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Qiu Y, Dai K, Zhong S, Chen S, Wang C, Chen H, Frydman L, Zhang Z. Spatiotemporal encoding MRI in a portable low-field system. Magn Reson Med 2024; 92:1011-1021. [PMID: 38623991 DOI: 10.1002/mrm.30104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 04/17/2024]
Abstract
PURPOSE Demonstrate the potential of spatiotemporal encoding (SPEN) MRI to deliver largely undistorted 2D, 3D, and diffusion weighted images on a 110 mT portable system. METHODS SPEN's quadratic phase modulation was used to subsample the low-bandwidth dimension of echo planar acquisitions, delivering alias-free images with an enhanced immunity to image distortions in a laboratory-built, low-field, portable MRI system lacking multiple receivers. RESULTS Healthy brain images with different SPEN time-bandwidth products and subsampling factors were collected. These compared favorably to EPI acquisitions including topup corrections. Robust 3D and diffusion weighted SPEN images of diagnostic value were demonstrated, with 2.5 mm isotropic resolutions achieved in 3 min scans. This performance took advantage of the low specific absorption rate and relative long TEs associated with low-field MRI. CONCLUSION SPEN MRI provides a robust and advantageous fast acquisition approach to obtain faithful 3D images and DWI data in low-cost, portable, low-field systems without parallel acceleration.
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Affiliation(s)
- Yueqi Qiu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- National Engineering Research Center of Advanced Magnetic Resonance Technologies for Diagnosis and Therapy (NERC-AMRT), Shanghai Jiao Tong University, Shanghai, People's Republic of China
- Institute of Medical Robotics, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Ke Dai
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- National Engineering Research Center of Advanced Magnetic Resonance Technologies for Diagnosis and Therapy (NERC-AMRT), Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Sijie Zhong
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- National Engineering Research Center of Advanced Magnetic Resonance Technologies for Diagnosis and Therapy (NERC-AMRT), Shanghai Jiao Tong University, Shanghai, People's Republic of China
- Institute of Medical Robotics, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Suen Chen
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- National Engineering Research Center of Advanced Magnetic Resonance Technologies for Diagnosis and Therapy (NERC-AMRT), Shanghai Jiao Tong University, Shanghai, People's Republic of China
- Institute of Medical Robotics, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Changyue Wang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Hao Chen
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- National Engineering Research Center of Advanced Magnetic Resonance Technologies for Diagnosis and Therapy (NERC-AMRT), Shanghai Jiao Tong University, Shanghai, People's Republic of China
- Institute of Medical Robotics, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Lucio Frydman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Zhiyong Zhang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- National Engineering Research Center of Advanced Magnetic Resonance Technologies for Diagnosis and Therapy (NERC-AMRT), Shanghai Jiao Tong University, Shanghai, People's Republic of China
- Institute of Medical Robotics, Shanghai Jiao Tong University, Shanghai, People's Republic of China
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Balaji S, Wiley N, Poorman ME, Kolind SH. Low-field MRI for use in neurological diseases. Curr Opin Neurol 2024; 37:381-391. [PMID: 38813835 DOI: 10.1097/wco.0000000000001282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
PURPOSE OF REVIEW To review recent clinical uses of low-field magnetic resonance imaging (MRI) to guide incorporation into neurological practice. RECENT FINDINGS Use of low-field MRI has been demonstrated in applications including tumours, vascular pathologies, multiple sclerosis, brain injury, and paediatrics. Safety, workflow, and image quality have also been evaluated. SUMMARY Low-field MRI has the potential to increase access to critical brain imaging for patients who otherwise may not obtain imaging in a timely manner. This includes areas such as the intensive care unit and emergency room, where patients could be imaged at the point of care rather than be transported to the MRI scanner. Such systems are often more affordable than conventional systems, allowing them to be more easily deployed in resource constrained settings. A variety of systems are available on the market or in a research setting and are currently being used to determine clinical uses for these devices. The utility of such devices must be fully evaluated in clinical scenarios before adoption into standard practice can be achieved. This review summarizes recent clinical uses of low-field MR as well as safety, workflows, and image quality to aid practitioners in assessing this new technology.
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Affiliation(s)
- Sharada Balaji
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - Neale Wiley
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | | | - Shannon H Kolind
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Medicine (Neurology)
- Department of Radiology
- International Collaboration on Repair Discoveries, Blusson Spinal Cord Centre, University of British Columbia, Vancouver, British Columbia, Canada
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Lin LP, Hu MS, Wei D, Li JJ, Liang JH, Xie YZ, Li ZH, Che X, Xie DX, Yang ZY, Jiang L, Zhao J. Quantitative evaluation of CTP derived time-density alterations versus CTP for collateral status prediction with stroke. Eur J Radiol 2024; 177:111571. [PMID: 38925043 DOI: 10.1016/j.ejrad.2024.111571] [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] [Received: 07/06/2023] [Revised: 03/27/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024]
Abstract
BACKGROUND AND OBJECTIVES Collateral status is a pivotal determinant of clinical outcomes in acute ischemic stroke (AIS); however, its evaluation can be challenging. We investigated the predictive value of CT perfusion (CTP) derived time and density alterations versus CTP for collateral status prediction in AIS. METHODS Consecutive patients with anterior circulation occlusion within 24 h were retrospectively included. Time-density curves of the CTP specified ischemic core, penumbra, and the corresponding contralateral unaffected brain were obtained. The collateral status was dichotomised into robust (4-5 scores) and poor (0-3 scores) using multiphase collateral scoring, as described by Menon et al.. Receiver operating characteristic curves and multivariable regression analysis were performed to assess the predictive ability of CTP-designated tissue time and density alterations, CTP for robust collaterals, and favourable outcomes (mRS score of 0-2 at 90 days). RESULTS One-hundred patients (median age, 68 years; interquartile range, 57-80 years; 61 men) were included. A smaller ischemic core, shorter peak time delay, lower peak density decrease, lower cerebral blood volume ratio, and cerebral blood flow ratio in the CTP specified ischemic core were significantly associated with robust collaterals (PFDR ≤ 0.004). The peak time delay demonstrated the highest diagnostic value (AUC, 0.74; P < 0.001) with 66.7 % sensitivity and 73.7 % specificity. Furthermore, the peak time delay of less than 8.5 s was an independent predictor of robust collaterals and favourable clinical outcomes. CONCLUSIONS Robust collateral status was significantly associated with the peak time delay in the ischemic core. It is a promising image marker for predicting collateral status and functional outcomes in AIS.
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Affiliation(s)
- Li-Ping Lin
- Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Man-Shi Hu
- Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Dan Wei
- Department of Radiology, Hui Ya Hospital of The First Affiliated Hospital, Sun Yat-sen University, Huizhou, China
| | - Jing-Jing Li
- Department of Neurology and Stroke Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Jia-Hui Liang
- Department of Medical Imaging, Sun Yat-sen University Cancer Center, China; State Key Laboratory of Oncology in South China, China; Collaborative Innovation Center for Cancer Medicine, China; Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangzhou, China
| | - Yan-Zhao Xie
- Department of Radiology, Guangdong Hospital of Traditional Chinese Medicine, Zhuhai Hospital, Zhuhai, China
| | - Zhu-Hao Li
- Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Xin Che
- Canon Medical Systems (China) Co, China
| | - Ding-Xiang Xie
- Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Zhi-Yun Yang
- Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Li Jiang
- Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Jing Zhao
- Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
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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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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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6
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Poojar P, Oiye IE, Aggarwal K, Jimeno MM, Vaughan JT, Geethanath S. Repeatability of image quality in very low-field MRI. NMR IN BIOMEDICINE 2024:e5198. [PMID: 38840502 DOI: 10.1002/nbm.5198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 04/12/2024] [Accepted: 05/13/2024] [Indexed: 06/07/2024]
Abstract
BACKGROUND Very low-field MR has emerged as a promising complementary device to high-field MRI scanners, offering several advantages. One of the key benefits is that very low-field scanners are generally more portable and affordable to purchase and maintain, making them an attractive option for medical facilities looking to reduce costs. Very low-field MRI systems also have lower RF power deposition, making them safer and less likely to cause tissue heating or other safety concerns. They are also simpler to maintain, as they do not require cooling agents such as liquid helium. However, these portable MR scanners are impacted by temperature, lower magnetic field strength, and inhomogeneity, resulting in images with lower signal-to-noise ratio (SNR) and higher geometric distortions. It is essential to investigate and tabulate the variations in these parameters to establish bounds so that subsequent in vivo studies and deployment of these portable systems can be well informed. PURPOSE The aim of this work is to investigate the repeatability of image quality metrics such as SNR and geometrical distortion at 0.05 T over 10 days and three sessions per day. METHODS We acquired repeatability data over 10 days with three sessions per day. The measurements included temperature, humidity, transmit frequency, off-resonance maps, and 3D turbo spin echo (TSE) images of an in vitro phantom. This resulted in a protocol with 11 sequences. We also acquired a 3 T data set for reference. The image quality metrics included computing SNR and eccentricity (to assess geometrical distortion) to investigate the repeatability of 0.05 T image quality. The image reconstruction included drift correction, k-space filtering, and off-resonance correction. We computed the experimental parameters' coefficient of variation (CV) and the resulting image quality metrics to assess repeatability. We have explored the impact of electromagnetic interference (EMI) on image quality in very low-field MRI. The investigation involved varying both the distance and amplitude of the EMI-producing coil from the signal generator to analyze their effects on image quality. RESULTS The range of temperature measured during the study was within 1.5 °C. The off-resonance maps acquired before and after the 3D TSE showed similar hotspots and were changed mainly by a global constant. The SNR measurements were highly repeatable across sessions and over the 10 days, quantified by a CV of 6.7%. The magnetic field inhomogeneity effects quantified by eccentricity showed a CV of 13.7%, but less than 5.1% in two of the three sessions over 10 days. The use of conjugate phase reconstruction mitigated geometrical distortion artifacts. Temperature and humidity did not significantly affect SNR or mean frequency drift within the ranges of these environmental factors investigated. The EMI experiment showed that as the amplitude increased the SNR decreased, and concurrently the root mean square of the background increased with a rise in EMI amplitude or a reduction in distance. CONCLUSIONS We found that humidity and temperature in the range investigated did not impact SNR or frequency. Based on the CV values computed session-wise and for the overall study, our findings indicate high repeatability for SNR and magnetic field homogeneity.
