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Bridgen P, Tomi-Tricot R, Uus A, Cromb D, Quirke M, Almalbis J, Bonse B, De la Fuente Botella M, Maggioni A, Cio PD, Cawley P, Casella C, Dokumaci AS, Thomson AR, Willers Moore J, Bridglal D, Saravia J, Finck T, Price AN, Pickles E, Cordero-Grande L, Egloff A, O’Muircheartaigh J, Counsell SJ, Giles SL, Deprez M, De Vita E, Rutherford MA, Edwards AD, Hajnal JV, Malik SJ, Arichi T. High resolution and contrast 7 tesla MR brain imaging of the neonate. FRONTIERS IN RADIOLOGY 2024; 3:1327075. [PMID: 38304343 PMCID: PMC10830693 DOI: 10.3389/fradi.2023.1327075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 12/29/2023] [Indexed: 02/03/2024]
Abstract
Introduction Ultra-high field MR imaging offers marked gains in signal-to-noise ratio, spatial resolution, and contrast which translate to improved pathological and anatomical sensitivity. These benefits are particularly relevant for the neonatal brain which is rapidly developing and sensitive to injury. However, experience of imaging neonates at 7T has been limited due to regulatory, safety, and practical considerations. We aimed to establish a program for safely acquiring high resolution and contrast brain images from neonates on a 7T system. Methods Images were acquired from 35 neonates on 44 occasions (median age 39 + 6 postmenstrual weeks, range 33 + 4 to 52 + 6; median body weight 2.93 kg, range 1.57 to 5.3 kg) over a median time of 49 mins 30 s. Peripheral body temperature and physiological measures were recorded throughout scanning. Acquired sequences included T2 weighted (TSE), Actual Flip angle Imaging (AFI), functional MRI (BOLD EPI), susceptibility weighted imaging (SWI), and MR spectroscopy (STEAM). Results There was no significant difference between temperature before and after scanning (p = 0.76) and image quality assessment compared favorably to state-of-the-art 3T acquisitions. Anatomical imaging demonstrated excellent sensitivity to structures which are typically hard to visualize at lower field strengths including the hippocampus, cerebellum, and vasculature. Images were also acquired with contrast mechanisms which are enhanced at ultra-high field including susceptibility weighted imaging, functional MRI, and MR spectroscopy. Discussion We demonstrate safety and feasibility of imaging vulnerable neonates at ultra-high field and highlight the untapped potential for providing important new insights into brain development and pathological processes during this critical phase of early life.
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Affiliation(s)
- Philippa Bridgen
- LondonCollaborative Ultra High Field System (LoCUS), King’s College London, London, United Kingdom
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
| | - Raphael Tomi-Tricot
- LondonCollaborative Ultra High Field System (LoCUS), King’s College London, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- MR Research Collaborations, Siemens Healthcare Limited, London, United Kingdom
| | - Alena Uus
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Daniel Cromb
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Megan Quirke
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Jennifer Almalbis
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Beya Bonse
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Miguel De la Fuente Botella
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Alessandra Maggioni
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Pierluigi Di Cio
- LondonCollaborative Ultra High Field System (LoCUS), King’s College London, London, United Kingdom
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
| | - Paul Cawley
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Chiara Casella
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Ayse Sila Dokumaci
- Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Alice R. Thomson
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King’s College London, London, United Kingdom
| | - Jucha Willers Moore
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King’s College London, London, United Kingdom
| | - Devi Bridglal
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Joao Saravia
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Thomas Finck
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Anthony N. Price
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Elisabeth Pickles
- LondonCollaborative Ultra High Field System (LoCUS), King’s College London, London, United Kingdom
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Lucilio Cordero-Grande
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- Biomedical Image Technologies, ETSI Telecomunicación, Universidad Politécnica de Madrid and CIBER-BBN, ISCIII, Madrid, Spain
| | - Alexia Egloff
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Jonathan O’Muircheartaigh
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King’s College London, London, United Kingdom
- Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Serena J. Counsell
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Sharon L. Giles
