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Samardzija A, Selvaganesan K, Zhang HZ, Sun H, Sun C, Ha Y, Galiana G, Constable RT. Low-Field, Low-Cost, Point-of-Care Magnetic Resonance Imaging. Annu Rev Biomed Eng 2024; 26:67-91. [PMID: 38211326 DOI: 10.1146/annurev-bioeng-110122-022903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
Low-field magnetic resonance imaging (MRI) has recently experienced a renaissance that is largely attributable to the numerous technological advancements made in MRI, including optimized pulse sequences, parallel receive and compressed sensing, improved calibrations and reconstruction algorithms, and the adoption of machine learning for image postprocessing. This new attention on low-field MRI originates from a lack of accessibility to traditional MRI and the need for affordable imaging. Low-field MRI provides a viable option due to its lack of reliance on radio-frequency shielding rooms, expensive liquid helium, and cryogen quench pipes. Moreover, its relatively small size and weight allow for easy and affordable installation in most settings. Rather than replacing conventional MRI, low-field MRI will provide new opportunities for imaging both in developing and developed countries. This article discusses the history of low-field MRI, low-field MRI hardware and software, current devices on the market, advantages and disadvantages, and low-field MRI's global potential.
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Affiliation(s)
- Anja Samardzija
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA;
| | - Kartiga Selvaganesan
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA;
| | - Horace Z Zhang
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA;
| | - Heng Sun
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA;
| | - Chenhao Sun
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut, USA
| | - Yonghyun Ha
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut, USA
| | - Gigi Galiana
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA;
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut, USA
| | - R Todd Constable
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA;
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut, USA
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Meng F, Guo Y, Wei H, Xu Z. Development of a Helmet-Shape Dual-Channel RF coil for brain imaging at 54 mT using inverse boundary element method. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 360:107636. [PMID: 38377783 DOI: 10.1016/j.jmr.2024.107636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 02/04/2024] [Accepted: 02/08/2024] [Indexed: 02/22/2024]
Abstract
Very-low field (VLF) magnetic resonance imaging (MRI) offers advantages in term of size, weight, cost, and the absence of robust shielding requirements. However, it encounters challenges in maintaining a high signal-to-noise ratio (SNR) due to low magnetic fields (below 100 mT). Developing a close-fitting radio frequency (RF) receive coil is crucial to improve the SNR. In this study, we devised and optimized a helmet-shaped dual-channel RF receive coil tailored for brain imaging at a magnetic field strength of 54 mT (2.32 MHz). The methodology integrates the inverse boundary element method (IBEM) to formulate initial coil structures and wiring patterns, followed by optimization through introducing regularization terms. This approach frames the design process as an inverse problem, ensuring a close fit to the head contour. Combining theoretical optimization with physical measurements of the coil's AC resistance, we identified the optimal loop count for both axial and radial coils as nine and eight loops, respectively. The effectiveness of the designed dual-channel coil was verified through the imaging of a CuSO4 phantom and a healthy volunteer's brain. Notably, the in-vivo images exhibited an approximate 16-25 % increase in SNR with poorer B1 homogeneity compared to those obtained using single-channel coils. The high-quality images achieved by T1, T2-weighted, and fluid-attenuated inversion-recovery (FLAIR) protocols enhance the diagnostic potential of VLF MRI, particularly in cases of cerebral stroke and trauma patients. This study underscores the adaptability of the design methodology for the customization of RF coil structures in alignment with individual imaging requirements.
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Affiliation(s)
- Fanqin Meng
- School of Electrical Engineering, Chongqing University, Chongqing 400044, China
| | - Yi Guo
- Central Hospital, Chongqing University, Chongqing 400014, China
| | - He Wei
- School of Electrical Engineering, Chongqing University, Chongqing 400044, China
| | - Zheng Xu
- School of Electrical Engineering, Chongqing University, Chongqing 400044, China.
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Shoghli A, Chow D, Kuoy E, Yaghmai V. Current role of portable MRI in diagnosis of acute neurological conditions. Front Neurol 2023; 14:1255858. [PMID: 37840918 PMCID: PMC10576557 DOI: 10.3389/fneur.2023.1255858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/06/2023] [Indexed: 10/17/2023] Open
Abstract
Neuroimaging is an inevitable component of the assessment of neurological emergencies. Magnetic resonance imaging (MRI) is the preferred imaging modality for detecting neurological pathologies and provides higher sensitivity than other modalities. However, difficulties such as intra-hospital transport, long exam times, and availability in strict access-controlled suites limit its utility in emergency departments and intensive care units (ICUs). The evolution of novel imaging technologies over the past decades has led to the development of portable MRI (pMRI) machines that can be deployed at point-of-care. This article reviews pMRI technologies and their clinical implications in acute neurological conditions. Benefits of pMRI include timely and accurate detection of major acute neurological pathologies such as stroke and intracranial hemorrhage. Additionally, pMRI can be potentially used to monitor the progression of neurological complications by facilitating serial measurements at the bedside.
