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Zhang B, Radder J, Giannakopoulos I, Grant A, Lagore R, Waks M, Tavaf N, van de Moortele PF, Adriany G, Sadeghi-Tarakameh A, Eryaman Y, Lattanzi R, Ugurbil K. Performance of receive head arrays versus ultimate intrinsic SNR at 7 T and 10.5 T. Magn Reson Med 2024; 92:1219-1231. [PMID: 38649922 PMCID: PMC11209800 DOI: 10.1002/mrm.30108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/26/2024] [Accepted: 03/21/2024] [Indexed: 04/25/2024]
Abstract
PURPOSE We examined magnetic field dependent SNR gains and ability to capture them with multichannel receive arrays for human head imaging in going from 7 T, the most commonly used ultrahigh magnetic field (UHF) platform at the present, to 10.5 T, which represents the emerging new frontier of >10 T in UHFs. METHODS Electromagnetic (EM) models of 31-channel and 63-channel multichannel arrays built for 10.5 T were developed for 10.5 T and 7 T simulations. A 7 T version of the 63-channel array with an identical coil layout was also built. Array performance was evaluated in the EM model using a phantom mimicking the size and electrical properties of the human head and a digital human head model. Experimental data was obtained at 7 T and 10.5 T with the 63-channel array. Ultimate intrinsic SNR (uiSNR) was calculated for the two field strengths using a voxelized cloud of dipoles enclosing the phantom or the digital human head model as a reference to assess the performance of the two arrays and field depended SNR gains. RESULTS uiSNR calculations in both the phantom and the digital human head model demonstrated SNR gains at 10.5 T relative to 7 T of 2.6 centrally, ˜2 at the location corresponding to the edge of the brain, ˜1.4 at the periphery. The EM models demonstrated that, centrally, both arrays captured ˜90% of the uiSNR at 7 T, but only ˜65% at 10.5 T, leading only to ˜2-fold gain in array SNR in going from 7 to 10.5 T. This trend was also observed experimentally with the 63-channel array capturing a larger fraction of the uiSNR at 7 T compared to 10.5 T, although the percentage of uiSNR captured were slightly lower at both field strengths compared to EM simulation results. CONCLUSIONS Major uiSNR gains are predicted for human head imaging in going from 7 T to 10.5 T, ranging from ˜2-fold at locations corresponding to the edge of the brain to 2.6-fold at the center, corresponding to approximately quadratic increase with the magnetic field. Realistic 31- and 63-channel receive arrays, however, approach the central uiSNR at 7 T, but fail to do so at 10.5 T, suggesting that more coils and/or different type of coils will be needed at 10.5 T and higher magnetic fields.
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Affiliation(s)
- Bei Zhang
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA
| | - Jerahmie Radder
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN 55455
| | - Ilias Giannakopoulos
- Center for Advanced Imaging Innovation and Research (CAI2R) and Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Andrea Grant
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN 55455
| | - Russell Lagore
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN 55455
| | - Matt Waks
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN 55455
| | - Nader Tavaf
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN 55455
| | | | - Gregor Adriany
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN 55455
| | | | - Yigitcan Eryaman
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN 55455
| | - Riccardo Lattanzi
- Center for Advanced Imaging Innovation and Research (CAI2R) and Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Kamil Ugurbil
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN 55455
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Gao Y, Liu T, Hong T, Fang Y, Jiang W, Zhang X. Subwavelength dielectric waveguide for efficient travelling-wave magnetic resonance imaging. Nat Commun 2024; 15:2298. [PMID: 38485742 PMCID: PMC10940709 DOI: 10.1038/s41467-024-46638-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 03/05/2024] [Indexed: 03/18/2024] Open
Abstract
Magnetic resonance imaging (MRI) has diverse applications in physics, biology, and medicine. Uniform excitation of nuclei spins through circular-polarized transverse magnetic component of electromagnetic field is vital for obtaining unbiased tissue contrasts. However, achieving this in the electrically large human body poses a significant challenge, especially at ultra-high fields (UHF) with increased working frequencies (≥297 MHz). Canonical volume resonators struggle to meet this challenge, while radiative excitation methods like travelling-wave (TW) show promise but often suffer from inadequate excitation efficiency. Here, we introduce a new technique using a subwavelength dielectric waveguide insert that enhances both efficiency and homogeneity at 7 T. Through TE11-to-TM11 mode conversion, power focusing, wave impedance matching, and phase velocity matching, we achieved a 114% improvement in TW efficiency and mitigated the center-brightening effect. This fundamental advancement in TW MRI through effective wave manipulation could promote the electromagnetic design of UHF MRI systems.
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Affiliation(s)
- Yang Gao
- Hangzhou Institute of Technology, Xidian University, Hangzhou, China.
- School of Electronic Engineering, National Key Laboratory of Antennas and Microwave Technology, Xidian University, Xi'an, China.
- College of Electrical Engineering, Zhejiang University, Hangzhou, China.
| | - Tong Liu
- Hangzhou Institute of Technology, Xidian University, Hangzhou, China
| | - Tao Hong
- Hangzhou Institute of Technology, Xidian University, Hangzhou, China
- School of Electronic Engineering, National Key Laboratory of Antennas and Microwave Technology, Xidian University, Xi'an, China
| | - Youtong Fang
- College of Electrical Engineering, Zhejiang University, Hangzhou, China
| | - Wen Jiang
- Hangzhou Institute of Technology, Xidian University, Hangzhou, China
- School of Electronic Engineering, National Key Laboratory of Antennas and Microwave Technology, Xidian University, Xi'an, China
| | - Xiaotong Zhang
- College of Electrical Engineering, Zhejiang University, Hangzhou, China.
- Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China.
- MOE Frontier Science Center for Brain Science and Brain-machine Integration, Zhejiang University, Hangzhou, China.
- Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China.
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Gapais PF, Luong M, Nizery F, Maitre G, Giacomini E, Guillot J, Vignaud A, Berrahou D, Dubois M, Abdeddaim R, Georget E, Hosseinnezhadian S, Amadon A. Efficiently building receive arrays with electromagnetic simulations and additive manufacturing: A two-layer, 32-channel prototype for 7T brain MRI. Magn Reson Med 2024; 91:1254-1267. [PMID: 37986237 DOI: 10.1002/mrm.29931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 10/26/2023] [Accepted: 10/30/2023] [Indexed: 11/22/2023]
Abstract
PURPOSE We propose a comprehensive workflow to design and build fully customized dense receive arrays for MRI, providing prediction of SNR and g-factor. Combined with additive manufacturing, this method allows an efficient implementation for any arbitrary loop configuration. To demonstrate the methodology, an innovative two-layer, 32-channel receive array is proposed. METHODS The design workflow is based on numerical simulations using a commercial 3D electromagnetic software associated with circuit model co-simulations to provide the most accurate results in an efficient time. A model to compute the noise covariance matrix from circuit model scattering parameters is proposed. A 32-channel receive array at 7 T is simulated and fabricated with a two-layer design made of non-geometrically decoupled loops. Decoupling between loops is achieved using home-built direct high-impedance preamplifiers. The loops are 3D-printed with a new additive manufacturing technique to speed up integration while preserving the detailed geometry as simulated. The SNR and parallel-imaging performances of the proposed design are compared with a commercial coil, and in vivo images are acquired. RESULTS The comparison of SNR and g-factors showed a good agreement between simulations and measurements. Experimental values are comparable with the ones measured on the commercial coil. Preliminary in vivo images also ensured the absence of any unexpected artifacts. CONCLUSION A new design and performance analysis workflow is proposed and tested with a non-conventional 32-channel prototype at 7 T. Additive manufacturing of dense arrays of loops for brain imaging at ultrahigh field is validated for clinical use.
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Affiliation(s)
- Paul-François Gapais
- Université Paris-Saclay, CEA, CNRS, Joliot, NeuroSpin, BAOBAB, Gif-sur-Yvette, France
- Multiwave Imaging SAS, Marseille, France
| | - Michel Luong
- Université Paris-Saclay, CEA, Irfu, DACM, Gif-sur-Yvette, France
| | - François Nizery
- Université Paris-Saclay, CEA, Irfu, LCAP, Gif-sur-Yvette, France
| | - Gabriel Maitre
- Université Paris-Saclay, CEA, Irfu, LCAP, Gif-sur-Yvette, France
| | - Eric Giacomini
- Université Paris-Saclay, CEA, CNRS, Joliot, NeuroSpin, BAOBAB, Gif-sur-Yvette, France
| | - Jules Guillot
- Université Paris-Saclay, CEA, CNRS, Joliot, NeuroSpin, BAOBAB, Gif-sur-Yvette, France
| | - Alexandre Vignaud
- Université Paris-Saclay, CEA, CNRS, Joliot, NeuroSpin, BAOBAB, Gif-sur-Yvette, France
| | | | | | - Redha Abdeddaim
- Aix-Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, Marseille, France
| | | | | | - Alexis Amadon
- Université Paris-Saclay, CEA, CNRS, Joliot, NeuroSpin, BAOBAB, Gif-sur-Yvette, France
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Gruber B, Stockmann JP, Mareyam A, Keil B, Bilgic B, Chang Y, Kazemivalipour E, Beckett AJ, Vu AT, Feinberg D, Wald LL. A 128-channel receive array for cortical brain imaging at 7 T. Magn Reson Med 2023; 90:2592-2607. [PMID: 37582214 PMCID: PMC10543549 DOI: 10.1002/mrm.29798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 08/17/2023]
Abstract
PURPOSE A 128-channel receive-only array for brain imaging at 7 T was simulated, designed, constructed, and tested within a high-performance head gradient designed for high-resolution functional imaging. METHODS The coil used a tight-fitting helmet geometry populated with 128 loop elements and preamplifiers to fit into a 39 cm diameter space inside a built-in gradient. The signal-to-noise ratio (SNR) and parallel imaging performance (1/g) were measured in vivo and simulated using electromagnetic modeling. The histogram of 1/g factors was analyzed to assess the range of performance. The array's performance was compared to the industry-standard 32-channel receive array and a 64-channel research array. RESULTS It was possible to construct the 128-channel array with body noise-dominated loops producing an average noise correlation of 5.4%. Measurements showed increased sensitivity compared with the 32-channel and 64-channel array through a combination of higher intrinsic SNR and g-factor improvements. For unaccelerated imaging, the 128-channel array showed SNR gains of 17.6% and 9.3% compared to the 32-channel and 64-channel array, respectively, at the center of the brain and 42% and 18% higher SNR in the peripheral brain regions including the cortex. For R = 5 accelerated imaging, these gains were 44.2% and 24.3% at the brain center and 86.7% and 48.7% in the cortex. The 1/g-factor histograms show both an improved mean and a tighter distribution by increasing the channel count, with both effects becoming more pronounced at higher accelerations. CONCLUSION The experimental results confirm that increasing the channel count to 128 channels is beneficial for 7T brain imaging, both for increasing SNR in peripheral brain regions and for accelerated imaging.
