterns of metabolite changes over the course of the images. RESULTS The mean tumour choline/NAA ratio decreased over the course of therapy, with a reduction observed between the baseline and post-radiotherapy studies (1.91 vs. 1.29, P=0.049). A similar decrease was identified with the mean normalized choline ratio, with a highly significant difference observed between the baseline and post-radiation images (1.61 vs. 0.96, P=0.001). Patients who exhibited more than 40% decrease in normalized choline between the week 4 and post-radiotherapy studies were associated with unfavourable survival (logrank test, P=0.003) and disease progression (logrank test, P=0.012). The Lactate/NAA ratio at the 4th week of radiotherapy and the change in normalized choline/creatine between baseline and week 4 of radiotherapy were also predictive of outcome suggesting the possibility of adaptive, response-based radiation treatment. Patients with two or more poor prognostic MRS indices had a significantly shorter progression-free survival compared with those with zero or one poor indices, with 15% and 68% at 1 year, respectively (logrank test, P=0.045). CONCLUSION The evolving pattern of spectral changes over the course of radiotherapy, in particular those associated with choline-containing compounds, appears to be prognostic of tumour response and outcome. Based on our data, a decision point may exist in the mid course of radical radiotherapy, at which time consideration of the choline levels could indicate the extent of radiotherapeutic response, thus allowing for individualized treatment modification.
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Affiliation(s)
- A Alexander
- Department of Radiation Oncology, Cross Cancer Institute, Edmonton, AB
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Lian J, Pervez N, Nijjar T, Quon H, Robinson D, Murray B, Butts C, Joy A, Reiman T, Smylie M, Hanson J, Amanie J, McEwan A, Roa W. 103 An Institutional experience of PET-guided high-dose IMRT with self-respiratory gating in the treatment of non-small cell lung cancer. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80844-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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McEwan A, Romsauerova A, Yerworth R, Horesh L, Bayford R, Holder D. Design and calibration of a compact multi-frequency EIT system for acute stroke imaging. Physiol Meas 2006; 27:S199-210. [PMID: 16636411 DOI: 10.1088/0967-3334/27/5/s17] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A new, compact UCLH Mk 2.5 EIT system has been developed and calibrated for EIT imaging of the head. Improvements include increased input and output impedances, increased bandwidth and improved CMRR (80 dB) and linearity over frequencies and load (0.2% on a single channel, +/-0.7% on a saline tank over 20 Hz-256 kHz and 10-65 Omega). The accuracy of the system is sufficient to image severe acute stroke according to the specification from recent detailed anatomical modelling (Horesh et al 2005 3rd European Medical and Biological Engineering Conference EMBEC'05). A preliminary human study has validated the main specifications of the modelling, the range of trans-impedance from the head (8-70 Omega) using a 32 electrode, 258 combination protocol and contact impedances of 300 Omega to 2.7 kOmega over 20 Hz to 256 kHz.
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Affiliation(s)
- A McEwan
- Department of Medical Physics and Bioengineering, UCL, London WC1E 6BT, UK.
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Abstract
MFEIT (multi-frequency electrical impedance tomography) has the potential to provide a portable non-invasive neuroimaging method ideal for use in acute stroke. Skin perception has not previously occurred in MFEIT with injected frequencies above 2 kHz, but use in brain imaging requires applied current below 100 Hz, which could stimulate cutaneous nerve endings. The purpose of this work was to find the most suitable current pattern that could be employed in MFEIT measurements in the adult head with the UCLH Mk2.5 system, which applies currents from 20 Hz-1.6 MHz. Single frequency current waveforms of 0.28 mA peak-to-peak at 20 Hz-80 Hz were applied to the forearms of three volunteers; although the skin was abraded, none of these were perceived, which agrees with similar studies in the literature. When a full frequency pattern at 20 Hz-1.6 MHz was applied to the forearm or head in four healthy subjects, with the same current amplitude of 0.28 mA for each component, an unpleasant tingling sensation was perceived, due to summation of the applied currents. The sensation was reduced or abolished by attenuation or removal of frequencies below 100 Hz; the optimal compromise was a pattern with absence of 40 Hz, and with 80 and 20 Hz respectively reduced to 75% and 50%.
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Affiliation(s)
- A Romsauerova
- Department of Medical Physics and Bioengineering, UCL, London, UK.