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Affiliation(s)
- Pavan Poojar
- Addiction Institute of Mount Sinai, Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Ivan Etoku Oiye
- Accessible Magnetic Resonance Laboratory, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Kunal Aggarwal
- Biomedical Imaging and Engineering Institute, Department of Diagnostic, Molecular and Interventional Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Marina Manso Jimeno
- Columbia Magnetic Resonance Research Center, Columbia University, New York, New York, USA
| | - John Thomas Vaughan
- Columbia Magnetic Resonance Research Center, Columbia University, New York, New York, USA
| | - Sairam Geethanath
- Accessible Magnetic Resonance Laboratory, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
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7
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Mazurek MH, Parasuram NR, Peng TJ, Beekman R, Yadlapalli V, Sorby-Adams AJ, Lalwani D, Zabinska J, Gilmore EJ, Petersen NH, Falcone GJ, Sujijantarat N, Matouk C, Payabvash S, Sze G, Schiff SJ, Iglesias JE, Rosen MS, de Havenon A, Kimberly WT, Sheth KN. Detection of Intracerebral Hemorrhage Using Low-Field, Portable Magnetic Resonance Imaging in Patients With Stroke. Stroke 2023; 54:2832-2841. [PMID: 37795593 PMCID: PMC11103256 DOI: 10.1161/strokeaha.123.043146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 09/13/2023] [Indexed: 10/06/2023]
Abstract
BACKGROUND Neuroimaging is essential for detecting spontaneous, nontraumatic intracerebral hemorrhage (ICH). Recent data suggest ICH can be characterized using low-field magnetic resonance imaging (MRI). Our primary objective was to investigate the sensitivity and specificity of ICH on a 0.064T portable MRI (pMRI) scanner using a methodology that provided clinical information to inform rater interpretations. As a secondary aim, we investigated whether the incorporation of a deep learning (DL) reconstruction algorithm affected ICH detection. METHODS The pMRI device was deployed at Yale New Haven Hospital to examine patients presenting with stroke symptoms from October 26, 2020 to February 21, 2022. Three raters independently evaluated pMRI examinations. Raters were provided the images alongside the patient's clinical information to simulate real-world context of use. Ground truth was the closest conventional computed tomography or 1.5/3T MRI. Sensitivity and specificity results were grouped by DL and non-DL software to investigate the effects of software advances. RESULTS A total of 189 exams (38 ICH, 89 acute ischemic stroke, 8 subarachnoid hemorrhage, 3 primary intraventricular hemorrhage, 51 no intracranial abnormality) were evaluated. Exams were correctly classified as positive or negative for ICH in 185 of 189 cases (97.9% overall accuracy). ICH was correctly detected in 35 of 38 cases (92.1% sensitivity). Ischemic stroke and no intracranial abnormality cases were correctly identified as blood-negative in 139 of 140 cases (99.3% specificity). Non-DL scans had a sensitivity and specificity for ICH of 77.8% and 97.1%, respectively. DL scans had a sensitivity and specificity for ICH of 96.6% and 99.3%, respectively. CONCLUSIONS These results demonstrate improvements in ICH detection accuracy on pMRI that may be attributed to the integration of clinical information in rater review and the incorporation of a DL-based algorithm. The use of pMRI holds promise in providing diagnostic neuroimaging for patients with ICH.
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Affiliation(s)
- Mercy H. Mazurek
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | | | - Teng J. Peng
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - Rachel Beekman
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | | | - Annabel J. Sorby-Adams
- Department of Neurology, Division of Neurocritical Care, Massachusetts General Hospital, Boston, MA, USA
| | - Dheeraj Lalwani
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - Julia Zabinska
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - Emily J. Gilmore
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - Nils H. Petersen
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - Guido J. Falcone
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | | | - Charles Matouk
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT, USA
| | - Sam Payabvash
- Department of Radiology, Yale University School of Medicine, New Haven, CT, USA
| | - Gordon Sze
- Department of Radiology, Yale University School of Medicine, New Haven, CT, USA
| | - Steven J. Schiff
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT, USA
- Yale Center for Brain & Mind Heath, Yale School of Medicine, New Haven, CT, USA
| | - Juan Eugenio Iglesias
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
- Centre for Medical Image Computing, University College London, London, UK
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Matthew S. Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
| | - Adam de Havenon
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - W. Taylor Kimberly
- Department of Neurology, Division of Neurocritical Care, Massachusetts General Hospital, Boston, MA, USA
| | - Kevin N. Sheth
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
- Yale Center for Brain & Mind Heath, Yale School of Medicine, New Haven, CT, USA
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8
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Campbell-Washburn AE, Keenan KE, Hu P, Mugler JP, Nayak KS, Webb AG, Obungoloch J, Sheth KN, Hennig J, Rosen MS, Salameh N, Sodickson DK, Stein JM, Marques JP, Simonetti OP. Low-field MRI: A report on the 2022 ISMRM workshop. Magn Reson Med 2023; 90:1682-1694. [PMID: 37345725 PMCID: PMC10683532 DOI: 10.1002/mrm.29743] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/21/2023] [Accepted: 05/17/2023] [Indexed: 06/23/2023]
Abstract
In March 2022, the first ISMRM Workshop on Low-Field MRI was held virtually. The goals of this workshop were to discuss recent low field MRI technology including hardware and software developments, novel methodology, new contrast mechanisms, as well as the clinical translation and dissemination of these systems. The virtual Workshop was attended by 368 registrants from 24 countries, and included 34 invited talks, 100 abstract presentations, 2 panel discussions, and 2 live scanner demonstrations. Here, we report on the scientific content of the Workshop and identify the key themes that emerged. The subject matter of the Workshop reflected the ongoing developments of low-field MRI as an accessible imaging modality that may expand the usage of MRI through cost reduction, portability, and ease of installation. Many talks in this Workshop addressed the use of computational power, efficient acquisitions, and contemporary hardware to overcome the SNR limitations associated with low field strength. Participants discussed the selection of appropriate clinical applications that leverage the unique capabilities of low-field MRI within traditional radiology practices, other point-of-care settings, and the broader community. The notion of "image quality" versus "information content" was also discussed, as images from low-field portable systems that are purpose-built for clinical decision-making may not replicate the current standard of clinical imaging. Speakers also described technical challenges and infrastructure challenges related to portability and widespread dissemination, and speculated about future directions for the field to improve the technology and establish clinical value.