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Affiliation(s)
- Bernhard Gruber
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Austria
| | - Jason P. Stockmann
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Azma Mareyam
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Boris Keil
- Institute of Medical Physics and Radiation Protection, Department of Life Science Engineering, Mittelhessen University of Applied Sciences, Giessen, Germany
- Department of Diagnostic and Interventional Radiology, University Hospital Marburg, Philipps University of Marburg, Marburg, Germany
| | - Berkin Bilgic
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Yulin Chang
- Siemens Medical Solutions USA, Inc., Malvern, PA, USA
| | - Ehsan Kazemivalipour
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Alexander J.S. Beckett
- Advanced MRI Technologies, Sebastopol, CA, USA
- Helen Wills Institute for Neuroscience, University of California, Berkeley, CA, USA
| | - An T. Vu
- Radiology, University of California, San Francisco, CA, USA
- San Francisco Veteran Affairs Health Care System, San Francisco, CA, USA
| | - David Feinberg
- Advanced MRI Technologies, Sebastopol, CA, USA
- Helen Wills Institute for Neuroscience, University of California, Berkeley, CA, USA
| | - Lawrence L. Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- Division of Health Sciences Technology, Harvard - Massachusetts Institute of Technology, Cambridge, MA, 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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6
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Obara M, Kwon J, Yoneyama M, Ueda Y, Cauteren MV. Technical Advancements in Abdominal Diffusion-weighted Imaging. Magn Reson Med Sci 2023; 22:191-208. [PMID: 36928124 PMCID: PMC10086402 DOI: 10.2463/mrms.rev.2022-0107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
Abstract
Since its first observation in the 18th century, the diffusion phenomenon has been actively studied by many researchers. Diffusion-weighted imaging (DWI) is a technique to probe the diffusion of water molecules and create a MR image with contrast based on the local diffusion properties. The DWI pixel intensity is modulated by the hindrance the diffusing water molecules experience. This hindrance is caused by structures in the tissue and reflects the state of the tissue. This characteristic makes DWI a unique and effective tool to gain more insight into the tissue's pathophysiological condition. In the past decades, DWI has made dramatic technical progress, leading to greater acceptance in clinical practice. In the abdominal region, however, acquiring DWI with good quality is challenging because of several reasons, such as large imaging volume, respiratory and other types of motion, and difficulty in achieving homogeneous fat suppression. In this review, we discuss technical advancements from the past decades that help mitigate these problems common in abdominal imaging. We describe the use of scan acceleration techniques such as parallel imaging and compressed sensing to reduce image distortion in echo planar imaging. Then we compare techniques developed to mitigate issues due to respiratory motion, such as free-breathing, respiratory-triggering, and navigator-based approaches. Commonly used fat suppression techniques are also introduced, and their effectiveness is discussed. Additionally, the influence of the abovementioned techniques on image quality is demonstrated. Finally, we discuss the current and future clinical applications of abdominal DWI, such as whole-body DWI, simultaneous multiple-slice excitation, intravoxel incoherent motion, and the use of artificial intelligence. Abdominal DWI has the potential to develop further in the future, thanks to scan acceleration and image quality improvement driven by technological advancements. The accumulation of clinical proof will further drive clinical acceptance.
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Affiliation(s)
| | | | | | - Yu Ueda
- MR Clinical Science, Philips Japan Ltd
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7
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Wang W, Sánchez-Heredia JD, Olin RB, Hansen ESS, Laustsen C, Zhurbenko V, Ardenkjaer-Larsen JH. A cryogenic 14-channel 13 C receiver array for 3T human head imaging. Magn Reson Med 2023; 89:1265-1277. [PMID: 36321576 PMCID: PMC10092528 DOI: 10.1002/mrm.29508] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/09/2022] [Accepted: 10/11/2022] [Indexed: 12/27/2022]
Abstract
PURPOSE This article presents a novel 14-channel receive-only array for 13 C human head imaging at 3 T that explores the SNR gain by operating at cryogenic temperature cooled by liquid nitrogen. METHODS Cryostats are developed to evaluate single-coil bench SNR performance and cool the 14-channel array with liquid nitrogen while having enough thermal insulation between the coils and the sample. The temperature distribution for the coil array is measured. Circuits are adapted to the -189°C environment and implemented in the 14-channel array. 13 C images are acquired with the array at cryogenic and room temperature in a 3T scanner. RESULTS Compared with room temperature, the array at cryogenic temperature provides 27%-168% SNR improvement over all voxels and 47% SNR improvement near the image center. The measurements show a decrease of the element noise correlation at cryogenic temperature. CONCLUSION It is demonstrated that higher SNR can be achieved by cryogenically cooling the 14-channel array. A cryogenic array suitable for clinical imaging can be further developed on the array proposed. The cryogenic coil array is most likely suited for scenarios in which high SNR deep in a head and decent SNR on the periphery are required.
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Affiliation(s)
- Wenjun Wang
- National Space Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | | | - Rie Beck Olin
- Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark
| | | | - Christoffer Laustsen
- MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Vitaliy Zhurbenko
- National Space Institute, Technical University of Denmark, Kongens Lyngby, Denmark
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Wang W, Zhurbenko V, Sánchez-Heredia JD, Ardenkjaer-Larsen JH. Trade-off between preamplifier noise figure and decoupling in MRI detectors. Magn Reson Med 2023; 89:859-871. [PMID: 36263582 PMCID: PMC10092476 DOI: 10.1002/mrm.29489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 12/13/2022]
Abstract
PURPOSE There is a limit to the maximum achievable preamplifier decoupling. In many cases, this level is not enough. To overcome this limit, the preamplifier noise figure can be compromised for further decoupling increase. This is useful in flexible MRI arrays where ensuring coil insensitivity to changes in other array elements is a challenge. METHODS This work establishes the relation between the preamplifier noise figure and preamplifier decoupling using closed-form equations. These equations allow the evaluation of preamplifier decoupling properties and benchmark different preamplifiers against each other. The method to design the corresponding decoupling networks is described. The derived generalized design equations, which are not limited to 50 Ω pre-matched preamplifiers, greatly improve design flexibility and enable use of new amplifiers in MRI detectors. RESULTS Using the method, the decoupling properties of three preamplifiers are studied. For demonstration, the coil decoupling is further increased by 10.8 dB using one of the preamplifiers. The noise figure is sacrificed by 0.5 dB, which is predicted by equations and verified experimentally. Although examples are shown for 3 T systems at 32.13 MHz and 127.7 MHz, the approach and equations apply to any field strength and nucleus. CONCLUSION Preamplifier decoupling can be improved beyond what is possible by traditional approaches. The derived design equations cover a wide range of cases, including inductive coils and self-resonant low-impedance and high-impedance coils.
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Affiliation(s)
- Wenjun Wang
- Technical University of Denmark (DTU), Kongens Lyngby, Denmark
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9
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Gilbert KM, Dureux A, Jafari A, Zanini A, Zeman P, Menon RS, Everling S. A radiofrequency coil to facilitate task-based fMRI of awake marmosets. J Neurosci Methods 2023; 383:109737. [PMID: 36341968 DOI: 10.1016/j.jneumeth.2022.109737] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 10/24/2022] [Accepted: 10/27/2022] [Indexed: 11/08/2022]
Abstract
BACKGROUND The small common marmoset (Callithrix jacchus) is an ideal nonhuman primate for awake fMRI in ultra-high field small animal MRI scanners. However, it can often be challenging in task-based fMRI experiments to provide a robust stimulus within the MRI environment while using hardware (an RF coil and restraint system) that is compatible with awake imaging. NEW METHOD Here we present an RF coil and restraint system that permits unimpeded access to an awake marmoset's head subsequent to immobilization, thereby permitting the setup of peripheral devices and stimuli proximal to the head. RESULTS As an example application, an fMRI experiment probing whole-brain activation in response to marmoset vocalizations was conducted-this paradigm showed significant bilateral activation in the inferior colliculus, medial lateral geniculate nucleus, and auditory cortex. COMPARISON WITH EXISTING METHOD(S) The coil performance was evaluated and compared to a previously published restraint system with integrated RF coil. The image and temporal SNR were improved by up to 58 % and 27 %, respectively, in the peripheral cortex and by 30 % and 3 % in the centre of the brain. The restraint-system topology limited head motion to less than 100 µm of translation and 0.30° of rotation when measured over a 15-minute acquisition. CONCLUSIONS The proposed hardware solution provides a versatile approach to awake-marmoset imaging and, as demonstrated, can facilitate task-based fMRI.
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Affiliation(s)
- Kyle M Gilbert
- Centre for Functional and Metabolic Mapping, The University of Western Ontario, London, ON, Canada; Department of Medical Biophysics, The University of Western Ontario, London, ON, Canada.
| | - Audrey Dureux
- Centre for Functional and Metabolic Mapping, The University of Western Ontario, London, ON, Canada
| | - Azadeh Jafari
- Centre for Functional and Metabolic Mapping, The University of Western Ontario, London, ON, Canada
| | - Alessandro Zanini
- Centre for Functional and Metabolic Mapping, The University of Western Ontario, London, ON, Canada
| | - Peter Zeman
- Centre for Functional and Metabolic Mapping, The University of Western Ontario, London, ON, Canada
| | - Ravi S Menon
- Centre for Functional and Metabolic Mapping, The University of Western Ontario, London, ON, Canada; Department of Medical Biophysics, The University of Western Ontario, London, ON, Canada
| | - Stefan Everling
- Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada
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10
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Shi Z, Zhao X, Zhu S, Miao X, Zhang Y, Han S, Wang B, Zhang B, Ye X, Dai Y, Chen C, Rao S, Lin J, Zeng M, Wang H. Time-of-Flight Intracranial MRA at 3 T versus 5 T versus 7 T: Visualization of Distal Small Cerebral Arteries. Radiology 2023; 306:207-217. [PMID: 36040333 DOI: 10.1148/radiol.220114] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Background Three-dimensional (3D) time-of-flight (TOF) MR angiography (MRA) at 7 T has been reported to have high image quality for visualizing small perforating vessels. However, B1 inhomogeneity and more physiologic considerations limit its applications. Angiography at 5 T may provide another choice for intracranial vascular imaging. Purpose To evaluate the image quality and cerebrovascular visualization of 5-T 3D TOF MRA for visualizing intracranial small branch arteries. Materials and Methods Participants (healthy volunteers or participants with a history of ischemic stroke undergoing intracranial CT angiography or MRA for identifying steno-occlusive disease) were prospectively included from September 2021 to November 2021. Each participant underwent 3-T, 5-T, and 7-T 3D TOF MRA with use of customized MR protocols within 48 hours. Radiologist scoring from 0 (invisible) to 3 (excellent) and quantitative assessment were obtained to evaluate the image quality. The Friedman test was used for comparison of characteristics derived from 3 T, 5 T, and 7 T. Results A total of 12 participants (mean age ± SD, 38 years ± 9; nine men) were included. Visualizations of the distal arteries and small vessels at 5-T TOF MRA were significantly higher than those at 3 T (median score: 3.0 vs 2.0, all P < .001 for distal segments and lenticulostriate artery; median score: 2.0 vs 0, P < .001 for pontine artery). The total length of small vessel branches detected at 5 T was larger than that at 3 T (5.1 m ± 0.7 vs 1.9 m ± 0.4; P < .001). However, there was no evidence of a significant difference compared with 7 T in either the depiction of distal segments and small vessel branches (average median score, 2.5; all P > .05) or the quantitative measurements (total length, 5.6 m ± 0.5; P = .41). Conclusion Three-dimensional time-of-flight MR angiography at 5 T presented the capability to provide superior visualization of distal large arteries and small vessel branches (in terms of subjective and quantitative assessment) to 3 T and had image quality similar to 7 T. © RSNA, 2022 Online supplemental material is available for this article. An earlier incorrect version appeared online. This article was corrected on September 14, 2022.
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Affiliation(s)
- Zhang Shi
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Xueying Zhao
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Shuo Zhu
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Xiyin Miao
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Yunfei Zhang
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Shihong Han
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Bei Wang
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Boyu Zhang
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Xiaodan Ye
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Yongming Dai
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Caizhong Chen
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Shengxiang Rao
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Jiang Lin
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - Mengsu Zeng
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
| | - He Wang
- From the Departments of Radiology (Z.S., S.Z., X.M., X.Y., C.C., S.R., J.L., M.Z.) and Neurology (H.W.), Zhongshan Hospital, Fudan University, No. 180 Fenglin Rd, Xuhui District, Shanghai 200032, China; Shanghai Institute of Medical Imaging, Shanghai, China (Z.S., S.Z., Y.Z., X.Y., C.C., S.R., J.L., M.Z.); Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China (X.Z., B.W., B.Z., H.W.); Central Research Institute, United Imaging Healthcare, Shanghai, China (Y.Z., Y.D.); Shanghai United Imaging Healthcare, Shanghai, China (S.H.)