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Affiliation(s)
| | | | | | - Vahid Yaghmai
- Department of Radiological Sciences, School of Medicine, University of California, Irvine, Irvine, CA, United States
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Kimberly WT, Sorby-Adams AJ, Webb AG, Wu EX, Beekman R, Bowry R, Schiff SJ, de Havenon A, Shen FX, Sze G, Schaefer P, Iglesias JE, Rosen MS, Sheth KN. Brain imaging with portable low-field MRI. NATURE REVIEWS BIOENGINEERING 2023; 1:617-630. [PMID: 37705717 PMCID: PMC10497072 DOI: 10.1038/s44222-023-00086-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/06/2023] [Indexed: 09/15/2023]
Abstract
The advent of portable, low-field MRI (LF-MRI) heralds new opportunities in neuroimaging. Low power requirements and transportability have enabled scanning outside the controlled environment of a conventional MRI suite, enhancing access to neuroimaging for indications that are not well suited to existing technologies. Maximizing the information extracted from the reduced signal-to-noise ratio of LF-MRI is crucial to developing clinically useful diagnostic images. Progress in electromagnetic noise cancellation and machine learning reconstruction algorithms from sparse k-space data as well as new approaches to image enhancement have now enabled these advancements. Coupling technological innovation with bedside imaging creates new prospects in visualizing the healthy brain and detecting acute and chronic pathological changes. Ongoing development of hardware, improvements in pulse sequences and image reconstruction, and validation of clinical utility will continue to accelerate this field. As further innovation occurs, portable LF-MRI will facilitate the democratization of MRI and create new applications not previously feasible with conventional systems.
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Affiliation(s)
- W Taylor Kimberly
- Department of Neurology and the Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Annabel J Sorby-Adams
- Department of Neurology and the Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Andrew G Webb
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Rachel Beekman
- Division of Neurocritical Care and Emergency Neurology, Department of Neurology, Yale New Haven Hospital and Yale School of Medicine, Yale Center for Brain & Mind Health, New Haven, CT, USA
| | - Ritvij Bowry
- Departments of Neurosurgery and Neurology, McGovern Medical School, University of Texas Health Neurosciences, Houston, TX, USA
| | - Steven J Schiff
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT, USA
| | - Adam de Havenon
- Division of Vascular Neurology, Department of Neurology, Yale New Haven Hospital and Yale School of Medicine, New Haven, CT, USA
| | - Francis X Shen
- Harvard Medical School Center for Bioethics, Harvard law School, Boston, MA, USA
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA
| | - Gordon Sze
- Department of Radiology, Yale New Haven Hospital and Yale School of Medicine, New Haven, CT, USA
| | - Pamela Schaefer
- Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Juan Eugenio Iglesias
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Centre for Medical Image Computing, University College London, London, UK
- Computer Science and AI Laboratory, Massachusetts Institute of Technology, Boston, MA, USA
| | - Matthew S Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Kevin N Sheth
- Division of Neurocritical Care and Emergency Neurology, Department of Neurology, Yale New Haven Hospital and Yale School of Medicine, Yale Center for Brain & Mind Health, New Haven, CT, USA
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Selvaganesan K, Wan Y, Ha Y, Wu B, Hancock K, Galiana G, Constable RT. Magnetic resonance imaging using a nonuniform Bo (NuBo) field-cycling magnet. PLoS One 2023; 18:e0287344. [PMID: 37319289 PMCID: PMC10270621 DOI: 10.1371/journal.pone.0287344] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 06/02/2023] [Indexed: 06/17/2023] Open
Abstract
Magnetic resonance imaging (MRI) is a powerful noninvasive diagnostic tool with superior soft tissue contrast. However, access to MRI is limited since current systems depend on homogeneous, high field strength main magnets (B0-fields), with strong switchable gradients which are expensive to install and maintain. In this work we propose a new approach to MRI where imaging is performed in an inhomogeneous field using radiofrequency spatial encoding, thereby eliminating the need for uniform B0-fields and conventional cylindrical gradient coils. The proposed technology uses an innovative data acquisition and reconstruction approach by integrating developments in field cycling, parallel imaging and non-Fourier based algebraic reconstruction. The scanner uses field cycling to image in an inhomogeneous B0-field; in this way magnetization is maximized during the high field polarization phase, and B0 inhomogeneity effects are minimized by using a low field during image acquisition. In addition to presenting the concept, this work provides experimental verification of a long-lived spin echo signal, spatially varying resolution, as well as both simulated and experimental 2D images. Our initial design creates an open MR system that can be installed in a patient examination table for body imaging (e.g., breast or liver) or built into a wall for weighted-spine imaging. The proposed system introduces a new class of inexpensive, open, silent MRIs that could be housed in doctor's offices much like ultrasound is today, making MRI more widely accessible.