- LondonCollaborative Ultra High Field System (LoCUS), King’s College London, London, United Kingdom
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Maria Deprez
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Enrico De Vita
- LondonCollaborative Ultra High Field System (LoCUS), King’s College London, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- MR Physics, Radiology Department, Great Ormond Street Hospital for Children, London, United Kingdom
| | - Mary A. Rutherford
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King’s College London, London, United Kingdom
| | - A. David Edwards
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King’s College London, London, United Kingdom
| | - Joseph V. Hajnal
- LondonCollaborative Ultra High Field System (LoCUS), King’s College London, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Shaihan J. Malik
- LondonCollaborative Ultra High Field System (LoCUS), King’s College London, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Tomoki Arichi
- Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King’s College London, London, United Kingdom
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2
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Clément J, Tomi-Tricot R, Malik SJ, Webb A, Hajnal JV, Ipek Ö. Towards an integrated neonatal brain and cardiac examination capability at 7 T: electromagnetic field simulations and early phantom experiments using an 8-channel dipole array. MAGMA (NEW YORK, N.Y.) 2022; 35:765-778. [PMID: 34997396 PMCID: PMC9463228 DOI: 10.1007/s10334-021-00988-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 12/06/2021] [Accepted: 12/06/2021] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Neonatal brain and cardiac imaging would benefit from the increased signal-to-noise ratio levels at 7 T compared to lower field. Optimal performance might be achieved using purpose designed RF coil arrays. In this study, we introduce an 8-channel dipole array and investigate, using simulations, its RF performances for neonatal applications at 7 T. METHODS The 8-channel dipole array was designed and evaluated for neonatal brain/cardiac configurations in terms of SAR efficiency (ratio between transmit-field and maximum specific-absorption-rate level) using adjusted dielectric properties for neonate. A birdcage coil operating in circularly polarized mode was simulated for comparison. Validation of the simulation model was performed on phantom for the coil array. RESULTS The 8-channel dipole array demonstrated up to 46% higher SAR efficiency levels compared to the birdcage coil in neonatal configurations, as the specific-absorption-rate levels were alleviated. An averaged normalized root-mean-square-error of 6.7% was found between measured and simulated transmit field maps on phantom. CONCLUSION The 8-channel dipole array design integrated for neonatal brain and cardiac MR was successfully demonstrated, in simulation with coverage of the baby and increased SAR efficiency levels compared to the birdcage. We conclude that the 8Tx-dipole array promises safe operating procedures for MR imaging of neonatal brain and heart at 7 T.
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Affiliation(s)
- Jérémie Clément
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
| | | | - Shaihan J Malik
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.,Centre for the Developing Brain, King's College London, London, UK
| | - Andrew Webb
- Department of Radiology, C. J Gorter Center for High Field MRI, Leiden University Medical Center, Leiden, The Netherlands
| | - Joseph V Hajnal
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.,Centre for the Developing Brain, King's College London, London, UK
| | - Özlem Ipek
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.
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3
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Neonatal body magnetic resonance imaging: preparation, performance and optimization. Pediatr Radiol 2022; 52:676-684. [PMID: 34156505 DOI: 10.1007/s00247-021-05118-4] [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: 03/24/2021] [Revised: 04/27/2021] [Accepted: 06/01/2021] [Indexed: 10/21/2022]
Abstract
Performing and optimizing MRI of the chest, abdomen and pelvis in neonates and young infants can be challenging. This is a result of several factors, including patient size, desire to avoid or minimize sedation/general anesthesia, and the relative rarity of these examinations. However, with proper preparation and protocol optimization, high-quality diagnostic images can be acquired that can aid in diagnosis and patient management. In addition, numerous special considerations arise when performing body MRI in neonates compared to older pediatric patients. This review article provides an update on the performance and optimization of MRI of the body in neonates and infants. Furthermore, the authors present common indications for neonatal body MRI and discuss the use of intravenous gadolinium-based contrast agents in this vulnerable patient population.