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11
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Kaza E, Guenette JP, Guthier CV, Hatch S, Marques A, Singer L, Schoenfeld JD. Image quality comparisons of coil setups in 3T MRI for brain and head and neck radiotherapy simulations. J Appl Clin Med Phys 2022; 23:e13794. [PMID: 36285814 PMCID: PMC9797171 DOI: 10.1002/acm2.13794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 07/11/2022] [Accepted: 09/06/2022] [Indexed: 01/01/2023] Open
Abstract
PURPOSE MRI is increasingly used for brain and head and neck radiotherapy treatment planning due to its superior soft tissue contrast. Flexible array coils can be arranged to encompass treatment immobilization devices, which do not fit in diagnostic head/neck coils. Selecting a flexible coil arrangement to replace a diagnostic coil should rely on image quality characteristics and patient comfort. We compared image quality obtained with a custom UltraFlexLarge18 (UFL18) coil setup against a commercial FlexLarge4 (FL4) coil arrangement, relative to a diagnostic Head/Neck20 (HN20) coil at 3T. METHODS The large American College of Radiology (ACR) MRI phantom was scanned monthly in the UFL18, FL4, and HN20 coil setup over 2 years, using the ACR series and three clinical sequences. High-contrast spatial resolution (HCSR), image intensity uniformity (IIU), percent-signal ghosting (PSG), low-contrast object detectability (LCOD), signal-to-noise ratio (SNR), and geometric accuracy were calculated according to ACR recommendations for each series and coil arrangement. Five healthy volunteers were scanned with the clinical sequences in all three coil setups. SNR, contrast-to-noise ratio (CNR) and artifact size were extracted from regions-of-interest along the head for each sequence and coil setup. For both experiments, ratios of image quality parameters obtained with UFL18 or FL4 over those from HN20 were formed for each coil setup, grouping the ACR and clinical sequences. RESULTS Wilcoxon rank-sum tests revealed significantly higher (p < 0.001) LCOD, IIU and SNR, and lower PSG ratios with UFL18 than FL4 on the phantom for the clinical sequences, with opposite PSG and SNR trends for the ACR series. Similar statistical tests on volunteer data corroborated that SNR ratios with UFL18 (0.58 ± 0.19) were significantly higher (p < 0.001) than with FL4 (0.51 ± 0.18) relative to HN20. CONCLUSIONS The custom UFL18 coil setup was selected for clinical application in MR simulations due to the superior image quality demonstrated on a phantom and volunteers for clinical sequences and increased volunteer comfort.
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Affiliation(s)
- Evangelia Kaza
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
| | - Jeffrey P. Guenette
- Division of Neuroradiology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
| | - Christian V. Guthier
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
| | - Steven Hatch
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
| | - Alexander Marques
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
| | - Lisa Singer
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA,Radiation OncologyUniversity of CaliforniaSan FranciscoCaliforniaUSA
| | - Jonathan D. Schoenfeld
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
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12
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Stelter JK, Ladd ME, Fiedler TM. Numerical comparison of local transceiver arrays of fractionated dipoles and microstrip antennas for body imaging at 7 T. NMR IN BIOMEDICINE 2022; 35:e4722. [PMID: 35226966 DOI: 10.1002/nbm.4722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 01/28/2022] [Accepted: 02/23/2022] [Indexed: 06/14/2023]
Abstract
Longitudinally orientated dipoles and microstrip antennas have both demonstrated superior results as RF transmit elements for body imaging at 7 T MRI, and are as of today the most commonly used transmit elements. In this study, the performances of the two antenna concepts were compared for use in local RF antenna arrays by numerical simulations. Antenna elements investigated are the fractionated dipole and the microstrip line with meander structures. Phantom simulations with a single antenna element were performed and evaluated with regard to specific absorption rate (SAR) efficiency in the center of the subject. Simulations of array configurations with 8 and 16 elements were performed with anatomical body models. Both antenna elements were combined with a loop coil to compare hybrid configurations. Singular value decomposition of the B1+ fields, RF shimming, and calculation of the voxel-wise power and SAR efficiencies were performed in regions of interest with varying sizes to evaluate the transmit performance. The signal-to-noise ratio (SNR) was evaluated to estimate the receive performance. Simulated data show similar transmit profiles for the two antenna types in the center of the phantom (penetration depth > 20 mm). For body imaging, no considerable differences were determined for the different antenna configurations with regard to the transmit performance. Results show the advantage of 16 transmit channels compared with today's commonly used 8-channel systems (minimum RF shimming excitation error of 4.7% (4.3%) versus 2.7% (2.8%) for the 8-channel and 16-channel configurations with the microstrip antennas in a (5 cm)3 cube in the center of a male (female) body model). Highest SNR is achieved for the 16-channel configuration with fractionated dipoles. The combination of either fractionated dipoles or microstrip antennas with loop coils is more favorable with regard to the transmit performance compared with only increasing the number of elements.
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Affiliation(s)
- Jonathan K Stelter
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Mark E Ladd
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Erwin L. Hahn Institute for MRI, University Duisburg-Essen, Essen, Germany
- Faculty of Physics and Astronomy, Heidelberg University, Heidelberg, Germany
- Faculty of Medicine, Heidelberg University, Heidelberg, Germany
| | - Thomas M Fiedler
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
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13
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Schick F. Automatic segmentation and volumetric assessment of internal organs and fatty tissue: what are the benefits? MAGNETIC RESONANCE MATERIALS IN PHYSICS, BIOLOGY AND MEDICINE 2022; 35:187-192. [PMID: 34919193 PMCID: PMC8995273 DOI: 10.1007/s10334-021-00986-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/03/2021] [Accepted: 12/05/2021] [Indexed: 02/07/2023]
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14
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Fan Q, Eichner C, Afzali M, Mueller L, Tax CMW, Davids M, Mahmutovic M, Keil B, Bilgic B, Setsompop K, Lee HH, Tian Q, Maffei C, Ramos-Llordén G, Nummenmaa A, Witzel T, Yendiki A, Song YQ, Huang CC, Lin CP, Weiskopf N, Anwander A, Jones DK, Rosen BR, Wald LL, Huang SY. Mapping the Human Connectome using Diffusion MRI at 300 mT/m Gradient Strength: Methodological Advances and Scientific Impact. Neuroimage 2022; 254:118958. [PMID: 35217204 DOI: 10.1016/j.neuroimage.2022.118958] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 01/27/2022] [Accepted: 01/31/2022] [Indexed: 12/20/2022] Open
Abstract
Tremendous efforts have been made in the last decade to advance cutting-edge MRI technology in pursuit of mapping structural connectivity in the living human brain with unprecedented sensitivity and speed. The first Connectom 3T MRI scanner equipped with a 300 mT/m whole-body gradient system was installed at the Massachusetts General Hospital in 2011 and was specifically constructed as part of the Human Connectome Project. Since that time, numerous technological advances have been made to enable the broader use of the Connectom high gradient system for diffusion tractography and tissue microstructure studies and leverage its unique advantages and sensitivity to resolving macroscopic and microscopic structural information in neural tissue for clinical and neuroscientific studies. The goal of this review article is to summarize the technical developments that have emerged in the last decade to support and promote large-scale and scientific studies of the human brain using the Connectom scanner. We provide a brief historical perspective on the development of Connectom gradient technology and the efforts that led to the installation of three other Connectom 3T MRI scanners worldwide - one in the United Kingdom in Cardiff, Wales, another in Continental Europe in Leipzig, Germany, and the latest in Asia in Shanghai, China. We summarize the key developments in gradient hardware and image acquisition technology that have formed the backbone of Connectom-related research efforts, including the rich array of high-sensitivity receiver coils, pulse sequences, image artifact correction strategies and data preprocessing methods needed to optimize the quality of high-gradient strength dMRI data for subsequent analyses. Finally, we review the scientific impact of the Connectom MRI scanner, including advances in diffusion tractography, tissue microstructural imaging, ex vivo validation, and clinical investigations that have been enabled by Connectom technology. We conclude with brief insights into the unique value of strong gradients for dMRI and where the field is headed in the coming years.
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Affiliation(s)
- Qiuyun Fan
- Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China; Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA
| | - Cornelius Eichner
- Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neuropsychology, Leipzig, Germany
| | - Maryam Afzali
- Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, Wales, UK; Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, LS2 9JT, UK
| | - Lars Mueller
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, LS2 9JT, UK
| | - Chantal M W Tax
- Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, Wales, UK; Image Sciences Institute, University Medical Center (UMC) Utrecht, Utrecht, Netherlands
| | - Mathias Davids
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA; Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Mirsad Mahmutovic
- Institute of Medical Physics and Radiation Protection (IMPS), TH-Mittelhessen University of Applied Sciences (THM), Giessen, Germany
| | - Boris Keil
- Institute of Medical Physics and Radiation Protection (IMPS), TH-Mittelhessen University of Applied Sciences (THM), Giessen, Germany
| | - Berkin Bilgic
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Kawin Setsompop
- Department of Radiology, Stanford University, Stanford, CA, USA; Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Hong-Hsi Lee
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA
| | - Qiyuan Tian
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA
| | - Chiara Maffei
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA
| | - Gabriel Ramos-Llordén
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA
| | - Aapo Nummenmaa
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA
| | | | - Anastasia Yendiki
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA
| | - Yi-Qiao Song
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA USA
| | - Chu-Chung Huang
- Key Laboratory of Brain Functional Genomics (MOE & STCSM), Affiliated Mental Health Center (ECNU), School of Psychology and Cognitive Science, East China Normal University, Shanghai, China; Shanghai Changning Mental Health Center, Shanghai, China
| | - Ching-Po Lin
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan; Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
| | - Nikolaus Weiskopf
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.; Felix Bloch Institute for Solid State Physics, Faculty of Physics and Earth Sciences, Leipzig University, Leipzig, Germany
| | - Alfred Anwander
- Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neuropsychology, Leipzig, Germany
| | - Derek K Jones
- Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, Wales, UK
| | - Bruce R Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Lawrence L Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Susie Y Huang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States.
