1
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Zhao Y, Bhosale AA, Zhang X. Multimodal surface coils for low field MR imaging. Magn Reson Imaging 2024; 112:107-115. [PMID: 38971265 DOI: 10.1016/j.mri.2024.07.005] [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: 04/16/2024] [Revised: 06/30/2024] [Accepted: 07/03/2024] [Indexed: 07/08/2024]
Abstract
Low field MRI is safer and more cost effective than the high field MRI. One of the inherent problems of low field MRI is its low signal-to-noise ratio or sensitivity. In this work, we introduce a multimodal surface coil technique for signal excitation and reception to improve the RF magnetic field (B1) efficiency and potentially improve MR sensitivity. The proposed multimodal surface coil consists of multiple identical resonators that are electromagnetically coupled to form a multimodal resonator. The field distribution of its lowest frequency mode is suitable for MR imaging applications. The prototype multimodal surface coils are built, and the performance is investigated and validated through numerical simulation, standard RF measurements and tests, and comparison with the conventional surface coil at low fields. Our results show that the B1 efficiency of the multimodal surface coil outperforms that of the conventional surface coil which is known to offer the highest B1 efficiency among all coil categories, i.e., volume coil, half-volume coil and surface coil. In addition, in low-field MRI, the required low-frequency coils often use large value capacitance to achieve the low resonant frequency which makes frequency tuning difficult. The proposed multimodal surface coil can be conveniently tuned to the required low frequency for low-field MRI with significantly reduced capacitance value, demonstrating excellent low-frequency operation capability over the conventional surface coil.
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Affiliation(s)
- Yunkun Zhao
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Aditya A Bhosale
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States; Department of Electrical Engineering, State University of New York at Buffalo, Buffalo, NY, United States.
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2
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Zhu H, Zhang Q, Li R, Chen Y, Zhang G, Wang R, Lu M, Yan X. Detunable wireless resonator arrays for TMJ MRI: A comparative study. Magn Reson Imaging 2024; 111:84-89. [PMID: 38621550 DOI: 10.1016/j.mri.2024.04.016] [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: 03/04/2024] [Revised: 04/12/2024] [Accepted: 04/12/2024] [Indexed: 04/17/2024]
Abstract
Temporomandibular Joint Magnetic Resonance Imaging (TMJ MRI) is crucial for diagnosing temporomandibular disorders (TMDs). This study advances the use of inductively coupled wireless coils to enhance imaging quality in TMJ MRI. After investigating multiple wireless resonator configurations, including a 1-loop design with a loop diameter of 9 cm, a 2-loop design with each loop having a diameter of 7 cm, and a 3-loop design with each loop having a diameter of 5 cm, our findings indicate that the 3-loop configuration achieves the optimal signal-to-noise ratio (SNR), surpassing other wireless arrays. Bilateral deployment of wireless coils further amplifies SNR, enabling superior visualization of TMJ structures, particularly with the 3-loop design. This cost-effective and comfortable solution, featuring a detunable design, eliminates the need for system parameter adjustments. The study indicates broad adaptability across MRI platforms, enhancing TMJ imaging for routine clinical diagnostics of TMDs.
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Affiliation(s)
- Haoqin Zhu
- Sino Canada Health Institute Inc., Winnipeg, Manitoba, Canada.
| | - Qiang Zhang
- The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia 010010, China
| | - Rangsong Li
- Sino Canada Health Engineering Research Institute (Hefei) Ltd. Hefei, Anhui 230088, China
| | - Yuanyuan Chen
- Sino Canada Health Engineering Research Institute (Hefei) Ltd. Hefei, Anhui 230088, China
| | - Gong Zhang
- Hubei Key Laboratory of Intelligent Conveying Technology and Device, Hubei Polytechnic University, China
| | - Ruilin Wang
- College of Nuclear Equipment and Nuclear Engineering, Yantai University, Yantai, Shandong, China
| | - Ming Lu
- College of Nuclear Equipment and Nuclear Engineering, Yantai University, Yantai, Shandong, China
| | - Xinqiang Yan
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, TN 37232, USA.
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3
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Kim J, Sun C, Moon CH, Hetherington H, Pan J. Evaluation of the performance of a 7-T 8 × 2 transceiver array. NMR IN BIOMEDICINE 2024; 37:e5146. [PMID: 38533593 DOI: 10.1002/nbm.5146] [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: 04/24/2023] [Revised: 02/16/2024] [Accepted: 02/21/2024] [Indexed: 03/28/2024]
Abstract
The decoupled 8 × 2 transceiver array has been shown to achieve a mean B1 + of 11.7 uT with a coefficient of variation of ~11% over the intracranial brain volume for 7-T MR imaging. However, this array may be thought to give lower signal-to-noise ratio (SNR) and higher g-factors for parallel imaging compared with a radio frequency (RF) receive-only coil due to the latter's higher coil count and use of coil overlap to reduce the mutual impedance. Nonetheless, because the transceiver's highly decoupled design (pertinent for transmission) should also be constructive for reception, we measured the noise correlation, g-factors, and SNR for the decoupled transceiver in comparison with a commercial reference coil. We found that although the transceiver has half the number of receive elements in comparison with the reference coil (16 vs. 32), comparable g-factors and SNR over the head were obtained. From five subjects, the transceiver versus reference coil SNR was 65 ± 10 versus 67 ± 15. The mean noise correlation for all coil pairs was 10% ± 5% and 12% ± 9% (transceiver and reference coil, respectively). As changes in load impedance may alter the S parameters, we also examined the performance of the transceiver with tuned and matched (TM) versus untuned and unmatched (UTM) conditions on five subjects. We found that the noise correlation and SNR are robust to load variation; a noise correlation of 10% ± 5% and 10% ± 6% was determined with TM versus UTM conditions (SNRUTM/SNRTM = 0.97 ± 0.08). Finally, we demonstrate the performance of the array in human brain using T2-weighted turbo spin echo imaging, finding excellent SNR performance in both caudal and rostral brain regions.
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Affiliation(s)
- Junghwan Kim
- Department of Radiology, University of Missouri, Columbia, Missouri, USA
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, Missouri, USA
| | - Changyu Sun
- Department of Radiology, University of Missouri, Columbia, Missouri, USA
- Department of Chemical and Biomedical Engineering, University of Missouri, Columbia, Missouri, USA
| | - Chan Hong Moon
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Hoby Hetherington
- Department of Radiology, University of Missouri, Columbia, Missouri, USA
- Resonance Research Inc., Billerica, Massachusetts, USA
| | - Jullie Pan
- Department of Radiology, University of Missouri, Columbia, Missouri, USA
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4
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Bhosale AA, Zhao Y, Zhang X. Electric field and SAR reduction in high-impedance RF arrays by using high permittivity materials for 7T MR imaging. PLoS One 2024; 19:e0305464. [PMID: 38959266 PMCID: PMC11221758 DOI: 10.1371/journal.pone.0305464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 05/30/2024] [Indexed: 07/05/2024] Open
Abstract
In the field of ultra-high field MR imaging, the challenges associated with higher frequencies and shorter wavelengths necessitate rigorous attention to multichannel array design. While the need for such arrays remains, and efforts to increase channel counts continue, a persistent impediment-inter-element coupling-constantly hinders development. This coupling degrades current and field distribution, introduces noise correlation between channels, and alters the frequency of array elements, affecting image quality and overall performance. The goal of optimizing ultra-high field MRI goes beyond resolving inter-element coupling and includes significant safety considerations related to the design changes required to achieve high-impedance coils. Although these coils provide excellent isolation, the higher impedance needs special design changes. However, such changes pose a significant safety risk in the form of strong electric fields across low-capacitance lumped components. This process may raise Specific Absorption Rate (SAR) values in the imaging subject, increasing power deposition and, as a result, the risk of tissue heating-related injury. To balance the requirement of inter-element decoupling with the critical need for safety, we suggest a new solution. Our method uses high-dielectric materials to efficiently reduce electric fields and SAR values in the imaging sample. This intervention tries to maintain B1 efficiency and inter-element decoupling within the existing array design, which includes high-impedance coils. Our method aims to promote the full potential of ultra-high field MRI by alleviating this critical safety concern with minimal changes to the existing array setup.
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Affiliation(s)
- Aditya A. Bhosale
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States of America
| | - Yunkun Zhao
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States of America
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States of America
- Department of Electrical Engineering, State University of New York at Buffalo, Buffalo, NY, United States of America
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5
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Payne K, Zhao Y, Bhosale AA, Zhang X. Dual-Tuned Coaxial-Transmission-Line RF Coils for Hyperpolarized 13C and Deuterium 2H Metabolic MRS Imaging at Ultrahigh Fields. IEEE Trans Biomed Eng 2024; 71:1521-1530. [PMID: 38090865 PMCID: PMC11095995 DOI: 10.1109/tbme.2023.3341760] [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] [Indexed: 12/26/2023]
Abstract
OBJECTIVE Information on the metabolism of tissues in healthy and diseased states plays a significant role in the detection and understanding of tumors, neurodegenerative diseases, diabetes, and other metabolic disorders. Hyperpolarized carbon-13 magnetic resonance imaging (13C-HPMRI) and deuterium metabolic imaging (2H-DMI) are two emerging X-nuclei used as practical imaging tools to investigate tissue metabolism. However due to their low gyromagnetic ratios (ɣ13C = 10.7 MHz/T; ɣ2H = 6.5 MHz/T) and natural abundance, such method required a sophisticated dual-tuned radiofrequency (RF) coil. METHODS Here, we report a dual-tuned coaxial transmission line (CTL) RF coil agile for metabolite information operating at 7T with independent tuning capability. The design analysis has demonstrated how both resonant frequencies can be individually controlled by simply varying the constituent of the design parameters. RESULTS Numerical results have demonstrated a broadband tuning range capability, covering most of the X-nucleus signal, especially the 13C and 2H spectra at 7T. Furthermore, in order to validate the feasibility of the proposed design, both dual-tuned 1H/13C and 1H/2H CTLs RF coils are fabricated using a semi-flexible RG-405 .086" coaxial cable and bench test results (scattering parameters and magnetic field efficiency/distribution) are successfully obtained. CONCLUSION The proposed dual-tuned RF coils reveal highly effective magnetic field obtained from both proton and heteronuclear signal which is crucial for accurate and detailed imaging. SIGNIFICANCE The successful development of this new dual-tuned RF coil technique would provide a tangible and efficient tool for ultrahigh field metabolic MR imaging.
