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Murali S, Ding H, Adedeji F, Qin C, Obungoloch J, Asllani I, Anazodo U, Ntusi NAB, Mammen R, Niendorf T, Adeleke S. Bringing MRI to low- and middle-income countries: Directions, challenges and potential solutions. NMR IN BIOMEDICINE 2024; 37:e4992. [PMID: 37401341 DOI: 10.1002/nbm.4992] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 05/27/2023] [Accepted: 05/30/2023] [Indexed: 07/05/2023]
Abstract
The global disparity of magnetic resonance imaging (MRI) is a major challenge, with many low- and middle-income countries (LMICs) experiencing limited access to MRI. The reasons for limited access are technological, economic and social. With the advancement of MRI technology, we explore why these challenges still prevail, highlighting the importance of MRI as the epidemiology of disease changes in LMICs. In this paper, we establish a framework to develop MRI with these challenges in mind and discuss the different aspects of MRI development, including maximising image quality using cost-effective components, integrating local technology and infrastructure and implementing sustainable practices. We also highlight the current solutions-including teleradiology, artificial intelligence and doctor and patient education strategies-and how these might be further improved to achieve greater access to MRI.
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Affiliation(s)
- Sanjana Murali
- School of Medicine, Faculty of Medicine, Imperial College London, London, UK
| | - Hao Ding
- School of Medicine, Faculty of Medicine, Imperial College London, London, UK
| | - Fope Adedeji
- School of Medicine, Faculty of Medicine, University College London, London, UK
| | - Cathy Qin
- Department of Imaging, Imperial College Healthcare NHS Trust, London, UK
| | - Johnes Obungoloch
- Department of Biomedical Engineering, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Iris Asllani
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Udunna Anazodo
- Department of Medical Biophysics, Western University, London, Ontario, Canada
- The Research Institute of London Health Sciences Centre and St. Joseph's Health Care, London, Ontario, Canada
| | - Ntobeko A B Ntusi
- Department of Medicine, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa
- South African Medical Research Council Extramural Unit on Intersection of Noncommunicable Diseases and Infectious Diseases, Cape Town, South Africa
| | - Regina Mammen
- Department of Cardiology, The Essex Cardiothoracic Centre, Basildon, UK
| | - Thoralf Niendorf
- Berlin Ultrahigh Field Facility (BUFF), Max-Delbrück Centre for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Sola Adeleke
- School of Cancer & Pharmaceutical Sciences, King's College London, London, UK
- High Dimensional Neuro-oncology, University College London Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London, London, UK
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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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Kotecha M, Wang L, Hameed S, Viswakarma N, Ma M, Stabler C, Hoesli CA, Epel B. In vitro oxygen imaging of acellular and cell-loaded beta cell replacement devices. Sci Rep 2023; 13:15641. [PMID: 37730815 PMCID: PMC10511476 DOI: 10.1038/s41598-023-42099-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 09/05/2023] [Indexed: 09/22/2023] Open
Abstract
Type 1 diabetes (T1D) is an autoimmune disease that leads to the loss of insulin-producing beta cells. Bioartificial pancreas (BAP) or beta cell replacement strategies have shown promise in curing T1D and providing long-term insulin independence. Hypoxia (low oxygen concentration) that may occur in the BAP devices due to cell oxygen consumption at the early stages after implantation damages the cells, in addition to imposing limitations to device dimensions when translating promising results from rodents to humans. Finding ways to provide cells with sufficient oxygenation remains the major challenge in realizing BAP devices' full potential. Therefore, in vitro oxygen imaging assessment of BAP devices is crucial for predicting the devices' in vivo efficiency. Electron paramagnetic resonance oxygen imaging (EPROI, also known as electron MRI or eMRI) is a unique imaging technique that delivers absolute partial pressure of oxygen (pO2) maps and has been used for cancer hypoxia research for decades. However, its applicability for assessing BAP devices has not been explored. EPROI utilizes low magnetic fields in the mT range, static gradients, and the linear relationship between the spin-lattice relaxation rate (R1) of oxygen-sensitive spin probes such as trityl OX071 and pO2 to generate oxygen maps in tissues. With the support of the Juvenile Diabetes Research Foundation (JDRF), an academic-industry partnership consortium, the "Oxygen Measurement Core" was established at O2M to perform oxygen imaging assessment of BAP devices originated from core members' laboratories. This article aims to establish the protocols and demonstrate a few examples of in vitro oxygen imaging of BAP devices using EPROI. All pO2 measurements were performed using a recently introduced 720 MHz/25 mT preclinical oxygen imager instrument, JIVA-25™. We began by performing pO2 calibration of the biomaterials used in BAPs at 25 mT magnetic field since no such data exist. We compared the EPROI pO2 measurement with a single-point probe for a few selected materials. We also performed trityl OX071 toxicity studies with fibroblasts, as well as insulin-producing cells (beta TC6, MIN6, and human islet cells). Finally, we performed proof-of-concept in vitro pO2 imaging of five BAP devices that varied in size, shape, and biomaterials. We demonstrated that EPROI is compatible with commonly used biomaterials and that trityl OX071 is nontoxic to cells. A comparison of the EPROI with a fluorescent-based point oxygen probe in selected biomaterials showed higher accuracy of EPROI. The imaging of typically heterogenous BAP devices demonstrated the utility of obtaining oxygen maps over single-point measurements. In summary, we present EPROI as a quality control tool for developing efficient cell transplantation devices and artificial tissue grafts. Although the focus of this work is encapsulation systems for diabetes, the techniques developed in this project are easily transferable to other biomaterials, tissue grafts, and cell therapy devices used in the field of tissue engineering and regenerative medicine (TERM). In summary, EPROI is a unique noninvasive tool to experimentally study oxygen distribution in cell transplantation devices and artificial tissues, which can revolutionize the treatment of degenerative diseases like T1D.