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15
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Thapa B, Mareyam A, Stockmann J, Strasser B, Keil B, Hoecht P, Carp S, Li X, Wang Z, Chang YV, Dietrich J, Uhlmann E, Cahill DP, Batchelor T, Wald L, Andronesi OC. In Vivo Absolute Metabolite Quantification Using a Multiplexed ERETIC-RX Array Coil for Whole-Brain MR Spectroscopic Imaging. J Magn Reson Imaging 2021; 56:121-133. [PMID: 34958166 DOI: 10.1002/jmri.28028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/01/2021] [Accepted: 12/03/2021] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Absolute quantification of metabolites in MR spectroscopic imaging (MRSI) requires a stable reference signal of known concentration. The Electronic REference To access In vivo Concentrations (ERETIC) has shown great promise but has not been applied in patients and 3D MRSI. ERETIC hardware has not been integrated with receive arrays due to technical challenges, such as coil combination and unwanted coupling between multiple ERETIC and receive channels, for which we developed mitigation strategies. PURPOSE To develop absolute quantification for whole-brain MRSI in glioma patients. STUDY TYPE Prospective. POPULATION Five healthy volunteers and three patients with isocitrate dehydrogenase mutant glioma (27% female). Calibration and coil loading phantoms. FIELD STRENGTH/SEQUENCE A 3 T; Adiabatic spin-echo spiral 3D MRSI with real-time motion correction, Fluid Attenuated Inversion Recovery (FLAIR), Gradient Recalled Echo (GRE), Multi-echo Magnetization Prepared Rapid Acquisition of Gradient Echo (MEMPRAGE). ASSESSMENT Absolute quantification was performed for five brain metabolites (total N-acetyl-aspartate [NAA]/creatine/choline, glutamine + glutamate, myo-inositol) and the oncometabolite 2-hydroxyglutarate using a custom-built 4x-ERETIC/8x-receive array coil. Metabolite quantification was performed with both EREIC and internal water reference methods. ERETIC signal was transmitted via optical link and used to correct coil loading. Inductive and radiative coupling between ERETIC and receive channels were measured. STATISTICAL TESTS ERETIC and internal water methods for metabolite quantification were compared using Bland-Altman (BA) analysis and the nonparametric Mann-Whitney test. P < 0.05 was considered statistically significant. RESULTS ERETIC could be integrated in receive arrays and inductive coupling dominated (5-886 times) radiative coupling. Phantoms show proportional scaling of the ERETIC signal with coil loading. The BA analysis demonstrated very good agreement (3.3% ± 1.6%) in healthy volunteers, while there was a large difference (36.1% ± 3.8%) in glioma tumors between metabolite concentrations by ERETIC and internal water quantification. CONCLUSION Our results indicate that ERETIC integrated with receive arrays and whole-brain MRSI is feasible for brain metabolites quantification. Further validation is required to probe that ERETIC provides more accurate metabolite concentration in glioma patients. EVIDENCE LEVEL 2 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Bijaya Thapa
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Azma Mareyam
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Jason Stockmann
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Bernhard Strasser
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Boris Keil
- Institute of Medical Physics and Radiation Protection, TH-Mittelhessen University of Applied Sciences (THM), Giessen, Germany
| | | | - Stefan Carp
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Xianqi Li
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Zhe Wang
- Siemens Medical Solutions USA, Boston, Massachusetts, USA
| | - Yulin V Chang
- Siemens Medical Solutions USA, Boston, Massachusetts, USA
| | - Jorg Dietrich
- Harvard Medical School, Boston, Massachusetts, USA.,Division of Neuro-Oncology, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Erik Uhlmann
- Harvard Medical School, Boston, Massachusetts, USA.,Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Daniel P Cahill
- Harvard Medical School, Boston, Massachusetts, USA.,Department of Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Tracy Batchelor
- Harvard Medical School, Boston, Massachusetts, USA.,Department of Neurology, Brigham's and Women Hospital, Boston, Massachusetts, USA.,Dana Farber Cancer Institute, Boston, Massachusetts, USA
| | - Lawrence Wald
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Ovidiu C Andronesi
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
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16
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Meng Y, Mo Z, Hao J, Peng Y, Yan H, Mu J, Ma D, Zhang X, Li Y. High-resolution intravascular magnetic resonance imaging of the coronary artery wall at 3.0 Tesla: toward evaluation of atherosclerotic plaque vulnerability. Quant Imaging Med Surg 2021; 11:4522-4529. [PMID: 34737920 DOI: 10.21037/qims-21-286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/05/2021] [Indexed: 11/06/2022]
Abstract
Background To validate the feasibility of generating high-resolution intravascular 3.0 Tesla (T) magnetic resonance imaging of the coronary artery wall to further plaque imaging. Methods A receive-only 0.014-inch diameter magnetic resonance imaging guidewire (MRIG) was manufactured for intravascular imaging within a phantom experiment and the coronary artery wall of the swine. For coronary artery wall imaging, both high-resolution images and conventional resolution images were acquired. A 16-channel commercial surface coil for magnetic resonance imaging was employed for the control group. Results For the phantom experiment, the MRIG showed a higher signal-to-noise ratio than the surface coil. The peak signal-to-noise ratio of the MRIG and the surface coil-generated imaging were 213.6 and 19.8, respectively. The signal-to-noise ratio decreased rapidly as the distance from the MRIG increased. For the coronary artery wall experiment, the vessel wall imaging by the MRIG could be identified clearly, whereas the vessel wall imaging by the surface coil was blurred. The average signal-to-noise ratio of the artery wall was 21.1±5.40 by the MRIG compared to 8.4±2.19 by the surface coil, where the resolution was set at 0.2 mm × 0.2 mm × 2 mm. As expected, the high-resolution sequence clearly showed more details than the conventional resolution sequence set at 0.7 mm × 0.7 mm × 2.0 mm. Histological examination showed no evidence of mechanical injuries in the target vessel walls. Conclusions The study validated the feasibility of generating magnetic resonance imaging (MRI) at 0.2 mm × 0.2 mm × 2 mm for the coronary artery wall using a 0.014 inch MRIG.
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Affiliation(s)
- Yanfeng Meng
- Department of MRI, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Zhiguang Mo
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,The Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen, China
| | - Jinying Hao
- Department of MRI, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Yueyou Peng
- Department of MRI, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Hui Yan
- Department of MRI, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Jingbo Mu
- Department of Cardiology, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Dengfeng Ma
- Department of Cardiology, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, State University of New York at Buffalo, NY, USA
| | - Ye Li
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,The Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen, China
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17
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Ghotra A, Kosakowski HL, Takahashi A, Etzel R, May MW, Scholz A, Jansen A, Wald LL, Kanwisher N, Saxe R, Keil B. A size-adaptive 32-channel array coil for awake infant neuroimaging at 3 Tesla MRI. Magn Reson Med 2021; 86:1773-1785. [PMID: 33829546 DOI: 10.1002/mrm.28791] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 11/12/2022]
Abstract
PURPOSE Functional magnetic resonance imaging (fMRI) during infancy poses challenges due to practical, methodological, and analytical considerations. The aim of this study was to implement a hardware-related approach to increase subject compliance for fMRI involving awake infants. To accomplish this, we designed, constructed, and evaluated an adaptive 32-channel array coil. METHODS To allow imaging with a close-fitting head array coil for infants aged 1-18 months, an adjustable head coil concept was developed. The coil setup facilitates a half-seated scanning position to improve the infant's overall scan compliance. Earmuff compartments are integrated directly into the coil housing to enable the usage of sound protection without losing a snug fit of the coil around the infant's head. The constructed array coil was evaluated from phantom data using bench-level metrics, signal-to-noise ratio (SNR) performances, and accelerated imaging capabilities for both in-plane and simultaneous multislice (SMS) reconstruction methodologies. Furthermore, preliminary fMRI data were acquired to evaluate the in vivo coil performance. RESULTS Phantom data showed a 2.7-fold SNR increase on average when compared with a commercially available 32-channel head coil. At the center and periphery regions of the infant head phantom, the SNR gains were measured to be 1.25-fold and 3-fold, respectively. The infant coil further showed favorable encoding capabilities for undersampled k-space reconstruction methods and SMS techniques. CONCLUSIONS An infant-friendly head coil array was developed to improve sensitivity, spatial resolution, accelerated encoding, motion insensitivity, and subject tolerance in pediatric MRI. The adaptive 32-channel array coil is well-suited for fMRI acquisitions in awake infants.
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Affiliation(s)
- Anpreet Ghotra
- Institute of Medical Physics and Radiation Protection, Department of Life Science Engineering, TH Mittelhessen University of Applied Sciences, Giessen, Germany
| | - Heather L Kosakowski
- Department of Brain and Cognitive Sciences and McGovern Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Atsushi Takahashi
- Department of Brain and Cognitive Sciences and McGovern Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Robin Etzel
- Institute of Medical Physics and Radiation Protection, Department of Life Science Engineering, TH Mittelhessen University of Applied Sciences, Giessen, Germany
| | - Markus W May
- Institute of Medical Physics and Radiation Protection, Department of Life Science Engineering, TH Mittelhessen University of Applied Sciences, Giessen, Germany
| | - Alina Scholz
- Institute of Medical Physics and Radiation Protection, Department of Life Science Engineering, TH Mittelhessen University of Applied Sciences, Giessen, Germany
| | - Andreas Jansen
- Department of Psychiatry and Psychotherapy, University of Marburg, Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), Marburg, Germany
| | - Lawrence L Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA
| | - Nancy Kanwisher
- Department of Brain and Cognitive Sciences and McGovern Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Rebecca Saxe
- Department of Brain and Cognitive Sciences and McGovern Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Boris Keil
- Institute of Medical Physics and Radiation Protection, Department of Life Science Engineering, TH Mittelhessen University of Applied Sciences, Giessen, Germany
- Center for Mind, Brain and Behavior (CMBB), Marburg, Germany
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18
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Scholz A, Etzel R, May MW, Mahmutovic M, Tian Q, Ramos-Llordén G, Maffei C, Bilgiç B, Witzel T, Stockmann JP, Mekkaoui C, Wald LL, Huang SY, Yendiki A, Keil B. A 48-channel receive array coil for mesoscopic diffusion-weighted MRI of ex vivo human brain on the 3 T connectome scanner. Neuroimage 2021; 238:118256. [PMID: 34118399 PMCID: PMC8439104 DOI: 10.1016/j.neuroimage.2021.118256] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 12/14/2022] Open
Abstract
In vivo diffusion-weighted magnetic resonance imaging is limited in signal-to-noise-ratio (SNR) and acquisition time, which constrains spatial resolution to the macroscale regime. Ex vivo imaging, which allows for arbitrarily long scan times, is critical for exploring human brain structure in the mesoscale regime without loss of SNR. Standard head array coils designed for patients are sub-optimal for imaging ex vivo whole brain specimens. The goal of this work was to design and construct a 48-channel ex vivo whole brain array coil for high-resolution and high b-value diffusion-weighted imaging on a 3T Connectome scanner. The coil was validated with bench measurements and characterized by imaging metrics on an agar brain phantom and an ex vivo human brain sample. The two-segment coil former was constructed for a close fit to a whole human brain, with small receive elements distributed over the entire brain. Imaging tests including SNR and G-factor maps were compared to a 64-channel head coil designed for in vivo use. There was a 2.9-fold increase in SNR in the peripheral cortex and a 1.3-fold gain in the center when compared to the 64-channel head coil. The 48-channel ex vivo whole brain coil also decreases noise amplification in highly parallel imaging, allowing acceleration factors of approximately one unit higher for a given noise amplification level. The acquired diffusion-weighted images in a whole ex vivo brain specimen demonstrate the applicability and advantage of the developed coil for high-resolution and high b-value diffusion-weighted ex vivo brain MRI studies.
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Affiliation(s)
- Alina Scholz
- Institute of Medical Physics and Radiation Protection (IMPS), TH-Mittelhessen University of Applied Sciences (THM), 14 Wiesenstrasse, Giessen 35390, Germany.
| | - Robin Etzel
- Institute of Medical Physics and Radiation Protection (IMPS), TH-Mittelhessen University of Applied Sciences (THM), 14 Wiesenstrasse, Giessen 35390, Germany
| | - Markus W May
- Institute of Medical Physics and Radiation Protection (IMPS), TH-Mittelhessen University of Applied Sciences (THM), 14 Wiesenstrasse, Giessen 35390, Germany
| | - Mirsad Mahmutovic
- Institute of Medical Physics and Radiation Protection (IMPS), TH-Mittelhessen University of Applied Sciences (THM), 14 Wiesenstrasse, Giessen 35390, Germany
| | - Qiyuan Tian
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Gabriel Ramos-Llordén
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Chiara Maffei
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Berkin Bilgiç
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA
| | - Thomas Witzel
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Jason P Stockmann
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Choukri Mekkaoui
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Lawrence L Wald
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA
| | - Susie Yi Huang
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA
| | - Anastasia Yendiki
- A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Boris Keil
- Institute of Medical Physics and Radiation Protection (IMPS), TH-Mittelhessen University of Applied Sciences (THM), 14 Wiesenstrasse, Giessen 35390, Germany; Center for Mind, Brain and Behavior (CMBB), Marburg, Germany
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19
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Frässle S, Aponte EA, Bollmann S, Brodersen KH, Do CT, Harrison OK, Harrison SJ, Heinzle J, Iglesias S, Kasper L, Lomakina EI, Mathys C, Müller-Schrader M, Pereira I, Petzschner FH, Raman S, Schöbi D, Toussaint B, Weber LA, Yao Y, Stephan KE. TAPAS: An Open-Source Software Package for Translational Neuromodeling and Computational Psychiatry. Front Psychiatry 2021; 12:680811. [PMID: 34149484 PMCID: PMC8206497 DOI: 10.3389/fpsyt.2021.680811] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 05/10/2021] [Indexed: 12/26/2022] Open
Abstract
Psychiatry faces fundamental challenges with regard to mechanistically guided differential diagnosis, as well as prediction of clinical trajectories and treatment response of individual patients. This has motivated the genesis of two closely intertwined fields: (i) Translational Neuromodeling (TN), which develops "computational assays" for inferring patient-specific disease processes from neuroimaging, electrophysiological, and behavioral data; and (ii) Computational Psychiatry (CP), with the goal of incorporating computational assays into clinical decision making in everyday practice. In order to serve as objective and reliable tools for clinical routine, computational assays require end-to-end pipelines from raw data (input) to clinically useful information (output). While these are yet to be established in clinical practice, individual components of this general end-to-end pipeline are being developed and made openly available for community use. In this paper, we present the Translational Algorithms for Psychiatry-Advancing Science (TAPAS) software package, an open-source collection of building blocks for computational assays in psychiatry. Collectively, the tools in TAPAS presently cover several important aspects of the desired end-to-end pipeline, including: (i) tailored experimental designs and optimization of measurement strategy prior to data acquisition, (ii) quality control during data acquisition, and (iii) artifact correction, statistical inference, and clinical application after data acquisition. Here, we review the different tools within TAPAS and illustrate how these may help provide a deeper understanding of neural and cognitive mechanisms of disease, with the ultimate goal of establishing automatized pipelines for predictions about individual patients. We hope that the openly available tools in TAPAS will contribute to the further development of TN/CP and facilitate the translation of advances in computational neuroscience into clinically relevant computational assays.