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Tang M, Yamamoto T. Progress in Understanding Radiofrequency Heating and Burn Injuries for Safer MR Imaging. Magn Reson Med Sci 2022; 22:7-25. [PMID: 35228437 PMCID: PMC9849420 DOI: 10.2463/mrms.rev.2021-0047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
RF electromagnetic wave exposure during MRI scans induces heat and occasionally causes burn injuries to patients. Among all the types of physical injuries that have occurred during MRI examinations, RF burn injuries are the most common ones. The number of RF burn injuries increases as the static magnetic field of MRI systems increases because higher RFs lead to higher heating. The commonly believed mechanisms of RF burn injuries are the formation of a conductive loop by the patient's posture or cables, such as an electrocardiogram lead; however, the mechanisms of RF burn injuries that occur at the contact points, such as the bore wall and the elbow, remain unclear. A comprehensive understanding of RF heating is needed to address effective countermeasures against all RF burn injuries for safe MRI examinations. In this review, we summarize the occurrence of RF burn injury cases by categorizing RF burn injuries reported worldwide in recent decades. Safety standards and regulations governing RF heating that occurs during MRI examinations are presented, along with their theoretical and physiological backgrounds. The experimental assessment techniques for RF heating are then reviewed, and the development of numerical simulation techniques is explained. In addition, a comprehensive theoretical interpretation of RF burn injuries is presented. By including the results of recent experimental and numerical simulation studies on RF heating, this review describes the progress achieved in understanding RF heating from the standpoint of MRI burn injury prevention.
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Affiliation(s)
- Minghui Tang
- Department of Diagnostic Imaging, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Toru Yamamoto
- Division of Biomedical Engineering and Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan,Corresponding author: Faculty of Health Sciences, Hokkaido University, Kita 12 Nishi 5, Kita-ku, Sapporo, Hokkaido 060-0812, Japan. Phone: +81-11-706-3412, Fax: +81-11-706-4916, E-mail:
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Korom M, Camacho MC, Filippi CA, Licandro R, Moore LA, Dufford A, Zöllei L, Graham AM, Spann M, Howell B, Shultz S, Scheinost D. Dear reviewers: Responses to common reviewer critiques about infant neuroimaging studies. Dev Cogn Neurosci 2021; 53:101055. [PMID: 34974250 PMCID: PMC8733260 DOI: 10.1016/j.dcn.2021.101055] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 11/28/2021] [Accepted: 12/26/2021] [Indexed: 01/07/2023] Open
Abstract
The field of adult neuroimaging relies on well-established principles in research design, imaging sequences, processing pipelines, as well as safety and data collection protocols. The field of infant magnetic resonance imaging, by comparison, is a young field with tremendous scientific potential but continuously evolving standards. The present article aims to initiate a constructive dialog between researchers who grapple with the challenges and inherent limitations of a nascent field and reviewers who evaluate their work. We address 20 questions that researchers commonly receive from research ethics boards, grant, and manuscript reviewers related to infant neuroimaging data collection, safety protocols, study planning, imaging sequences, decisions related to software and hardware, and data processing and sharing, while acknowledging both the accomplishments of the field and areas of much needed future advancements. This article reflects the cumulative knowledge of experts in the FIT’NG community and can act as a resource for both researchers and reviewers alike seeking a deeper understanding of the standards and tradeoffs involved in infant neuroimaging. The field of infant MRI is young with evolving standards. We address 20 questions that researchers commonly receive reviewers. These come from research ethics boards, grant, and manuscript reviewers. This article reflects the cumulative knowledge of experts in the FIT’NG community.
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Affiliation(s)
- Marta Korom
- Department of Psychological and Brain Sciences, University of Delaware, Newark, DE, USA.
| | - M Catalina Camacho
- Division of Biology and Biomedical Sciences (Neurosciences), Washington University School of Medicine, St. Louis, MO, USA.
| | - Courtney A Filippi
- Emotion and Development Branch, National Institute of Mental Health, Bethesda, MD, USA
| | - Roxane Licandro
- Institute of Visual Computing and Human-Centered Technology, Computer Vision Lab, TU Wien, Vienna, Austria; Department of Biomedical Imaging and Image-guided Therapy, Computational Imaging Research, Medical University of Vienna, Vienna, Austria
| | - Lucille A Moore
- Department of Psychiatry, Oregon Health and Science University, Portland, OR, USA
| | - Alexander Dufford
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
| | - Lilla Zöllei
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA
| | - Alice M Graham
- Department of Psychiatry, Oregon Health and Science University, Portland, OR, USA
| | - Marisa Spann
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, USA
| | - Brittany Howell
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Department of Human Development and Family Science, Virginia Polytechnic Institute and State University, Roanoke, VA, USA
| | | | - Sarah Shultz
- Division of Autism & Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA; Marcus Autism Center, Children's Healthcare of Atlanta, Atlanta, GA, USA.
| | - Dustin Scheinost
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA.