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Affiliation(s)
- Adrienne E Campbell-Washburn
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Kathryn E Keenan
- Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado, USA
| | - Peng Hu
- School of Biomedical Engineering, ShanghaiTech University, Shanghai, China
| | - John P Mugler
- Department of Radiology & Medical Imaging, Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Krishna S Nayak
- Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Andrew G Webb
- Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
| | | | - Kevin N Sheth
- Division of Neurocritical Care and Emergency Neurology, Departments of Neurology and Neurosurgery, and the Yale Center for Brain and Mind Health, Yale School of Medicine, New Haven, Connecticut, USA
| | - Jürgen Hennig
- Dept.of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany
- Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Matthew S Rosen
- Massachusetts General Hospital, A. A. Martinos Center for Biomedical Imaging, Boston, Massachusetts, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts, USA
| | - Najat Salameh
- Center for Adaptable MRI Technology (AMT Center), Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland
| | - Daniel K Sodickson
- Department of Radiology, NYU Langone Health, New York, New York, USA
- Center for Advanced Imaging Innovation and Research, NYU Langone Health, New York, New York, USA
| | - Joel M Stein
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - José P Marques
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Orlando P Simonetti
- Division of Cardiovascular Medicine, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, Ohio, USA
- Department of Radiology, The Ohio State University, Columbus, Ohio, USA
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9
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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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Gheibi Y, Shirini K, Razavi SN, Farhoudi M, Samad-Soltani T. CNN-Res: deep learning framework for segmentation of acute ischemic stroke lesions on multimodal MRI images. BMC Med Inform Decis Mak 2023; 23:192. [PMID: 37752508 PMCID: PMC10521570 DOI: 10.1186/s12911-023-02289-y] [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] [Received: 04/24/2022] [Accepted: 09/04/2023] [Indexed: 09/28/2023] Open
Abstract
BACKGROUND Accurate segmentation of stroke lesions on MRI images is very important for neurologists in the planning of post-stroke care. Segmentation helps clinicians to better diagnose and evaluation of any treatment risks. However, manual segmentation of brain lesions relies on the experience of neurologists and is also a very tedious and time-consuming process. So, in this study, we proposed a novel deep convolutional neural network (CNN-Res) that automatically performs the segmentation of ischemic stroke lesions from multimodal MRIs. METHODS CNN-Res used a U-shaped structure, so the network has encryption and decryption paths. The residual units are embedded in the encoder path. In this model, to reduce gradient descent, the residual units were used, and to extract more complex information in images, multimodal MRI data were applied. In the link between the encryption and decryption subnets, the bottleneck strategy was used, which reduced the number of parameters and training time compared to similar research. RESULTS CNN-Res was evaluated on two distinct datasets. First, it was examined on a dataset collected from the Neuroscience Center of Tabriz University of Medical Sciences, where the average Dice coefficient was equal to 85.43%. Then, to compare the efficiency and performance of the model with other similar works, CNN-Res was evaluated on the popular SPES 2015 competition dataset where the average Dice coefficient was 79.23%. CONCLUSION This study presented a new and accurate method for the segmentation of MRI medical images using a deep convolutional neural network called CNN-Res, which directly predicts segment maps from raw input pixels.
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Affiliation(s)
- Yousef Gheibi
- Department of Software Engineering, Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, East Azerbaijan, Iran
| | - Kimia Shirini
- Department of Software Engineering, Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, East Azerbaijan, Iran
| | - Seyed Naser Razavi
- Department of Software Engineering, Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, East Azerbaijan, Iran
| | - Mehdi Farhoudi
- Neurosciences Research Center (NSRC), Tabriz University of Medical Sciences, Tabriz, Iran
| | - Taha Samad-Soltani
- Department of Health Information Technology, School of Management and Medical Informatics, Tabriz University of Medical Sciences, Tabriz, Iran.
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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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12
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Oberdick SD, Jordanova KV, Lundstrom JT, Parigi G, Poorman ME, Zabow G, Keenan KE. Iron oxide nanoparticles as positive T 1 contrast agents for low-field magnetic resonance imaging at 64 mT. Sci Rep 2023; 13:11520. [PMID: 37460669 DOI: 10.1038/s41598-023-38222-6] [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: 07/05/2023] [Indexed: 07/20/2023] Open
Abstract
We have investigated the efficacy of superparamagnetic iron oxide nanoparticles (SPIONs) as positive T1 contrast agents for low-field magnetic resonance imaging (MRI) at 64 millitesla (mT). Iron oxide-based agents, such as the FDA-approved ferumoxytol, were measured using a variety of techniques to evaluate T1 contrast at 64 mT. Additionally, we characterized monodispersed carboxylic acid-coated SPIONs with a range of diameters (4.9-15.7 nm) in order to understand size-dependent properties of T1 contrast at low-field. MRI contrast properties were measured using 64 mT MRI, magnetometry, and nuclear magnetic resonance dispersion (NMRD). We also measured MRI contrast at 3 T to provide comparison to a standard clinical field strength. SPIONs have the capacity to perform well as T1 contrast agents at 64 mT, with measured longitudinal relaxivity (r1) values of up to 67 L mmol-1 s-1, more than an order of magnitude higher than corresponding r1 values at 3 T. The particles exhibit size-dependent longitudinal relaxivities and outperform a commercial Gd-based agent (gadobenate dimeglumine) by more than eight-fold at physiological temperatures. Additionally, we characterize the ratio of transverse to longitudinal relaxivity, r2/r1 and find that it is ~ 1 for the SPION based agents at 64 mT, indicating a favorable balance of relaxivities for T1-weighted contrast imaging. We also correlate the magnetic and structural properties of the particles with models of nanoparticle relaxivity to understand generation of T1 contrast. These experiments show that SPIONs, at low fields being targeted for point-of-care low-field MRI systems, have a unique combination of magnetic and structural properties that produce large T1 relaxivities.
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Affiliation(s)
- Samuel D Oberdick
- Department of Physics, University of Colorado, Boulder, CO, 80309, USA.
- National Institute of Standards and Technology, Boulder, CO, 80305, USA.
| | | | - John T Lundstrom
- Department of Physics, University of Colorado, Boulder, CO, 80309, USA
- National Institute of Standards and Technology, Boulder, CO, 80305, USA
| | - Giacomo Parigi
- Magnetic Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Italy
- Department of Chemistry "Ugo Schiff", University of Florence, Via Della Lastruccia 3, 50019, Sesto Fiorentino, Italy
- Consorzio Interuniversitario Risonanze Magnetiche Metallo Proteine (CIRMMP), Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Italy
| | | | - Gary Zabow
- National Institute of Standards and Technology, Boulder, CO, 80305, USA
| | - Kathryn E Keenan
- National Institute of Standards and Technology, Boulder, CO, 80305, USA
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13
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Bryden N, Atalla SW, Kelley M, Holmes LR, Branca RT. Enhanced 129 Xe T 1 relaxation in whole blood and in the presence of SPIONs at low magnetic field strengths. Magn Reson Med 2023; 90:21-33. [PMID: 36797796 PMCID: PMC10963042 DOI: 10.1002/mrm.29619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/23/2023] [Accepted: 01/30/2023] [Indexed: 02/18/2023]
Abstract
PURPOSE To compare the effect of superparamagnetic iron oxide nanoparticles (SPIONs) on the T1 of 129 Xe and 1 H and to measure the relaxation of 129 Xe in blood at low and high magnetic field strengths. METHODS 129 Xe and 1 H T1 relaxometry was performed at low- and high-field strengths in samples containing different SPION concentrations, while imaging was used to compare the contrast obtainable in these two field regimes. In vivo experiments at variable field strengths were performed to determine the depolarization of 129 Xe in blood and the feasibility of in vivo dissolved-phase spectroscopy and imaging at low field. RESULTS The SPION relaxivity was substantially greater at low field for 1 H, increasing from 0.92 ± 0.06 mM s-1 at 11.7T to 31.5 ± 1.8 mM s-1 at 0.6 mT, and for 129 Xe, which increased from 0.13 ± 0.03 mM s-1 at 11.7T to 7.32 ± 0.71 mM s-1 at 2.1 mT. The additional MR signal loss increased from 0.7% at 9.4T to 20.6 ± 4.2% at 0.6 mT for 1 H and from -0.7 ± 3.4% at 9.4T to 12.7 ± 3.5% at 2.1 mT for 129 Xe. Blood was found to depolarize 129 Xe below 3T in a manner inversely proportional to the field strength. In vitro studies at 2.1 mT suggest 129 Xe relaxation times below 5 s in blood dilutions as low as 0.4% volume. CONCLUSION SPIONs longitudinal relaxivity increases at low field both for 1 H and 129 Xe. The depolarization of xenon in blood, which is found to increase below 3T, effectively prevents in vivo dissolved-phase spectroscopy and imaging at low-field strengths.
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Affiliation(s)
- Nicholas Bryden
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Sebastian W Atalla
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Michele Kelley
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Leah R Holmes
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Rosa T Branca
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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14
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Ramasawmy R, Mugler JP, Javed A, Wang Z, Herzka DA, Meyer CH, Campbell-Washburn AE. Concomitant field compensation of spiral turbo spin-echo at 0.55 T. MAGMA (NEW YORK, N.Y.) 2023; 36:465-475. [PMID: 37306784 PMCID: PMC10771127 DOI: 10.1007/s10334-023-01103-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 04/26/2023] [Accepted: 05/15/2023] [Indexed: 06/13/2023]
Abstract
OBJECTIVE Diagnostic-quality neuroimaging methods are vital for widespread clinical adoption of low field MRI. Spiral imaging is an efficient acquisition method that can mitigate the reduced signal-to-noise ratio at lower field strengths. As concomitant field artifacts are worse at lower field, we propose a generalizable quadratic gradient-field nulling as an echo-to-echo compensation and apply it to spiral TSE at 0.55 T. MATERIALS AND METHODS A spiral in-out TSE acquisition was developed with a compensation for concomitant field variation between spiral interleaves, by adding bipolar gradients around each readout to minimize phase differences at each refocusing pulse. Simulations were performed to characterize concomitant field compensation approaches. We demonstrate our proposed compensation method in phantoms and (n = 8) healthy volunteers at 0.55 T. RESULTS Spiral read-outs with integrated spoiling demonstrated strong concomitant field artifacts but were mitigated using the echo-to-echo compensation. Simulations predicted a decrease of concomitant field phase RMSE between echoes of 42% using the proposed compensation. Spiral TSE improved SNR by 17.2 ± 2.3% compared to reference Cartesian acquisition. DISCUSSION We demonstrated a generalizable approach to mitigate concomitant field artifacts for spiral TSE acquisitions via the addition of quadratic-nulling gradients, which can potentially improve neuroimaging at low-field through increased acquisition efficiency.