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Affiliation(s)
- Stefan Frässle
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Eduardo A. Aponte
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Saskia Bollmann
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States
- Department of Radiology, Harvard Medical School, Charlestown, MA, United States
| | - Kay H. Brodersen
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
- Department of Computer Science, ETH Zurich, Zurich, Switzerland
| | - Cao T. Do
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Olivia K. Harrison
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - Samuel J. Harrison
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Jakob Heinzle
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Sandra Iglesias
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Lars Kasper
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
- Techna Institute, University Health Network, Toronto, ON, Canada
| | - Ekaterina I. Lomakina
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
- Department of Computer Science, ETH Zurich, Zurich, Switzerland
| | - Christoph Mathys
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
- Interacting Minds Center, Aarhus University, Aarhus, Denmark
| | - Matthias Müller-Schrader
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Inês Pereira
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Frederike H. Petzschner
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Sudhir Raman
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Dario Schöbi
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Birte Toussaint
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Lilian A. Weber
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Yu Yao
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Klaas E. Stephan
- Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
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20
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Abstract
Functional magnetic resonance imaging (fMRI) has become one of the most powerful tools for investigating the human brain. Ultrahigh magnetic field (UHF) of 7 Tesla has played a critical role in enabling higher resolution and more accurate (relative to the neuronal activity) functional maps. However, even with these gains, the fMRI approach is challenged relative to the spatial scale over which brain function is organized. Therefore, going forward, significant advances in fMRI are still needed. Such advances will predominantly come from magnetic fields significantly higher than 7 Tesla, which is the most commonly used UHF platform today, and additional technologies that will include developments in pulse sequences, image reconstruction, noise suppression, and image analysis in order to further enhance and augment the gains than can be realized by going to higher magnetic fields.
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Affiliation(s)
- Kamil Uğurbil
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, 2021 6 Street SE, Minneapolis, MN 55456
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21
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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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22
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Tavaf N, Lagore RL, Jungst S, Gunamony S, Radder J, Grant A, Moeller S, Auerbach E, Ugurbil K, Adriany G, Van de Moortele PF. A self-decoupled 32-channel receive array for human-brain MRI at 10.5 T. Magn Reson Med 2021; 86:1759-1772. [PMID: 33780032 DOI: 10.1002/mrm.28788] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 03/02/2021] [Accepted: 03/07/2021] [Indexed: 11/10/2022]
Abstract
PURPOSE Receive array layout, noise mitigation, and B0 field strength are crucial contributors to SNR and parallel-imaging performance. Here, we investigate SNR and parallel-imaging gains at 10.5 T compared with 7 T using 32-channel receive arrays at both fields. METHODS A self-decoupled 32-channel receive array for human brain imaging at 10.5 T (10.5T-32Rx), consisting of 31 loops and one cloverleaf element, was co-designed and built in tandem with a 16-channel dual-row loop transmitter. Novel receive array design and self-decoupling techniques were implemented. Parallel imaging performance, in terms of SNR and noise amplification (g-factor), of the 10.5T-32Rx was compared with the performance of an industry-standard 32-channel receiver at 7 T (7T-32Rx) through experimental phantom measurements. RESULTS Compared with the 7T-32Rx, the 10.5T-32Rx provided 1.46 times the central SNR and 2.08 times the peripheral SNR. Minimum inverse g-factor value of the 10.5T-32Rx (min[1/g] = 0.56) was 51% higher than that of the 7T-32Rx (min[1/g] = 0.37) with R = 4 × 4 2D acceleration, resulting in significantly enhanced parallel-imaging performance at 10.5 T compared with 7 T. The g-factor values of 10.5 T-32 Rx were on par with those of a 64-channel receiver at 7 T (eg, 1.8 vs 1.9, respectively, with R = 4 × 4 axial acceleration). CONCLUSION Experimental measurements demonstrated effective self-decoupling of the receive array as well as substantial gains in SNR and parallel-imaging performance at 10.5 T compared with 7 T.
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Affiliation(s)
- Nader Tavaf
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Russell L Lagore
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Steve Jungst
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Shajan Gunamony
- Center for Cognitive Neuroimaging, University of Glasgow, Glasgow, Scotland
| | - Jerahmie Radder
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Andrea Grant
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Steen Moeller
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Edward Auerbach
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Kamil Ugurbil
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Gregor Adriany
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
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23
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Viessmann O, Polimeni JR. High-resolution fMRI at 7 Tesla: challenges, promises and recent developments for individual-focused fMRI studies. Curr Opin Behav Sci 2021; 40:96-104. [PMID: 33816717 DOI: 10.1016/j.cobeha.2021.01.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Limited detection power has been a bottleneck for subject-specific functional MRI (fMRI) studies, however the higher signal-to-noise ratio afforded by ultra-high magnetic fields (≥ 7 Tesla) provides levels of sensitivity and resolution needed to study individual subjects. What may be surprising is that higher imaging resolution may provide both higher specificity and sensitivity due to reductions in partial volume effects and reduced physiological noise. However, challenges remain to ensure high data quality and to reduce variability in ultra-high field fMRI. We discuss session-specific biases including those caused by factors related to instrumentation, anatomy, and physiology-which can translate into variability across sessions-and how to minimize these to help ultra-high field fMRI reach its full potential for individual-focused studies.
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Affiliation(s)
- Olivia Viessmann
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.,Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Jonathan R Polimeni
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.,Department of Radiology, Harvard Medical School, Boston, MA, USA.,Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA
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24
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Wilcox M, Ogier S, Cheshkov S, Dimitrov I, Malloy C, Wright S, McDougall M. A 16-Channel 13C Array Coil for Magnetic Resonance Spectroscopy of the Breast at 7T. IEEE Trans Biomed Eng 2021; 68:2036-2046. [PMID: 33651680 DOI: 10.1109/tbme.2021.3063061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Considering the reported elevation of ω-6/ω-3 fatty acid ratios in breast neoplasms, one particularly important application of 13C MRS could be in more fully understanding the breast lipidome's relationship to breast cancer incidence. However, the low natural abundance and gyromagnetic ratio of the 13C isotope lead to detection sensitivity challenges. Previous 13C MRS studies have relied on the use of small surface coils with limited field-of-view and shallow penetration depths to achieve adequate signal-to-noise ratio (SNR), and the use of receive array coils is still mostly unexplored. METHODS This work presents a unilateral breast 16-channel 13C array coil and interfacing hardware designed to retain the surface sensitivity of a single small loop coil while improving penetration depth and extending the field-of-view over the entire breast at 7T. The coil was characterized through bench measurements and phantom 13C spectroscopy experiments. RESULTS Bench measurements showed receive coil matching better than -17 dB and average preamplifier decoupling of 16.2 dB with no evident peak splitting. Phantom MRS studies show better than a three-fold increase in average SNR over the entirety of the breast region compared to volume coil reception alone as well as an ability for individual array elements to be used for coarse metabolite localization without the use of single-voxel or spectroscopic imaging methods. CONCLUSION Our current study has shown the benefits of the array. Future in vivo lipidomics studies can be pursued. SIGNIFICANCE Development of the 16-channel breast array coil opens possibilities of in vivo lipidomics studies to elucidate the link between breast cancer incidence and lipid metabolics.
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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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Machado-Rivas F, Jaimes C, Kirsch JE, Gee MS. Image-quality optimization and artifact reduction in fetal magnetic resonance imaging. Pediatr Radiol 2020; 50:1830-1838. [PMID: 33252752 DOI: 10.1007/s00247-020-04672-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/09/2020] [Accepted: 03/31/2020] [Indexed: 11/28/2022]
Abstract
Fetal MRI allows for earlier and better detection of complex congenital anomalies. However, its diagnostic utility is often limited by technical barriers that introduce artifacts and reduce image quality. The main determinants of fetal MR image quality are speed of acquisition, spatial resolution and signal-to-noise ratio (SNR). Imaging optimization is a challenge because a change to improve one scan parameter often leads to worsening of another. Moreover, the recent introduction of fetal MRI on 3-tesla (T) scanners to achieve better SNR can amplify some technical issues. Motion, banding artifacts and aliasing artifacts impact the quality of fetal acquisitions at any field strength. High specific absorption rate (SAR) and artifacts from inhomogeneities in the radiofrequency field are important limitations of high-field-strength imaging. We discuss technical barriers that impact image quality and are important limitations to prenatal MRI diagnosis, and propose solutions to improve image quality and reduce artifacts.
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Affiliation(s)
- Fedel Machado-Rivas
- Department of Radiology, Massachusetts General Hospital, 55 Fruit St., Boston, MA, 02114, USA.,Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Camilo Jaimes
- Department of Radiology, Harvard Medical School, Boston, MA, USA.,Department of Radiology, Boston Children's Hospital, Boston, MA, USA
| | - John E Kirsch
- Department of Radiology, Massachusetts General Hospital, 55 Fruit St., Boston, MA, 02114, USA.,Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Michael S Gee
- Department of Radiology, Massachusetts General Hospital, 55 Fruit St., Boston, MA, 02114, USA. .,Department of Radiology, Harvard Medical School, Boston, MA, 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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28
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Felder J, Choi CH, Ko Y, Shah NJ. Optimization of high-channel count, switch matrices for multinuclear, high-field MRI. PLoS One 2020; 15:e0237494. [PMID: 32804972 PMCID: PMC7430713 DOI: 10.1371/journal.pone.0237494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 07/28/2020] [Indexed: 12/11/2022] Open
Abstract
Modern magnetic resonance imaging systems are equipped with a large number of receive connectors in order to optimally support a large field-of-view and/or high acceleration in parallel imaging using high-channel count, phased array coils. Given that the MR system is equipped with a limited number of digitizing receivers and in order to support operation of multinuclear coil arrays, these connectors need to be flexibly routed to the receiver outside the RF shielded examination room. However, for a number of practical, economic and safety reasons, it is better to only route a subset of the connectors. This is usually accomplished with the use of switch matrices. These exist in a variety of topologies and differ in routing flexibility and technological implementation. A highly flexible implementation is a crossbar topology that allows to any one input to be routed to any one output and can use single PIN diodes as active elements. However, in this configuration, long open-ended transmission lines can potentially remain connected to the signal path leading to high transmission losses. Thus, especially for high-field systems compensation mechanisms are required to remove the effects of open-ended transmission line stubs. The selection of a limited number of lumped element reactance values to compensate for the for the effect of transmission line stubs in large-scale switch matrices capable of supporting multi-nuclear operation is non-trivial and is a combinatorial problem of high order. Here, we demonstrate the use of metaheuristic approaches to optimize the circuit design of these matrices that additionally carry out the optimization of distances between the parallel transmission lines. For a matrix with 128 inputs and 64 outputs a realization is proposed that displays a worst-case insertion loss of 3.8 dB.