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Kowal R, Prier M, Pannicke E, Vick R, Rose G, Speck O. Simulation of SAR Induced Heating in Infants undergoing 1.5 T Magnetic Resonance Imaging. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:3382-3386. [PMID: 34891965 DOI: 10.1109/embc46164.2021.9630221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
RF absorption in patients undergoing MRI procedures poses a major safety risk due to resulting heating in the tissue. In order to stay below permitted temperature limits the SAR has to be quantified and limited. Based on the model of an infant inside a birdcage coil we have investigated the SAR distribution in the body at 1.5T. Thermal simulations could thus be performed to establish a relationship between the limitations of SAR and temperature. Results show a thermal hotspot in the neck region caused by high local absorption. The temperature limits in this local area were exceeded after 7min of excitation within regulatory SAR limits. For a long-term exposure critical organs in the body's core also undergo thermal stress beyond limitations. This indicates the need for constraints in regard to long MR procedures to consider the temporal aspect of heating.Clinical Relevance-This work establishes a relationship between SAR and temperature in infants undergoing MRI and shows potential risks of long-term procedures due to induced thermal stress.
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7
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Jeong H, Ntolkeras G, Grant PE, Bonmassar G. Numerical simulation of the radiofrequency safety of 128-channel hd-EEG nets on a 29-month-old whole-body model in a 3 Tesla MRI. IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY 2021; 63:1748-1756. [PMID: 34675444 PMCID: PMC8522907 DOI: 10.1109/temc.2021.3097732] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
This study investigates the radiofrequency (RF) induced heating in a pediatric whole-body voxel model with a high-density electroencephalogram (hd-EEG) net during magnetic resonance imaging (MRI) at 3 Tesla. A total of three cases were studied: no net (NoNet), a resistive hd-EEG (NeoNet), and a copper (CuNet) net. The maximum values of specific absorption rate averaged over 10g-mass (10gSAR) in the head were calculated with the NeoNet was 12.51 W/kg and in the case of the NoNet was 12.40 W/kg. In contrast, the CuNet case was 17.04 W/Kg. Temperature simulations were conducted to determine the RF-induced heating without and with hd-EEG nets (NeoNet and CuNet) during an MRI scan using an age-corrected and thermoregulated perfusion for the child model. The results showed that the maximum temperature estimated in the child's head was 38.38 °C for the NoNet, 38.43 °C for the NeoNet, and 43.05 °C for the CuNet. In the case of NeoNet, the maximum temperature estimated in the child's head remained compliant with IEC 60601 for the MRI RF safety limit. However, the case of CuNet estimated to exceed the RF safety limit, which may require an appropriate cooling period or a hardware design to suppress the RF-induced heating.