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6
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Payne K, Zhao Y, Bhosale AA, Zhang X. Eight-channel dual-tuned coaxial-transmission-line coils array for human head imaging at 10.5 Tesla. PROCEEDINGS OF THE INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE ... SCIENTIFIC MEETING AND EXHIBITION. INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE. SCIENTIFIC MEETING AND EXHIBITION 2024; 32:0465. [PMID: 38798757 PMCID: PMC11127717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Affiliation(s)
- Komlan Payne
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Yunkun Zhao
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Aditya Ashok Bhosale
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
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7
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Zhao Y, Bhosale AA, Zhang X. Multimodal surface coils for low field MR imaging. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.04.14.24305802. [PMID: 38699318 PMCID: PMC11065021 DOI: 10.1101/2024.04.14.24305802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
Low field MRI is safer and more cost effective than the high field MRI. One of the inherent problems of low field MRI is its low signal-to-noise ratio or sensitivity. In this work, we introduce a multimodal surface coil technique for signal excitation and reception to improve the RF magnetic field (B 1 ) efficiency and potentially improve MR sensitivity. The proposed multimodal surface coil consists of multiple identical resonators that are electromagnetically coupled to form a multimodal resonator. The field distribution of its lowest frequency mode is suitable for MR imaging applications. The prototype multimodal surface coils are built, and the performance is investigated and validated through numerical simulation, standard RF measurements and tests, and comparison with the conventional surface coil at low fields. Our results show that the B 1 efficiency of the multimodal surface coil outperforms that of the conventional surface coil which is known to offer the highest B 1 efficiency among all coil categories, i.e., volume coil, half-volume coil and surface coil. In addition, in low-field MRI, the required low-frequency coils often use large value capacitance to achieve the low resonant frequency which makes frequency tuning difficult. The proposed multimodal surface coil can be conveniently tuned to the required low frequency for low-field MRI with significantly reduced capacitance value, demonstrating excellent low-frequency operation capability over the conventional surface coil.
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8
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Bhosale AA, Zhao Y, Zhang X. Electric Field and SAR Reduction in High Impedance RF Arrays by Using High Permittivity Materials for 7T MR Imaging. ARXIV 2023:arXiv:2312.04491v1. [PMID: 38106453 PMCID: PMC10723527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Higher frequencies and shorter wavelengths present significant design issues at ultra-high fields, making multi-channel array setup a critical component for ultra-high field MR imaging. The requirement for multi-channel arrays, as well as ongoing efforts to increase the number of channels in an array, are always limited by the major issue known as inter-element coupling. This coupling affects the current and field distribution, noise correlation between channels, and frequency of array elements, lowering imaging quality and performance. To realize the full potential of UHF MRI, we must ensure that the coupling between array elements is kept to a minimum. High-impedance coils allow array systems to completely realize their potential by providing optimal isolation while requiring minimal design modifications. These minor design changes, which demand the use of low capacitance on the conventional loop to induce elevated impedance, result in a significant safety hazard that cannot be overlooked. High electric fields are formed across these low capacitance lumped elements, which may result in higher SAR values in the imaging subject, depositing more power and, ultimately, providing a greater risk of tissue heating-related injury to the human sample. We propose an innovative method of utilizing high-dielectric material to effectively reduce electric fields and SAR values in the imaging sample while preserving the B1 efficiency and inter-element decoupling between the array elements to address this important safety concern with minimal changes to the existing array design comprising high-impedance coils.
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Affiliation(s)
- Aditya A Bhosale
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Yunkun Zhao
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
- Department of Electrical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
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9
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Payne K, Zhao Y, Bhosale AA, Zhang X. Dual-tuned Coaxial-transmission-line RF coils for Hyperpolarized 13C and Deuterium 2H Metabolic MRS Imaging at Ultrahigh Fields. ARXIV 2023:arXiv:2307.11221v3. [PMID: 37502626 PMCID: PMC10370217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Objective Information on the metabolism of tissues in healthy and diseased states plays a significant role in the detection and understanding of tumors, neurodegenerative diseases, diabetes, and other metabolic disorders. Hyperpolarized carbon-13 magnetic resonance imaging (13C-HPMRI) and deuterium metabolic imaging (2H-DMI) are two emerging X-nuclei used as practical imaging tools to investigate tissue metabolism. However due to their low gyromagnetic ratios (ɣ13C = 10.7 MHz/T; ɣ 2H = 6.5 MHz/T) and natural abundance, such method required a sophisticated dual-tuned radiofrequency (RF) coil. Methods Here, we report a dual-tuned coaxial transmission line (CTL) RF coil agile for metabolite information operating at 7T with independent tuning capability. The design analysis has demonstrated how both resonant frequencies can be individually controlled by simply varying the constituent of the design parameters. Results Numerical results have demonstrated a broadband tuning range capability, covering most of the X-nucleus signal, especially the 13C and 2H spectra at 7T. Furthermore, in order to validate the feasibility of the proposed design, both dual-tuned 1H/13C and 1H/2H CTLs RF coils are fabricated using a semi-flexible RG-405 .086" coaxial cable and bench test results (scattering parameters and magnetic field efficiency/distribution) are successfully obtained. Conclusion The proposed dual-tuned RF coils reveal highly effective magnetic field obtained from both proton and heteronuclear signal which is crucial for accurate and detailed imaging. Significance The successful development of this new dual-tuned RF coil technique would provide a tangible and efficient tool for ultrahigh field metabolic MR imaging.
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Affiliation(s)
- Komlan Payne
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260 USA
| | - Yunkun Zhao
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260 USA
| | - Aditya Ashok Bhosale
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260 USA
| | - Xiaoliang Zhang
- Departments of Biomedical Engineering and Electrical Engineering, State University of New York at Buffalo, Buffalo, NY 14260 USA
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Payne K, Bhosale AA, Zhang X. Double cross magnetic wall decoupling for quadrature transceiver RF array coils using common-mode differential-mode resonators. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 353:107498. [PMID: 37295282 PMCID: PMC10527004 DOI: 10.1016/j.jmr.2023.107498] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/09/2023] [Accepted: 05/31/2023] [Indexed: 06/12/2023]
Abstract
In contrast to linearly polarized RF coil arrays, quadrature transceiver coil arrays are capable of improving signal-to-noise ratio (SNR), spatial resolution, and parallel imaging performance. Owing to a reduced excitation power, a low specific absorption rate can also be obtained using quadrature RF coils. However, due to the complex nature of their structure and their electromagnetic properties, it is challenging to achieve sufficient electromagnetic decoupling while designing multichannel quadrature RF coil arrays, particularly in ultra-high fields. In this work, we proposed a double-cross magnetic wall decoupling for quadrature transceiver RF arrays and implemented the decoupling method on common-mode differential mode quadrature (CMDM) quadrature transceiver arrays at an ultrahigh field of 7 T. The proposed magnetic decoupling wall, comprised of two intrinsically decoupled loops, is used to reduce the mutual coupling between all the multi-mode currents present in the quadrature CMDM array. The decoupling network has no physical connection with the CMDMs' resonators, which provides less design constraint over size-adjustable RF arrays. To validate the feasibility of the proposed cross-magnetic decoupling wall, systematic studies on the decoupling performance based on the impedance of two intrinsic loops are numerically performed. A pair of quadrature transceiver CMDMs is constructed along with the proposed decoupling network, and their scattering matrix is characterized using a network analyzer. The measured results indicate that all the current modes from coupling are simultaneously suppressed using the proposed cross-magnetic wall. Moreover, field distribution and local specific absorption rate (SAR) are numerically obtained for a well-decoupled 8-channel quadrature knee-coil array.
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Affiliation(s)
- Komlan Payne
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA.
| | - Aditya Ashok Bhosale
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA.
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA; Department of Electrical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA.
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Payne K, Bhosale AA, Ying LL, Zhang X. Design of a Highly Decoupled Compact Dual-tuned Transceiver RF Coil Arrays for 1H MRI and 31P MRSI at 7T. PROCEEDINGS OF THE INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE ... SCIENTIFIC MEETING AND EXHIBITION. INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE. SCIENTIFIC MEETING AND EXHIBITION 2023; 31:3912. [PMID: 37600530 PMCID: PMC10440076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 08/22/2023]
Affiliation(s)
- Komlan Payne
- Department of Biomedical Engineering, University at Buffalo, Buffalo, NY, United States
| | - Aditya Ashok Bhosale
- Department of Biomedical Engineering, University at Buffalo, Buffalo, NY, United States
| | - Leslie Lei Ying
- Department of Biomedical Engineering, University at Buffalo, Buffalo, NY, United States
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, University at Buffalo, Buffalo, NY, United States
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12
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Zhao Y, Payne K, YIng L, Zhang X. A coupled planar RF array for ultrahigh field MR imaging. PROCEEDINGS OF THE INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE ... SCIENTIFIC MEETING AND EXHIBITION. INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE. SCIENTIFIC MEETING AND EXHIBITION 2023; 31:3910. [PMID: 37600537 PMCID: PMC10438998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 08/22/2023]
Affiliation(s)
- Yunkun Zhao
- Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Komlan Payne
- Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Leslie YIng
- Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Xiaoliang Zhang
- Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
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13
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Bhosale AA, Ying L, Zhang X. Investigating the Optimal Number of Channels in an Array System for Human Head Imaging at 7T. PROCEEDINGS OF THE INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE ... SCIENTIFIC MEETING AND EXHIBITION. INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE. SCIENTIFIC MEETING AND EXHIBITION 2023; 31:4075. [PMID: 37600536 PMCID: PMC10440070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 08/22/2023]
Affiliation(s)
- Aditya Ashok Bhosale
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Leslie Ying
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States
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14
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Du F, Li N, Yang X, Zhang B, Zhang X, Li Y. Design and construction of an 8-channel transceiver coil array for rat imaging at 9.4 T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 351:107302. [PMID: 37116433 DOI: 10.1016/j.jmr.2022.107302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 08/27/2022] [Accepted: 09/11/2022] [Indexed: 05/29/2023]
Abstract
Ultra-high field (UHF) small animal magnetic resonance imaging (MRI) is a crucial tool permitting investigation of metabolic diseases and identification of imaging biomarkers suitable for clinical diagnosis and translation. Radiofrequency (RF) coils are critical components in enabling acquisition of high-quality rat abdomen MRI data. However, efficient RF coils with high-channel count, capable of sensitive and accelerated rat abdomen imaging at 9.4 T, are not available commercially. The SNR of the commonly-used 9.4 T birdcage coil is relatively weak, particularly in the peripheral area of the subject. In addition, the birdcage is not readily to perform parallel imaging due to unavailability of the required multiple channels. Consequently, the extended scanning duration may cause unnecessary hazards to the rat. In this work, an 8-channel transceiver coil array was designed and constructed to provide good image quality and large coverage for rat abdomen imaging at 9.4 T. The structure and the performance of the developed array was optimized and evaluated by numerical electromagnetic simulations and bench tests, respectively. The MR imaging experiments in phantoms and rat models were also performed on a Bruker 9.4 T preclinical MRI system to validate the feasibility of the proposed design. The coil array supports a one-dimensional acceleration factor up to R = 4, providing good parallel imaging capabilities. These results demonstrated that the proposed 8-channel transceiver coil array for rat imaging has the ability to obtain high spatial resolution of rat abdomen anatomical structure images at 9.4 T.