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Affiliation(s)
- Jörg Felder
- Institute of Neuroscience and Medicine -4, Forschungszentrum Jülich, Jülich, Germany
| | - Chang-Hoon Choi
- Institute of Neuroscience and Medicine -4, Forschungszentrum Jülich, Jülich, Germany
| | - Yunkyoung Ko
- Institute of Neuroscience and Medicine -4, Forschungszentrum Jülich, Jülich, Germany
| | - N. Jon Shah
- Institute of Neuroscience and Medicine -4, Forschungszentrum Jülich, Jülich, Germany
- Institute of Neuroscience and Medicine -11, Forschungszentrum Jülich, Jülich, Germany
- JARA—BRAIN—Translational Medicine, Aachen, Germany
- Department of Neurology, RWTH Aachen University, Aachen, Germany
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29
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Ahamed SH, Lee KJ, Tang PH. Role of a modified ultrafast MRI brain protocol in clinical paediatric neuroimaging. Clin Radiol 2020; 75:914-920. [PMID: 32782127 DOI: 10.1016/j.crad.2020.07.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 07/06/2020] [Indexed: 11/18/2022]
Abstract
AIM To establish a role for modified ultrafast magnetic resonance imaging (MRI) of the brain in clinical paediatric patients based on clinically acceptable image quality and diagnostic accuracy. MATERIALS AND METHODS A prospective study was conducted with institutional review board approval on an ultrafast MRI brain protocol consisting of sagittal T1-weighted, axial T2-weighted, axial fluid-attenuated inversion recovery (FLAIR), axial diffusion-weighted imaging (DWI), and axial T2∗-weighted sequences. Preliminary investigations revealed that the default ultrafast T2-weighted sequence was prone to pulsation artefacts. A modified ultrafast T2-weighted sequence was therefore developed to replace the default ultrafast T2-weighted sequence. Thirty-five patients with clinical indication for neuroimaging underwent ultrafast MRI, modified ultrafast T2-weighted sequence and standard MRI at 3 T. Image quality of ultrafast MRI sequences were graded as clinically "diagnostic" or "non-diagnostic" and compared against the corresponding standard MRI sequences as the reference standard. The modified ultrafast T2-weighted sequence surpassed the default ultrafast T2-weighted sequence in image quality. The ultrafast MRI protocol was therefore replaced with the modified ultrafast T2-weighted sequence creating a modified ultrafast MRI protocol. The clinical reports of modified ultrafast MRI were compared against standard MRI for diagnostic concordance, categorised further as "normal", "clinically significant", or "clinically minor" abnormalities. RESULTS Ultrafast T1-weighted, FLAIR, and DWI sequences had comparable image quality to standard MRI sequences. The ultrafast T2∗-weighted sequence had significantly higher non-diagnostic images (42.9%) compared to the standard MRI sequence (2.9%). The default ultrafast T2-weighted sequence had significantly higher non-diagnostic images compared to the modified ultrafast T2-weighted sequence and standard T2-weighted sequence (82.9%, 5.7%, 8.6%, respectively). There was 100% concordance for normal and clinically significant abnormalities and 23% discordance for clinically minor abnormalities. Modified ultrafast MRI takes 5 minutes 41 seconds compared to standard MRI time of 14 minutes 57 seconds. CONCLUSION The modified ultrafast MRI protocol for brain imaging demonstrates clinically acceptable image quality in four out of five sequences and has high accuracy in diagnosing normal and clinically significant abnormalities when compared against the standard MRI protocol for brain imaging. It could potentially benefit a select group of paediatric patients who require neuroimaging.
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Affiliation(s)
- S H Ahamed
- Department of Diagnostic and Interventional Imaging, KK Women's and Children's Hospital, 100 Bukit Timah Road, 229899, Singapore.
| | - K J Lee
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A∗STAR), 11 Biopolis Way, #02-02 Helios, 138667, Singapore
| | - P H Tang
- Department of Diagnostic and Interventional Imaging, KK Women's and Children's Hospital, 100 Bukit Timah Road, 229899, Singapore
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30
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Stout JN, Rouhani S, Turk EA, Ha CG, Luo J, Rich K, Wald LL, Adalsteinsson E, Barth WH, Grant PE, Roberts DJ. Placental MRI: Development of an MRI compatible ex vivo system for whole placenta dual perfusion. Placenta 2020; 101:4-12. [PMID: 32905974 DOI: 10.1016/j.placenta.2020.07.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/24/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE Placental dysfunction plays a key role in diseases that affect the fetus in utero and after birth. Aiming to develop a platform for validating in vivo placental MRI and investigations into placental physiology, we designed and built a prototype MRI-compatible perfusion chamber with an integrated MRI receive coil for high SNR ex vivo placental imaging. PRINCIPAL RESULTS After optimizing placenta vascular clearing and perfusion protocols, we performed contrast enhanced MR angiography and MR relaxometry on eight carefully selected placentas while they were perfused via the umbilical arteries (UAs). Additionally, two of these placentas underwent maternal perfusion via the intervillous space (IVS). Despite striving for homogenous perfusion across the whole placenta, imaging results were highly heterogeneous for both UA and IVS perfused placentas. By histology, we observed blood congestion in the villi in regions that showed low UA perfusion during MRI. In two placentas prominent chorionic arteries followed by adjacent veins underwent contrast enhancement in the absence of villous capillary blush. The single placenta from a pregnancy affected by IUGR had the most homogeneous villous capillary perfusion. MAJOR CONCLUSIONS A dual perfusion system for ex vivo placentas compatible with MRI permitted assessment of UA and IVS placental perfusion. We observed spatial UA perfusion heterogeneity and evidence for arteriovenous shunting in placentas from normal pregnancies and deliveries, but relative villous capillary perfusion homogeneity in a single IUGR placenta. Future work will focus on system optimization, followed by physiological manipulation and validation of in vivo placental MRI.
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Affiliation(s)
- Jeffrey N Stout
- Fetal-Neonatal Neuroimaging & Developmental Sciences Center, Boston Children's Hospital, Boston, MA, USA.
| | - Shahin Rouhani
- Fetal-Neonatal Neuroimaging & Developmental Sciences Center, Boston Children's Hospital, Boston, MA, USA; Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
| | - Esra Abaci Turk
- Fetal-Neonatal Neuroimaging & Developmental Sciences Center, Boston Children's Hospital, Boston, MA, USA
| | - Christopher G Ha
- Fetal-Neonatal Neuroimaging & Developmental Sciences Center, Boston Children's Hospital, Boston, MA, USA
| | - Jie Luo
- Fetal-Neonatal Neuroimaging & Developmental Sciences Center, Boston Children's Hospital, Boston, MA, USA
| | - Karen Rich
- Department of Radiology, Massachusetts General Hospital, Boston, MA, USA
| | - Lawerence L Wald
- Department of Radiology, Massachusetts General Hospital, Boston, MA, USA
| | - Elfar Adalsteinsson
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA; Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - William H Barth
- Maternal-Fetal Medicine, Obstetrics and Gynecology, Massachusetts General Hospital, Boston, MA, USA
| | - P Ellen Grant
- Fetal-Neonatal Neuroimaging & Developmental Sciences Center, Boston Children's Hospital, Boston, MA, USA
| | - Drucilla J Roberts
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
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31
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Brunnquell CL, Hoff MN, Balu N, Nguyen XV, Oztek MA, Haynor DR. Making Magnets More Attractive: Physics and Engineering Contributions to Patient Comfort in MRI. Top Magn Reson Imaging 2020; 29:167-174. [PMID: 32541257 DOI: 10.1097/rmr.0000000000000246] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Patient comfort is an important factor of a successful magnetic resonance (MR) examination, and improvements in the patient's MR scanning experience can contribute to improved image quality, diagnostic accuracy, and efficiency in the radiology department, and therefore reduced cost. Magnet designs that are more open and accessible, reduced auditory noise of MR examinations, light and flexible radiofrequency (RF) coils, and faster motion-insensitive imaging techniques can all significantly improve the patient experience in MR imaging. In this work, we review the design, development, and implementation of these physics and engineering approaches to improve patient comfort.
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Affiliation(s)
- Christina L Brunnquell
- Department of Radiology, University of Washington, Seattle, WA Department of Radiology, The Ohio State University Wexler Medical Center, Columbus, OH
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32
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Sung D, Risk BB, Owusu‐Ansah M, Zhong X, Mao H, Fleischer CC. Optimized truncation to integrate multi-channel MRS data using rank-R singular value decomposition. NMR IN BIOMEDICINE 2020; 33:e4297. [PMID: 32249522 PMCID: PMC7317403 DOI: 10.1002/nbm.4297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 02/28/2020] [Accepted: 02/29/2020] [Indexed: 06/01/2023]
Abstract
Multi-channel phased receive arrays have been widely adopted for magnetic resonance imaging (MRI) and spectroscopy (MRS). An important step in the use of receive arrays for MRS is the combination of spectra collected from individual coil channels. The goal of this work was to implement an improved strategy termed OpTIMUS (i.e., optimized truncation to integrate multi-channel MRS data using rank-R singular value decomposition) for combining data from individual channels. OpTIMUS relies on spectral windowing coupled with a rank-R decomposition to calculate the optimal coil channel weights. MRS data acquired from a brain spectroscopy phantom and 11 healthy volunteers were first processed using a whitening transformation to remove correlated noise. Whitened spectra were then iteratively windowed or truncated, followed by a rank-R singular value decomposition (SVD) to empirically determine the coil channel weights. Spectra combined using the vendor-supplied method, signal/noise2 weighting, previously reported whitened SVD (rank-1), and OpTIMUS were evaluated using the signal-to-noise ratio (SNR). Significant increases in SNR ranging from 6% to 33% (P ≤ 0.05) were observed for brain MRS data combined with OpTIMUS compared with the three other combination algorithms. The assumption that a rank-1 SVD maximizes SNR was tested empirically, and a higher rank-R decomposition, combined with spectral windowing prior to SVD, resulted in increased SNR.
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Affiliation(s)
- Dongsuk Sung
- Department of Biomedical EngineeringGeorgia Institute of Technology and Emory University School of MedicineAtlantaGeorgia
| | - Benjamin B. Risk
- Department of Biostatistics and BioinformaticsEmory UniversityAtlantaGeorgia
| | - Maame Owusu‐Ansah
- Department of Radiology and Imaging SciencesEmory University School of MedicineAtlantaGeorgia
| | - Xiaodong Zhong
- MR R&D Collaborations, Siemens HealthcareLos AngelesCalifornia
| | - Hui Mao
- Department of Radiology and Imaging SciencesEmory University School of MedicineAtlantaGeorgia
| | - Candace C. Fleischer
- Department of Biomedical EngineeringGeorgia Institute of Technology and Emory University School of MedicineAtlantaGeorgia
- Department of Radiology and Imaging SciencesEmory University School of MedicineAtlantaGeorgia
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33
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Börnert P, Norris DG. A half-century of innovation in technology-preparing MRI for the 21st century. Br J Radiol 2020; 93:20200113. [PMID: 32496816 DOI: 10.1259/bjr.20200113] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
MRI developed during the last half-century from a very basic concept to an indispensable non-ionising medical imaging technique that has found broad application in diagnostics, therapy control and far beyond. Due to its excellent soft-tissue contrast and the huge variety of accessible tissue- and physiological-parameters, MRI is often preferred to other existing modalities. In the course of its development, MRI underwent many substantial transformations. From the beginning, starting as a proof of concept, much effort was expended to develop the appropriate basic scanning technology and methodology, and to establish the many clinical contrasts (e.g., T1, T2, flow, diffusion, water/fat, etc.) that MRI is famous for today. Beyond that, additional prominent innovations to the field have been parallel imaging and compressed sensing, leading to significant scanning time reductions, and the move towards higher static magnetic field strengths, which led to increased sensitivity and improved image quality. Improvements in workflow and the use of artificial intelligence are among many current trends seen in this field, paving the way for a broad use of MRI. The 125th anniversary of the BJR is a good point to reflect on all these changes and developments and to offer some slightly speculative ideas as to what the future may bring.
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Affiliation(s)
- Peter Börnert
- Philips Research, Hamburg, Germany.,Department of Radiology, LUMC, Leiden, the Netherlands
| | - David G Norris
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, Netherlands.,Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany.,Magnetic Detection and Imaging, Science and Technology Faculty, University of Twente, Enschede, Netherlands
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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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35
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Reber J, Marjanovic J, Brunner DO, Port A, Schmid T, Dietrich BE, Moser U, Barmet C, Pruessmann KP. An In-Bore Receiver for Magnetic Resonance Imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:997-1007. [PMID: 31484112 DOI: 10.1109/tmi.2019.2939090] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In magnetic resonance imaging, the use of array detection and the number of detector elements have seen a steady increase over the past two decades. As a result, per-channel analog connection via long coaxial cable, as commonly used, poses an increasing challenge in terms of handling, safety, and coupling among cables. This situation is exacerbated when complementary recording of radiofrequency transmission or NMR-based magnetic field sensing further add to channel counts. A generic way of addressing this trend is the transition to digital signal transmission, enabled by digitization and first-level digital processing close to detector coils and sensors in the magnet bore. The foremost challenge that comes with this approach is to achieve high dynamic range, linearity, and phase stability despite interference by strong static, audiofrequency, and radiofrequency fields. The present work reports implementation of a 16-channel in-bore receiver, performing signal digitization and processing with subsequent optical transmission over fiber. Along with descriptions of the system design and construction, performance evaluation is reported. The resulting device is fully MRI compatible providing practically equal performance and signal quality compared to state-of-the-art RF digitizers operating outside the magnet. Its use is demonstrated by examples of head imaging and magnetic field recording.