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Affiliation(s)
- Hongbae Jeong
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Med-ical School, Charlestown, MA 02129 USA
| | - Georgios Ntolkeras
- Boston Children's Hospital, Harvard Medical School, Boston, MA 02115 USA
| | - P Ellen Grant
- Boston Children's Hospital, Harvard Medical School, Boston, MA 02115 USA
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Med-ical School, Charlestown, MA 02129 USA
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8
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Malik SJ, Hand JW, Satnarine R, Price AN, Hajnal JV. Specific absorption rate and temperature in neonate models resulting from exposure to a 7T head coil. Magn Reson Med 2021; 86:1299-1313. [PMID: 33811667 DOI: 10.1002/mrm.28784] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 02/11/2021] [Accepted: 03/06/2021] [Indexed: 11/07/2022]
Abstract
PURPOSE To investigate safe limits for neonatal imaging using a 7T head coil, including both specific absorption rate (SAR) and temperature predictions. METHODS Head-centered neonate models were simulated using finite-difference time domain-based electromagnetic and thermal solvers. The effects of higher water content of neonatal tissues compared with adults, position shifts, and thermal insulation were also considered. An adult model was simulated for comparison. RESULTS Maximum and average SAR are both elevated in the neonate when compared with an adult model. When normalized to B1+ , the SAR experienced by a neonate is greater than an adult by approximately a factor of 2; when normalized to net forward power (forward-reflected), this increases to a factor of 2.5-3.0; and when normalized to absorbed power, approximately a factor of 4. Use of age-adjusted dielectric properties significantly increases the predicted SAR, compared with using adult tissue properties for the neonates. Thermal simulations predict that change in core temperature/maximum temperature remain compliant with International Electrotechnical Commission limits when a thermally insulated neonate is exposed at the SAR limit for up to an hour. CONCLUSION This study of two neonate models cannot quantify the variability expected within a larger population. Likewise, the use of age-adjusted dielectric properties have a significant effect, but while their use is well motivated by literature, there is uncertainty in the true dielectric properties of neonatal tissue. Nevertheless, the main finding is that unlike at lower field strengths, operational limits for 7T neonatal MRI using an adult head coil should be more conservative than limits for use on adults.
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Affiliation(s)
- Shaihan J Malik
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London, United Kingdom.,Center for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London, United Kingdom
| | - Jeffrey W Hand
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London, United Kingdom
| | - Ryan Satnarine
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London, United Kingdom
| | - Anthony N Price
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London, United Kingdom.,Center for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London, United Kingdom
| | - Joseph V Hajnal
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London, United Kingdom.,Center for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London, United Kingdom
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9
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Electromagnetic simulation of RF burn injuries occurring at skin-skin and skin-bore wall contact points in an MRI scanner with a birdcage coil. Phys Med 2021; 82:219-227. [DOI: 10.1016/j.ejmp.2021.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 02/03/2021] [Accepted: 02/15/2021] [Indexed: 11/20/2022] Open
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10
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Jeong H, Ntolkeras G, Alhilani M, Atefi SR, Zöllei L, Fujimoto K, Pourvaziri A, Lev MH, Grant PE, Bonmassar G. Development, validation, and pilot MRI safety study of a high-resolution, open source, whole body pediatric numerical simulation model. PLoS One 2021; 16:e0241682. [PMID: 33439896 PMCID: PMC7806143 DOI: 10.1371/journal.pone.0241682] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 10/19/2020] [Indexed: 11/30/2022] Open
Abstract
Numerical body models of children are used for designing medical devices, including but not limited to optical imaging, ultrasound, CT, EEG/MEG, and MRI. These models are used in many clinical and neuroscience research applications, such as radiation safety dosimetric studies and source localization. Although several such adult models have been reported, there are few reports of full-body pediatric models, and those described have several limitations. Some, for example, are either morphed from older children or do not have detailed segmentations. Here, we introduce a 29-month-old male whole-body native numerical model, "MARTIN", that includes 28 head and 86 body tissue compartments, segmented directly from the high spatial resolution MRI and CT images. An advanced auto-segmentation tool was used for the deep-brain structures, whereas 3D Slicer was used to segment the non-brain structures and to refine the segmentation for all of the tissue compartments. Our MARTIN model was developed and validated using three separate approaches, through an iterative process, as follows. First, the calculated volumes, weights, and dimensions of selected structures were adjusted and confirmed to be within 6% of the literature values for the 2-3-year-old age-range. Second, all structural segmentations were adjusted and confirmed by two experienced, sub-specialty certified neuro-radiologists, also through an interactive process. Third, an additional validation was performed with a Bloch simulator to create synthetic MR image from our MARTIN model and compare the image contrast of the resulting synthetic image with that of the original MRI data; this resulted in a "structural resemblance" index of 0.97. Finally, we used our model to perform pilot MRI safety simulations of an Active Implantable Medical Device (AIMD) using a commercially available software platform (Sim4Life), incorporating the latest International Standards Organization guidelines. This model will be made available on the Athinoula A. Martinos Center for Biomedical Imaging website.
