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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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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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3
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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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Zhang G, Zhu W, Li X, Zhu XH, Chen W. Dual-frequency resonant coil design for low-γ X-nuclear and proton magnetic resonance imaging at ultrahigh fields. NMR IN BIOMEDICINE 2023; 36:e4930. [PMID: 36939997 PMCID: PMC11089849 DOI: 10.1002/nbm.4930] [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: 04/10/2022] [Revised: 02/13/2023] [Accepted: 03/13/2023] [Indexed: 05/04/2023]
Abstract
Low-γ X-nuclear MRS and imaging have played a key role in studying metabolism and physiopathology, especially at ultrahigh fields. We design and demonstrate a novel and simple dual-frequency RF resonant coil that can operate at both low-γ X-nuclear and proton frequencies. The dual-frequency resonant coil comprises an LC coil loop and a tuning-matching circuit bridged by two short wires of the desired length to generate two resonant modes: one for proton MRI and the other for low-γ X-nuclear MRS imaging with a large difference in their Larmor frequencies at ultrahigh fields. The coil parameters for the desired coil size and resonant frequencies can be determined via numerical simulations based on LC circuit theory. We designed, constructed, and evaluated several prototype surface coils and quadrature array coils for 1 H and 2 H or 17 O imaging, with small-sized (diameter ≤ 5 cm) coils evaluated using a 16.4 T animal scanner, and a large-sized (15 cm diameter) coil on a 7 T human scanner. All coils could be tuned/matched and driven in the single coil or array coil mode to the resonant frequencies of 1 H (698 and 298 MHz), 2 H (107 and 45.8 MHz), or 17 O (94.7 and 40.4 MHz) for imaging measurements and evaluation at 16.4 and 7 T, respectively. The dual-frequency resonant coil or array provides adequate detection sensitivity for 1 H MRI and excellent performance for low-γ X-nuclear MRS imaging applications, and excellent coil decoupling efficiency between the array coils at both resonant frequencies with an optimal geometric overlap. It provides a simple, cost-effective dual-frequency RF coil solution to perform low-γ X-nuclear MRS imaging for preclinical and human applications, especially at ultrahigh fields.
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Affiliation(s)
- Guangle Zhang
- Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, Minnesota, USA
| | - Wei Zhu
- Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, Minnesota, USA
| | - Xin Li
- Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, Minnesota, USA
| | - Xiao-Hong Zhu
- Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, Minnesota, USA
| | - Wei Chen
- Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, Minnesota, USA
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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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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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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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Emetere M, Falade A. Loss Path Influence on the MRI Radio Frequency Pulse Sequence: A Theoretical Evidence. Open Access Maced J Med Sci 2019; 7:2715-2722. [PMID: 31844426 PMCID: PMC6901837 DOI: 10.3889/oamjms.2019.728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/23/2019] [Accepted: 07/24/2019] [Indexed: 11/15/2022] Open
Abstract
The RF pulse is initiated from either the loop or loopless MRI antenna. It has shown an increased advancement in recent times. Somehow, the concept has proven successful in the MR imaging procedure. Using the fundamental theories of the MRI concept, mathematical experimentation was carried out analytically to investigate the Loss Path Concept (LPC). The LPC was proposed to be one of the defects responsible for poor/blurred medical imaging of certain parts of the body. The LPC results obtain in this mathematical experimentation was found to be -56 dB and 6.7 dB. Theoretically, the LPC can be resolved mathematically by incorporating the molecular boundaries of the tissues. Practically, LPC can be resolved by introducing a detachable RF strip detector to synchronise-particles across different molecular boundaries and prevent patients from excess exposure to RF radiation.