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36
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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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37
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Gao Y, Mareyam A, Sun Y, Witzel T, Arango N, Kuang I, White J, Roe AW, Wald L, Stockmann J, Zhang X. A 16-channel AC/DC array coil for anesthetized monkey whole-brain imaging at 7T. Neuroimage 2019; 207:116396. [PMID: 31778818 DOI: 10.1016/j.neuroimage.2019.116396] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 11/21/2019] [Accepted: 11/22/2019] [Indexed: 01/07/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) in monkeys is important for bridging the gap between invasive animal brain studies and non-invasive human brain studies. To resolve the finer functional structure of the monkey brain, ultra-high-field (UHF) MR is essential, and high-performance, close-fitting RF receive coils are typically desired to fully leverage the intrinsic gains provided by UHF MRI. Moreover, static field (B0) inhomogeneity arising from the tissue susceptibility interface is more severe at UHF, presenting an obstacle to achieving high-resolution fMRI. B0 shim of the monkey head is challenging due to its smaller size and more complex sources of B0 offsets in multi-modal imaging tasks. In the present work, we have customized an array coil for lightly-anesthetized monkey fMRI in the 7T human scanner that combines RF and multi-coil (MC) B0 shim functionality (also referred to as AC/DC coils) to provide high imaging SNR and high-spatial-order, rapidly switchable B0-shim capability. Additional space was retained on the coil to render it compatible with monkey multi-modal imaging studies. Both MC global (whole-volume) and dynamic (slice-optimized) shim methods were tested and evaluated, and the benefits of MC shim for fMRI experiments was also studied. A minor reduction in RF coil performance was found after introducing additional B0 shim circuitry. However, the proposed RF coil provided higher image SNR and more uniform contrast compared to a commercially available coil for human knee imaging. Compared with static 2nd-order shim, the B0 inhomogeneity was reduced by 56.8%, and 95-percentile B0 offset was reduced to within 28.2 Hz through MC shim, versus 68.7 Hz with 2nd-order static shim. As a result, functional image quality could be improved, and brain activation can be better detected using the proposed AC/DC monkey coil.
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Affiliation(s)
- Yang Gao
- Interdisciplinary Institute of Neuroscience and Technology, Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States; School of Medicine, Zhejiang University, Hangzhou, China
| | - Azma Mareyam
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States
| | - Yi Sun
- MR Collaboration, Siemens Healthcare, Shanghai, China
| | - Thomas Witzel
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, United States
| | - Nicolas Arango
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Irene Kuang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Jacob White
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Anna Wang Roe
- Interdisciplinary Institute of Neuroscience and Technology, Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China; School of Medicine, Zhejiang University, Hangzhou, China
| | - Lawrence Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, United States
| | - Jason Stockmann
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States; Harvard Medical School, Boston, MA, United States
| | - Xiaotong Zhang
- Interdisciplinary Institute of Neuroscience and Technology, Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China; School of Medicine, Zhejiang University, Hangzhou, China.
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Chen Q, Li Y, Jiang R, Zou C, Tie C, Wen J, Yang X, Zhang X, Liu X, Zheng H. A flexible 9-channel coil array for fast 3D MR thermometry in MR-guided high-intensity focused ultrasound (HIFU) studies on rabbits at 3 T. Magn Reson Imaging 2019; 65:37-44. [PMID: 31655140 DOI: 10.1016/j.mri.2019.10.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 09/12/2019] [Accepted: 10/14/2019] [Indexed: 01/09/2023]
Abstract
Signal-to-noise ratio (SNR) is a critical factor in MR-guided high-intensity focused ultrasound (HIFU) for local heating, which can affect the accuracy of temperature measurement. In order to achieve high SNR and higher temporal resolution, dedicated coil arrays for MR-guided HIFU applications need to be developed. In this work, a flexible 9-channel coil array was designed, and constructed at 3 T to achieve fast temperature mapping for MR-guided HIFU applications on rabbit leg muscle. Coil performance was evaluated for SNR, and parallel imaging capability by in-vivo studies. Compared to a commercially available 4-channel flexible coil array, the dedicated 9-channel coil array has a much higher SNR, with at least a 2.6-fold increment in the region of interest (ROI). The inverse g-factors maps demonstrated that the dedicated 9-channel coil array has a better parallel imaging capability than the Flex Small 4. With accelerations normal to the array direction, both coil arrays showed much higher g-factors than those of accelerations along the array direction. Room temperature mapping was implemented to evaluate the temperature measurement accuracy by in-vivo experiments. The precisions of the 9-channel coil, ±0.18 °C for un-acceleration and ± 0.56 °C for acceleration at R = 2 × 2, both improved by an order of magnitude than these of the 4-channel coil, which were ± 1.45 °C for un-acceleration and ± 3.52 °C for acceleration at R = 2 × 2. In the fast temperature imaging on the rabbit leg muscle with heating, a high temporal resolution of 3.3 s with a temperature measurement precision of ±0.56 °C has been achieved using the dedicated 9-channel coil. This study demonstrates that the dedicated 9-channel coil array for rabbit leg imaging provides improved performance in SNR, parallel imaging capability, and the accuracy of temperature measurement compared to a commercial 4-channel coil, and it also achieves fast temperature mapping in practical MR-guided HIFU applications.
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Affiliation(s)
- Qiaoyan Chen
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen Key Laboratory for MRI, Shenzhen, China
| | - Ye Li
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen Key Laboratory for MRI, Shenzhen, China
| | - Rui Jiang
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen Key Laboratory for MRI, Shenzhen, China
| | - Chao Zou
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen Key Laboratory for MRI, Shenzhen, China
| | - Changjun Tie
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen Key Laboratory for MRI, Shenzhen, China
| | - Jianhong Wen
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen Key Laboratory for MRI, Shenzhen, China
| | - Xing Yang
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen Key Laboratory for MRI, Shenzhen, China
| | - Xiaoliang Zhang
- Department of Radiology and Biomedical Imaging, University of California San Francisco, CA, United States; UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, CA, United States
| | - Xin Liu
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen Key Laboratory for MRI, Shenzhen, China
| | - Hairong Zheng
- Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen Key Laboratory for MRI, Shenzhen, China.
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Bliesener Y, Lingala SG, Haldar JP, Nayak KS. Impact of (k,t) sampling on DCE MRI tracer kinetic parameter estimation in digital reference objects. Magn Reson Med 2019; 83:1625-1639. [PMID: 31605556 PMCID: PMC6982604 DOI: 10.1002/mrm.28024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/06/2019] [Accepted: 09/09/2019] [Indexed: 12/12/2022]
Abstract
Purpose To evaluate the impact of (k,t) data sampling on the variance of tracer‐kinetic parameter (TK) estimation in high‐resolution whole‐brain dynamic contrast enhanced magnetic resonance imaging (DCE‐MRI) using digital reference objects. We study this in the context of TK model constraints, and in the absence of other constraints. Methods Three anatomically and physiologically realistic brain‐tumor digital reference objects were generated. Data sampling strategies included uniform and variable density; zone‐based, lattice, pseudo‐random, and pseudo‐radial; with 50‐time frames and 4‐fold to 25‐fold undersampling. In all cases, we assume a fully sampled first time frame, and prior knowledge of the arterial input function. TK parameters were estimated by indirect estimation (i.e., image‐time‐series reconstruction followed by model fitting), and direct estimation from the under‐sampled data. We evaluated methods based on the Cramér‐Rao bound and Monte‐Carlo simulations, over the range of signal‐to‐noise ratio (SNR) seen in clinical brain DCE‐MRI. Results Lattice‐based sampling provided the lowest SDs, followed by pseudo‐random, pseudo‐radial, and zone‐based. This ranking was consistent for the Patlak and extended Tofts model. Pseudo‐random sampling resulted in 19% higher averaged SD compared to lattice‐based sampling. Zone‐based sampling resulted in substantially higher SD at undersampling factors above 10. CRB analysis showed only a small difference between uniform and variable density for both lattice‐based and pseudo‐random sampling up to undersampling factors of 25. Conclusion Lattice sampling provided the lowest SDs, although the differences between sampling schemes were not substantial at low undersampling factors. The differences between lattice‐based and pseudo‐random sampling strategies with both uniform and variable density were within the range of error induced by other sources, at up to 25‐fold undersampling.
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Affiliation(s)
- Yannick Bliesener
- Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, California
| | - Sajan G Lingala
- Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, California
| | - Justin P Haldar
- Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, California
| | - Krishna S Nayak
- Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, California
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van Zijl P, Knutsson L. In vivo magnetic resonance imaging and spectroscopy. Technological advances and opportunities for applications continue to abound. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 306:55-65. [PMID: 31377150 PMCID: PMC6703925 DOI: 10.1016/j.jmr.2019.07.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 06/19/2019] [Accepted: 07/08/2019] [Indexed: 05/07/2023]
Abstract
Over the past decades, the field of in vivo magnetic resonance (MR) has built up an impressive repertoire of data acquisition and analysis technologies for anatomical, functional, physiological, and molecular imaging, the description of which requires many book volumes. As such it is impossible for a few authors to have an authoritative overview of the field and for a brief article to be inclusive. We will therefore focus mainly on data acquisition and attempt to give some insight into the principles underlying current advanced methods in the field and the potential for further innovation. In our view, the foreseeable future is expected to show continued rapid progress, for instance in imaging of microscopic tissue properties in vivo, assessment of functional and anatomical connectivity, higher resolution physiologic and metabolic imaging, and even imaging of receptor binding. In addition, acquisition speed and information content will continue to increase due to the continuous development of approaches for parallel imaging (including simultaneous multi-slice imaging), compressed sensing, and MRI fingerprinting. Finally, artificial intelligence approaches are becoming more realistic and will have a tremendous effect on both acquisition and analysis strategies. Together, these developments will continue to provide opportunity for scientific discovery and, in combination with large data sets from other fields such as genomics, allow the ultimate realization of precision medicine in the clinic.
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Affiliation(s)
- Peter van Zijl
- Department of Radiology, Johns Hopkins University, F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
| | - Linda Knutsson
- Department of Medical Radiation Physics, Lund University, Lund, Sweden
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Trampel R, Bazin PL, Pine K, Weiskopf N. In-vivo magnetic resonance imaging (MRI) of laminae in the human cortex. Neuroimage 2019; 197:707-715. [DOI: 10.1016/j.neuroimage.2017.09.037] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 09/13/2017] [Accepted: 09/19/2017] [Indexed: 11/16/2022] Open
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Navarro de Lara LI, Frass-Kriegl R, Renner A, Sieg J, Pichler M, Bogner T, Moser E, Beyer T, Birkfellner W, Figl M, Laistler E. Design, Implementation, and Evaluation of a Head and Neck MRI RF Array Integrated with a 511 keV Transmission Source for Attenuation Correction in PET/MR. SENSORS 2019; 19:s19153297. [PMID: 31357545 PMCID: PMC6696210 DOI: 10.3390/s19153297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/23/2019] [Accepted: 07/25/2019] [Indexed: 01/13/2023]
Abstract
The goal of this work is to further improve positron emission tomography (PET) attenuation correction and magnetic resonance (MR) sensitivity for head and neck applications of PET/MR. A dedicated 24-channel receive-only array, fully-integrated with a hydraulic system to move a transmission source helically around the patient and radiofrequency (RF) coil array, is designed, implemented, and evaluated. The device enables the calculation of attenuation coefficients from PET measurements at 511 keV including the RF coil and the particular patient. The RF coil design is PET-optimized by minimizing photon attenuation from coil components and housing. The functionality of the presented device is successfully demonstrated by calculating the attenuation map of a water bottle based on PET transmission measurements; results are in excellent agreement with reference values. It is shown that the device itself has marginal influence on the static magnetic field B0 and the radiofrequency transmit field B1 of the 3T PET/MR system. Furthermore, the developed RF array is shown to outperform a standard commercial 16-channel head and neck coil in terms of signal-to-noise ratio (SNR) and parallel imaging performance. In conclusion, the presented hardware enables accurate calculation of attenuation maps for PET/MR systems while improving the SNR of corresponding MR images in a single device without degrading the B0 and B1 homogeneity of the scanner.