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Affiliation(s)
- Hongbae Jeong
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Georgios Ntolkeras
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Michel Alhilani
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Medicine, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Seyed Reza Atefi
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Lilla Zöllei
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Kyoko Fujimoto
- Center for Devices and Radiological Health, U. S. Food and Drug Administration, Silver Spring, MD, United States of America
| | - Ali Pourvaziri
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Michael H. Lev
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - P. Ellen Grant
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
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Abstract
Neuroimaging of the preterm infant is a common assessment performed in the NICU. Timely and focused studies can be used for diagnostic, therapeutic, and prognostic information. However, significant variability exists among neonatal units as to which modalities are used and when imaging studies are obtained. Appropriate timing and selection of neuroimaging studies can help identify neonates with brain injury who may require therapeutic intervention or who may be at risk for neurodevelopmental impairment. This clinical report reviews the different modalities of imaging broadly available to the clinician. Evidence-based indications for each modality, optimal timing of examinations, and prognostic value are discussed.
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Affiliation(s)
- Ivan L Hand
- Department of Pediatrics, New York City Health + Hospitals/Kings County, State University of New York Downstate Medical Center, Brooklyn, New York;
| | - Renée A Shellhaas
- Pediatric Neurology Division, Department of Pediatrics, Michigan Medicine, University of Michigan, Ann Arbor, Michigan; and
| | - Sarah S Milla
- Departments of Radiology and Pediatrics, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia
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12
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Annink KV, van der Aa NE, Dudink J, Alderliesten T, Groenendaal F, Lequin M, Jansen FE, Rhebergen KS, Luijten P, Hendrikse J, Hoogduin HJM, Huijing ER, Versteeg E, Visser F, Raaijmakers AJE, Wiegers EC, Klomp DWJ, Wijnen JP, Benders MJNL. Introduction of Ultra-High-Field MR Imaging in Infants: Preparations and Feasibility. AJNR Am J Neuroradiol 2020; 41:1532-1537. [PMID: 32732273 DOI: 10.3174/ajnr.a6702] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 05/19/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND PURPOSE Cerebral MR imaging in infants is usually performed with a field strength of up to 3T. In adults, a growing number of studies have shown added diagnostic value of 7T MR imaging. 7T MR imaging might be of additional value in infants with unexplained seizures, for example. The aim of this study was to investigate the feasibility of 7T MR imaging in infants. We provide information about the safety preparations and show the first MR images of infants at 7T. MATERIALS AND METHODS Specific absorption rate levels during 7T were simulated in Sim4life using infant and adult models. A newly developed acoustic hood was used to guarantee hearing protection. Acoustic noise damping of this hood was measured and compared with the 3T Nordell hood and no hood. In this prospective pilot study, clinically stable infants, between term-equivalent age and the corrected age of 3 months, underwent 7T MR imaging immediately after their standard 3T MR imaging. The 7T scan protocols were developed and optimized while scanning this cohort. RESULTS Global and peak specific absorption rate levels in the infant model in the centered position and 50-mm feet direction did not exceed the levels in the adult model. Hearing protection was guaranteed with the new hood. Twelve infants were scanned. No MR imaging-related adverse events occurred. It was feasible to obtain good-quality imaging at 7T for MRA, MRV, SWI, single-shot T2WI, and MR spectroscopy. T1WI had lower quality at 7T. CONCLUSIONS 7T MR imaging is feasible in infants, and good-quality scans could be obtained.