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Affiliation(s)
- Kartiga Selvaganesan
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States of America
| | - Yuqing Wan
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, United States of America
| | - Yonghyun Ha
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, United States of America
| | - Baosong Wu
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, United States of America
| | - Kasey Hancock
- Department of Electrical Engineering, Yale University, New Haven, CT, United States of America
| | - Gigi Galiana
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States of America
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, United States of America
| | - R. Todd Constable
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States of America
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, United States of America
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6
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Jordanova KV, Martin MN, Ogier SE, Poorman ME, Keenan KE. In vivo quantitative MRI: T 1 and T 2 measurements of the human brain at 0.064 T. MAGMA (NEW YORK, N.Y.) 2023:10.1007/s10334-023-01095-x. [PMID: 37208553 PMCID: PMC10386946 DOI: 10.1007/s10334-023-01095-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 04/03/2023] [Accepted: 04/19/2023] [Indexed: 05/21/2023]
Abstract
OBJECTIVE To measure healthy brain [Formula: see text] and [Formula: see text] relaxation times at 0.064 T. MATERIALS AND METHODS [Formula: see text] and [Formula: see text] relaxation times were measured in vivo for 10 healthy volunteers using a 0.064 T magnetic resonance imaging (MRI) system and for 10 test samples on both the MRI and a separate 0.064 T nuclear magnetic resonance (NMR) system. In vivo [Formula: see text] and [Formula: see text] values are reported for white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) for automatic segmentation regions and manual regions of interest (ROIs). RESULTS [Formula: see text] sample measurements on the MRI system were within 10% of the NMR measurement for 9 samples, and one sample was within 11%. Eight [Formula: see text] sample MRI measurements were within 25% of the NMR measurement, and the two longest [Formula: see text] samples had more than 25% variation. Automatic segmentations generally resulted in larger [Formula: see text] and [Formula: see text] estimates than manual ROIs. DISCUSSION [Formula: see text] and [Formula: see text] times for brain tissue were measured at 0.064 T. Test samples demonstrated accuracy in WM and GM ranges of values but underestimated long [Formula: see text] in the CSF range. This work contributes to measuring quantitative MRI properties of the human body at a range of field strengths.
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Affiliation(s)
- Kalina V Jordanova
- Physical Measurement Laboratory, National Institute of Standards and Technology, NIST, Boulder, CO, USA.
| | - Michele N Martin
- Physical Measurement Laboratory, National Institute of Standards and Technology, NIST, Boulder, CO, USA
| | - Stephen E Ogier
- Physical Measurement Laboratory, National Institute of Standards and Technology, NIST, Boulder, CO, USA
- Department of Physics, University of Colorado Boulder, Boulder, CO, USA
| | | | - Kathryn E Keenan
- Physical Measurement Laboratory, National Institute of Standards and Technology, NIST, Boulder, CO, USA
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Wei S, Wei Z, Wang Z, Wang H, He Q, He H, Li L, Yang W. Optimization design of a permanent magnet used for a low field (0.2 T) movable MRI system. MAGMA (NEW YORK, N.Y.) 2023:10.1007/s10334-023-01090-2. [PMID: 37081246 DOI: 10.1007/s10334-023-01090-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 04/06/2023] [Accepted: 04/11/2023] [Indexed: 04/22/2023]
Abstract
OBJECTIVE To design a lightweight permanent magnet for a lowfield movable head imaging MRI system. MATERIALS AND METHODS To reduce the weight of the magnet, the pole pieces, anti-eddy current plates, and shimming rings were removed, and the distance between the two vertical yokes was shortened as much as possible. To compensate for the magnetic field deformation caused by the shortened distance between two vertical iron yokes, two side magnetic poles were added to the vertical yokes. The magnetic field distributions in magnetic poles, the iron yoke, and the spherical imaging region were simulated. Phantom and in vivo head imaging were conducted with a lowfield movable MRI prototype scanner equipped with the proposed permanent magnet. RESULTS A permanent magnet with a center field of 0.19815 T, a homogeneity of 46 ppm over the 20 cm spherical imaging region, and a weight of 654 kg have been achieved. Acceptable images of a phantom and a human brain have been acquired with the prototype MRI scanner. DISCUSSION The proposed permanent magnet design significantly reduces the magnet's weight compared with the conventional magnet structure and shows promise in promoting the development of lowfield compact MRI systems.
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Affiliation(s)
- Shufeng Wei
- Department of Electromagnetic Detection and Imaging Research, Institute of Electrical Engineering, Chinese Academy of Sciences, Zhongguancun Beiertiao NO.6, Beijing, 100190, China
| | - Zhao Wei
- Department of Electromagnetic Detection and Imaging Research, Institute of Electrical Engineering, Chinese Academy of Sciences, Zhongguancun Beiertiao NO.6, Beijing, 100190, China
| | - Zheng Wang
- Department of Electromagnetic Detection and Imaging Research, Institute of Electrical Engineering, Chinese Academy of Sciences, Zhongguancun Beiertiao NO.6, Beijing, 100190, China
| | - Huixian Wang
- Department of Electromagnetic Detection and Imaging Research, Institute of Electrical Engineering, Chinese Academy of Sciences, Zhongguancun Beiertiao NO.6, Beijing, 100190, China
| | - Qingyuan He
- Peking University Third Hospital, Beijing, 100191, China
| | - Hongyan He
- Department of Electromagnetic Detection and Imaging Research, Institute of Electrical Engineering, Chinese Academy of Sciences, Zhongguancun Beiertiao NO.6, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lei Li
- Department of Electromagnetic Detection and Imaging Research, Institute of Electrical Engineering, Chinese Academy of Sciences, Zhongguancun Beiertiao NO.6, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wenhui Yang
- Department of Electromagnetic Detection and Imaging Research, Institute of Electrical Engineering, Chinese Academy of Sciences, Zhongguancun Beiertiao NO.6, Beijing, 100190, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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8
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Perron S, Ouriadov A. Hyperpolarized 129Xe MRI at low field: Current status and future directions. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 348:107387. [PMID: 36731353 DOI: 10.1016/j.jmr.2023.107387] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 12/07/2022] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Magnetic Resonance Imaging (MRI) is dictated by the magnetization of the sample, and is thus a low-sensitivity imaging method. Inhalation of hyperpolarized (HP) noble gases, such as helium-3 and xenon-129, is a non-invasive, radiation-risk free imaging technique permitting high resolution imaging of the lungs and pulmonary functions, such as the lung microstructure, diffusion, perfusion, gas exchange, and dynamic ventilation. Instead of increasing the magnetic field strength, the higher spin polarization achievable from this method results in significantly higher net MR signal independent of tissue/water concentration. Moreover, the significantly longer apparent transverse relaxation time T2* of these HP gases at low magnetic field strengths results in fewer necessary radiofrequency (RF) pulses, permitting larger flip angles; this allows for high-sensitivity imaging of in vivo animal and human lungs at conventionally low (<0.5 T) field strengths and suggests that the low field regime is optimal for pulmonary MRI using hyperpolarized gases. In this review, theory on the common spin-exchange optical-pumping method of hyperpolarization and the field dependence of the MR signal of HP gases are presented, in the context of human lung imaging. The current state-of-the-art is explored, with emphasis on both MRI hardware (low field scanners, RF coils, and polarizers) and image acquisition techniques (pulse sequences) advancements. Common challenges surrounding imaging of HP gases and possible solutions are discussed, and the future of low field hyperpolarized gas MRI is posed as being a clinically-accessible and versatile imaging method, circumventing the siting restrictions of conventional high field scanners and bringing point-of-care pulmonary imaging to global facilities.