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Affiliation(s)
- Rajiv Ramasawmy
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | - John P Mugler
- Department of Radiology & Medical Imaging, University of Virginia, Charlottesville, VA, USA
| | - Ahsan Javed
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Zhixing Wang
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Daniel A Herzka
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Craig H Meyer
- Department of Radiology & Medical Imaging, University of Virginia, Charlottesville, VA, USA
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Adrienne E Campbell-Washburn
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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15
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Kumar M, Hu S, Beyea S, Kamal N. Is improved access to magnetic resonance imaging imperative for optimal ischemic stroke care? J Neurol Sci 2023; 446:120592. [PMID: 36821945 DOI: 10.1016/j.jns.2023.120592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 02/14/2023] [Indexed: 02/20/2023]
Abstract
Neuroimaging, including CT and MRI, is integral to ischemic stroke (IS) treatment, management, and prevention. However, the use of MRI for IS patients is limited despite its potential to provide high-quality images that yield definitive information related to the management of IS. MRI is beneficial when the information provided by CT is insufficient for decisions related to the diagnosis, etiology, or treatment of IS. In the emergency setting, MRI can improve the diagnostic accuracy of CT-negative acute ischemic strokes (AIS) and ensure a better selection of patients for reperfusion therapies with thrombolysis and/or thrombectomy. Moreover, MR imaging may help avoid hospital admissions for patients with stroke mimics, facilitate earlier discharge, and reduce overall hospital costs. MRI in the in-patient setting can help determine stroke etiology to aid in stroke prevention management upon discharge. Furthermore, early access to MRI in IS out-patients can aid in diagnosing, risk stratifying, and determining optimal management strategies for patients with a TIA or a minor stroke. Recent technological advances, particularly low-to-mid-field MR scanners, can improve access to MRI. These MR scanners provide faster protocols, cost-effectiveness, smaller footprints, safety, and lower power requirements. In conclusion, MRI use for IS treatment, management, and prevention is imperative and justifiable, and the latest technological advancements in MR scanners hold the potential to enhance access.
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Affiliation(s)
- Mukesh Kumar
- Department of Industrial Engineering, Dalhousie University, Halifax, Canada.
| | - Sherry Hu
- Department of Medicine, Division of Neurology, Dalhousie University, Halifax, Canada
| | - Steven Beyea
- Department of Diagnostic Radiology, Dalhousie University, Halifax, Canada; IWK Health, Halifax, Canada
| | - Noreen Kamal
- Department of Industrial Engineering, Dalhousie University, Halifax, Canada; Department of Medicine, Division of Neurology, Dalhousie University, Halifax, Canada; Department of Community Health and Epidemiology, Dalhousie University, Halifax, Canada
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16
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Anazodo UC, Ng JJ, Ehiogu B, Obungoloch J, Fatade A, Mutsaerts HJMM, Secca MF, Diop M, Opadele A, Alexander DC, Dada MO, Ogbole G, Nunes R, Figueiredo P, Figini M, Aribisala B, Awojoyogbe BO, Aduluwa H, Sprenger C, Wagner R, Olakunle A, Romeo D, Sun Y, Fezeu F, Orunmuyi AT, Geethanath S, Gulani V, Nganga EC, Adeleke S, Ntobeuko N, Minja FJ, Webb AG, Asllani I, Dako F. A framework for advancing sustainable magnetic resonance imaging access in Africa. NMR IN BIOMEDICINE 2023; 36:e4846. [PMID: 36259628 DOI: 10.1002/nbm.4846] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 06/16/2023]
Abstract
Magnetic resonance imaging (MRI) technology has profoundly transformed current healthcare systems globally, owing to advances in hardware and software research innovations. Despite these advances, MRI remains largely inaccessible to clinicians, patients, and researchers in low-resource areas, such as Africa. The rapidly growing burden of noncommunicable diseases in Africa underscores the importance of improving access to MRI equipment as well as training and research opportunities on the continent. The Consortium for Advancement of MRI Education and Research in Africa (CAMERA) is a network of African biomedical imaging experts and global partners, implementing novel strategies to advance MRI access and research in Africa. Upon its inception in 2019, CAMERA sets out to identify challenges to MRI usage and provide a framework for addressing MRI needs in the region. To this end, CAMERA conducted a needs assessment survey (NAS) and a series of symposia at international MRI society meetings over a 2-year period. The 68-question NAS was distributed to MRI users in Africa and was completed by 157 clinicians and scientists from across Sub-Saharan Africa (SSA). On average, the number of MRI scanners per million people remained at less than one, of which 39% were obsolete low-field systems but still in use to meet daily clinical needs. The feasibility of coupling stable energy supplies from various sources has contributed to the growing number of higher-field (1.5 T) MRI scanners in the region. However, these systems are underutilized, with only 8% of facilities reporting clinical scans of 15 or more patients per day, per scanner. The most frequently reported MRI scans were neurological and musculoskeletal. The CAMERA NAS combined with the World Health Organization and International Atomic Energy Agency data provides the most up-to-date data on MRI density in Africa and offers a unique insight into Africa's MRI needs. Reported gaps in training, maintenance, and research capacity indicate ongoing challenges in providing sustainable high-value MRI access in SSA. Findings from the NAS and focused discussions at international MRI society meetings provided the basis for the framework presented here for advancing MRI capacity in SSA. While these findings pertain to SSA, the framework provides a model for advancing imaging needs in other low-resource settings.
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Affiliation(s)
- Udunna C Anazodo
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Jinggang J Ng
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Boaz Ehiogu
- Lawson Health Research Institute, London, Ontario, Canada
| | | | | | - Henk J M M Mutsaerts
- Department of Radiology and Nuclear Medicine, Amsterdam UMC Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Brain Imaging, Amsterdam, The Netherlands
| | | | - Mamadou Diop
- Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Abayomi Opadele
- Molecular and Cellular Dynamics Research, Graduate School of Biomedical Science and Engineering, Hokkaido University, Hokkaido, Japan
| | | | - Michael O Dada
- Department of Physics, Federal University of Technology, Minna, Niger State, Nigeria
| | - Godwin Ogbole
- Department of Radiology, University College Hospital Ibadan, Ibadan, Nigeria
| | - Rita Nunes
- Department of Bioengineering, Instituto Superior, Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Patricia Figueiredo
- Department of Bioengineering, Instituto Superior, Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Matteo Figini
- Department of Computer Science, University College London, London, UK
| | | | - Bamidele O Awojoyogbe
- Department of Physics, Federal University of Technology, Minna, Niger State, Nigeria
| | | | - Christian Sprenger
- Department of Anesthesiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Rachel Wagner
- Mbarara University of Science and Technology, Mbarara, Uganda
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | | | - Dominic Romeo
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yusha Sun
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Francis Fezeu
- Neurosurgery & Neurology, BRAIN Global, Salisbury, Maryland, USA
| | - Akintunde T Orunmuyi
- Department of Nuclear Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria
| | - Sairam Geethanath
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, USA
| | - Vikas Gulani
- Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Sola Adeleke
- Department of Oncology, Guy's & St Thomas' Hospital, London, UK
| | - Ntusi Ntobeuko
- Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - Frank J Minja
- Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia, USA
| | - Andrew G Webb
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Iris Asllani
- Department of Neuroscience, University of Sussex, Brighton, UK
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Farouk Dako
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- RAD-AID International, Chevy Chase, Maryland, USA
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17
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Guallart‐Naval T, O'Reilly T, Algarín JM, Pellicer‐Guridi R, Vives‐Gilabert Y, Craven‐Brightman L, Negnevitsky V, Menküc B, Galve F, Stockmann JP, Webb A, Alonso J. Benchmarking the performance of a low-cost magnetic resonance control system at multiple sites in the open MaRCoS community. NMR IN BIOMEDICINE 2023; 36:e4825. [PMID: 36097704 PMCID: PMC10078257 DOI: 10.1002/nbm.4825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 08/15/2022] [Accepted: 08/26/2022] [Indexed: 05/15/2023]
Abstract
PURPOSE To describe the current properties and capabilities of an open-source hardware and software package that is being developed by many sites internationally with the aim of providing an inexpensive yet flexible platform for low-cost MRI. METHODS This article describes three different setups from 50 to 360 mT in different settings, all of which used the MaRCoS console for acquiring data, and different types of software interface (custom-built GUI or Pulseq overlay) to acquire it. RESULTS Images are presented both from phantoms and in vivo from healthy volunteers to demonstrate the image quality that can be obtained from the MaRCoS hardware/software interfaced to different low-field magnets. CONCLUSIONS The results presented here show that a number of different sequences commonly used in the clinic can be programmed into an open-source system relatively quickly and easily, and can produce good quality images even at this early stage of development. Both the hardware and software will continue to develop, and it is an aim of this article to encourage other groups to join this international consortium.