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Affiliation(s)
- K V Annink
- From the Departments of Neonatology (K.V.A., N.E.v.d.A., J.D., T.A., F.G., M.J.N.L.B.), and Paediatric Neurology (F.E.J.), University Medical Center Utrecht Brain Center
| | - N E van der Aa
- From the Departments of Neonatology (K.V.A., N.E.v.d.A., J.D., T.A., F.G., M.J.N.L.B.), and Paediatric Neurology (F.E.J.), University Medical Center Utrecht Brain Center
| | - J Dudink
- From the Departments of Neonatology (K.V.A., N.E.v.d.A., J.D., T.A., F.G., M.J.N.L.B.), and Paediatric Neurology (F.E.J.), University Medical Center Utrecht Brain Center
| | - T Alderliesten
- From the Departments of Neonatology (K.V.A., N.E.v.d.A., J.D., T.A., F.G., M.J.N.L.B.), and Paediatric Neurology (F.E.J.), University Medical Center Utrecht Brain Center
| | - F Groenendaal
- From the Departments of Neonatology (K.V.A., N.E.v.d.A., J.D., T.A., F.G., M.J.N.L.B.), and Paediatric Neurology (F.E.J.), University Medical Center Utrecht Brain Center
| | - M Lequin
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - F E Jansen
- From the Departments of Neonatology (K.V.A., N.E.v.d.A., J.D., T.A., F.G., M.J.N.L.B.), and Paediatric Neurology (F.E.J.), University Medical Center Utrecht Brain Center
| | - K S Rhebergen
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - P Luijten
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - J Hendrikse
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - H J M Hoogduin
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - E R Huijing
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - E Versteeg
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - F Visser
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - A J E Raaijmakers
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - E C Wiegers
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - D W J Klomp
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - J P Wijnen
- the Departments of Radiology (M.L., P.L., J.H., H.J.M.H., E.R.H., E.V., F.V., A.J.E.R., E.C.W., D.W.J.K., J.P.W.), and Otorhinolaryngology and Head and Neck Surgery (K.S.R.), University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands
| | - M J N L Benders
- From the Departments of Neonatology (K.V.A., N.E.v.d.A., J.D., T.A., F.G., M.J.N.L.B.), and Paediatric Neurology (F.E.J.), University Medical Center Utrecht Brain Center
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13
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High-resolution rapid neonatal whole-body composition using 3.0 Tesla chemical shift magnetic resonance imaging. Pediatr Res 2018; 83:638-644. [PMID: 29168981 DOI: 10.1038/pr.2017.294] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 10/17/2017] [Indexed: 11/08/2022]
Abstract
BackgroundTo evaluate a whole-body rapid imaging technique to calculate neonatal lean body mass and percentage adiposity using 3.0 Tesla chemical shift magnetic resonance imaging (MRI).MethodsA 2-Point Dixon MRI technique was used to calculate whole-body fat and water images in term (n=10) and preterm (n=15) infants.ResultsChemical shift images were obtained in 42 s. MRI calculated whole-body mass correlated closely with measured body weight (R2=0.87; P<0.001). Scan-rescan analysis demonstrated a 95% limit of agreement of 1.3% adiposity. Preterm infants were born at a median of 25.7 weeks' gestation with birth weight 840 g. At term-corrected age, former preterm infants were lighter than term-born controls, 2,519 vs. 3,094 g regressing out age and group as covariates (P=0.005). However, this was not because of reduced percentage adiposity 26% vs. 24% (P=0.28). At term-corrected age, former preterm infants had significantly reduced lean body mass compared with that of term-born controls 1,935 vs. 2,416 g (P=0.002).ConclusionRapid whole-body imaging for assessment of lean body mass and adiposity in term and preterm infants is feasible, accurate, and repeatable. Deficits in whole-body mass in former preterm infants at term-corrected age are due to reductions in lean body mass not due to differences in adiposity.
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14
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Chen X, Steckner M. Electromagnetic computation and modeling in MRI. Med Phys 2017; 44:1186-1203. [PMID: 28079264 DOI: 10.1002/mp.12103] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 09/26/2016] [Accepted: 01/07/2017] [Indexed: 12/13/2022] Open
Abstract
Electromagnetic (EM) computational modeling is used extensively during the development of a Magnetic Resonance Imaging (MRI) scanner, its installation, and use. MRI, which relies on interactions between nuclear magnetic moments and the applied magnetic fields, uses a range of EM tools to optimize all of the magnetic fields required to produce the image. The main field magnet is designed to exacting specifications but challenges in manufacturing, installation, and use require additional tools to maintain target operational performance. The gradient magnetic fields, which provide the primary signal localization mechanism, are designed under another set of complex design trade-offs which include conflicting imaging performance specifications and patient physiology. Gradients are largely impervious to external influences, but are also used to enhance main field operational performance. The radiofrequency (RF) magnetic fields, which are used to elicit the signals fundamental to the MR image, are a challenge to optimize for a host of reasons that include patient safety, image quality, cost optimization, and secondary signal localization capabilities. This review outlines these issues and the EM modeling used to optimize MRI system performance.