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Affiliation(s)
- Samuel Perron
- Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada.
| | - Alexei Ouriadov
- Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada; School of Biomedical Engineering, Faculty of Engineering, The University of Western Ontario, London, Ontario, Canada
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9
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Arnold TC, Freeman CW, Litt B, Stein JM. Low-field MRI: Clinical promise and challenges. J Magn Reson Imaging 2023; 57:25-44. [PMID: 36120962 PMCID: PMC9771987 DOI: 10.1002/jmri.28408] [Citation(s) in RCA: 63] [Impact Index Per Article: 63.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 02/03/2023] Open
Abstract
Modern MRI scanners have trended toward higher field strengths to maximize signal and resolution while minimizing scan time. However, high-field devices remain expensive to install and operate, making them scarce outside of high-income countries and major population centers. Low-field strength scanners have drawn renewed academic, industry, and philanthropic interest due to advantages that could dramatically increase imaging access, including lower cost and portability. Nevertheless, low-field MRI still faces inherent limitations in image quality that come with decreased signal. In this article, we review advantages and disadvantages of low-field MRI scanners, describe hardware and software innovations that accentuate advantages and mitigate disadvantages, and consider clinical applications for a new generation of low-field devices. In our review, we explore how these devices are being or could be used for high acuity brain imaging, outpatient neuroimaging, MRI-guided procedures, pediatric imaging, and musculoskeletal imaging. Challenges for their successful clinical translation include selecting and validating appropriate use cases, integrating with standards of care in high resource settings, expanding options with actionable information in low resource settings, and facilitating health care providers and clinical practice in new ways. By embracing both the promise and challenges of low-field MRI, clinicians and researchers have an opportunity to transform medical care for patients around the world. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 6.
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Affiliation(s)
- Thomas Campbell Arnold
- Department of Bioengineering, School of Engineering & Applied ScienceUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
- Center for Neuroengineering and TherapeuticsUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Colbey W. Freeman
- Department of Radiology, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Brian Litt
- Center for Neuroengineering and TherapeuticsUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
- Department of Neurology, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Joel M. Stein
- Center for Neuroengineering and TherapeuticsUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
- Department of Radiology, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
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10
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Srinivas SA, Cauley SF, Stockmann JP, Sappo CR, Vaughn CE, Wald LL, Grissom WA, Cooley CZ. External Dynamic InTerference Estimation and Removal (EDITER) for low field MRI. Magn Reson Med 2022; 87:614-628. [PMID: 34480778 PMCID: PMC8920578 DOI: 10.1002/mrm.28992] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 07/25/2021] [Accepted: 08/10/2021] [Indexed: 02/03/2023]
Abstract
PURPOSE Point-of-care MRI requires operation outside of Faraday shielded rooms normally used to block image-degrading electromagnetic interference (EMI). To address this, we introduce the EDITER method (External Dynamic InTerference Estimation and Removal), an external sensor-based method to retrospectively remove image artifacts from time-varying external interference sources. THEORY AND METHODS The method acquires data from multiple EMI detectors (tuned receive coils as well as untuned electrodes placed on the body) simultaneously with the primary MR coil during and between image data acquisition. We calculate impulse response functions dynamically that map the data from the detectors to the time varying artifacts then remove the transformed detected EMI from the MR data. Performance of the EDITER algorithm was assessed in phantom and in vivo imaging experiments in an 80 mT portable brain MRI in a controlled EMI environment and with an open 47.5 mT MRI scanner in an uncontrolled EMI setting. RESULTS In the controlled setting, the effectiveness of the EDITER technique was demonstrated for specific types of introduced EMI sources with up to a 97% reduction of structured EMI and up to 76% reduction of broadband EMI in phantom experiments. In the uncontrolled EMI experiments, we demonstrate EMI reductions of up to 99% using an electrode and pick-up coil in vivo. We demonstrate up to a nine-fold improvement in image SNR with the method. CONCLUSION The EDITER technique is a flexible and robust method to improve image quality in portable MRI systems with minimal passive shielding and could reduce the reliance of MRI on shielded rooms and allow for truly portable MRI.