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Affiliation(s)
- Teresa Guallart‐Naval
- MRILab, Institute for Molecular Imaging and Instrumentation (i3M)Spanish National Research Council (CSIC) and Universitat Politècnica de València (UPV)ValenciaSpain
- Tesoro Imaging S.L.ValenciaSpain
| | - Thomas O'Reilly
- Department of RadiologyLeiden University Medical CenterLeidenThe Netherlands
| | - José M. Algarín
- MRILab, Institute for Molecular Imaging and Instrumentation (i3M)Spanish National Research Council (CSIC) and Universitat Politècnica de València (UPV)ValenciaSpain
| | | | - Yolanda Vives‐Gilabert
- Intelligent Data Analysis Laboratory, Department of Electronic EngineeringUniversitat de ValènciaValenciaSpain
| | | | | | - Benjamin Menküc
- University of Applied Sciences and Arts DortmundDortmundGermany
| | - Fernando Galve
- MRILab, Institute for Molecular Imaging and Instrumentation (i3M)Spanish National Research Council (CSIC) and Universitat Politècnica de València (UPV)ValenciaSpain
| | - Jason P. Stockmann
- Massachusetts General Hospital, A. A. Martinos Center for Biomedical ImagingCharlestownMAUSA
| | - Andrew Webb
- Department of RadiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Joseba Alonso
- MRILab, Institute for Molecular Imaging and Instrumentation (i3M)Spanish National Research Council (CSIC) and Universitat Politècnica de València (UPV)ValenciaSpain
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18
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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: 62] [Impact Index Per Article: 62.0] [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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19
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Muacevic A, Adler JR, Salphale VG. Impact of Proprioceptive Neuromuscular Facilitation Technique for Early Rehabilitation to Restore Motor Impairments in a Classic Case of Left Middle Cerebral Artery Stroke. Cureus 2022; 14:e31222. [PMID: 36514562 PMCID: PMC9733788 DOI: 10.7759/cureus.31222] [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: 09/30/2022] [Accepted: 11/07/2022] [Indexed: 11/11/2022] Open
Abstract
An abrupt hemorrhage or ischemia causes acute onset of stroke. The characteristic feature of hemiplegia is the loss of voluntary movement with the alteration of muscle tone, reflexes, and sensation. In this case, we present a 56-year-old man who suffered from right hemiplegia, facial palsy, and expressive aphasia. The MRI of the brain revealed a hemorrhagic transformation of acute infarct in the left frontoparietal-temporo-occipital lobe. The patient was managed immediately by medical interventions. The physiotherapy treatment was initiated after the stabilization of acute symptoms at an early stage. This case report details the management of the patient with physical therapy and highlights the advantages of exercise therapy, particularly the proprioceptive neuromuscular facilitation technique for enhancing the patient's condition by incorporating physiotherapy protocol from an early stage.
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20
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Qiu Y, Bai H, Chen H, Zhao Y, Luo H, Wu Z, Zhang Z. Susceptibility-weighted imaging at high-performance 0.5T magnetic resonance imaging system: Protocol considerations and experimental results. Front Neurosci 2022; 16:999240. [PMID: 36312037 PMCID: PMC9597077 DOI: 10.3389/fnins.2022.999240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 09/22/2022] [Indexed: 11/13/2022] Open
Abstract
The high-performance low-field magnetic resonance imaging (MRI) system, equipped with modern hardware and contemporary imaging capabilities, has garnered interest within the MRI community in recent years. It has also been proven to have unique advantages over high-field MRI in both physical and cost aspects. However, for susceptibility weighted imaging (SWI), the low signal-to-noise ratio and the long echo time inherent at low field hinder the SWI from being applied to clinical applications. This work optimized the imaging protocol to select suitable parameters such as the values of time of echo (TE), repetition time (TR), and the flip angle (FA) of the RF pulse according to the signal simulations for low-field SWI. To improve the signal-to-noise ratio (SNR) performance, averaging multi-echo magnitude images and BM4D phase denoising were proposed. A comparison of the SWI in 0.5T and 1.5T was carried out, demonstrating the capability to identify magnetic susceptibility differences between variable tissues, especially, the blood veins. This would open the possibility to extend SWI applications in the high-performance low field MRI.
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Affiliation(s)
- Yueqi Qiu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
- Institute of Medical Robotics, Shanghai Jiao Tong University, Shanghai, China
| | - Haoran Bai
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Hao Chen
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
- Institute of Medical Robotics, Shanghai Jiao Tong University, Shanghai, China
| | - Yue Zhao
- Wuxi Marvel Stone Healthcare Co., Ltd., Wuxi, Jiangsu, China
| | - Hai Luo
- Wuxi Marvel Stone Healthcare Co., Ltd., Wuxi, Jiangsu, China
| | - Ziyue Wu
- Wuxi Marvel Stone Healthcare Co., Ltd., Wuxi, Jiangsu, China
| | - Zhiyong Zhang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
- Institute of Medical Robotics, Shanghai Jiao Tong University, Shanghai, China
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21
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Jiang B, Mackay MT, Stence N, Domi T, Dlamini N, Lo W, Wintermark M. Neuroimaging in Pediatric Stroke. Semin Pediatr Neurol 2022; 43:100989. [PMID: 36344022 DOI: 10.1016/j.spen.2022.100989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/30/2022]
Abstract
Pediatric stroke is unfortunately not a rare condition. It is associated with severe disability and mortality because of the complexity of potential clinical manifestations, and the resulting delay in seeking care and in diagnosis. Neuroimaging plays an important role in the multidisciplinary response for pediatric stroke patients. The rapid development of adult endovascular thrombectomy has created a new momentum in health professionals caring for pediatric stroke patients. Neuroimaging is critical to make decisions of identifying appropriate candidates for thrombectomy. This review article will review current neuroimaging techniques, imaging work-up strategies and special considerations in pediatric stroke. For resources limited areas, recommendation of substitute imaging approaches will be provided. Finally, promising new techniques and hypothesis-driven research protocols will be discussed.
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Affiliation(s)
- Bin Jiang
- Department of Radiology, Neuroradiology Section, Stanford University, Stanford, CA.
| | - Mark T Mackay
- Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Victoria, Australia.
| | - Nicholas Stence
- Department of Radiology, pediatric Neuroradiology Section, University of Colorado School of Medicine, Aurora, CO
| | - Trish Domi
- Department of Neurology, Hospital for Sick Children, Toronto, Canada.
| | - Nomazulu Dlamini
- Department of Neurology, Hospital for Sick Children, Toronto, Canada.
| | - Warren Lo
- Department of Pediatrics and Neurology, The Ohio State University & Nationwide Children's Hospital, Columbus, OH.
| | - Max Wintermark
- Department of Neuroradiology, University of Texas MD Anderson Center, Houston, TX.
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22
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Kojima S, Ito T, Hayashi T. Denoising Using Noise2Void for Low-Field Magnetic Resonance Imaging: A Phantom Study. J Med Phys 2022; 47:387-393. [PMID: 36908491 PMCID: PMC9997543 DOI: 10.4103/jmp.jmp_71_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/14/2022] [Accepted: 09/26/2022] [Indexed: 01/11/2023] Open
Abstract
To reduce noise for low-field magnetic resonance imaging (MRI) using Noise2Void (N2V) and to demonstrate the N2V validity. N2V is one of the denoising convolutional neural network methods that allows the training of a model without a noiseless clean image. In this study, a kiwi fruit was scanned using a 0.35 Tesla MRI system, and the image qualities at pre- and postdenoising were evaluated. Structural similarity (SSIM), signal-to-noise ratio (SNR), and contrast ratio (CR) were measured, and visual assessment of noise and sharpness was observed. Both SSIM and SNR were significantly improved using N2V (P < 0.05). CR was unchanged between pre- and postdenoising images. The results of visual assessment for noise revealed higher scores in postdenoising images than that in predenoising images. The sharpness scores of postdenoising images were high when SNR was low. N2V provides effective noise reduction and is a useful denoising technique in low-field MRI.
