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Tesfai AS, Fischer J, Özen AC, Eppenberger P, Oehrstroem L, Rühli F, Ludwig U, Bock M. Multi-parameter Analytical Method for B1 and SNR Analysis (MAMBA): An open source RF coil design tool. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 319:106825. [PMID: 32947127 DOI: 10.1016/j.jmr.2020.106825] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 08/05/2020] [Accepted: 09/03/2020] [Indexed: 06/11/2023]
Abstract
In Magnetic Resonance Imaging (MRI), radio frequency (RF) coils of different forms and shapes are used to maximize signal-to-noise ratio (SNR). RF coils are designed for clinical applications and have dimensions comparable with the target body part to be imaged, and they perform best when loaded by human tissue majority of which have conductivity values higher than 0.5 S/m. However, they are not properly tuned and matched for samples having low conductivity such as solid samples with low water content. Moreover, for samples with low filling factor and low conductivity, the noise in MRI is dominated by RF coil losses. In this case, RF coil design can be optimized to improve image SNR. Here, a new software tool (Multi-parameter Analytical Method for B1 and SNR Analysis) MAMBA is presented to design and compare volume coils of birdcage, solenoid, and loop-gap design for these samples. The input parameters of the tool are the sample properties, the coil design and the hardware properties, of which a relative SNR is determined. For that, a figure of merit is calculated from the coil sensitivity, applied resonant frequency and the resistive losses of sample, coil and capacitive components. The tool was tested in an ancient Egyptian mummy head which represents an extreme case of MRI with short T2*. Two optimized birdcage coils were designed using MAMBA, constructed and compared to a commercial transmit receive head coil. Calculated relative SNR values are in good agreement with the measurements.
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Affiliation(s)
- Agazi Samuel Tesfai
- Dept. of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - Johannes Fischer
- Dept. of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ali Caglar Özen
- Dept. of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany; German Consortium for Translational Cancer Research Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Patrick Eppenberger
- Institute of Evolutionary Medicine, Faculty of Medicine, University of Zurich, Switzerland
| | - Lena Oehrstroem
- Institute of Evolutionary Medicine, Faculty of Medicine, University of Zurich, Switzerland
| | - Frank Rühli
- Institute of Evolutionary Medicine, Faculty of Medicine, University of Zurich, Switzerland
| | - Ute Ludwig
- Dept. of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Bock
- Dept. of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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Killner MHM, Tosin G, Carvalho AS, Firme Bernardes D, Colnago LA. Increasing the detection distance of remote NMR using wireless inductive coupling coil. Sci Rep 2017; 7:12686. [PMID: 28978913 PMCID: PMC5627268 DOI: 10.1038/s41598-017-12854-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/14/2017] [Indexed: 12/02/2022] Open
Abstract
Unilateral nuclear magnetic resonance (UNMR) spectrometers have been applied in a variety of fields such as petrochemistry, materials science, and process control1. In UNMR measurements the sample is placed outside of the UNMR sensor and the signal intensity is reduced almost exponentially as the sample-to-sensor distances increases. To expand the detection limits of remote UNMR sensors, wireless inductive coupling was proposed and tested. This strategy was proved to reduce signal attenuation due to sample detachment from sensor, resulting in an increase in detection distance by one order of magnitude (i.e., from few millimeters to few centimeters). This novel approach broadens the potential applications of UNMR sensors and opens new opportunities in several areas, from chemical to biomedical applications.
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Affiliation(s)
- Mario Henrique M Killner
- Embrapa Instrumentação, Rua XV de Novembro 1452, São Carlos, SP, 13560-970, Brazil.,Universidade Estadual de Londrina, Pr 445-km 380, Londrina, PR, 86057-970, Brazil
| | - Giancarlo Tosin
- LMA Magnet Consultancy, Rua Filomeno Rispoli 509, 13564-200, São Carlos, São Paulo, Brazil
| | - André S Carvalho
- Instituto de Química de Sao Carlos, Universidade de São Paulo, Av. Trabalhador São-carlense 400, São Carlos, SP, Brazil
| | | | - Luiz Alberto Colnago
- Embrapa Instrumentação, Rua XV de Novembro 1452, São Carlos, SP, 13560-970, Brazil.