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Affiliation(s)
- Sai Abitha Srinivas
- Vanderbilt University Institute of imaging science, Nashville, TN, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
| | - Stephen F Cauley
- Harvard Medical School, Boston, MA, United States
- Dept. of Radiology, Massachusetts General Hospital, Athinoula A Martinos Center for Biomedical Imaging, Boston, MA, United States
| | - Jason P Stockmann
- Harvard Medical School, Boston, MA, United States
- Dept. of Radiology, Massachusetts General Hospital, Athinoula A Martinos Center for Biomedical Imaging, Boston, MA, United States
| | - Charlotte R Sappo
- Vanderbilt University Institute of imaging science, Nashville, TN, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
| | - Christopher E Vaughn
- Vanderbilt University Institute of imaging science, Nashville, TN, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
| | - Lawrence L Wald
- Harvard Medical School, Boston, MA, United States
- Dept. of Radiology, Massachusetts General Hospital, Athinoula A Martinos Center for Biomedical Imaging, Boston, MA, United States
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, United States
| | - William A Grissom
- Vanderbilt University Institute of imaging science, Nashville, TN, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Electrical Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Radiology, Vanderbilt University, Nashville, TN, United States
| | - Clarissa Z Cooley
- Harvard Medical School, Boston, MA, United States
- Dept. of Radiology, Massachusetts General Hospital, Athinoula A Martinos Center for Biomedical Imaging, Boston, MA, United States
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11
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Liu Y, Leong ATL, Zhao Y, Xiao L, Mak HKF, Tsang ACO, Lau GKK, Leung GKK, Wu EX. A low-cost and shielding-free ultra-low-field brain MRI scanner. Nat Commun 2021; 12:7238. [PMID: 34907181 PMCID: PMC8671508 DOI: 10.1038/s41467-021-27317-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 11/10/2021] [Indexed: 12/21/2022] Open
Abstract
Magnetic resonance imaging is a key diagnostic tool in modern healthcare, yet it can be cost-prohibitive given the high installation, maintenance and operation costs of the machinery. There are approximately seven scanners per million inhabitants and over 90% are concentrated in high-income countries. We describe an ultra-low-field brain MRI scanner that operates using a standard AC power outlet and is low cost to build. Using a permanent 0.055 Tesla Samarium-cobalt magnet and deep learning for cancellation of electromagnetic interference, it requires neither magnetic nor radiofrequency shielding cages. The scanner is compact, mobile, and acoustically quiet during scanning. We implement four standard clinical neuroimaging protocols (T1- and T2-weighted, fluid-attenuated inversion recovery like, and diffusion-weighted imaging) on this system, and demonstrate preliminary feasibility in diagnosing brain tumor and stroke. Such technology has the potential to meet clinical needs at point of care or in low and middle income countries.
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Affiliation(s)
- Yilong Liu
- grid.194645.b0000000121742757Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR China ,grid.194645.b0000000121742757Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR China
| | - Alex T. L. Leong
- grid.194645.b0000000121742757Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR China ,grid.194645.b0000000121742757Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR China
| | - Yujiao Zhao
- grid.194645.b0000000121742757Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR China ,grid.194645.b0000000121742757Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR China
| | - Linfang Xiao
- grid.194645.b0000000121742757Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR China ,grid.194645.b0000000121742757Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR China
| | - Henry K. F. Mak
- grid.194645.b0000000121742757Department of Diagnostic Radiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR China
| | - Anderson Chun On Tsang
- grid.194645.b0000000121742757Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR China
| | - Gary K. K. Lau
- grid.194645.b0000000121742757Division of Neurology, Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR China
| | - Gilberto K. K. Leung
- grid.194645.b0000000121742757Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR China
| | - Ed X. Wu
- grid.194645.b0000000121742757Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR China ,grid.194645.b0000000121742757Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR China ,grid.194645.b0000000121742757School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR China
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12
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Portable, bedside, low-field magnetic resonance imaging for evaluation of intracerebral hemorrhage. Nat Commun 2021; 12:5119. [PMID: 34433813 PMCID: PMC8387402 DOI: 10.1038/s41467-021-25441-6] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 08/05/2021] [Indexed: 02/07/2023] Open
Abstract
Radiological examination of the brain is a critical determinant of stroke care pathways. Accessible neuroimaging is essential to detect the presence of intracerebral hemorrhage (ICH). Conventional magnetic resonance imaging (MRI) operates at high magnetic field strength (1.5-3 T), which requires an access-controlled environment, rendering MRI often inaccessible. We demonstrate the use of a low-field MRI (0.064 T) for ICH evaluation. Patients were imaged using conventional neuroimaging (non-contrast computerized tomography (CT) or 1.5/3 T MRI) and portable MRI (pMRI) at Yale New Haven Hospital from July 2018 to November 2020. Two board-certified neuroradiologists evaluated a total of 144 pMRI examinations (56 ICH, 48 acute ischemic stroke, 40 healthy controls) and one ICH imaging core lab researcher reviewed the cases of disagreement. Raters correctly detected ICH in 45 of 56 cases (80.4% sensitivity, 95%CI: [0.68-0.90]). Blood-negative cases were correctly identified in 85 of 88 cases (96.6% specificity, 95%CI: [0.90-0.99]). Manually segmented hematoma volumes and ABC/2 estimated volumes on pMRI correlate with conventional imaging volumes (ICC = 0.955, p = 1.69e-30 and ICC = 0.875, p = 1.66e-8, respectively). Hematoma volumes measured on pMRI correlate with NIH stroke scale (NIHSS) and clinical outcome (mRS) at discharge for manual and ABC/2 volumes. Low-field pMRI may be useful in bringing advanced MRI technology to resource-limited settings.