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Affiliation(s)
- Moses Emetere
- Covenant University, Ota, Nigeria
- Department of Mechanical Engineering Science, University of Johannesburg, Johannesburg, South Africa
| | - A Falade
- Covenant University, Ota, Nigeria
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Davoodi H, Jouda M, Korvink JG, MacKinnon N, Badilita V. Broadband and multi-resonant sensors for NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2019; 112-113:34-54. [PMID: 31481158 DOI: 10.1016/j.pnmrs.2019.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/08/2019] [Accepted: 05/08/2019] [Indexed: 06/10/2023]
Abstract
It has always been of considerable interest to study the nuclear magnetic resonance response of multiple nuclei simultaneously, whether these signals arise from internuclear couplings within the same molecule, or from uncoupled nuclei within sample mixtures. The literature contains numerous uncorrelated reports on techniques employed to achieve multi-nuclear NMR detection. This paper consolidates the subset of techniques in which single coil detectors are utilized, and highlights the strengths and weaknesses of each approach, at the same time pointing the way towards future developments in the field of multi-nuclear NMR. We compare the different multi-nuclear NMR techniques in terms of performance, and present a guide to NMR probe designers towards application-based optimum design. We also review the applicability of micro-coils in the context of multi-nuclear methods. Micro-coils benefit from compact geometries and exhibit lower impedance, which provide new opportunities and challenges for the NMR probe designer.
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Affiliation(s)
- Hossein Davoodi
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Baden-Württemberg, Germany
| | - Mazin Jouda
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Baden-Württemberg, Germany
| | - Jan G Korvink
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Baden-Württemberg, Germany.
| | - Neil MacKinnon
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Baden-Württemberg, Germany
| | - Vlad Badilita
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Baden-Württemberg, Germany.
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10
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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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11
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Cao P, Zhang X, Park I, Najac C, Nelson SJ, Ronen S, Larson PEZ. 1 H- 13 C independently tuned radiofrequency surface coil applied for in vivo hyperpolarized MRI. Magn Reson Med 2015; 76:1612-1620. [PMID: 26597845 DOI: 10.1002/mrm.26046] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 10/07/2015] [Accepted: 10/20/2015] [Indexed: 01/20/2023]
Abstract
PURPOSE To develop a lump-element double-tuned common-mode-differential-mode (CMDM) radiofrequency (RF) surface coil with independent frequency tuning capacity for MRS and MRI applications. METHODS The presented design has two modes that can operate with different current paths, allowing independent frequency adjustment. The coil prototype was tested on the bench and then examined in phantom and in vivo experiments. RESULTS Standard deviations of frequency and impedance fluctuations measured in one resonator, while changing the tuning capacitor of another resonator, were less than 13 kHz and 0.55 Ω. The unloaded S21 was -36 dB and -41 dB, while the unloaded Q factor was 260 and 287, for 13 C and 1 H, respectively. In vivo hyperpolarized 13 C MR spectroscopy data demonstrated the feasibility of using the CMDM coil to measure the dynamics of lactate, alanine, pyruvate and bicarbonate signal in a normal rat head along with acquiring 1 H anatomical reference images. CONCLUSION Independent frequency tuning capacity was demonstrated in the presented lump-element double-tuned CMDM coil. This CMDM coil maintained intrinsically decoupled magnetic fields, which provided sufficient isolation between the two resonators. The results from in vivo experiments demonstrated high sensitivity of both the 1 H and 13 C resonators. Magn Reson Med 76:1612-1620, 2016. © 2015 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Peng Cao
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
| | - Xiaoliang Zhang
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
| | - Ilwoo Park
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
| | - Chloe Najac
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
| | - Sarah J Nelson
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
| | - Sabrina Ronen
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
| | - Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA.
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12
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Zhao Y, Zhao T, Raval SB, Krishnamurthy N, Zheng H, Harris CT, Handler WB, Chronik BA, Ibrahim TS. Dual optimization method of radiofrequency and quasistatic field simulations for reduction of eddy currents generated on 7T radiofrequency coil shielding. Magn Reson Med 2014; 74:1461-9. [PMID: 25367703 DOI: 10.1002/mrm.25424] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 06/26/2014] [Accepted: 08/04/2014] [Indexed: 01/20/2023]
Abstract
PURPOSE To optimize the design of radiofrequency (RF) shielding of transmit coils at 7T and reduce eddy currents generated on the RF shielding when imaging with rapid gradient waveforms. METHODS One set of a four-element, 2 × 2 Tic-Tac-Toe head coil structure was selected and constructed to study eddy currents on the RF coil shielding. The generated eddy currents were quantitatively studied in the time and frequency domains. The RF characteristics were studied using the finite difference time domain method. Five different kinds of RF shielding were tested on a 7T MRI scanner with phantoms and in vivo human subjects. RESULTS The eddy current simulation method was verified by the measurement results. Eddy currents induced by solid/intact and simple-structured slotted RF shielding significantly distorted the gradient fields. Echo-planar images, B1+ maps, and S matrix measurements verified that the proposed slot pattern suppressed the eddy currents while maintaining the RF characteristics of the transmit coil. CONCLUSION The presented dual-optimization method could be used to design RF shielding and reduce the gradient field-induced eddy currents while maintaining the RF characteristics of the transmit coil.