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Affiliation(s)
- Feng Du
- Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen 518055, Guang Dong, China
| | - Nan Li
- Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen 518055, Guang Dong, China
| | - Xing Yang
- Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen 518055, Guang Dong, China
| | - Baogui Zhang
- State Key Laboratory of Brain and Cognitive Sciences, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China; Brainnetome Center, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, State University of New York at Buffalo, NY, United States., Buffalo, NY, United States
| | - Ye Li
- Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen 518055, Guang Dong, China.
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15
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Lu M, Zhang X, Chai S, Yan X. Improving Specific Absorption Rate Efficiency and Coil Robustness of Self-Decoupled Transmit/Receive Coils by Elevating Feed and Mode Conductors. SENSORS (BASEL, SWITZERLAND) 2023; 23:1800. [PMID: 36850397 PMCID: PMC9960379 DOI: 10.3390/s23041800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
Self-decoupling technology was recently proposed for radio frequency (RF) coil array designs. Here, we propose a novel geometry to reduce the peak local specific absorption rate (SAR) and improve the robustness of the self-decoupled coil. We first demonstrate that B1 is determined by the arm conductors, while the maximum E-field and local SAR are determined by the feed conductor in a self-decoupled coil. Then, we investigate how the B1, E-field, local SAR, SAR efficiency, and coil robustness change with respect to different lift-off distances for feed and mode conductors. Next, the simulation of self-decoupled coils with optimal lift-off distances on a realistic human body is performed. Finally, self-decoupled coils with optimal lift-off distances are fabricated and tested on the workbench and MRI experiments. The peak 10 g-averaged SAR of the self-decoupled coil on the human body can be reduced by 34% by elevating the feed conductor. Less coil mismatching and less resonant frequency shift with respect to loadings were observed by elevating the mode conductor. Both the simulation and experimental results show that the coils with elevated conductors can preserve the high interelement isolation, B1+ efficiency, and SNR of the original self-decoupled coils.
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Affiliation(s)
- Ming Lu
- College of Nuclear Equipment and Nuclear Engineering, Yantai University, Yantai 264005, China
| | - Xiaoyang Zhang
- College of Nuclear Equipment and Nuclear Engineering, Yantai University, Yantai 264005, China
| | - Shuyang Chai
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Xinqiang Yan
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, TN 37232, USA
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Marwah H, Pant J, Yadav J, Shah K, Dewangan HK. Biosensor Detection of COVID-19 in Lung Cancer: Hedgehog and Mucin Signaling Insights. Curr Pharm Des 2023; 29:3442-3457. [PMID: 38270161 DOI: 10.2174/0113816128276948231204111531] [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: 09/05/2023] [Accepted: 10/25/2023] [Indexed: 01/26/2024]
Abstract
Coronavirus disease 2019 is a global pandemic, particularly affecting individuals with pre-existing lung conditions and potentially leading to pulmonary fibrosis. Age and healthcare system limitations further amplify susceptibility to both diseases, especially in low- and middle-income countries. The intricate relationship between Coronavirus disease 2019 and lung cancer highlights their clinical implications and the potential for early detection through biosensor techniques involving hedgehog and mucin signaling. This study highlights the connection between Coronavirus disease 2019 and lung cancer, focusing on the mucosa, angiotensin- altering enzyme 2 receptors, and their impact on the immune system. It details the inflammatory mechanisms triggered by Coronavirus disease 2019, which can result in pulmonary fibrosis and influence the cancer microenvironment. Various cytokines like Interleukins-6 and Tumor Necrosis Factor-alpha are examined for their roles in both diseases. Moreover, the review delves into the Hedgehog signaling pathways and their significance in lung cancer, particularly their influence on embryonic cell proliferation and tissue integrity. Mucin signaling is another vital aspect, highlighting the diverse mucin expression patterns in respiratory epithelial tissues and their potential as biomarkers. The review concludes with insights into diagnostic imaging techniques like chest computed tomography, Positron Emission Tomography and Computed Tomography, and Magnetic Resonance Imaging for early lung cancer detection, emphasizing the crucial role of biosensors in identifying specific biomarkers for early disease detection. This review provides a comprehensive overview of the clinical impact of Coronavirus disease 2019 on lung cancer patients and the potential for biosensors utilizing hedgehog and mucin signaling for early detection. It underscores the ongoing need for research and innovation to address these critical healthcare challenges.
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Affiliation(s)
- Harneet Marwah
- University Institute of Pharma Sciences (UIPS), Chandigarh University, NH-95 Chandigarh Ludhiana Highway, Mohali, Punjab, India
| | - Janmejay Pant
- University Institute of Pharma Sciences (UIPS), Chandigarh University, NH-95 Chandigarh Ludhiana Highway, Mohali, Punjab, India
| | - Jiten Yadav
- University Institute of Pharma Sciences (UIPS), Chandigarh University, NH-95 Chandigarh Ludhiana Highway, Mohali, Punjab, India
| | - Kamal Shah
- Institute of Pharmaceutical Research (IPR), GLA University Mathura, NH-2 Delhi Mathura Road, Po-CHaumuhan, Uttar Pradesh, India
| | - Hitesh Kumar Dewangan
- University Institute of Pharma Sciences (UIPS), Chandigarh University, NH-95 Chandigarh Ludhiana Highway, Mohali, Punjab, India
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Payne K, Ying LL, Zhang X. Hairpin RF resonators for MR imaging transceiver arrays with high inter-channel isolation and B 1 efficiency at ultrahigh field 7 T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 345:107321. [PMID: 36335877 DOI: 10.1016/j.jmr.2022.107321] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 10/17/2022] [Accepted: 10/22/2022] [Indexed: 06/03/2023]
Abstract
Electromagnetic decoupling among a close-fitting or high-density transceiver RF array elements is required to maintain the integrity of the magnetic flux density from individual channel for enhanced performance in detection sensitivity and parallel imaging. High-impedance RF coils have demonstrated to be a prominent design method to circumvent these coupling issues. Yet, inherent characteristics of these coils have ramification on the B1 field efficiency and SNR. In this work, we propose a hairpin high impedance RF resonator design for highly decoupled multichannel transceiver arrays at ultrahigh magnetic fields. Due to the high impedance property of the hairpin resonators, the proposed transceiver array can provide high decoupling performance without using any dedicated decoupling circuit among the resonant elements. Because of elimination of lumped inductors in the resonator circuit, higher B1 field efficiency in imaging subjects can be expected. In order to validate the feasibility of the proposed hairpin RF coils, systematical studies on decoupling performance, field distribution, and SNR are performed, and the results are compared with those obtained from existing high-impedance RF coil, e.g., "self-decoupled RF coil". To further investigate its performance, an 8-channel head coil array using the proposed hairpin resonators loaded with a cylindrical phantom is designed, demonstrating a 19 % increase of the B1+ field intensity compared to the self-decoupled coils at 7 T. Furthermore, the characteristics of the hairpin RF coils are evaluated using a more realistic human head voxel model numerically. The proposed hairpin RF coil provides excellent decoupling performance and superior RF magnetic field efficiency compared to the "self-decoupled" high impedance coils. Bench test of a pair of fabricated hairpin coils prove to be in good accordance with numerical results.
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Affiliation(s)
- Komlan Payne
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA.
| | - Leslie L Ying
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA; Department of Electrical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA.
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA; Department of Electrical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA.
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18
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Lu M, Sengupta S, Gore JC, Grissom WA, Yan X. High-Density MRI RF Arrays Using Mixed Dipole Antennas and Microstrip Transmission Line Resonators. IEEE Trans Biomed Eng 2022; 69:3243-3252. [PMID: 35404807 PMCID: PMC9587496 DOI: 10.1109/tbme.2022.3166279] [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] [Indexed: 11/08/2022]
Abstract
OBJECTIVE High-density multi-coil arrays are desirable in MRI because they provide high signal-to-noise ratios (SNR), enable highly accelerated parallel imaging, and provide more uniform transmit fields at high fields. For high-density arrays such as a head array with 16 elements in a row, popular dipole antennas and microstrip transmission line (also referred to as "MTL") resonators both have severe coupling issues. METHODS In this work, we show that dipoles and MTLs have naturally low coupling and propose a novel array configuration in which they are interleaved. We first show the electromagnetic (EM) coupling between a single dipole and a single MTL across different separations in bench tests. Then we validate and analyze this through EM simulations. Finally, we construct a 16-channel mixed dipole and MTL array and evaluate its performance on the bench and through MRI experiments. RESULTS Without any decoupling treatments, the worst coupling between a dipole and an MTL was only -15.8 dB when their center-to-center distance was 4.7 cm (versus -5.4 dB for two dipole antennas and -6.0 dB for two MTL resonators). Even in a dense 16-channel mixed array, the inter-element isolation among all elements was better than -14 dB. CONCLUSION This study reveals, analyzes, and validates a novel finding that the popular dipole antennas and MTL resonators used in ultrahigh field MRI have naturally low coupling. SIGNIFICANCE These findings will simplify the construction of high-density arrays, enable new applications, and benefit imaging performance in ultrahigh field MRI.