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13
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Natukunda F, Twongyirwe TM, Schiff SJ, Obungoloch J. Approaches in cooling of resistive coil-based low-field Magnetic Resonance Imaging (MRI) systems for application in low resource settings. BMC Biomed Eng 2021; 3:3. [PMID: 33579373 PMCID: PMC7881601 DOI: 10.1186/s42490-021-00048-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 02/02/2021] [Indexed: 11/10/2022] Open
Abstract
Magnetic Resonance Imaging (MRI), a non-invasive method for the diagnosis of diverse health conditions has experienced growing popularity over other imaging modalities like ultrasound and Computer Tomography. Initially, proof-of-concept and earlier MRI systems were based on resistive and permanent magnet technology. However, superconducting magnets have long held monopoly of the market for MRI systems with their high-field (HF) strength capability, although they present high construction, installation, and siting requirements. Such stringent prerequisites restrict their availability and use in low-middle income countries. Resistive coil-based magnet, albeit low-field (LF) in capacity, represent a plausible boost for the availability and use of MRI systems in resource constrained settings. These systems are characterized by low costs coupled with substantial image quality for diagnosis of some conditions such as hydrocephalus common is such regions. However, the nature of resistive coils causes them to heat up during operation, thus necessitating a dedicated cooling system to improve image quality and enhance system longevity. This paper explores a range of cooling methods as have been applied to resistive magnets, citing their pros and cons and areas for improvement.
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Affiliation(s)
- Faith Natukunda
- Department of Biomedical Engineering, Mbarara University of Science and Technology, Mbarara, Uganda.
| | - Theodora M Twongyirwe
- Department of Mechanical Engineering, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Steven J Schiff
- Centre for Neural Engineering, Departments of Engineering Science and Mechanics, Neurosurgery, and Physics, The Pennsylvania State University, Pennsylvania, USA
| | - Johnes Obungoloch
- Department of Biomedical Engineering, Mbarara University of Science and Technology, Mbarara, Uganda
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14
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Wald LL, McDaniel PC, Witzel T, Stockmann JP, Cooley CZ. Low-cost and portable MRI. J Magn Reson Imaging 2020; 52:686-696. [PMID: 31605435 PMCID: PMC10644353 DOI: 10.1002/jmri.26942] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/04/2019] [Indexed: 11/16/2023] Open
Abstract
Research in MRI technology has traditionally expanded diagnostic benefit by developing acquisition techniques and instrumentation to enable MRI scanners to "see more." This typically focuses on improving MRI's sensitivity and spatiotemporal resolution, or expanding its range of biological contrasts and targets. In complement to the clear benefits achieved in this direction, extending the reach of MRI by reducing its cost, siting, and operational burdens also directly benefits healthcare by increasing the number of patients with access to MRI examinations and tilting its cost-benefit equation to allow more frequent and varied use. The introduction of low-cost, and/or truly portable scanners, could also enable new point-of-care and monitoring applications not feasible for today's scanners in centralized settings. While cost and accessibility have always been considered, we have seen tremendous advances in the speed and spatial-temporal capabilities of general-purpose MRI scanners and quantum leaps in patient comfort (such as magnet length and bore diameter), but only modest success in the reduction of cost and siting constraints. The introduction of specialty scanners (eg, extremity, brain-only, or breast-only scanners) have not been commercially successful enough to tilt the balance away from the prevailing model: a general-purpose scanner in a centralized healthcare location. Portable MRI scanners equivalent to their counterparts in ultrasound or even computed tomography have not emerged and MR monitoring devices exist only in research laboratories. Nonetheless, recent advances in hardware and computational technology as well as burgeoning markets for MRI in the developing world has created a resurgence of interest in the topic of low-cost and accessible MRI. This review examines the technical forces and trade-offs that might facilitate a large step forward in the push to "jail-break" MRI from its centralized location in healthcare and allow it to reach larger patient populations and achieve new uses. Level of Evidence: 5 Technical Efficacy Stage: 6 J. Magn. Reson. Imaging 2019. J. Magn. Reson. Imaging 2020;52:686-696.