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Affiliation(s)
- Yujuan Zhao
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Tiejun Zhao
- Siemens Medical Solutions, Pittsburgh, Pennsylvania, USA
| | - Shailesh B Raval
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | | | - Hai Zheng
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Chad T Harris
- Department of Physics and Astronomy, University of Western Ontario, London, Canada
| | - William B Handler
- Department of Physics and Astronomy, University of Western Ontario, London, Canada
| | - Blaine A Chronik
- Department of Physics and Astronomy, University of Western Ontario, London, Canada
| | - Tamer S Ibrahim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Yan X, Xue R, Zhang X. A monopole/loop dual-tuned RF coil for ultrahigh field MRI. Quant Imaging Med Surg 2014; 4:225-31. [PMID: 25202657 DOI: 10.3978/j.issn.2223-4292.2014.08.03] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 08/06/2014] [Indexed: 01/27/2023]
Abstract
Proton and heteronuclear MRI/MRS using dual-tuned (DT) coils could provide both anatomical and metabolic images without repositioning the subject. However, it is technologically challenging to attain sufficiently electromagnetic (EM) decoupling between the heteronuclear channel and proton channel, and keep the imaging areas and profiles of two nuclear channels highly matched. In this study, a hybrid monopole/loop technique was proposed for DT coil design and this technique was validated by implementing and testing a DT (1)H/(23)Na coil for MR imaging at 7T. The RF fields of the monopole ((1)H channel) and regular L/C loop ((23)Na channel) were orthogonal and intrinsically EM decoupled. Bench measurement results demonstrated the isolation between the two nuclear channels was better than -28 dB at both nuclear frequencies. Compared with the conventional DT coil using trap circuits, the monopole/loop DT coil had higher MR sensitivity for sodium imaging. The experimental results indicated that the monopole/loop technique might be a simple and efficient design for multinuclear imaging at ultrahigh fields. Additionally, the proposed DT coils based on the monopole/loop technique can be used as building blocks in designing multichannel DT coil arrays.
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Affiliation(s)
- Xinqiang Yan
- 1 State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China ; 2 Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China ; 3 Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing 100049, China ; 4 Beijing Institute for Brain Disorders, Beijing 100053, China ; 5 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California 94158, USA ; 6 UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, California 94158, USA
| | - Rong Xue
- 1 State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China ; 2 Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China ; 3 Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing 100049, China ; 4 Beijing Institute for Brain Disorders, Beijing 100053, China ; 5 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California 94158, USA ; 6 UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, California 94158, USA
| | - Xiaoliang Zhang
- 1 State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China ; 2 Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China ; 3 Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing 100049, China ; 4 Beijing Institute for Brain Disorders, Beijing 100053, China ; 5 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California 94158, USA ; 6 UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, California 94158, USA
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14
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Pang Y, Wong EWH, Yu B, Zhang X. Design and numerical evaluation of a volume coil array for parallel MR imaging at ultrahigh fields. Quant Imaging Med Surg 2014; 4:50-6. [PMID: 24649435 DOI: 10.3978/j.issn.2223-4292.2014.02.07] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 02/26/2014] [Indexed: 11/14/2022]
Abstract
In this work, we propose and investigate a volume coil array design method using different types of birdcage coils for MR imaging. Unlike the conventional radiofrequency (RF) coil arrays of which the array elements are surface coils, the proposed volume coil array consists of a set of independent volume coils including a conventional birdcage coil, a transverse birdcage coil, and a helix birdcage coil. The magnetic fluxes of these three birdcage coils are intrinsically cancelled, yielding a highly decoupled volume coil array. In contrast to conventional non-array type volume coils, the volume coil array would be beneficial in improving MR signal-to-noise ratio (SNR) and also gain the capability of implementing parallel imaging. The volume coil array is evaluated at the ultrahigh field of 7T using FDTD numerical simulations, and the g-factor map at different acceleration rates was also calculated to investigate its parallel imaging performance.