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Sample-centred shimming enables independent parallel NMR detection. Sci Rep 2022; 12:14149. [PMID: 35986044 PMCID: PMC9389490 DOI: 10.1038/s41598-022-17694-y] [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: 04/20/2022] [Accepted: 07/29/2022] [Indexed: 11/24/2022] Open
Abstract
Two major technical challenges facing parallel nuclear magnetic resonance (NMR) spectroscopy, at the onset, include the need to achieve exceptional \documentclass[12pt]{minimal}
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\begin{document}$$B_0$$\end{document}B0 homogeneity, and good inter-detector radiofrequency signal decoupling, and have remained as technical obstacles that limit high throughput compound screening via NMR. In this contribution, we consider a compact detector system, consisting of two NMR ‘unit cell’ resonators that implement parallel \documentclass[12pt]{minimal}
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\begin{document}$$B_0$$\end{document}B0 shimming with parallel radiofrequency detection, as a prototype NMR environment, pointing the way towards achieving accelerated NMR analysis. The utility of our approach is established by achieving local field correction within the bore of a 1.05T permanent magnet MRI. Our forerunner platform suppresses signal cross-coupling in the range of \documentclass[12pt]{minimal}
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\begin{document}$$-21$$\end{document}-21 dB to \documentclass[12pt]{minimal}
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\begin{document}$$-30$$\end{document}-30 dB, under a geometrically decoupled scheme, leading to a halving of the necessary inter-coil separation. In this permanent magnet environment, two decoupled parallel NMR detector sites simultaneously achieve narrow spectral linewidth, overcoming the spatial inhomogeneity of the magnet from 400 to 28 Hz.
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Zhu Y, Lu M, Yan X. Resistor-free and one-board-fits-all ratio adjustable power splitter for add-on RF shimming in high field MRI. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 338:107194. [PMID: 35316747 PMCID: PMC9050946 DOI: 10.1016/j.jmr.2022.107194] [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: 11/16/2021] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 05/03/2023]
Abstract
Ratio adjustable power splitter (RAPS) circuits were recently proposed for add-on RF shimming. Previous RAPSs split the input RF signal with a Wilkinson splitter or 50-Ω-terminated hybrid coupler into two branches, delay these two signals with cable/microstrip line phase shifters, and recombine them with another hybrid coupler. They require resistors to provide high output isolation and a cable/microstrip line library to realize desired splitting ratios. Here we propose a novel resistor-free RAPS circuit in which the Wilkinson splitter/50-Ω-terminated hybrid is replaced with a resistor-free T-junction splitter. A novel sliding mechanism was employed to further combine the T-junction's output arms with subsequent phase shifters and realize a one-board-fits-all design. The resistor-free RAPS was theoretically analyzed, simulated, and validated on workbench and MRI experiments. The resistor-free RAPS's splitting ratio has a tan/cot dependence on the phase/length difference between the T-junction output arms. The ratio can be continuously adjusted to any value by sliding the input arm without additional cable/microstrip libraries, largely saving time and effort when determining the best RF weights in practice. The fabricated resistor-free RAPS has a compact size, excellent input impedance matching, and a low insertion loss. Potential safety concerns caused by unwanted power dissipation on RF resistors are eliminated. The simulation and MRI experiments demonstrated that the resistor-free RAPS functions well on a widely-used Tx coil.
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Affiliation(s)
- Yue Zhu
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Ming Lu
- College of Nuclear Equipment and Nuclear Engineering, Yantai University, Yantai, Shandong, China
| | - Xinqiang Yan
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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21
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Payne K, Khan SI, Zhang X. Investigation of Magnetic Wall Decoupling for planar Quadrature RF Array coils using Common-Mode Differential-mode Resonators. PROCEEDINGS OF THE INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE ... SCIENTIFIC MEETING AND EXHIBITION. INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE. SCIENTIFIC MEETING AND EXHIBITION 2022; 30:4504. [PMID: 36071707 PMCID: PMC9445056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Affiliation(s)
- Komlan Payne
- Jacobs School of Medicine & Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, United States
| | - Salik Inayat Khan
- Jacobs School of Medicine & Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, United States
| | - Xiaoliang Zhang
- Jacobs School of Medicine & Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, United States
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22
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Choi CH, Hong SM, Felder J, Tellmann L, Scheins J, Kops ER, Lerche C, Shah NJ. A Novel J-Shape Antenna Array for Simultaneous MR-PET or MR-SPECT Imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2022; 41:1104-1113. [PMID: 34860648 DOI: 10.1109/tmi.2021.3132576] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Simultaneous MR-PET/-SPECT is an emerging technology that capitalises on the invaluable advantages of both modalities, allowing access to numerous sensitive tracers and superior soft-tissue contrast alongside versatile functional imaging capabilities. However, to optimise these capabilities, concurrent acquisitions require the MRI antenna located inside the PET/SPECT field-of-view to be operated without compromising any aspects of system performance or image quality compared to the stand-alone instrumentation. Here, we report a novel gamma-radiation-transparent antenna concept. The end-fed J-shape antenna is particularly adept for hybrid ultra-high field MR-PET/-SPECT applications as it enables all highly attenuating materials to be placed outside the imaging field-of-view. Furthermore, this unique configuration also provides advantages in stand-alone MR applications by reducing the amount of coupling between the cables and the antenna elements, and by lowering the potential specific absorption rate burden. The use of this new design was experimentally verified according to the important features for both ultra-high field MRI and the 511 keV transmission scan. The reconstructed attenuation maps evidently showed much lower attenuation ( ∼ 15 %) for the proposed array when compared to the conventional dipole antenna array since there were no high-density components. In MR, it was observed that the signal-to-noise ratio from the whole volume obtained using the proposed array was comparable to that acquired by the conventional array which was also in agreement with the simulation results. The unique feature, J-shape array, would enable simultaneous MR-PET/-SPECT experiments to be conducted without unduly compromising any aspects of system performance and image quality compared to the stand-alone instrumentation.
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Li N, Zheng H, Xu G, Gui T, Yin Q, Chen Q, Lee J, Xin Y, Zhang S, He Q, Zhang X, Liu X, Zheng H, Wang D, Li Y. Simultaneous Head and Spine MR Imaging in Children Using a Dedicated Multichannel Receiver System at 3T. IEEE Trans Biomed Eng 2021; 68:3659-3670. [PMID: 34014817 DOI: 10.1109/tbme.2021.3082149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The purpose of this work was to enable simultaneous head and spine Magnetic Resonance imaging (MRI) in children at 3T by using a dedicated multichannel radiofrequency coil array system. METHODS A 24-channel head and spine pediatric coil system was developed and constructed. The coils performance was compared with a commercially available 24-channel adult head-neck coil and a spine coil (1-4 spine of 16-channel were selected). Signal-to-noise ratio (SNR) and parallel imaging capability were quantitatively evaluated by phantom studies and in vivo imaging experiments. With Institutional Review Board and Ethics Committee approval, the designed coil was used to acquire head and spine images on 27 children in clinical settings. RESULTS The pediatric coil provided substantial SNR improvements with an increase of 32 % to 40 % in the brain region and up to a two-fold increase in the surface. SNR increased by at least 18 % in the spine region. The coil enabled higher resolution and a faster imaging speed, owing to significantly improved SNR. Extensive coverage of the coil enabled high-quality fast imaging from head-neck to the whole spine. Good image quality with an average score 4.63 out of 5 was achieved using the developed pediatric coil in clinical studies. CONCLUSION Simultaneous head and spine MRI with superior performance have been successfully acquired in children subjects at 3T using the dedicated 24-channel head and spine pediatric coil system. SIGNIFICANCE The 24-channel pediatric coil system potentially can enhance pediatric head and spine MRI in clinical research and diagnosis.
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Avdievich NI, Solomakha G, Ruhm L, Henning A, Scheffler K. Unshielded bent folded-end dipole 9.4 T human head transceiver array decoupled using modified passive dipoles. Magn Reson Med 2021; 86:581-597. [PMID: 33629436 DOI: 10.1002/mrm.28711] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 01/14/2021] [Accepted: 01/14/2021] [Indexed: 11/10/2022]
Abstract
PURPOSE To develop an unshielded dipole transceiver array for human head imaging at 9.4 Tesla and to improve decoupling of adjacent dipole elements, a novel array design with modified passive dipole antennas was developed, evaluated, and tested. METHODS The new array consisted of 8 bent folded-end dipole elements placed in a single row and surrounding the head. Adjacent elements of RF transceiver arrays are usually decoupled by introducing circuits electrically connected to elements. These methods are difficult to use for dipole arrays because of the distant location of the adjacent antennas. A recently developed decoupling technique using passive dipoles is simple and does not require any electrical connection. However, common parallel passive dipoles can produce destructive interference with the RF field of the array itself. To minimize this interference, we placed the passive dipoles perpendicularly to the active dipoles and positioned them at the ends of the array. We also evaluated the effect of different passive dipoles on the array transmit performance. Finally, we optimized the array transmit performance by varying the length of the dipole folded portion. RESULTS By rotating the passive dipoles 90º and moving them toward the ends of the array, we minimized the destructive interference to an acceptable level without compromising decoupling and the transmit efficiency. CONCLUSION While keeping the benefits of the passive dipole decoupling method, the new modified dipoles produce substantially less destructive interference with the RF field of the array than the common design. The constructed transceiver array demonstrated good decoupling and whole-brain coverage.