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Affiliation(s)
- Lawrence L. Wald
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
- Division of Health Sciences and Technology, Harvard – Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Patrick C. McDaniel
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Thomas Witzel
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Jason P. Stockmann
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Clarissa Zimmerman Cooley
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
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15
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Waddington DEJ, Boele T, Maschmeyer R, Kuncic Z, Rosen MS. High-sensitivity in vivo contrast for ultra-low field magnetic resonance imaging using superparamagnetic iron oxide nanoparticles. SCIENCE ADVANCES 2020; 6:eabb0998. [PMID: 32733998 PMCID: PMC7367688 DOI: 10.1126/sciadv.abb0998] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 06/03/2020] [Indexed: 05/04/2023]
Abstract
Magnetic resonance imaging (MRI) scanners operating at ultra-low magnetic fields (ULF; <10 mT) are uniquely positioned to reduce the cost and expand the clinical accessibility of MRI. A fundamental challenge for ULF MRI is obtaining high-contrast images without compromising acquisition sensitivity to the point that scan times become clinically unacceptable. Here, we demonstrate that the high magnetization of superparamagnetic iron oxide nanoparticles (SPIONs) at ULF makes possible relaxivity- and susceptibility-based effects unachievable with conventional contrast agents (CAs). We leverage these effects to acquire high-contrast images of SPIONs in a rat model with ULF MRI using short scan times. This work overcomes a key limitation of ULF MRI by enabling in vivo imaging of biocompatible CAs. These results open a new clinical translation pathway for ULF MRI and have broader implications for disease detection with low-field portable MRI scanners.
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Affiliation(s)
- David E. J. Waddington
- Institute of Medical Physics, School of Physics A28, University of Sydney, Sydney, NSW 2006, Australia
- A. A. Martinos Center for Biomedical Imaging, 149 Thirteenth St., Charlestown, MA 02129, USA
- ACRF Image X Institute, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2006, Australia
| | - Thomas Boele
- A. A. Martinos Center for Biomedical Imaging, 149 Thirteenth St., Charlestown, MA 02129, USA
- ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, University of Sydney, Sydney, NSW 2006, Australia
| | - Richard Maschmeyer
- Institute of Medical Physics, School of Physics A28, University of Sydney, Sydney, NSW 2006, Australia
| | - Zdenka Kuncic
- Institute of Medical Physics, School of Physics A28, University of Sydney, Sydney, NSW 2006, Australia
- The University of Sydney Nano Institute, Sydney, NSW 2006, Australia
| | - Matthew S. Rosen
- A. A. Martinos Center for Biomedical Imaging, 149 Thirteenth St., Charlestown, MA 02129, USA
- Department of Physics, Harvard University, 17 Oxford St., Cambridge, MA 02138, USA
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA
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16
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McDaniel PC, Cooley CZ, Stockmann JP, Wald LL. The MR Cap: A single-sided MRI system designed for potential point-of-care limited field-of-view brain imaging. Magn Reson Med 2019; 82:1946-1960. [PMID: 31231885 DOI: 10.1002/mrm.27861] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/06/2019] [Accepted: 05/23/2019] [Indexed: 01/08/2023]
Abstract
PURPOSE The size, cost, and siting requirements of conventional MRI systems limit their availability and preclude usage as monitoring or point-of-care devices. To address this, we developed a lightweight MRI for point-of-care brain imaging over a reduced field of view (FOV). METHODS The B0 magnet was designed with a genetic algorithm optimizing homogeneity over a 3 × 8 × 8 cm FOV and a built-in gradient for slice selection or readout encoding. An external pair of gradient coils enables phase encoding in the other two directions and a radiofrequency (RF) coil provides excitation and detection. The system was demonstrated with high-resolution 1D "depth profiling" and 3D phantom imaging. RESULTS The lightweight B0 magnet achieved a 64-mT average field over the imaging region at a materials cost of <$450 USD. The weight of the magnet, gradient, and RF coil was 8.3 kg. Depth profiles were obtained at high resolution (0.89 mm) and multislice rapid acquisition with refocused echoes (RARE) images were obtained with a resolution ~2 mm in-plane and ~6-mm slice thickness, each in an imaging time of 11 min. CONCLUSION The system demonstrates the feasibility of a lightweight brain MRI system capable of 1D to 3D imaging within a reduced FOV. The proposed system is low-cost and small enough to be used in point-of-care applications.
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Affiliation(s)
- Patrick C McDaniel
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts.,Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts
| | - Clarissa Zimmerman Cooley
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts.,Harvard Medical School, Boston, Massachusetts
| | - Jason P Stockmann
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts.,Harvard Medical School, Boston, Massachusetts
| | - Lawrence L Wald
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts.,Harvard Medical School, Boston, Massachusetts.,Division of Health Sciences and Technology, Harvard-Massachusetts Institute of Technology, Cambridge, Massachusetts
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17
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Geethanath S, Vaughan JT. Accessible magnetic resonance imaging: A review. J Magn Reson Imaging 2019; 49:e65-e77. [DOI: 10.1002/jmri.26638] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 12/15/2018] [Accepted: 12/17/2018] [Indexed: 02/01/2023] Open
Affiliation(s)
- Sairam Geethanath
- Columbia Magnetic Resonance Research CenterColumbia University in the City of New York New York USA
| | - John Thomas Vaughan
- Columbia Magnetic Resonance Research CenterColumbia University in the City of New York New York USA
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18
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Griffiths PD, Jarvis D, Armstrong L, Connolly DJA, Bayliss P, Cook J, Hart AR, Pilling E, Williams T, Paley MNJ. Initial experience of an investigational 3T MR scanner designed for use on neonatal wards. Eur Radiol 2018; 28:4438-4446. [PMID: 29713778 PMCID: PMC6132701 DOI: 10.1007/s00330-018-5357-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/25/2018] [Accepted: 01/26/2018] [Indexed: 11/30/2022]
Abstract
OBJECTIVES MR imaging of neonates is difficult for many reasons and a major factor is safe transport to the MR facilities. In this article we describe the use of a small, investigational 3-T MR customised for brain imaging and sited on a neonatal unit of a tertiary centre in the UK, which is in contrast to a 300-m journey to the whole-body MR scanner used at present for clinical cases. METHODS We describe our methods for preparing babies for safe transport and scanning on an investigational 3-T MR scanner on a neonatal unit and the development of appropriate MR sequences. The MR scanner does not have CE marking at present so this early development work was undertaken on normal neonates whose parents consented to a research examination. RESULTS Fifty-two babies were scanned and there were no serious adverse events. The MR examinations were considered to be diagnostically evaluable in all 52 cases and in 90% the imaging was considered to be at least as good as the quality obtained on the 1.5-T scanner currently used for clinical cases. CONCLUSION We have shown that this investigational 3-T MR scanner can be used safely on a neonatal unit and we have refined the MR sequences to a point that they are clinically usable. KEY POINTS • Access to neonatal MR imaging is limited. • We describe an investigational 3-T MR scanner site on a neonatal unit. • The scanner produces images suitable for clinical practice.