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Affiliation(s)
- Yong Pang
- 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA ; 2 Agilent Technologies, Santa Clara, CA, USA ; 3 Magwale, Palo Alto, CA, USA ; 4 UC Berkeley/UCSF Joint Graduate Group in Bioengineering, San Francisco & Berkeley, CA, USA ; 5 California Institute for Quantitative Biosciences (QB3), San Francisco, CA, USA
| | - Ernest W H Wong
- 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA ; 2 Agilent Technologies, Santa Clara, CA, USA ; 3 Magwale, Palo Alto, CA, USA ; 4 UC Berkeley/UCSF Joint Graduate Group in Bioengineering, San Francisco & Berkeley, CA, USA ; 5 California Institute for Quantitative Biosciences (QB3), San Francisco, CA, USA
| | - Baiying Yu
- 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA ; 2 Agilent Technologies, Santa Clara, CA, USA ; 3 Magwale, Palo Alto, CA, USA ; 4 UC Berkeley/UCSF Joint Graduate Group in Bioengineering, San Francisco & Berkeley, CA, USA ; 5 California Institute for Quantitative Biosciences (QB3), San Francisco, CA, USA
| | - Xiaoliang Zhang
- 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA ; 2 Agilent Technologies, Santa Clara, CA, USA ; 3 Magwale, Palo Alto, CA, USA ; 4 UC Berkeley/UCSF Joint Graduate Group in Bioengineering, San Francisco & Berkeley, CA, USA ; 5 California Institute for Quantitative Biosciences (QB3), San Francisco, CA, USA
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15
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Pang Y, Yu B, Vigneron DB, Zhang X. Quadrature transmit array design using single-feed circularly polarized patch antenna for parallel transmission in MR imaging. Quant Imaging Med Surg 2014; 4:11-8. [PMID: 24649430 DOI: 10.3978/j.issn.2223-4292.2014.02.03] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 02/14/2014] [Indexed: 11/14/2022]
Abstract
Quadrature coils are often desired in MR applications because they can improve MR sensitivity and also reduce excitation power. In this work, we propose, for the first time, a quadrature array design strategy for parallel transmission at 298 MHz using single-feed circularly polarized (CP) patch antenna technique. Each array element is a nearly square ring microstrip antenna and is fed at a point on the diagonal of the antenna to generate quadrature magnetic fields. Compared with conventional quadrature coils, the single-feed structure is much simple and compact, making the quadrature coil array design practical. Numerical simulations demonstrate that the decoupling between elements is better than -35 dB for all the elements and the RF fields are homogeneous with deep penetration and quadrature behavior in the area of interest. Bloch equation simulation is also performed to simulate the excitation procedure by using an 8-element quadrature planar patch array to demonstrate its feasibility in parallel transmission at the ultrahigh field of 7 Tesla.