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Riaz B, Pfeiffer C, Schneiderman JF. Evaluation of realistic layouts for next generation on-scalp MEG: spatial information density maps. Sci Rep 2017; 7:6974. [PMID: 28765594 PMCID: PMC5539206 DOI: 10.1038/s41598-017-07046-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 06/21/2017] [Indexed: 02/08/2023] Open
Abstract
While commercial magnetoencephalography (MEG) systems are the functional neuroimaging state-of-the-art in terms of spatio-temporal resolution, MEG sensors have not changed significantly since the 1990s. Interest in newer sensors that operate at less extreme temperatures, e.g., high critical temperature (high-T c) SQUIDs, optically-pumped magnetometers, etc., is growing because they enable significant reductions in head-to-sensor standoff (on-scalp MEG). Various metrics quantify the advantages of on-scalp MEG, but a single straightforward one is lacking. Previous works have furthermore been limited to arbitrary and/or unrealistic sensor layouts. We introduce spatial information density (SID) maps for quantitative and qualitative evaluations of sensor arrays. SID-maps present the spatial distribution of information a sensor array extracts from a source space while accounting for relevant source and sensor parameters. We use it in a systematic comparison of three practical on-scalp MEG sensor array layouts (based on high-T c SQUIDs) and the standard Elekta Neuromag TRIUX magnetometer array. Results strengthen the case for on-scalp and specifically high-T c SQUID-based MEG while providing a path for the practical design of future MEG systems. SID-maps are furthermore general to arbitrary magnetic sensor technologies and source spaces and can thus be used for design and evaluation of sensor arrays for magnetocardiography, magnetic particle imaging, etc.
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Affiliation(s)
- Bushra Riaz
- MedTech West and the Institute of Neuroscience and Physiology, Sahlgrenska Academy and University of Gothenburg, Gothenburg, Sweden
| | - Christoph Pfeiffer
- Department of Microtechnology and Nanoscience - MC2, Chalmers University of Technology, Gothenburg, Sweden
| | - Justin F Schneiderman
- MedTech West and the Institute of Neuroscience and Physiology, Sahlgrenska Academy and University of Gothenburg, Gothenburg, Sweden.
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Fugariu I, Soong R, Lane D, Fey M, Maas W, Vincent F, Beck A, Schmidig D, Treanor B, Simpson AJ. Towards single egg toxicity screening using microcoil NMR. Analyst 2017; 142:4812-4824. [DOI: 10.1039/c7an01339f] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Planar NMR microcoils are evaluated, their application to single eggs is demonstrated, and their potential for studying smaller single cells is discussed.
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Affiliation(s)
- I. Fugariu
- Dept. of Chemistry and Dept. Phys. Env. Sci
- University of Toronto at Scarborough
- Scarborough
- Canada
| | - R. Soong
- Dept. of Chemistry and Dept. Phys. Env. Sci
- University of Toronto at Scarborough
- Scarborough
- Canada
| | - D. Lane
- Dept. of Chemistry and Dept. Phys. Env. Sci
- University of Toronto at Scarborough
- Scarborough
- Canada
| | - M. Fey
- Bruker Biospin
- Billerica
- USA
| | | | | | - A. Beck
- Bruker Biospin
- 8117 Fällanden
- Switzerland
| | | | - B. Treanor
- Dept. of Biological Science
- University of Toronto at Scarborough
- Scarborough
- Canada
| | - A. J. Simpson
- Dept. of Chemistry and Dept. Phys. Env. Sci
- University of Toronto at Scarborough
- Scarborough
- Canada
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Song M, Chen JH, Chen J, Lin IT. Comparisons between the 35 mm quadrature surface resonator at 300 K and the 40 mm high-temperature superconducting surface resonator at 77 K in a 3T MRI imager. PLoS One 2015; 10:e0118892. [PMID: 25812124 PMCID: PMC4374922 DOI: 10.1371/journal.pone.0118892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 01/22/2015] [Indexed: 11/29/2022] Open
Abstract
This study attempts to compare the signal-to-noise ratio (SNR) of the 40 mm High-Temperature Superconducting (HTS) surface resonator at 77 K and the 35 mm commercial quadrature (QD) surface resonator at 300 K in a 3 Tesla (T) MRI imager. To aquire images for the comparison, we implemented a phantom experiment using the 40 mm diameter Bi2Sr2Ca2Cu3Ox (Bi-2223) HTS surface resonator, the 35 mm commercial QD surface resonator and the 40 mm professionally-made copper surface resonator. The HTS surface resonator at 77 K provided a 1.43-fold SNR gain over the QD surface resonator at 300 K and provided a 3.84-fold SNR gain over the professionally-made copper surface resonator at 300 K on phantom images. The results agree with the predictions, and the difference between the predicted SNR gains and measured SNR gains is 1%. Although the geometry of the HTS surface resonator is different from the QD surface resonator, its SNR is still higher. The results demonstrate that a higher image quality can be obtained with the HTS surface resonator at 77 K. With the HTS surface resonator, the SNR can be improved, suggesting that the HTS surface resonator is a potentially helpful diagnostic tool for MRI imaging in various applications.
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Affiliation(s)
- Manli Song
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen Fujian, China
- Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, Xiamen Fujian, China
| | - Jyh-Horng Chen
- Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan
| | - Ji Chen
- Department of Physiology and Neurobiology, Medical College of Xiamen University, Xiamen Fujian, China
| | - In-Tsang Lin
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen Fujian, China
- Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, Xiamen Fujian, China
- * E-mail:
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