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Affiliation(s)
- Mrignayani Kotecha
- Oxygen Measurement Core, O2M Technologies, LLC, Chicago, IL, 60612, USA.
| | - Longhai Wang
- Department of Biological and Environmental Engineering, Cornell University, NY, 14853, USA
| | - Safa Hameed
- Oxygen Measurement Core, O2M Technologies, LLC, Chicago, IL, 60612, USA
| | - Navin Viswakarma
- Oxygen Measurement Core, O2M Technologies, LLC, Chicago, IL, 60612, USA
| | - Minglin Ma
- Department of Biological and Environmental Engineering, Cornell University, NY, 14853, USA
| | - Cherie Stabler
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Corinne A Hoesli
- Department of Chemical Engineering, McGill University, Montreal, QC, H3C 0C5, Canada
| | - Boris Epel
- Oxygen Measurement Core, O2M Technologies, LLC, Chicago, IL, 60612, USA
- Department of Radiation and Cellular Oncology, The University of Chicago, Chicago, IL, 60637, USA
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de Iure D, Conti A, Galante A, Spadone S, Hilschenz I, Caulo M, Sensi S, Del Gratta C, Della Penna S. Analyzing the sensitivity of quantitative 3D MRI of longitudinal relaxation at very low field in Gd-doped phantoms. PLoS One 2023; 18:e0285391. [PMID: 37146058 PMCID: PMC10162526 DOI: 10.1371/journal.pone.0285391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 04/20/2023] [Indexed: 05/07/2023] Open
Abstract
PURPOSE Recently, new MRI systems working at magnetic field below 10 mT (Very and Ultra Low Field regime) have been developed, showing improved T1-contrast in projected 2D maps (i.e. images without slice selection). Moving from projected 2D to 3D maps is not trivial due to the low SNR of such devices. This work aimed to demonstrate the ability and the sensitivity of a VLF-MRI scanner operating at 8.9 mT in quantitatively obtaining 3D longitudinal relaxation rate (R1) maps and distinguishing between voxels intensities. We used phantoms consisting of vessels doped with different Gadolinium (Gd)-based Contrast Agent (CA) concentrations, providing a set of various R1 values. As CA, we used a commercial compound (MultiHance®, gadobenate dimeglumine) routinely used in clinical MRI. METHODS 3D R1 maps and T1-weighted MR images were analysed to identify each vessel. R1 maps were further processed by an automatic clustering analysis to evaluate the sensitivity at the single-voxel level. Results obtained at 8.9 mT were compared with commercial scanners operating at 0.2 T, 1.5 T, and 3 T. RESULTS VLF R1 maps offered a higher sensitivity in distinguishing the different CA concentrations and an improved contrast compared to higher fields. Moreover, the high sensitivity of 3D quantitative VLF-MRI allowed an effective clustering of the 3D map values, assessing their reliability at the single voxel level. Conversely, in all fields, T1-weighted images were less reliable, even at higher CA concentrations. CONCLUSION In summary, with few excitations and an isotropic voxel size of 3 mm, VLF-MRI 3D quantitative mapping showed a sensitivity better than 2.7 s-1 corresponding to a concentration difference of 0.17 mM of MultiHance in copper sulfate doped water, and improved contrast compared to higher fields. Based on these results, future studies should characterize R1 contrast at VLF, also with other CA, in the living tissues.