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Affiliation(s)
- Yong Pang
- 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA ; 2 Magwale, Palo Alto, CA, USA ; 3 UCSF/UC Berkeley Joint Bioengineering Program, San Francisco & Berkeley, CA, USA
| | - Baiying Yu
- 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA ; 2 Magwale, Palo Alto, CA, USA ; 3 UCSF/UC Berkeley Joint Bioengineering Program, San Francisco & Berkeley, CA, USA
| | - Daniel B Vigneron
- 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA ; 2 Magwale, Palo Alto, CA, USA ; 3 UCSF/UC Berkeley Joint Bioengineering Program, San Francisco & Berkeley, CA, USA
| | - Xiaoliang Zhang
- 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA ; 2 Magwale, Palo Alto, CA, USA ; 3 UCSF/UC Berkeley Joint Bioengineering Program, San Francisco & Berkeley, CA, USA
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16
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Li Y, Yu B, Pang Y, Vigneron DB, Zhang X. Planar quadrature RF transceiver design using common-mode differential-mode (CMDM) transmission line method for 7T MR imaging. PLoS One 2013; 8:e80428. [PMID: 24265823 PMCID: PMC3827179 DOI: 10.1371/journal.pone.0080428] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 10/02/2013] [Indexed: 11/19/2022] Open
Abstract
The use of quadrature RF magnetic fields has been demonstrated to be an efficient method to reduce transmit power and to increase the signal-to-noise (SNR) in magnetic resonance (MR) imaging. The goal of this project was to develop a new method using the common-mode and differential-mode (CMDM) technique for compact, planar, distributed-element quadrature transmit/receive resonators for MR signal excitation and detection and to investigate its performance for MR imaging, particularly, at ultrahigh magnetic fields. A prototype resonator based on CMDM method implemented by using microstrip transmission line was designed and fabricated for 7T imaging. Both the common mode (CM) and the differential mode (DM) of the resonator were tuned and matched at 298MHz independently. Numerical electromagnetic simulation was performed to verify the orthogonal B1 field direction of the two modes of the CMDM resonator. Both workbench tests and MR imaging experiments were carried out to evaluate the performance. The intrinsic decoupling between the two modes of the CMDM resonator was demonstrated by the bench test, showing a better than -36 dB transmission coefficient between the two modes at resonance frequency. The MR images acquired by using each mode and the images combined in quadrature showed that the CM and DM of the proposed resonator provided similar B1 coverage and achieved SNR improvement in the entire region of interest. The simulation and experimental results demonstrate that the proposed CMDM method with distributed-element transmission line technique is a feasible and efficient technique for planar quadrature RF coil design at ultrahigh fields, providing intrinsic decoupling between two quadrature channels and high frequency capability. Due to its simple and compact geometry and easy implementation of decoupling methods, the CMDM quadrature resonator can possibly be a good candidate for design blocks in multichannel RF coil arrays.
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Affiliation(s)
- Ye Li
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, United States of America
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Key Laboratory for MRI, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Baiying Yu
- Magwale, Palo Alto, California, United States of America
| | - Yong Pang
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, United States of America
| | - Daniel B. Vigneron
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, United States of America
- UC Berkeley/UCSF Joint Graduate Group in Bioengineering, Berkeley & San Francisco, California, United States of America
- California Institute for Quantitative Biosciences (QB3), San Francisco, California, United States of America
| | - Xiaoliang Zhang
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, United States of America
- UC Berkeley/UCSF Joint Graduate Group in Bioengineering, Berkeley & San Francisco, California, United States of America
- California Institute for Quantitative Biosciences (QB3), San Francisco, California, United States of America
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17
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Multi-reception strategy with improved SNR for multichannel MR imaging. PLoS One 2012; 7:e42237. [PMID: 22879921 PMCID: PMC3411773 DOI: 10.1371/journal.pone.0042237] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 07/04/2012] [Indexed: 12/03/2022] Open
Abstract
A multi-reception strategy with extended GRAPPA is proposed in this work to improve MR imaging performance at ultra-high field MR systems with limited receiver channels. In this method, coil elements are separated to two or more groups under appropriate grouping criteria. Those groups are enabled in sequence for imaging first, and then parallel acquisition is performed to compensate for the redundant scan time caused by the multiple receptions. To efficiently reconstruct the data acquired from elements of each group, a specific extended GRAPPA was developed. This approach was evaluated by using a 16-element head array on a 7 Tesla whole-body MRI scanner with 8 receive channels. The in-vivo experiments demonstrate that with the same scan time, the 16-element array with twice receptions and acceleration rate of 2 can achieve significant SNR gain in the periphery area of the brain and keep nearly the same SNR in the center area over an eight-element array, which indicates the proposed multi-reception strategy and extended GRAPPA are feasible to improve image quality for MRI systems with limited receive channels. This study also suggests that it is advantageous for a MR system with N receiver channels to utilize a coil array with more than N elements if an appropriate acquisition strategy is applied.
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