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Fabrizi L, Sparkes M, Horesh L, Perez-Juste Abascal JF, McEwan A, Bayford RH, Elwes R, Binnie CD, Holder DS. Factors limiting the application of electrical impedance tomography for identification of regional conductivity changes using scalp electrodes during epileptic seizures in humans. Physiol Meas 2006; 27:S163-74. [PMID: 16636408 DOI: 10.1088/0967-3334/27/5/s14] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Electrical impedance tomography (EIT) has the potential to produce images during epileptic seizures. This might improve the accuracy of the localization of epileptic foci in patients undergoing presurgical assessment for curative neurosurgery. It has already been shown that impedance increases by up to 22% during induced epileptic seizures in animal models, using cortical or implanted electrodes in controlled experiments. The purpose of this study was to determine if reproducible raw impedance changes and EIT images could be collected during epileptic seizures in patients who were undergoing observation with video-electroencephalography (EEG) telemetry as part of evaluation prior to neurosurgery to resect the region of brain causing the epilepsy. A secondary purpose was to develop an objective method for processing and evaluating data, as seizures arose at unpredictable times from a noisy baseline. Four-terminal impedance measurements from 258 combinations were collected continuously using 32 EEG scalp electrodes in 22 seizure episodes from 7 patients during their presurgical assessment together with the standard EEG recordings. A reliable method for defining the pre-seizure baseline and recording impedance data and EIT images was developed, in which EIT and EEG could be acquired simultaneously after filtering of EIT artefact from the EEG signal. Fluctuations of several per cent over minutes were observed in the baseline between seizures. During seizures, boundary voltage changes diverged with a standard deviation of 1-54% from the baseline. No reproducible changes with the expected time course of some tens of seconds and magnitude of about 0.1% could be reliably measured. This demonstrates that it is feasible to acquire EIT images in parallel with standard EEG during presurgical assessment but, unfortunately, expected EIT changes on the scalp of about 0.1% are swamped by much larger movement and systematic artefact. Nevertheless, EIT has the unique potential to provide invaluable neuroimaging data for this purpose and may still become possible with improvements in electrode design and instrumentation.
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Affiliation(s)
- L Fabrizi
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK.
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Romsauerova A, McEwan A, Horesh L, Yerworth R, Bayford RH, Holder DS. Multi-frequency electrical impedance tomography (EIT) of the adult human head: initial findings in brain tumours, arteriovenous malformations and chronic stroke, development of an analysis method and calibration. Physiol Meas 2006; 27:S147-61. [PMID: 16636407 DOI: 10.1088/0967-3334/27/5/s13] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
MFEIT (multi-frequency electrical impedance tomography) could distinguish between ischaemic and haemorrhagic stroke and permit the urgent use of thrombolytic drugs in patients with ischaemic stroke. The purpose of this study was to characterize the UCLH Mk 2 MFEIT system, designed for this purpose, with 32 electrodes and a multiplexed 2 kHz to 1.6 MHz single impedance measuring circuit. Data were collected in seven subjects with brain tumours, arteriovenous malformations or chronic stroke, as these resembled the changes in haemorrhagic or ischaemic stroke. Calibration studies indicated that the reliable bandwidth was only 16-64 kHz because of front-end components placed to permit simultaneous EEG recording. In raw in-phase component data, the SD of 16-64 kHz data for one electrode combination across subjects was 2.45 +/- 0.9%, compared to a largest predicted change of 0.35% estimated using the FEM of the head. Using newly developed methods of examining the most sensitive channels from the FEM, and nonlinear imaging constrained to the known site of the lesion, no reproducible changes between pathologies were observed. This study has identified a specification for accuracy in EITS in acute stroke, identified the size of variability in relation to this in human recordings, and presents new methods for analysis of data. Although no reproducible changes were identified, we hope this will provide a foundation for future studies in this demanding but potentially powerful novel application.
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Affiliation(s)
- A Romsauerova
- Department of Medical Physics and Bioengineering, UCL, London, UK.
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Roa W, Alexander A, Yaremko B, Riauka T, Robinson D, Murray B, McEwan A. 29 Tumor-Immobilization in Non-Small Cell Lung Cancer - An Examination of Idealized Tumor Motion Using CT, PET, and Respiratory Gating. Radiother Oncol 2005. [DOI: 10.1016/s0167-8140(05)80190-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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