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Affiliation(s)
- Shinya Kojima
- Department of Radiological Technology, Faculty of Medical Technology, Teikyo University, Itabashi-ku, Tokyo, Japan
| | - Toshimune Ito
- Department of Radiological Technology, Faculty of Medical Technology, Teikyo University, Itabashi-ku, Tokyo, Japan
| | - Tatsuya Hayashi
- Department of Radiological Technology, Faculty of Medical Technology, Teikyo University, Itabashi-ku, Tokyo, Japan
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23
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Kilbride BF, Narsinh KH, Jordan CD, Mueller K, Moore T, Martin AJ, Wilson MW, Hetts SW. MRI-guided endovascular intervention: current methods and future potential. Expert Rev Med Devices 2022; 19:763-778. [PMID: 36373162 PMCID: PMC9869980 DOI: 10.1080/17434440.2022.2141110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 10/25/2022] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Image-guided endovascular interventions, performed using the insertion and navigation of catheters through the vasculature, have been increasing in number over the years, as minimally invasive procedures continue to replace invasive surgical procedures. Such endovascular interventions are almost exclusively performed under x-ray fluoroscopy, which has the best spatial and temporal resolution of all clinical imaging modalities. Magnetic resonance imaging (MRI) offers unique advantages and could be an attractive alternative to conventional x-ray guidance, but also brings with it distinctive challenges. AREAS COVERED In this review, the benefits and limitations of MRI-guided endovascular interventions are addressed, systems and devices for guiding such interventions are summarized, and clinical applications are discussed. EXPERT OPINION MRI-guided endovascular interventions are still relatively new to the interventional radiology field, since significant technical hurdles remain to justify significant costs and demonstrate safety, design, and robustness. Clinical applications of MRI-guided interventions are promising but their full potential may not be realized until proper tools designed to function in the MRI environment are available. Translational research and further preclinical studies are needed before MRI-guided interventions will be practical in a clinical interventional setting.
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Affiliation(s)
- Bridget F. Kilbride
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | - Kazim H. Narsinh
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | | | | | - Teri Moore
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | - Alastair J. Martin
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | - Mark W. Wilson
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | - Steven W. Hetts
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
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24
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Zeng M, Oakden-Rayner L, Bird A, Smith L, Wu Z, Scroop R, Kleinig T, Jannes J, Jenkinson M, Palmer LJ. Pre-thrombectomy prognostic prediction of large-vessel ischemic stroke using machine learning: A systematic review and meta-analysis. Front Neurol 2022; 13:945813. [PMID: 36158960 PMCID: PMC9495610 DOI: 10.3389/fneur.2022.945813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 08/18/2022] [Indexed: 11/20/2022] Open
Abstract
Introduction Machine learning (ML) methods are being increasingly applied to prognostic prediction for stroke patients with large vessel occlusion (LVO) treated with endovascular thrombectomy. This systematic review aims to summarize ML-based pre-thrombectomy prognostic models for LVO stroke and identify key research gaps. Methods Literature searches were performed in Embase, PubMed, Web of Science, and Scopus. Meta-analyses of the area under the receiver operating characteristic curves (AUCs) of ML models were conducted to synthesize model performance. Results Sixteen studies describing 19 models were eligible. The predicted outcomes include functional outcome at 90 days, successful reperfusion, and hemorrhagic transformation. Functional outcome was analyzed by 10 conventional ML models (pooled AUC=0.81, 95% confidence interval [CI]: 0.77–0.85, AUC range: 0.68–0.93) and four deep learning (DL) models (pooled AUC=0.75, 95% CI: 0.70–0.81, AUC range: 0.71–0.81). Successful reperfusion was analyzed by three conventional ML models (pooled AUC=0.72, 95% CI: 0.56–0.88, AUC range: 0.55–0.88) and one DL model (AUC=0.65, 95% CI: 0.62–0.68). Conclusions Conventional ML and DL models have shown variable performance in predicting post-treatment outcomes of LVO without generally demonstrating superiority compared to existing prognostic scores. Most models were developed using small datasets, lacked solid external validation, and at high risk of potential bias. There is considerable scope to improve study design and model performance. The application of ML and DL methods to improve the prediction of prognosis in LVO stroke, while promising, remains nascent. Systematic review registration https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021266524, identifier CRD42021266524
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Affiliation(s)
- Minyan Zeng
- Australian Institute for Machine Learning, University of Adelaide, Adelaide, SA, Australia
- School of Public Health, University of Adelaide, Adelaide, SA, Australia
- *Correspondence: Minyan Zeng
| | - Lauren Oakden-Rayner
- Australian Institute for Machine Learning, University of Adelaide, Adelaide, SA, Australia
- School of Public Health, University of Adelaide, Adelaide, SA, Australia
- Department of Radiology, Royal Adelaide Hospital, Adelaide, SA, Australia
| | - Alix Bird
- Australian Institute for Machine Learning, University of Adelaide, Adelaide, SA, Australia
- School of Public Health, University of Adelaide, Adelaide, SA, Australia
| | - Luke Smith
- Australian Institute for Machine Learning, University of Adelaide, Adelaide, SA, Australia
- School of Public Health, University of Adelaide, Adelaide, SA, Australia
| | - Zimu Wu
- School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia
| | - Rebecca Scroop
- Department of Radiology, Royal Adelaide Hospital, Adelaide, SA, Australia
- Faculty Health and Medical Science, School of Medicine, University of Adelaide, Adelaide, SA, Australia
| | - Timothy Kleinig
- Faculty Health and Medical Science, School of Medicine, University of Adelaide, Adelaide, SA, Australia
- Department of Neurology, Royal Adelaide Hospital, Adelaide, SA, Australia
| | - Jim Jannes
- Faculty Health and Medical Science, School of Medicine, University of Adelaide, Adelaide, SA, Australia
- Department of Neurology, Royal Adelaide Hospital, Adelaide, SA, Australia
| | - Mark Jenkinson
- Australian Institute for Machine Learning, University of Adelaide, Adelaide, SA, Australia
- Functional Magnetic Resonance Imaging of the Brain Centre, University of Oxford, Oxford, United Kingdom
| | - Lyle J. Palmer
- Australian Institute for Machine Learning, University of Adelaide, Adelaide, SA, Australia
- School of Public Health, University of Adelaide, Adelaide, SA, Australia
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25
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Ding Z, Jiang N, Yang T, Han H, Hou M, Kumar G, Wu Y, Song L, Li X, Ma C, Su Y. Mapping the research trends of astrocytes in stroke: A bibliometric analysis. Front Cell Neurosci 2022; 16:949521. [PMID: 36159395 PMCID: PMC9492963 DOI: 10.3389/fncel.2022.949521] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 08/22/2022] [Indexed: 11/17/2022] Open
Abstract
Background Stroke, including ischemic stroke and hemorrhagic stroke, possesses complex pathological mechanisms such as neuroinflammation, oxidative stress and blood-brain barrier damage. Astrocyte functions have been reported during injury, neuroprotection and cell crosstalk. It plays a key role in exacerbating stroke injury, promoting neurological repair and enhancing neuroregeneration. Aim This holistic bibliometric analysis aimed to provide a general overview of the recent advancement and the hotspots in the field of stroke and astrocyte from 2001 to 2021. Materials and methods Publications between 2001 and 2021, related to stroke and astrocyte were retrieved from the Web of Science (WOS) and analyzed in Gephi and VOSviewer. Results In total, 3789 documents were extracted from the WOS databases. The publications showed stable growth since 2001. The United States and China were the most prolific countries and University of California San Francisco and Oakland University were the most influential institutes. The top four most productive journals were Brain Research, Journal of Cerebral Blood Flow and Metabolism, Glia and Journal of Neuroinflammation. Keywords frequency and co-occurrence analysis revealed that the topics related to “micro-RNA”, “toll like receptor”, “neuroinflammation”, “autophagy” and “interleukin” were research frontiers. The field of stroke and astrocyte focused on several aspects, such as the role of astrocytes in the treatment of stroke, metabolic changes in astrocytes, the protective role of apoptosis in astrocytes after oxidative stress injury and neurovascular units. Conclusion This comprehensive bibliometric study provides an updated perspective on the trend of research associated with stroke and astrocyte. It will benefit scientific community to identify the important issues, future directions and provide a novel understanding of stroke pathophysiology, hotspots and frontiers to facilitate future research direction.