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Affiliation(s)
- Nikolai I Avdievich
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Georgiy Solomakha
- Department of Physics and Engineering, ITMO University, St. Petersburg, Russia
| | - Loreen Ruhm
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Anke Henning
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Klaus Scheffler
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Department for Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany
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25
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Li X, Pan JW, Avdievich NI, Hetherington HP, Rispoli JV. Electromagnetic simulation of a 16-channel head transceiver at 7 T using circuit-spatial optimization. Magn Reson Med 2021; 85:3463-3478. [PMID: 33533500 DOI: 10.1002/mrm.28672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 12/16/2020] [Accepted: 12/17/2020] [Indexed: 11/07/2022]
Abstract
PURPOSE With increased interest in parallel transmission in ultrahigh-field MRI, methods are needed to correctly calculate the S-parameters and complex field maps of the parallel transmission coil. We present S-parameters paired with spatial field optimization to fully simulate a double-row 16-element transceiver array for brain MRI at 7 T. METHODS We implemented a closed-form equation of the coil S-parameters and overall spatial B 1 + field. We minimized a cost function, consisting of coil S-parameters and the B 1 + homogeneity in brain tissue, by optimizing transceiver components, including matching, decoupling circuits, and lumped capacitors. With this, we are able to compare the in silico results determined with and without B 1 + homogeneity weighting. Using the known voltage range from the host console, we reconstructed the B 1 + maps of the array and performed RF shimming with four realistic head models. RESULTS As performed with B 1 + homogeneity weighting, the optimized coil circuit components were highly consistent over the four heads, producing well-tuned, matched, and decoupled coils. The mean peak forward powers and B 1 + statistics for the head models are consistent with in vivo human results (N = 8). There are systematic differences in the transceiver components as optimized with or without B 1 + homogeneity weighting, resulting in an improvement of 28.4 ± 7.5% in B 1 + homogeneity with a small 1.9 ± 1.5% decline in power efficiency. CONCLUSION This co-simulation methodology accurately simulates the transceiver, predicting consistent S-parameters, component values, and B 1 + field. The RF shimming of the calculated field maps match the in vivo performance.
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Affiliation(s)
- Xin Li
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Jullie W Pan
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Neurology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Nikolai I Avdievich
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Hoby P Hetherington
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Joseph V Rispoli
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, USA
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26
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Beck MJ, Parker DL, Hadley JR. Capacitive versus Overlap Decoupling of Adjacent Radio Frequency Phased Array Coil Elements: An Imaging Robustness Comparison When Sample Load Varies for 3 Tesla MRI. CONCEPTS IN MAGNETIC RESONANCE. PART B, MAGNETIC RESONANCE ENGINEERING 2020; 2020:8828047. [PMID: 34867110 PMCID: PMC8640609 DOI: 10.1155/2020/8828047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Phased array (PA) receive coils are built such that coil elements approximate independent antenna behavior. One method of achieving this goal is to use an available decoupling method to decouple adjacent coil elements. The purpose of this work was to compare the relative performance of two decoupling methods as a function of variation in sample load. Two PA receive coils with 5 channels (5-ch) each, equal outer dimensions, and formed on 12 cm diameter cylindrical phantoms of conductivities 0.3, 0.6, and 0.9 S/m were evaluated for relative signal-to-noise ratio (SNR) and parallel imaging performance. They were only tuned and matched to the 0.6 S/m phantom. Simulated and measured axial, sagittal, and coronal 5-ch PA coil SNR ratios were compared by dividing the overlap by the capacitive decoupled coil SNR results. Issues related to the selection of capacitor values for the two decoupling methods were evaluated by taking the ratio of the match and tune capacitors for large and small 2 channel (2-ch) PA coils. The SNR ratios showed that the SNR of the two decoupling methods were very similar. The inverse geometry-factor maps showed similar but better overall parallel imaging performance for the capacitive decoupled method. The quotients for the 2-ch PA coils' maximum and minimum capacitor value ratios are 3.28 and 1.38 for the large and 3.28 and 2.22 for the small PA. The results of this paper demonstrate that as the sample load varies, the capacitive and overlap decoupling methods are very similar in relative SNR and this similarity continues for parallel imaging performance. Although, for the 5-ch coils studied, the capacitive decoupling method has a slight SNR and parallel imaging advantage and it was noted that the capacitive decoupled coil is more likely to encounter unbuildable PA coil configurations.
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Affiliation(s)
- Michael J Beck
- Department of Radiology and Imaging Sciences, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City 84132, USA
| | - Dennis L Parker
- Department of Radiology and Imaging Sciences, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City 84132, USA
| | - J Rock Hadley
- Department of Radiology and Imaging Sciences, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City 84132, USA
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Li Y, Lee J, Long X, Qiao Y, Ma T, He Q, Cao P, Zhang X, Zheng H. A Magnetic Resonance-Guided Focused Ultrasound Neuromodulation System With a Whole Brain Coil Array for Nonhuman Primates at 3 T. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:4401-4412. [PMID: 32833632 DOI: 10.1109/tmi.2020.3019087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The phased-array radio frequency (RF) coil plays a vital role in magnetic resonance-guided focused ultrasound (MRgFUS) neuromodulation studies, where accurate brain functional stimulations and neural circuit observations are required. Although various designs of phased-array coils have been reported, few are suitable for ultrasound stimulations. In this study, an MRgFUS neuromodulation system comprised of a whole brain coverage non-human primate (NHP) RF coil and an MRI-compatible ultrasound device was developed. When compared to a single loop coil, the NHP coil provided up to a 50% increase in the signal-to-noise ratio (SNR) in the brain and acquired better anatomical image-quality. The NHP coil also demonstrated the ability to achieve higher spatial resolution and reduce distortion in echo-planer imaging (EPI). Ultrasound beam characteristics and transcranial magnetic resonance acoustic radiation force (MR-ARF) were measured for simulated positions, and calculated B0 maps were employed to establish MRI-compatibility. The differences between focused off and on ultrasound techniques were measured using SNR, g-factors, and temporal SNR (tSNR) analyses and all deviations were under 2.3%. The EPI images quality and stable tSNR demonstrated the suitability of the MRgFUS neuromodulation system to conduct functional MRI studies. Last, the time course of the blood oxygen level dependent (BOLD) signal of posterior cingulate cortex in a focused ultrasound neuromodulation study was detected and repeated with MR thermometry.
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Choi CH, Hong SM, Felder J, Shah NJ. The state-of-the-art and emerging design approaches of double-tuned RF coils for X-nuclei, brain MR imaging and spectroscopy: A review. Magn Reson Imaging 2020; 72:103-116. [DOI: 10.1016/j.mri.2020.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/16/2020] [Accepted: 07/01/2020] [Indexed: 12/18/2022]
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Luo S, Xiao L, Zong F, Li X, Liao G, Shi G, Men B, Zhang X, Wang Z, Sun Z, Deng F. Inside-out azimuthally selective NMR tool using array coil and capacitive decoupling. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 315:106735. [PMID: 32408240 DOI: 10.1016/j.jmr.2020.106735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 04/14/2020] [Accepted: 04/17/2020] [Indexed: 06/11/2023]
Abstract
Inside-out nuclear magnetic resonance (NMR) is a unique technique for investigating large in-situ objects outside of tools, to provide pore structure and pore-bearing fluids properties. However, in borehole, objects towards azimuthal orientations pose different properties, referred to as azimuthal spatial heterogeneity. This may lead to ambiguous evaluations by utilizing present inside-out NMR measurement, which hardly resolves azimuthal information and loses the location information of oil/gas. In this paper, we for the first time design and construct an innovative tool to investigate the heterogeneity of large in-situ samples. The most key component, array coil, which performs with azimuthal selection, measurement consistency and interactive isolation, configured in this novel tool to capture heterogeneity information. Whereas, strong coupling between neighboring coil elements largely decrease the coil sensitivity. Capacitive decoupling network is bridged into adjacent ports without segmenting coils to be decoupled and could be easily adjusted by electrical relays. The coil model and numerical simulation are firstly given to demonstrate the array coil configuration, B1 field map and mutual coupling effects on coil sensitivity. Capacitive network is then introduced to be theoretically and practically analyzed to minimize coupling effects. Simulation and experimental results demonstrate that these coil elements have excellent consistency and independence to feasibly acquire the azimuthal NMR data.
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Affiliation(s)
- Sihui Luo
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, China
| | - Lizhi Xiao
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, China; Harvard SEAS-CUPB Joint Laboratory on Petroleum Science, Harvard University, Cambridge, USA.
| | - Fangrong Zong
- Institute of Biophysics, China Academy of Sciences, Beijing, China
| | - Xin Li
- Sinopec Research Institute of Petroleum Engineering, Beijing, China
| | - Guangzhi Liao
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, China
| | - Guuanghui Shi
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, China
| | - Baiyong Men
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, China
| | | | - Zhengduo Wang
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, China
| | - Zhe Sun
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, China
| | - Feng Deng
- PetroChina Research Institute of Petroleum Exploration and Development, Beijing, China
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Optimization of a transmit/receive surface coil for squirrel monkey spinal cord imaging. Magn Reson Imaging 2020; 68:197-202. [PMID: 32087231 DOI: 10.1016/j.mri.2020.02.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 02/14/2020] [Accepted: 02/15/2020] [Indexed: 12/20/2022]
Abstract
MR Imaging the spinal cord of non-human primates (NHP), such as squirrel monkey, is important since the injuries in NHP resemble those that afflict human spinal cords. Our previous studies have reported a multi-parametric MRI protocol, including functional MRI, diffusion tensor imaging, quantitative magnetization transfer and chemical exchange saturation transfer, which allows non-invasive detection and monitoring of injury-associated structural, functional and molecular changes over time. High signal-to-noise ratio (SNR) is critical for obtaining high-resolution images and robust estimates of MRI parameters. In this work, we describe our construction and use of a single channel coil designed to maximize the SNR for imaging the squirrel monkey cervical spinal cord in a 21 cm bore magnet at 9.4 T. We first numerically optimized the coil dimension of a single loop coil and then evaluated the benefits of a quadrature design. We then built an optimized coil based on the simulation results and compared its SNR performance with a non-optimized single coil in both phantoms and in vivo.