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Affiliation(s)
- Xin Chen
- Toshiba Medical Research Institute USA, Inc. 777 Beta Drive, Mayfield Village, OH, 44143, USA
| | - Michael Steckner
- Toshiba Medical Research Institute USA, Inc. 777 Beta Drive, Mayfield Village, OH, 44143, USA
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Murbach M, Neufeld E, Samaras T, Córcoles J, Robb FJ, Kainz W, Kuster N. Pregnant women models analyzed for RF exposure and temperature increase in 3T RF shimmed birdcages. Magn Reson Med 2016; 77:2048-2056. [PMID: 27174499 DOI: 10.1002/mrm.26268] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 04/15/2016] [Accepted: 04/15/2016] [Indexed: 12/31/2022]
Abstract
PURPOSE MRI is increasingly used to scan pregnant patients. We investigated the effect of 3 Tesla (T) two-port radiofrequency (RF) shimming in anatomical pregnant women models. THEORY AND METHODS RF shimming improves B1+ uniformity, but may at the same time significantly alter the induced current distribution and result in large changes in both the level and location of the absorbed RF energy. In this study, we evaluated the electrothermal exposure of pregnant women in the third, seventh, and ninth month of gestation at various imaging landmarks in RF body coils, including modes with RF shimming. RESULTS Although RF shimmed configurations may lower the local RF exposure for the mother, they can increase the thermal load on the fetus. In worst-case configurations, whole-body exposure and local peak temperatures-up to 40.8°C-are equal in fetus and mother. CONCLUSIONS Two-port RF shimming can significantly increase the fetal exposure in pregnant women, requiring further research to derive a very robust safety management. For the time being, restriction to the CP mode, which reduces fetal SAR exposure compared with linear-horizontal polarization modes, may be advisable. Results from this study do not support scanning pregnant patients above the normal operating mode. Magn Reson Med 77:2048-2056, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
| | | | - Theodoros Samaras
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Juan Córcoles
- Department of Electronic and Communication Technology, Universidad Autónoma de Madrid (UAM), Escuela Politécnica Superior, Madrid, Spain
| | | | - Wolfgang Kainz
- US Food and Drug Administration (FDA), Center for Devices and Radiological Health (CDRH), Silver Spring, Maryland, USA
| | - Niels Kuster
- IT'IS Foundation, Zurich, Switzerland.,Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
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[New aspects from legislation, guidelines and safety standards for MRI]. Radiologe 2015. [PMID: 26220129 DOI: 10.1007/s00117-015-2859-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Many aspects of magnetic resonance (MR) operation are not directly regulated by law but in standards, guidelines and the operating instructions of the MR scanner. The mandatory contents of the operating instructions are regulated in a central standard of the International Electrotechnical Commission (IEC) 60601-2-33. In this standard, the application of static magnetic fields in MRI up to 8 Tesla (T) in the clinical routine (first level controlled mode) has recently been approved. Furthermore, the equally necessary CE certification of ultra-high field scanners (7-8 T) in Europe is expected for future devices. The existing installations will not be automatically certified but will retain their experimental status. The current extension of IEC 60601-2-33 introduces a new add-on option, the so-called fixed parameter option (FPO). This option might also be switched on in addition to the established operating modes and defines a fixed device constellation and certain parameters of the energy output of MR scanners designed to simplify the testing of patients with implants in the future.The employment of pregnant workers in an MRI environment is still not generally regulated in Europe. In parts of Germany and Austria pregnant and lactating employees were prohibited from working in the MR control zone (0.5 mT) in 2014. This is based on the mostly unresolved question of the applicability of limits for employees (exposure of extremities to static magnetic fields up to 8 T allowed) or the thresholds for the general population (maximum 400 mT). According to the European Society of Urogenital Radiology (ESUR), the discarding of breast milk after i.v. administration of gadolinium-based contrast agents in the case of a breastfeeding woman is only recommended when using contrast agents in the nephrogenic systemic fibrosis (NSF) high-risk category.
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