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Affiliation(s)
- Zhibin Ding
- Department of Neurology, Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, China
- The Key Research Laboratory of Benefiting Qi for Acting Blood Circulation Method to Treat Multiple Sclerosis of State Administration of Traditional Chinese Medicine, Research Center of Neurobiology, Shanxi University of Chinese Medicine, Jinzhong, China
| | - Nan Jiang
- Department of Neurology, Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, China
| | - Ting Yang
- Department of Neurology, Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, China
| | - Hongxia Han
- Shanxi Cardiovascular Hospital, Shanxi Medical University, Taiyuan, China
| | - Miaomiao Hou
- Department of Neurology, Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, China
| | - Gajendra Kumar
- Department of Neuroscience, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Yige Wu
- The Key Research Laboratory of Benefiting Qi for Acting Blood Circulation Method to Treat Multiple Sclerosis of State Administration of Traditional Chinese Medicine, Research Center of Neurobiology, Shanxi University of Chinese Medicine, Jinzhong, China
| | - Lijuan Song
- The Key Research Laboratory of Benefiting Qi for Acting Blood Circulation Method to Treat Multiple Sclerosis of State Administration of Traditional Chinese Medicine, Research Center of Neurobiology, Shanxi University of Chinese Medicine, Jinzhong, China
| | - Xinyi Li
- Department of Neurology, Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, China
| | - Cungen Ma
- The Key Research Laboratory of Benefiting Qi for Acting Blood Circulation Method to Treat Multiple Sclerosis of State Administration of Traditional Chinese Medicine, Research Center of Neurobiology, Shanxi University of Chinese Medicine, Jinzhong, China
- *Correspondence: Cungen Ma,
| | - Yanbing Su
- General Surgery Department, Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, China
- Yanbing Su,
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26
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Barlas BA, Bahadir CD, Kafali SG, Yilmaz U, Saritas EU. Sheared two-dimensional radiofrequency excitation for off-resonance robustness and fat suppression in reduced field-of-view imaging. Magn Reson Med 2022; 88:2504-2519. [PMID: 36000548 DOI: 10.1002/mrm.29416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 07/16/2022] [Accepted: 07/27/2022] [Indexed: 11/09/2022]
Abstract
PURPOSE Two-dimensional (2D) echo-planar radiofrequency (RF) pulses are widely used for reduced field-of-view (FOV) imaging in applications such as diffusion-weighted imaging. However, long pulse durations render the 2D RF pulses sensitive to off-resonance effects, causing local signal losses in reduced-FOV images. This work aims to achieve off-resonance robustness for 2D RF pulses via a sheared trajectory design. THEORY AND METHODS A sheared 2D RF pulse design is proposed to reduce pulse durations while covering identical excitation k-space extent as a standard 2D RF pulse. For a given shear angle, the number of sheared trajectory lines is minimized to obtain the shortest pulse duration, such that the excitation replicas are repositioned outside the slice stack to guarantee unlimited slice coverage. A target fat/water signal ratio of 5% is chosen to achieve robust fat suppression. RESULTS Simulations, imaging experiments on a custom head and neck phantom, and in vivo imaging experiments in the spinal cord at 3 T demonstrate that the sheared 2D RF design provides significant improvement in image quality while preserving profile sharpnesses. In regions with high off-resonance effects, the sheared 2D RF pulse improves the signal by more than 50% when compared to the standard 2D RF pulse. CONCLUSION The proposed sheared 2D RF design successfully reduces pulse durations, exhibiting significantly improved through-plane off-resonance robustness, while providing unlimited slice coverage and high fidelity fat suppression. This method will be especially beneficial in regions suffering from a variety of off-resonance effects, such as spinal cord and breast.
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Affiliation(s)
- Bahadir Alp Barlas
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey.,National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
| | - Cagla Deniz Bahadir
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey.,National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey.,Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - Sevgi Gokce Kafali
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey.,National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey.,Department of Bioengineering, University of California Los Angeles, Los Angeles, California, USA
| | - Ugur Yilmaz
- National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
| | - Emine Ulku Saritas
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey.,National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey.,Neuroscience Graduate Program, Bilkent University, Ankara, Turkey
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27
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Zhang Y, Guo Y, Kong X, Zeng P, Yin H, Wu J, He Y, Xu Z. Improving local SNR of a single-channel 54.6 mT MRI system using additional LC-resonator. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 339:107215. [PMID: 35421711 DOI: 10.1016/j.jmr.2022.107215] [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: 08/22/2021] [Revised: 03/15/2022] [Accepted: 04/02/2022] [Indexed: 06/14/2023]
Abstract
Very-low field magnetic resonance imaging (VLF-MRI, B0 < 0.1T) has an essential application in medical imaging diagnosis because of its light weight and low cost. For single-channel RF coil VLF-MRI system, a planar spiral LC-resonator placed on the surface of samples was designed to improve the local SNR. First, an equivalent circuit model was established to evaluate the boosting effects on radiofrequency (RF) magnetic field and SNR. Second, the relationship between the resonant capacitance and the transmission coefficient was deduced according to the circuit model, and the appropriate resonant capacitance was obtained. Then, the influence of the diameter and the number of turns of the LC-resonator on the SNR is considered, and the structure of the LC-resonator was optimized to maximize the SNR. Finally, a phantom MRI experiment was carried out with our home-built 54.6 mT MRI system to compare the SNR of the experiment with the calculation, the SNR enhancement trend of the two was consistent. Additional experiments were conducted using orange and chicken leg to demonstrate the SNR enhancement abilities of the LC-resonator. The enhancement of SNR reached up to 1.8-fold and 2.2-fold depending on the distance between the sample and LC-resonator. For comparison, we conducted imaging experiments on surface receiving coil with the same parameters, and the results show that the SNR of the LC resonator is comparable to that of the surface coil. The reported LC-resonator provide a low-cost local enhancement method for VLF-MRI.
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Affiliation(s)
- Yana Zhang
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, 174 Shazheng St., Shapingba Dist., Chongqing 400044, China
| | - Yi Guo
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, 174 Shazheng St., Shapingba Dist., Chongqing 400044, China
| | - Xiaohan Kong
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, 174 Shazheng St., Shapingba Dist., Chongqing 400044, China
| | - Ping Zeng
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, 174 Shazheng St., Shapingba Dist., Chongqing 400044, China
| | - Hang Yin
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, 174 Shazheng St., Shapingba Dist., Chongqing 400044, China
| | - Jiamin Wu
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, 174 Shazheng St., Shapingba Dist., Chongqing 400044, China
| | - Yucheng He
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, 174 Shazheng St., Shapingba Dist., Chongqing 400044, China
| | - Zheng Xu
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, 174 Shazheng St., Shapingba Dist., Chongqing 400044, China.
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28
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Potential of Stroke Imaging Using a New Prototype of Low-Field MRI: A Prospective Direct 0.55 T/1.5 T Scanner Comparison. J Clin Med 2022; 11:jcm11102798. [PMID: 35628923 PMCID: PMC9147033 DOI: 10.3390/jcm11102798] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/06/2022] [Accepted: 05/13/2022] [Indexed: 12/05/2022] Open
Abstract
Objectives: Ischemic stroke is a leading cause of mortality and acquired disability worldwide and thus plays an enormous health-economic role. Imaging of choice is computed-tomographic (CT) or magnetic resonance imaging (MRI), especially diffusion-weighted (DW) sequences. However, MR imaging is associated with high costs and therefore has a limited availability leading to low-field-MRI techniques increasingly coming into focus. Thus, the aim of our study was to assess the potential of stroke imaging with low-field MRI. Material and Methods: A scanner comparison was performed including 27 patients (17 stroke cohort, 10 control group). For each patient, a brain scan was performed first with a 1.5T scanner and afterwards with a 0.55T scanner. Scan protocols were as identical as possible and optimized. Data analysis was performed in three steps: All DWI/ADC (apparent diffusion coefficient) and FLAIR (fluid attenuated inversion recovery) sequences underwent Likert rating with respect to image impression, resolution, noise, contrast, and diagnostic quality and were evaluated by two radiologists regarding number and localization of DWI and FLAIR lesions in a blinded fashion. Then segmentation of lesion volumes was performed by two other radiologists on DWI/ADC and FLAIR. Results: DWI/ADC lesions could be diagnosed with the same reliability by the most experienced reader in the 0.55T and 1.5T sequences (specificity 100% and sensitivity 92.9%, respectively). False positive findings did not occur. Detection of number/location of FLAIR lesions was mostly equivalent between 0.55T and 1.5T sequences. No significant difference (p = 0.789−0.104) for FLAIR resolution and contrast was observed regarding Likert scaling. For DWI/ADC noise, the 0.55T sequences were significantly superior (p < 0.026). Otherwise, the 1.5T sequences were significantly superior (p < 0.029). There was no significant difference in infarct volume and volume of infarct demarcation between the 0.55T and 1.5T sequences, when detectable. Conclusions: Low-field MRI stroke imaging at 0.55T may not be inferior to scanners with higher field strengths and thus has great potential as a low-cost alternative in future stroke diagnostics. However, there are limitations in the detection of very small infarcts. Further technical developments with follow-up studies must show whether this problem can be solved.