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Affiliation(s)
- Paul D Griffiths
- Academic Unit of Radiology, University of Sheffield, Floor C Royal Hallamshire Hospital Glossop Road, Sheffield, S10 2JF, UK.
| | - Deborah Jarvis
- Academic Unit of Radiology, University of Sheffield, Floor C Royal Hallamshire Hospital Glossop Road, Sheffield, S10 2JF, UK
| | - Leanne Armstrong
- Academic Unit of Radiology, University of Sheffield, Floor C Royal Hallamshire Hospital Glossop Road, Sheffield, S10 2JF, UK
| | | | - Pauline Bayliss
- Sheffield Teaching Hospitals Foundation Trust, Sheffield, UK
| | - Julie Cook
- Sheffield Teaching Hospitals Foundation Trust, Sheffield, UK
| | - Anthony R Hart
- Sheffield Children's Hospitals Foundation Trust, Sheffield, UK
| | | | | | - Martyn N J Paley
- Academic Unit of Radiology, University of Sheffield, Floor C Royal Hallamshire Hospital Glossop Road, Sheffield, S10 2JF, UK
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19
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Obungoloch J, Harper JR, Consevage S, Savukov IM, Neuberger T, Tadigadapa S, Schiff SJ. Design of a sustainable prepolarizing magnetic resonance imaging system for infant hydrocephalus. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2018; 31:665-676. [PMID: 29644479 DOI: 10.1007/s10334-018-0683-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 03/11/2018] [Accepted: 03/15/2018] [Indexed: 10/17/2022]
Abstract
OBJECTIVES The need for affordable and appropriate medical technologies for developing countries continues to rise as challenges such as inadequate energy supply, limited technical expertise, and poor infrastructure persist. Low-field magnetic resonance imaging (LF MRI) is a technology that can be tailored to meet specific imaging needs within such countries. Its low power requirements and the possibility of operating in minimally shielded or unshielded environments make it especially attractive. Although the technology has been widely demonstrated over several decades, it is yet to be shown that it can be diagnostic and improve patient outcomes in clinical applications. We here demonstrate the robustness of prepolarizing MRI (PMRI) technology for assembly and deployment in developing countries for the specific application to infant hydrocephalus. Hydrocephalus treatment planning and management requires only modest spatial resolution, such that the brain can be distinguished from fluid-tissue contrast detail within the brain parenchyma is not essential. MATERIALS AND METHODS We constructed an internally shielded PMRI system based on the Lee-Whiting coil system with a 22-cm diameter of spherical volume. RESULTS In an unshielded room, projection phantom images were acquired at 113 kHz with in-plane resolution of 3 mm × 3 mm, by introducing gradient fields of sufficient magnitude to dominate the 5000 ppm inhomogeneity of the readout field. DISCUSSION The low cost, straightforward assembly, deployment potential, and maintenance requirements demonstrate the suitability of our PMRI system for developing countries. Further improvement in image spatial resolution and contrast of LF MRI will broaden its potential clinical utility beyond hydrocephalus.
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Affiliation(s)
- Johnes Obungoloch
- Center for Neural Engineering, The Pennsylvania State University, University Park, 16802, USA.,Department of Biomedical Engineering, The Pennsylvania State University, University Park, 16802, USA.,Mbarara University of Science and Technology, P.O Box 1410, Mbarara, Uganda
| | - Joshua R Harper
- Center for Neural Engineering, The Pennsylvania State University, University Park, 16802, USA.,Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, 16802, USA
| | - Steven Consevage
- Center for Neural Engineering, The Pennsylvania State University, University Park, 16802, USA.,Department of Physics, The Pennsylvania State University, University Park, 16802, USA
| | | | - Thomas Neuberger
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, 16802, USA.,The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, 16802, USA
| | - Srinivas Tadigadapa
- Department of Electrical Engineering, The Pennsylvania State University, University Park, 16802, USA
| | - Steven J Schiff
- Center for Neural Engineering, The Pennsylvania State University, University Park, 16802, USA. .,Department of Biomedical Engineering, The Pennsylvania State University, University Park, 16802, USA. .,Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, 16802, USA. .,Department of Physics, The Pennsylvania State University, University Park, 16802, USA. .,Department of Neurosurgery, Penn State College of Medicine, Hershey, 17033, USA.
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