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Affiliation(s)
- Danilo de Iure
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
| | - Allegra Conti
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
- Medical Physics Section, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Angelo Galante
- MESVA, Department of Life, Health & Environmental Sciences, L'Aquila University, L'Aquila, AQ, Italy
- INFN, National Institute of Nuclear Physics, Gran Sasso National Laboratories, Assergi, L'Aquila, Italy
- CNR, SPIN-CNR Institute, Dept. of Physical and Chemical Sciences, L'Aquila, Italy
| | - Sara Spadone
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
| | - Ingo Hilschenz
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
| | - Massimo Caulo
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
- Institute for Advanced Biomedical Technologies (ITAB), G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
| | - Stefano Sensi
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
- Institute for Advanced Biomedical Technologies (ITAB), G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
| | - Cosimo Del Gratta
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
- Institute for Advanced Biomedical Technologies (ITAB), G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
| | - Stefania Della Penna
- Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
- Institute for Advanced Biomedical Technologies (ITAB), G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy
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Su J, Pellicer-Guridi R, Edwards T, Fuentes M, Rosen MS, Vegh V, Reutens D. A CNN Based Software Gradiometer for Electromagnetic Background Noise Reduction in Low Field MRI Applications. IEEE TRANSACTIONS ON MEDICAL IMAGING 2022; 41:1007-1016. [PMID: 35089856 DOI: 10.1109/tmi.2022.3147450] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The shielding of electromagnetic noise is critical in obtaining magnetic resonance imaging measurements in the ultra-low magnetic field regime where the intrinsic signal-to-noise ratio is very small. The traditional approach of using an enclosure for electromagnetic shielding is expensive and hinders system portability. We describe here the use of a CNN-based software gradiometer to suppress the effect of electromagnetic ambient background noise sources that inductively couple into the signal detection coils. The system involves three ambient noise monitoring coils placed at a distance from the magnetic resonance signal detector. The three coils were used to synthesize the ambient noise captured by the signal detector; a convolutional neural network approach was used. Mathematical foundations are provided to justify the noise suppression framework. The results show that as much as 20-fold noise suppression can be achieved using an optimized convolutional neural network and simultaneous ambient noise measurements. The proposed approach has the potential to replace the requirement for magnetically shielded enclosures and make ultra-low field magnetic resonance imaging truly portable.
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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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Kamimura HAS, Conti A, Toschi N, Konofagou EE. Ultrasound neuromodulation: mechanisms and the potential of multimodal stimulation for neuronal function assessment. FRONTIERS IN PHYSICS 2020; 8:150. [PMID: 32509757 PMCID: PMC7274478 DOI: 10.3389/fphy.2020.00150] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Focused ultrasound (FUS) neuromodulation has shown that mechanical waves can interact with cell membranes and mechanosensitive ion channels, causing changes in neuronal activity. However, the thorough understanding of the mechanisms involved in these interactions are hindered by different experimental conditions for a variety of animal scales and models. While the lack of complete understanding of FUS neuromodulation mechanisms does not impede benefiting from the current known advantages and potential of this technique, a precise characterization of its mechanisms of action and their dependence on experimental setup (e.g., tuning acoustic parameters and characterizing safety ranges) has the potential to exponentially improve its efficacy as well as spatial and functional selectivity. This could potentially reach the cell type specificity typical of other, more invasive techniques e.g., opto- and chemogenetics or at least orientation-specific selectivity afforded by transcranial magnetic stimulation. Here, the mechanisms and their potential overlap are reviewed along with discussions on the potential insights into mechanisms that magnetic resonance imaging sequences along with a multimodal stimulation approach involving electrical, magnetic, chemical, light, and mechanical stimuli can provide.
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Affiliation(s)
- Hermes A. S. Kamimura
- Ultrasound Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New Yor, NY, USA
| | - Allegra Conti
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Nicola Toschi
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
- Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Charlestown, MA, USA
| | - Elisa E. Konofagou
- Ultrasound Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New Yor, NY, USA
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Optimized 3D co-registration of ultra-low-field and high-field magnetic resonance images. PLoS One 2018; 13:e0193890. [PMID: 29509780 PMCID: PMC5839578 DOI: 10.1371/journal.pone.0193890] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 02/19/2018] [Indexed: 12/19/2022] Open
Abstract
The prototypes of ultra-low-field (ULF) MRI scanners developed in recent years represent new, innovative, cost-effective and safer systems, which are suitable to be integrated in multi-modal (Magnetoencephalography and MRI) devices. Integrated ULF-MRI and MEG scanners could represent an ideal solution to obtain functional (MEG) and anatomical (ULF MRI) information in the same environment, without errors that may limit source reconstruction accuracy. However, the low resolution and signal-to-noise ratio (SNR) of ULF images, as well as their limited coverage, do not generally allow for the construction of an accurate individual volume conductor model suitable for MEG localization. Thus, for practical usage, a high-field (HF) MRI image is also acquired, and the HF-MRI images are co-registered to the ULF-MRI ones. We address here this issue through an optimized pipeline (SWIM—Sliding WIndow grouping supporting Mutual information). The co-registration is performed by an affine transformation, the parameters of which are estimated using Normalized Mutual Information as the cost function, and Adaptive Simulated Annealing as the minimization algorithm. The sub-voxel resolution of the ULF images is handled by a sliding-window approach applying multiple grouping strategies to down-sample HF MRI to the ULF-MRI resolution. The pipeline has been tested on phantom and real data from different ULF-MRI devices, and comparison with well-known toolboxes for fMRI analysis has been performed. Our pipeline always outperformed the fMRI toolboxes (FSL and SPM). The HF–ULF MRI co-registration obtained by means of our pipeline could lead to an effective integration of ULF MRI with MEG, with the aim of improving localization accuracy, but also to help exploit ULF MRI in tumor imaging.
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