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Brizi D, Fontana N, Costa F, Tiberi G, Galante A, Alecci M, Monorchio A. Design of Distributed Spiral Resonators for the Decoupling of MRI Double-Tuned RF Coils. IEEE Trans Biomed Eng 2020; 67:2806-2816. [PMID: 32031927 DOI: 10.1109/tbme.2020.2971843] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE A systematic analytical approach to design Spiral Resonators (SRs), acting as distributed magnetic traps (DMTs), for the decoupling of concentric Double-Tuned (DT) RF coils suitable for Ultra-High Field (7 T) MRI is presented. METHODS The design is based on small planar SRs placed in between the two RF loops (used for signal detection of the two nuclei of interest). We developed a general framework based on a fully analytical approach to estimate the mutual coupling between the RF coils and to provide design guidelines for the geometry and number of SRs to be employed. Starting from the full-analytical estimations of the SRs geometry, electromagnetic simulations for improving and validating the performance can be carried out. RESULTS AND CONCLUSION We applied the method to a test case of a DT RF coil consisting of two concentric and coplanar loops used for 7 T MRI, tuned at the Larmor frequencies of the proton (1H, 298 MHz) and sodium (23Na, 79 MHz) nuclei, respectively. We performed numerical simulations and experimental measurements on fabricated prototypes, which both demonstrated the effectiveness of the proposed design procedure. SIGNIFICANCE The decoupling is achieved by printing the SRs on the same dielectric substrate of the RF coils thus allowing a drastic simplification of the fabrication procedure. It is worth noting that there are no physical connections between the decoupling SRs and the 1H/23Na RF coils, thus providing a mechanically robust experimental set-up, and improving the transceiver design with respect to other traditional decoupling techniques.
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Li Y, Chen Q, Wei Z, Zhang L, Tie C, Zhu Y, Jia S, Xia J, Liang D, He Q, Zhang X, Liu X, Zhang B, Zheng H. One-Stop MR Neurovascular Vessel Wall Imaging With a 48-Channel Coil System at 3 T. IEEE Trans Biomed Eng 2019; 67:2317-2327. [PMID: 31831406 DOI: 10.1109/tbme.2019.2959030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE The purpose of this article was to build a radio frequency (RF) coil system to achieve high vessel wall image quality with coverage extending from the aortic arch to the intracranial vessels. METHODS A 48-channel coil system was built and characterized at a 3 tesla (T) Magnetic Resonance Imaging (MRI) scanner (uMR 790, Shanghai United Imaging Healthcare, Shanghai, China). The coil's performance was compared with a commercially available 36-channel coil system. By human studies, signal-to-noise ratio (SNR) units were evaluated and g-factors were calculated in the transverse planes of the brain and neck regions. RESULTS The SNR was increased by at least 28% in the brain region and up to fourfold in the neck region. The average g-factor with the acceleration factor, R = 3, was lowered by 21% in the transverse plane of the neck region. Intracranial and carotid arterial wall images with an isotropic spatial resolution of 0.63 mm were acquired within 7.7 minutes and thoracic aorta wall images with an isotropic spatial resolution of 1.1 mm were acquired within 2.7 minutes with the 48-channel coil system. The vessel wall can be more clearly visualized with the 48-channel coil system compared with the 36-channel coil system. CONCLUSION A 48-channel coil system was developed and demonstrated superior performance for vessel wall imaging at the intracranial and cervical carotid arteries compared with a commercial 36-channel coil. SIGNIFICANCE The 48-channel coil system is potentially useful for clinical diagnostics, especially when attempting to diagnose ischemic stroke.
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Vincent JM, Rispoli JV. Conductive Thread-Based Stretchable and Flexible Radiofrequency Coils for Magnetic Resonance Imaging. IEEE Trans Biomed Eng 2019; 67:2187-2193. [PMID: 31794385 DOI: 10.1109/tbme.2019.2956682] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE We propose a novel flexible and entirely stretchable radiofrequency coil for magnetic resonance imaging. This coil design aims at increasing patient comfort during imaging while maintaining or improving image quality. METHODS Conductive silver-coated thread was zigzag stitched onto stretchable athletic fabric to create a single-loop receive coil. The stitched coil was mounted in draped and stretched fashions and compared to a coil fabricated on flexible printed circuit board. Match/tune circuits, detuning circuits, and baluns were incorporated into the final setup for bench measurements and imaging on a 3T MR scanner. A fast spin echo sequence was used to obtain images for comparison. RESULTS The fabricated coil presents multi-directional stretchability and flexibility while maintaining conductivity and stitch integrity. SNR calculations show that this stretchable coil design is comparable to a flexible, standard PCB coil with a 13-30% decrease in SNR depending on stretch degree and direction. In vivo human wrist images were obtained using the stitched coil. CONCLUSION Despite the reduction in SNR for this combination of materials, there is a reduced percentage of SNR drop as compared to existing stretch coil designs. These imaging results and calculations support further experimentation into more complex coil geometries. SIGNIFICANCE This coil is uniquely stretchable in all directions, allowing for joint imaging at various degrees of flexion, while offering the closest proximity of placement to the skin. The materials provide a similar level of comfort to athletic wear and could be incorporated into coils for a variety of anatomies.
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Sun H, AlZubaidi A, Purchase A, Sharp JC. A geometrically decoupled, twisted solenoid single‐axis gradient coil set for TRASE. Magn Reson Med 2019; 83:1484-1498. [DOI: 10.1002/mrm.28003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 08/23/2019] [Accepted: 08/28/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Hongwei Sun
- Department of Oncology University of Alberta Edmonton AlbertaCanada
| | - Abbas AlZubaidi
- Division of Biomedical Engineering University of Saskatchewan Saskatoon SaskatchewanCanada
| | - Aaron Purchase
- Department of Oncology University of Alberta Edmonton AlbertaCanada
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Li Y, Lee J, Zhang L, Chen Q, Tie C, Luo C, Zhang X, Liang D, Liu X, Zheng H. Design and testing of a 24-channel head coil for MR imaging at 3 T. Magn Reson Imaging 2019; 58:162-173. [DOI: 10.1016/j.mri.2019.01.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 12/07/2018] [Accepted: 01/22/2019] [Indexed: 11/29/2022]
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Chen Q, Xie G, Luo C, Yang X, Zhu J, Lee J, Su S, Liang D, Zhang X, Liu X, Li Y, Zheng H. A Dedicated 36-Channel Receive Array for Fetal MRI at 3T. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:2290-2297. [PMID: 29994303 PMCID: PMC6312740 DOI: 10.1109/tmi.2018.2839191] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Due to a lack of fetal imaging coils, the standard commercial abdominal coil is often used for fetal imaging, the performance of which is limited by its insufficient coverage, element number, and Signal-to-noise ratio (SNR). In this paper, a dedicated 36-channel coil array, of which size can best fit the body sizes of pregnancy gestation from 20 to 37+ weeks, was designed for fetal imaging at 3T. SNR with full phase encoding and G-factor denoted as noise amplification for parallel imaging were quantitatively evaluated by phantom studies. Compared with a commercial abdominal coil array, the proposed 36-channel fetal array provides not only SNR improvements in full phase encoding (with 10% in the region where the whole fetal body was located, and up to 40% in the edge region where the fetal brain and heart may appear) but also an augmented parallel imaging capability and remarkable SNR improvements at high acceleration factors.
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Affiliation(s)
- Qiaoyan Chen
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China, and also with Shenzhen Key Laboratory for MRI, Shenzhen 518055, China
| | - Guoxi Xie
- School of Basic Science, Guangzhou Medical University, Guangzhou 511436, China
| | - Chao Luo
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China, and also with Shenzhen Key Laboratory for MRI, Shenzhen 518055, China
| | - Xing Yang
- High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, Chengdu 610054, China
| | - Jin Zhu
- Shenzhen People’s Hospital, Shenzhen 518020, China
| | - Jo Lee
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China, and also with Shenzhen Key Laboratory for MRI, Shenzhen 518055, China
| | - Shi Su
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China, and also with Shenzhen Key Laboratory for MRI, Shenzhen 518055, China
| | - Dong Liang
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China, and also with Shenzhen Key Laboratory for MRI, Shenzhen 518055, China
| | - Xiaoliang Zhang
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158 USA, and also with the UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, CA 94158 USA
| | - Xin Liu
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China, and also with Shenzhen Key Laboratory for MRI, Shenzhen 518055, China
| | - Ye Li
- Corresponding authors: Ye Li, and Hairong Zheng. ; .
| | - Hairong Zheng
- Corresponding authors: Ye Li, and Hairong Zheng. ; .
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Yan X, Gore JC, Grissom WA. Self-decoupled radiofrequency coils for magnetic resonance imaging. Nat Commun 2018; 9:3481. [PMID: 30154408 PMCID: PMC6113296 DOI: 10.1038/s41467-018-05585-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 07/06/2018] [Indexed: 11/08/2022] Open
Abstract
Arrays of radiofrequency coils are widely used in magnetic resonance imaging to achieve high signal-to-noise ratios and flexible volume coverage, to accelerate scans using parallel reception, and to mitigate field non-uniformity using parallel transmission. However, conventional coil arrays require complex decoupling technologies to reduce electromagnetic coupling between coil elements, which would otherwise amplify noise and limit transmitted power. Here we report a novel self-decoupled RF coil design with a simple structure that requires only an intentional redistribution of electrical impedances around the length of the coil loop. We show that self-decoupled coils achieve high inter-coil isolation between adjacent and non-adjacent elements of loop arrays and mixed arrays of loops and dipoles. Self-decoupled coils are also robust to coil separation, making them attractive for size-adjustable and flexible coil arrays.
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Affiliation(s)
- Xinqiang Yan
- Vanderbilt University Institute of Imaging Science, Nashville, TN, 37232, USA.
- Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, 37232, USA.