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29
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Sheth KN, Yuen MM, Mazurek MH, Cahn BA, Prabhat AM, Salehi S, Shah JT, By S, Welch EB, Sofka M, Sacolick LI, Kim JA, Payabvash S, Falcone GJ, Gilmore EJ, Hwang DY, Matouk C, Gordon-Kundu B, Rn AW, Petersen N, Schindler J, Gobeske KT, Sansing LH, Sze G, Rosen MS, Kimberly WT, Kundu P. Bedside detection of intracranial midline shift using portable magnetic resonance imaging. Sci Rep 2022; 12:67. [PMID: 34996970 PMCID: PMC8742125 DOI: 10.1038/s41598-021-03892-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 12/02/2021] [Indexed: 12/17/2022] Open
Abstract
Neuroimaging is crucial for assessing mass effect in brain-injured patients. Transport to an imaging suite, however, is challenging for critically ill patients. We evaluated the use of a low magnetic field, portable MRI (pMRI) for assessing midline shift (MLS). In this observational study, 0.064 T pMRI exams were performed on stroke patients admitted to the neuroscience intensive care unit at Yale New Haven Hospital. Dichotomous (present or absent) and continuous MLS measurements were obtained on pMRI exams and locally available and accessible standard-of-care imaging exams (CT or MRI). We evaluated the agreement between pMRI and standard-of-care measurements. Additionally, we assessed the relationship between pMRI-based MLS and functional outcome (modified Rankin Scale). A total of 102 patients were included in the final study (48 ischemic stroke; 54 intracranial hemorrhage). There was significant concordance between pMRI and standard-of-care measurements (dichotomous, κ = 0.87; continuous, ICC = 0.94). Low-field pMRI identified MLS with a sensitivity of 0.93 and specificity of 0.96. Moreover, pMRI MLS assessments predicted poor clinical outcome at discharge (dichotomous: adjusted OR 7.98, 95% CI 2.07–40.04, p = 0.005; continuous: adjusted OR 1.59, 95% CI 1.11–2.49, p = 0.021). Low-field pMRI may serve as a valuable bedside tool for detecting mass effect.
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Affiliation(s)
- Kevin N Sheth
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA.
| | - Matthew M Yuen
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - Mercy H Mazurek
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - Bradley A Cahn
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - Anjali M Prabhat
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | | | - Jill T Shah
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | | | | | | | | | - Jennifer A Kim
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | | | - Guido J Falcone
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - Emily J Gilmore
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - David Y Hwang
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - Charles Matouk
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT, USA
| | - Barbara Gordon-Kundu
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - Adrienne Ward Rn
- Neuroscience Intensive Care Unit, Yale New Haven Hospital, New Haven, CT, USA
| | - Nils Petersen
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - Joseph Schindler
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - Kevin T Gobeske
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - Lauren H Sansing
- Department of Neurology, Yale School of Medicine, 15 York Street, LLCI Room 1003C, P.O. Box 208018, New Haven, CT, 06520, USA
| | - Gordon Sze
- Department of Neuroradiology, Yale School of Medicine, New Haven, CT, USA
| | - Matthew S Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
| | - W Taylor Kimberly
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
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Goswami LN, Chakravarty S, Cai QY, Shapiro EM, Hawthorne MF, Ma L. Amphiphilic DTPA Multimer Assembled on Icosahedral Closo-Borane Motif as High-Performance MRI Blood Pool Contrast Agent. ACS APPLIED BIO MATERIALS 2021; 4:6658-6663. [DOI: 10.1021/acsabm.1c00717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lalit N. Goswami
- International Institute of Nano and Molecular Medicine and Department of Radiology, University of Missouri, Columbia, Missouri 65212, United States
| | - Shatadru Chakravarty
- International Institute of Nano and Molecular Medicine and Department of Radiology, University of Missouri, Columbia, Missouri 65212, United States
- Molecular and Cellular Imaging Laboratory, Department of Radiology, Michigan State University, East Lansing, Michigan 48823, United States
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, Michigan 48823, United States
| | - Quan-Yu Cai
- International Institute of Nano and Molecular Medicine and Department of Radiology, University of Missouri, Columbia, Missouri 65212, United States
- Harry S. Truman Memorial Veterans’ Hospital, Columbia, Missouri 65201, United States
| | - Erik M. Shapiro
- Molecular and Cellular Imaging Laboratory, Department of Radiology, Michigan State University, East Lansing, Michigan 48823, United States
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, Michigan 48823, United States
| | - M. Frederick Hawthorne
- International Institute of Nano and Molecular Medicine and Department of Radiology, University of Missouri, Columbia, Missouri 65212, United States
| | - Lixin Ma
- International Institute of Nano and Molecular Medicine and Department of Radiology, University of Missouri, Columbia, Missouri 65212, United States
- Harry S. Truman Memorial Veterans’ Hospital, Columbia, Missouri 65201, United States
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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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ESMRMB annual meeting roundtable discussion: "when less is more: the view of MRI vendors on low-field MRI". MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2021; 34:479-482. [PMID: 34259951 PMCID: PMC8278376 DOI: 10.1007/s10334-021-00938-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 06/21/2021] [Indexed: 11/12/2022]
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Zubair AS, Crawford A, Prabhat AM, Sheth KN. Use of Portable Imaging Modalities in Patients With Neurologic Disorders: A Case-Based Discussion. Cureus 2021; 13:e15841. [PMID: 34327077 PMCID: PMC8301273 DOI: 10.7759/cureus.15841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2021] [Indexed: 02/06/2023] Open
Abstract
Imaging technologies have significantly improved over the past few decades and play a critical role in the diagnosis and management of patients with neurologic conditions. With the evolution of these technologies to portable versions, significant implications exist for current neurologic care as well as potential improvements for the future. This article serves to describe portable imaging technologies and their potential impact on the field of neurology highlighted through the case of a patient who presented with symptoms consistent with a stroke.
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Schweitzer ME. On Health Care Disparities and (J)MRI. J Magn Reson Imaging 2021; 54:339-340. [PMID: 34021660 DOI: 10.1002/jmri.27728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 05/10/2021] [Indexed: 11/11/2022] Open
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Characterization of displacement forces and image artifacts in the presence of passive medical implants in low-field (<100 mT) permanent magnet-based MRI systems, and comparisons with clinical MRI systems. Phys Med 2021; 84:116-124. [PMID: 33894581 DOI: 10.1016/j.ejmp.2021.04.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/27/2021] [Accepted: 04/06/2021] [Indexed: 12/19/2022] Open
Abstract
PURPOSE To investigate the displacement forces and image artifacts associated with passive medical implants for recently-developed low-field (<100 mT) MRI systems, and to compare these with values from higher field strengths used for clinical diagnosis. METHODS Setups were constructed to measure displacement forces in a permanent magnet-based Halbach array used for in vivo MRI at 50 mT, and results compared with measurements at 7 T. Image artifacts were assessed using turbo (fast) spin echo imaging sequences for four different passive medical implants: a septal occluder, iliac stent, pedicle screw and (ferromagnetic) endoscopic clip. Comparisons were made with artifacts produced at 1.5, 3 and 7 T. Finally, specific absorption rate (SAR) simulations were performed to determine under what operating conditions the limits might be approached at low-field. RESULTS Displacement forces at 50 mT on all but the ferromagnetic implant were between 1 and 10 mN. Image artifacts at 50 mT were much less than at clinical field strengths for all passive devices, and with the exception of the ferromagnetic clip. SAR simulations show that very long echo train (>128) turbo spin echo sequences can be run with short inter-pulse times (5-10 ms) within SAR limits. CONCLUSIONS This work presents the first evaluation of the effects of passive implants at field strengths less than 100 mT in terms of displacement forces, image artifacts and SAR. The results support previous claims that such systems can be used safely and usefully in challenging enviroments such as the intensive care unit.
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Tewari S, O'Reilly T, Webb A. Improving the field homogeneity of fixed- and variable-diameter discrete Halbach magnet arrays for MRI via optimization of the angular magnetization distribution. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 324:106923. [PMID: 33567389 DOI: 10.1016/j.jmr.2021.106923] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 01/05/2021] [Accepted: 01/18/2021] [Indexed: 06/12/2023]
Abstract
The aim of this work was to maximize the homogeneity of fixed- or variable-diameter Halbach array of discrete magnets by optimizing the angular rotation of individual magnets within each ring of the array. Numerical simulations have been performed for magnet arrays with various length:radius ratios (L/R) using a dipole-approximation model. These simulations used an uninformed random-search algorithm, with the initial state corresponding to the classical Halbach dipole configuration. Two different classes of systems were studied, one with magnet rings of constant radius, and the other in which the radius of the rings was allowed to vary to increase the homogeneity. Simulation results showed that for a fixed-diameter array optimization of the angular orientation of individual magnets increased the homogeneity by ~17% for very short magnets, with the improvement dropping to ~5% for L/R values greater than ~3:1, where the homogeneity was measured over a region-of-interest equal to one-half the diameter of the magnet array. An empirical formula was derived which allows easy estimation of the required magnetization angles for any L/R. For a 23-ring variable diameter magnet with L/R of ~4:1 the optimization procedure produces an increase in homogeneity of ~18%.
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Affiliation(s)
- Sumit Tewari
- C.J. Gorter Center for High-Field MRI, Leiden University Medical Center, Department of Radiology, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Thomas O'Reilly
- C.J. Gorter Center for High-Field MRI, Leiden University Medical Center, Department of Radiology, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Andrew Webb
- C.J. Gorter Center for High-Field MRI, Leiden University Medical Center, Department of Radiology, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
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