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Nashville, TN, 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, 37232, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37232, USA
| | - William A Grissom
- Vanderbilt University Institute of Imaging Science, Nashville, TN, 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, 37232, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37232, USA
- Department of Electrical Engineering, Vanderbilt University, Nashville, TN, USA
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Cui J, Dimitrov IE, Cheshkov S, Gu M, Malloy CR, Wright SM. An Adjustable-Length Dipole Using Forced-Current Excitation for 7T MR. IEEE Trans Biomed Eng 2018; 65:2259-2266. [PMID: 29989961 DOI: 10.1109/tbme.2017.2788864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Ultrahigh field imaging of the body and the spine is challenging due to the large field-of-view (FOV) required. It is especially difficult for RF transmission due to its requirement on both the length and the depth of the ${\rm{B}}_{1}^{{\rm + }}$ field. One solution is to use a long dipole to provide continuous current distribution. The drawback is the natural falloff of the ${\rm{B}}_{1}$ field toward the ends of the dipole, therefore the ${\rm{B}}_{1}^{{\rm + }}$ per unit square root of maximum specific absorption rate ${\rm{(B}}_{1}^{{\rm + }}{\rm{/ \surd SAR}}_{{\rm{max}}})$ performance is particularly poor toward the end of the dipole. In this study, a segmented element design using forced-current excitation and a switching circuit is presented. The design provides long FOV when desired and allows flexible FOV switching and power distribution without additional power amplifiers. Different element types and arrangements were explored and a segmented dipole design was chosen as the best design. The segmented dipole was implemented and tested on the bench and with a phantom on a 7T whole body scanner. The switchable mode dipole enabled a large FOV in the long mode and improved ${\rm{B}}_{1}^{{\rm + }}{\rm{/ \surd SAR}}_{{\rm{max}}}$ efficiency in a smaller FOV in the short mode.
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Ha Y, Choi CH, Shah NJ. Development and Implementation of a PIN-Diode Controlled, Quadrature-Enhanced, Double-Tuned RF Coil for Sodium MRI. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:1626-1631. [PMID: 29969413 DOI: 10.1109/tmi.2017.2786466] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Sodium (23Na) MRI provides complementary cellular and metabolic information. However, the intrinsic MR sensitivity of 23Na is considerably lower compared with that of the proton, making it difficult to measure MR-detectable sodium signals. It is therefore important to maintain the signal-to-noise ratio (SNR) of the sodium signal as high as possible. Double-tuned coils are often employed in combinationwith a 1H coil, providing structural images and B0 shimming capability. The double-tuned coil design can be achieved with the use of two geometrically decoupled coils whose B1 field directions are perpendicular to each other. This can be used to design quadrature-driven, single-nucleus coils to improve SNR, and additionally, this coil can also be utilized as a linear-driven double-resonant mode. Here, we have developed and evaluateda quadrature-enhanced, double-tuned coil. The novel coil uses PIN-diode switches, inserted only in the loop coil, to shift the resonance frequency between 1H and 23Na so that 23Na signals can be acquired in quadrature and the capability of using 1H function remains. Consequently, the 23Na SNR values obtained with the double-tuned coil are nearly 33% and 17% higher in comparison with geometrically identical single-tuned coils. SNR plots also show the superiority of double-tuned coil in 23Na.
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Li N, Liu S, Hu X, Luo C, Zhang X, Li Y. Electromagnetic Field and Radio Frequency Circuit Co-Simulation for Magnetic Resonance Imaging Dual-Tuned Radio Frequency Coils. IEEE TRANSACTIONS ON MAGNETICS 2018; 54:5100504. [PMID: 29755135 PMCID: PMC5947962 DOI: 10.1109/tmag.2017.2758518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Electromagnetic (EM) field simulation plays a key role in the design of magnetic resonance imaging radio frequency (RF) coils. However, the values of the components in tuning and matching circuits often need to be iterated repeatedly in the conventional simulation method in order to achieve optimal scattering parameters. This leads to a time-consuming optimization to tune and match RF coils, particularly dual-tuned coils that are comprised of multiple lumped elements. A method combining EM field simulation and circuit simulation was employed in this paper, which can dramatically improve simulation efficiency for the optimization of the values of the lumped elements and corresponding EM field distribution. A systematical theoretical analysis of the co-simulation method was presented. To validate the accuracy and efficiency of the co-simulation method, a comparison study was conducted between the conventional simulation and the proposed co-simulation approaches.
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Affiliation(s)
- Nan Li
- Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
- Department of Biomedical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Shengping Liu
- Department of Biomedical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Xiaoqing Hu
- Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Chao Luo
- Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Xiaoliang Zhang
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA 94158 USA
- UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, CA 94158 USA
| | - Ye Li
- Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
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Barry RL, Vannesjo SJ, By S, Gore JC, Smith SA. Spinal cord MRI at 7T. Neuroimage 2018; 168:437-451. [PMID: 28684332 PMCID: PMC5894871 DOI: 10.1016/j.neuroimage.2017.07.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 06/30/2017] [Accepted: 07/02/2017] [Indexed: 11/25/2022] Open
Abstract
Magnetic resonance imaging (MRI) of the human spinal cord at 7T has been demonstrated by a handful of research sites worldwide, and the spinal cord remains one of the areas in which higher fields and resolution could have high impact. The small diameter of the cord (∼1 cm) necessitates high spatial resolution to minimize partial volume effects between gray and white matter, and so MRI of the cord can greatly benefit from increased signal-to-noise ratio and contrasts at ultra-high field (UHF). Herein we review the current state of UHF spinal cord imaging. Technical challenges to successful UHF spinal cord MRI include radiofrequency (B1) nonuniformities and a general lack of optimized radiofrequency coils, amplified physiological noise, and an absence of methods for robust B0 shimming along the cord to mitigate image distortions and signal losses. Numerous solutions to address these challenges have been and are continuing to be explored, and include novel approaches for signal excitation and acquisition, dynamic shimming and specialized shim coils, and acquisitions with increased coverage or optimal slice angulations.
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Affiliation(s)
- Robert L Barry
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA.
| | - S Johanna Vannesjo
- Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Samantha By
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Seth A Smith
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
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Ruytenberg T, Webb AG. Design of a dielectric resonator receive array at 7 Tesla using detunable ceramic resonators. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 284:94-98. [PMID: 29024876 DOI: 10.1016/j.jmr.2017.09.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 08/30/2017] [Accepted: 09/30/2017] [Indexed: 06/07/2023]
Abstract
Ceramic-based dielectric resonators can be used for high frequency magnetic resonance imaging and microscopy. When used as elements in a transmit array, the intrinsically low inter-element coupling allows flexibility in designing different geometric arrangements for different regions-of-interest. However, without being able to detune such resonators, they cannot be used as elements in a receive-only array. Here, we propose and implement a method, based on mode-disruption, for detuning ceramic-based dielectric resonators to enable them to be used as receive-only elements.
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Affiliation(s)
- Thomas Ruytenberg
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Andrew G Webb
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
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43
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O'Reilly TPA, Ruytenberg T, Webb AG. Modular transmit/receive arrays using very-high permittivity dielectric resonator antennas. Magn Reson Med 2017. [PMID: 28635034 PMCID: PMC5811774 DOI: 10.1002/mrm.26784] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE Dielectric resonator antenna (DRAs) are compact structures that exhibit low coupling between adjacent elements and therefore can be used as MRI transmit arrays. In this study, we use very high permittivity materials to construct modular flexible transceive arrays of a variable numbers of elements for operation at 7T. METHODS DRAs were constructed using rectangular blocks of ceramic (lead zirconate titanate, εr = 1070) with the transverse electric (TE)01 mode tuned to 298 MHz. Finite-difference time-domain simulations were used to determine the B1 and specific absorption rate distributions. B1+ maps were acquired in a phantom to validate the simulations. Performance was compared to an equally sized surface coil. In vivo images were acquired of the wrist (four elements), ankle (seven elements), and calf muscle (16 elements). RESULTS Coupling between DRAs spaced 5 mm apart on a phantom was -18.2 dB compared to -9.1 dB for equivalently spaced surface coils. DRAs showed a higher B1+ intensity close to the antenna but a lower penetration depth compared to the surface coil. CONCLUSION DRAs show very low coupling compared to equally sized surface coils and can be used in transceive arrays without requiring decoupling networks. The penetration depth of the current DRA geometry means they are ideally suited to imaging of extremities. Magn Reson Med 79:1781-1788, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
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Affiliation(s)
- Thomas P A O'Reilly
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Thomas Ruytenberg
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Andrew G Webb
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
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Zhang X. Sensitivity enhancement of traveling wave MRI using free local resonators: an experimental demonstration. Quant Imaging Med Surg 2017; 7:170-176. [PMID: 28516042 DOI: 10.21037/qims.2017.02.10] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Traveling wave MR uses the far fields in signal excitation and reception, therefore its acquisition efficiency is low in contrast to the conventional near field magnetic resonance (MR). Here we show a simple and efficient method based on the local resonator to improving sensitivity of traveling wave MR technique. The proposed method utilizes a standalone or free local resonator to amplify the radio frequency magnetic fields in the interested target. The resonators have no wire connections to the MR system and thus can be conveniently placed to any place around imaging simples. METHODS A rectangular loop L/C resonator to be used as the free local resonator was tuned to the proton Larmor frequency at 7T. Traveling wave MR experiments with and without the wireless free local resonator were performed on a living rat using a 7T whole body MR scanner. The signal-to-noise ratio (SNR) or sensitivity of the images acquired was compared and evaluated. RESULTS In vivo 7T imaging results show that traveling wave MR with a wireless free local resonator placed near the head of a living rat achieves at least 10-fold SNR gain over the images acquired on the same rat using conventional traveling wave MR method, i.e. imaging with no free local resonators. CONCLUSIONS The proposed free local resonator technique is able to enhance the MR sensitivity and acquisition efficiency of traveling wave MR at ultrahigh fields in vivo. This method can be a simple solution to alleviating low sensitivity problem of traveling wave MRI.
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Affiliation(s)
- Xiaoliang Zhang
- Department of Radiology and Biomedical Imaging, School of Medicine, University of California, San Francisco, CA, USA.,UC Berkeley/UCSF Joint Graduate Group in Bioengineering, University of California, San Francisco, CA, USA.,California Institute for Quantitative Biosciences (QB3), San Francisco, CA, USA
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Yan X, Gore JC, Grissom WA. New resonator geometries for ICE decoupling of loop arrays. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 277:59-67. [PMID: 28236786 PMCID: PMC5389865 DOI: 10.1016/j.jmr.2017.02.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/10/2017] [Accepted: 02/13/2017] [Indexed: 06/06/2023]
Abstract
RF arrays with a large number of independent coil elements are advantageous for parallel transmission (pTx) and reception at high fields. One of the main challenges in designing RF arrays is to minimize the electromagnetic (EM) coupling between the coil elements. The induced current elimination (ICE) method, which uses additional resonator elements to cancel coils' mutual EM coupling, has proven to be a simple and efficient solution for decoupling microstrip, L/C loop, monopole and dipole arrays. However, in previous embodiments of conventional ICE decoupling, the decoupling elements acted as "magnetic-walls" with low transmit fields and consequently low MR signal near them. To solve this problem, new resonator geometries including overlapped and perpendicular decoupling loops are proposed. The new geometries were analyzed theoretically and validated in EM simulations, bench tests and MR experiments. The isolation between two closely-placed loops could be improved from about -5dB to <-45dB by using the new geometries.
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Affiliation(s)
- Xinqiang Yan
- Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA.
| | - John C Gore
- Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - William A Grissom
- Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
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Georget E, Luong M, Vignaud A, Giacomini E, Chazel E, Ferrand G, Amadon A, Mauconduit F, Enoch S, Tayeb G, Bonod N, Poupon C, Abdeddaim R. Stacked magnetic resonators for MRI RF coils decoupling. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 275:11-18. [PMID: 27951426 DOI: 10.1016/j.jmr.2016.11.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 11/01/2016] [Accepted: 11/20/2016] [Indexed: 06/06/2023]
Abstract
Parallel transmission is a very promising method to tackle B1+ field inhomogeneities at ultrahigh field in magnetic resonant imaging (MRI). This technique is however limited by the mutual coupling between the radiating elements. Here we propose to solve this problem by designing a passive magneto-electric resonator that we here refer to as stacked magnetic resonator (SMR). By combining numerical and experimental methodologies, we prove that this novelty passive solution allows an efficient decoupling of elements of a phased-array coil. We demonstrate the ability of this technique to significantly reduce by more than 10dB the coupling preserving the quality of images compared to ideally isolated linear resonators on a spherical salty agar gel phantom in a 7T MRI scanner.
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Affiliation(s)
- Elodie Georget
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | - Michel Luong
- Université Paris-Saclay, CEA-Saclay, DRF/IRFU/SACM, 91191 Gif-sur-Yvette Cedex, France.
| | - Alexandre Vignaud
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | - Eric Giacomini
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | - Edouard Chazel
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | - Guillaume Ferrand
- Université Paris-Saclay, CEA-Saclay, DRF/IRFU/SACM, 91191 Gif-sur-Yvette Cedex, France.
| | - Alexis Amadon
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | | | - Stefan Enoch
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France.
| | - Gérard Tayeb
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France.
| | - Nicolas Bonod
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France.
| | - Cyril Poupon
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | - Redha Abdeddaim
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France.
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47
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Connell IRO, Menon RS. General Coupling Matrix Synthesis for Decoupling MRI RF Arrays. IEEE TRANSACTIONS ON MEDICAL IMAGING 2016; 35:2229-2242. [PMID: 27093549 DOI: 10.1109/tmi.2016.2553844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Multi-channel radio-frequency (RF) arrays, composed of multiple resonant coils, provide significant benefits for MRI during both signal reception (receive) and excitation (transmit). Demonstration of increased signal-to-noise ratio (SNR) and acceleration factors during parallel acquisitions has lead to the development of receive arrays. Conversely, transmit arrays have demonstrated considerable potential for mitigating excitation inhomogeneity arising at ultra-high magnetic field strengths ( ≥ 7 T) , present due to wave-like interactions inside the sample. Due to geometric constraints, the design of both receive and transmit arrays requires the resonating coils to be closely spaced. Significant overlap in the near-field distributions from each coil results in coupling. Without an adequate decoupling strategy applied between individual elements in an RF array, the MRI performance of the array can be significantly degraded. This work presents a method to design decoupling networks for arbitrarily large RF arrays based on direct synthesis of a coupling matrix. Reflection coefficients are fitted to transfer polynomials with transmission coefficients simultaneously minimized through a nonlinear optimization. The method demonstrates the design of nth-order distributed filters and lumped element networks that compensate for all first-order and cross-coupling terms arising in an RF array suitable for MRI. The synthesis results are computed for 4-, 8-, and 32-channel RF arrays. Monte Carlo analyses and experimental results for two RF array constructions demonstrate the robustness of this approach.
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Yan X, Zhang X, Xue R, Gore JC, Grissom WA. Optimizing the ICE decoupling element distance to improve monopole antenna arrays for 7 Tesla MRI. Magn Reson Imaging 2016; 34:1264-1268. [PMID: 27469314 DOI: 10.1016/j.mri.2016.07.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 07/19/2016] [Accepted: 07/21/2016] [Indexed: 11/15/2022]
Abstract
The induced current elimination (ICE) method has been previously applied to decouple monopole coil arrays in ultrahigh field MRI. However, the method creates low B1+ spots near the decoupling elements. In this study, we aim to improve the performance of ICE-decoupled monopole array in human head imaging at 7 Tesla. Eight-channel ICE-decoupled monopole arrays were optimized by varying the position of the decoupling elements. A series of numerical studies were performed using the co-simulation method. In simulation, decoupling performance, quality (Q-) values and transmit field (B1+) were comparatively investigated. In addition, we constructed an optimized ICE-decoupled monopole array and compared its performance with the unoptimized array. The simulation results showed that a good trade-off between decoupling and B1+ loss can be obtained when decoupling elements were moved 2.5-cm away from coil elements. This was validated by in-vivo MR imaging using the constructed array. Compared with the unoptimized ICE decoupled monopole array, the optimized array had a more homogeneous transmit field and no dark spots or signal cancellations in the MR images.
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Affiliation(s)
- Xinqiang Yan
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA; Department of Radiology, Vanderbilt University, Nashville, TN, USA.
| | - Xiaoliang Zhang
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA; UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, CA, USA
| | - Rong Xue
- State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA; Department of Radiology, Vanderbilt University, Nashville, TN, USA
| | - William A Grissom
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
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Rutledge O, Kwak T, Cao P, Zhang X. Design and test of a double-nuclear RF coil for (1)H MRI and (13)C MRSI at 7T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 267:15-21. [PMID: 27078089 PMCID: PMC4862922 DOI: 10.1016/j.jmr.2016.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 03/09/2016] [Accepted: 04/02/2016] [Indexed: 05/20/2023]
Abstract
RF coil operation at the ultrahigh field of 7T is fraught with technical challenges that limit the advancement of novel human in vivo applications at 7T. In this work, a hybrid technique combining a microstrip transmission line and a lumped-element L-C loop coil to form a double-nuclear RF coil for proton magnetic resonance imaging and carbon magnetic resonance spectroscopy at 7T was proposed and investigated. Network analysis revealed a high Q-factor and excellent decoupling between the coils. Proton images and localized carbon spectra were acquired with high sensitivity. The successful testing of this novel double-nuclear coil demonstrates the feasibility of this hybrid design for double-nuclear MR imaging and spectroscopy studies at the ultrahigh field of 7T.
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Affiliation(s)
- Omar Rutledge
- Department of Radiology and Biomedical Imaging, University of California San Francisco, CA, USA
| | - Tiffany Kwak
- Department of Radiology and Biomedical Imaging, University of California San Francisco, CA, USA
| | - Peng Cao
- Department of Radiology and Biomedical Imaging, University of California San Francisco, CA, USA
| | - Xiaoliang Zhang
- Department of Radiology and Biomedical Imaging, University of California San Francisco, CA, USA; UCSF - UC Berkeley Joint Graduate Group in Bioengineering, San Francisco & Berkeley, CA, USA; California Institute for Quantitative Biosciences (QB3), San Francisco, CA, USA.
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50
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Yan X, Wei L, Chu S, Xue R, Zhang X. Eight-Channel Monopole Array Using ICE Decoupling for Human Head MR Imaging at 7 T. APPLIED MAGNETIC RESONANCE 2016; 47:527-538. [PMID: 29033501 PMCID: PMC5638452 DOI: 10.1007/s00723-016-0775-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 03/09/2016] [Indexed: 06/03/2023]
Abstract
Due to the unique structure of radiative coil elements, traditional decoupling methods face technical challenges in reducing the electromagnetic coupling of the radiative arrays. In this study, we aim to investigate the possibility of using the recently introduced induced current elimination (ICE) decoupling technique for cylindrical shaped radiative coil array designs. To evaluate the method, an eight-channel transmit/receive monopole array with the ICE decoupling, suitable for human head imaging at 7 T, was built and comparatively investigated. In vivo human head images were acquired and geometry factor maps were measured and calculated to evaluate the performance of the ICE-decoupled monopole array. Compared with the monopole array without decoupling methods, the ICE-decoupled monopole array had a higher signal-to-noise ratio and demonstrated improved parallel imaging ability. The experimental results indicate that the ICE decoupling method is a promising solution to addressing the coupling issue of radiative array at ultrahigh fields.
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Affiliation(s)
- Xinqiang Yan
- State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
- Beijing Engineering Research Center of Radiographic Techniques and Equipment, 19B Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Long Wei
- Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
- Beijing Engineering Research Center of Radiographic Techniques and Equipment, 19B Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Suoda Chu
- State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Rong Xue
- State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- Beijing Institute for Brain Disorders, Beijing 100053, China
| | - Xiaoliang Zhang
- Department of Radiology and Biomedical Imaging, University of California San Francisco, Byers Hall, Room 102, 1700 4th ST, San Francisco, CA 941582330, USA
- UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, CA 94158, USA
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