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Affiliation(s)
- Lucia Isabel Navarro de Lara
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Roberta Frass-Kriegl
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Andreas Renner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10/134, 1040 Vienna, Austria
| | - Jürgen Sieg
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Michael Pichler
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Thomas Bogner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Ewald Moser
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Thomas Beyer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Wolfgang Birkfellner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Michael Figl
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Elmar Laistler
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria.
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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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Holdsworth SJ, O'Halloran R, Setsompop K. The quest for high spatial resolution diffusion-weighted imaging of the human brain in vivo. NMR IN BIOMEDICINE 2019; 32:e4056. [PMID: 30730591 DOI: 10.1002/nbm.4056] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 09/11/2018] [Accepted: 11/08/2018] [Indexed: 06/09/2023]
Abstract
Diffusion-weighted imaging, a contrast unique to MRI, is used for assessment of tissue microstructure in vivo. However, this exquisite sensitivity to finer scales far above imaging resolution comes at the cost of vulnerability to errors caused by sources of motion other than diffusion motion. Addressing the issue of motion has traditionally limited diffusion-weighted imaging to a few acquisition techniques and, as a consequence, to poorer spatial resolution than other MRI applications. Advances in MRI imaging methodology have allowed diffusion-weighted MRI to push to ever higher spatial resolution. In this review we focus on the pulse sequences and associated techniques under development that have pushed the limits of image quality and spatial resolution in diffusion-weighted MRI.
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Affiliation(s)
- Samantha J Holdsworth
- Department of Anatomy Medical Imaging & Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | | | - Kawin Setsompop
- Harvard Medical School, Massachusetts General Hospital, Boston, MA, USA
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Yeh JNT, Lin JFL. A Flexible and Modular Receiver Coil Array for Magnetic Resonance Imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:824-833. [PMID: 30295617 DOI: 10.1109/tmi.2018.2873317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We propose a flexible form-fittingMRI receiver coil array assembledby individualcoilmodules. This design targetsMRI applications requiring a receiver array conforming to the anatomy of various shapes or sizes. Coil modules in our proposed array were arranged with gaps between them. Each coil module had a circumferential shielding structure stacked on top of the coil. Together they achieve robust decoupling when the array was bent differently. Two types of the circumferential shielding structure were investigatedby using full-wave electromagnetic simulations and imaging experiments. Results showed that our flexible coil array had good decoupling between coils whether they were on a flat or curved surface with the S21 magnitude ranged between -18.1 dB and -19.9 dB in simulations, and with the average of off-diagonal entries of the noise correlationmatrix less than 0.047 in experimentalmeasurements. Anatomical images of human brain, calf, and knee were acquired by our seven-channel prototype on a 3T MRI system. The maximal and the average SNR within 50 mm from our array surpassed those from the commercial 32-channel head and 4-channel flexible coil arrays by 2.63/1.35-fold and 3.89/1.50-fold, respectively.
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Winkler SA, Corea J, Lechêne B, O'Brien K, Bonanni JR, Chaudhari A, Alley M, Taviani V, Grafendorfer T, Robb F, Scott G, Pauly J, Lustig M, Arias AC, Vasanawala S. Evaluation of a Flexible 12-Channel Screen-printed Pediatric MRI Coil. Radiology 2019; 291:180-185. [PMID: 30806599 DOI: 10.1148/radiol.2019181883] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Background Screen-printed MRI coil technology may reduce the need for bulky and heavy housing of coil electronics and may provide a better fit to patient anatomy to improve coil performance. Purpose To assess the performance and caregiver and clinician acceptance of a pediatric-sized screen-printed flexible MRI coil array as compared with conventional coil technology. Materials and Methods A pediatric-sized 12-channel coil array was designed by using a screen-printing process. Element coupling and phantom signal-to-noise ratio (SNR) were assessed. Subjects were scanned by using the pediatric printed array between September and November 2017; results were compared with three age- and sex-matched historical control subjects by using a commercial 32-channel cardiac array at 3 T. Caregiver acceptance was assessed by asking nurses, technologists, anesthesiologists, and subjects or parents to rate their coil preference. Diagnostic quality of the images was evaluated by using a Likert scale (5 = high image quality, 1 = nondiagnostic). Image SNR was evaluated and compared. Results Twenty study participants were evaluated with the screen-printed coil (age range, 2 days to 12 years; 11 male and nine female subjects). Loaded pediatric phantom testing yielded similar noise covariance matrices and only slightly degraded SNR for the printed coil as compared with the commercial coil. The caregiver acceptance survey yielded a mean score of 4.1 ± 0.6 (scale: 1, preferred the commercial coil; 5, preferred the printed coil). Diagnostic quality score was 4.5 ± 0.6. Mean image SNR was 54 ± 49 (paraspinal muscle), 78 ± 51 (abdominal wall muscle), and 59 ± 35 (psoas) for the printed coil, as compared with 64 ± 55, 65 ± 48, and 57 ± 43, respectively, for the commercial coil; these SNR differences were not statistically significant (P = .26). Conclusion A flexible screen-printed pediatric MRI receive coil yields adequate signal-to-noise ratio in phantoms and pediatric study participants, with similar image quality but higher preference by subjects and their caregivers when compared with a conventional MRI coil. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Lamb in this issue.
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Affiliation(s)
- Simone Angela Winkler
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Joseph Corea
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Balthazar Lechêne
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Kendall O'Brien
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - John Ross Bonanni
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Akshay Chaudhari
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Marcus Alley
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Valentina Taviani
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Thomas Grafendorfer
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Fraser Robb
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Greig Scott
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - John Pauly
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Michael Lustig
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Ana Claudia Arias
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
| | - Shreyas Vasanawala
- From the Department of Radiology, Stanford University, 300 Pasteur Dr, Stanford, CA 94305 (S.A.W., A.C., M.A., S.V.); Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Calif (J.C., B.L., M.L., A.C.A.); Lucile Packard Children's Hospital at Stanford, Stanford, Calif (K.O., J.R.B.); GE Healthcare, Menlo Park, Calif (V.T.); GE Healthcare, Aurora, Ohio (T.G., F.R.); and Department of Electrical Engineering, Stanford University, Stanford, Calif (G.S., J.P.)
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47
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Uğurbil K, Auerbach E, Moeller S, Grant A, Wu X, Van de Moortele PF, Olman C, DelaBarre L, Schillak S, Radder J, Lagore R, Adriany G. Brain imaging with improved acceleration and SNR at 7 Tesla obtained with 64-channel receive array. Magn Reson Med 2019; 82:495-509. [PMID: 30803023 DOI: 10.1002/mrm.27695] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 12/28/2018] [Accepted: 01/25/2019] [Indexed: 12/27/2022]
Abstract
PURPOSE Despite the clear synergy between high channel counts in a receive array and magnetic fields ≥ 7 Tesla, to date such systems have been restricted to a maximum of 32 channels. Here, we examine SNR gains at 7 Tesla in unaccelerated and accelerated images with a 64-receive channel (64Rx) RF coil. METHODS A 64Rx coil was built using circular loops tiled in 2 separable sections of a close-fitting form; custom designed preamplifier boards were integrated into each coil element. A 16-channel transmitter arranged in 2 rows along the z-axis was employed. The performance of the 64Rx array was experimentally compared to that of an industry-standard 32-channel receive (32Rx) array for SNR in unaccelerated images and for noise amplification under parallel imaging. RESULTS SNR gains were observed in the periphery but not in the center of the brain in unaccelerated imaging compared to the 32Rx coil. With either 1D or 2D undersampling of k-space, or with slice acceleration together with 1D undersampling of k-space, significant reductions in g-factor noise were observed throughout the brain, yielding effective gains in SNR in the entire brain compared to the 32Rx coil. Task-based FMRI data with 12-fold 2D (slice and phase-encode) acceleration yielded excellent quality functional maps with the 64Rx coil but was significantly beyond the capabilities of the 32Rx coil. CONCLUSION The results confirm the expectations from modeling studies and demonstrate that whole-brain studies with up to 16-fold, 2D acceleration would be feasible with the 64Rx coil.
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Affiliation(s)
- Kamil Uğurbil
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, Minnesota
| | - Edward Auerbach
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, Minnesota
| | - Steen Moeller
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, Minnesota
| | - Andrea Grant
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, Minnesota
| | - Xiaoping Wu
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, Minnesota
| | | | - Cheryl Olman
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, Minnesota
| | - Lance DelaBarre
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, Minnesota
| | | | - Jerahmie Radder
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, Minnesota
| | - Russell Lagore
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, Minnesota
| | - Gregor Adriany
- Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, Minnesota
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48
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Avdievich NI, Giapitzakis IA, Bause J, Shajan G, Scheffler K, Henning A. Double-row 18-loop transceive-32-loop receive tight-fit array provides for whole-brain coverage, high transmit performance, and SNR improvement near the brain center at 9.4T. Magn Reson Med 2018; 81:3392-3405. [PMID: 30506725 DOI: 10.1002/mrm.27602] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/12/2018] [Accepted: 10/19/2018] [Indexed: 11/06/2022]
Abstract
PURPOSE To improve the transmit (Tx) and receive (Rx) performance of a human head array and provide whole-brain coverage at 9.4T, a novel 32-element array design was developed, constructed, and tested. METHODS The array consists of 18 transceiver (TxRx) surface loops and 14 Rx-only vertical loops all placed in a single layer. The new design combines benefits of both TxRx and transmit-only-receive-only (ToRo) designs. The general idea of the design is that the total number of array elements (both TxRx and Rx) should not exceed the number of required Rx elements. First, the necessary number of TxRx loops is placed around the object tightly to optimize the Tx performance. The rest of the elements are loops, which are used only for reception. We also compared the performance of the new array with that of a state-of-the-art ToRo array consisting of 16 Tx-only loops and 31 Rx-only loops. RESULTS The new array provides whole-brain coverage, ~1.5 times greater Tx efficiency and 1.3 times higher SNR near the brain center as compared to the ToRo array, while the latter delivers higher (up to 1.5 times) peripheral SNR. CONCLUSION In general, the new approach of constructing a single-layer array consisting of both TxRx- and Rx-only elements simplifies the array construction by minimizing the total number of elements and makes the entire design more robust and, therefore, safe. Overall, our work provides a recipe for a Tx- and Rx-efficient head array coil suitable for parallel transmission and reception as well as whole-brain imaging at UHF.
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Affiliation(s)
- Nikolai I Avdievich
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Ioannis-Angelos Giapitzakis
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Graduate School of Neural and Behavioral Sciences, Tübingen, Germany
| | - Jonas Bause
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Graduate School of Neural and Behavioral Sciences, Tübingen, Germany
| | - Gunamony Shajan
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Klaus Scheffler
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Department for Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany
| | - Anke Henning
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
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49
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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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50
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Hendriks AD, Luijten PR, Klomp DWJ, Petridou N. Potential acceleration performance of a 256-channel whole-brain receive array at 7 T. Magn Reson Med 2018; 81:1659-1670. [PMID: 30257049 PMCID: PMC6585755 DOI: 10.1002/mrm.27519] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 08/09/2018] [Accepted: 08/11/2018] [Indexed: 11/21/2022]
Abstract
Purpose Assess the potential gain in acceleration performance of a 256‐channel versus 32‐channel receive coil array at 7 T in combination with a 2D CAIPIRINHA sequence for 3D data sets. Methods A 256‐channel receive setup was simulated by placing 2 small 16‐channel high‐density receive arrays at 2 × 8 different locations on the head of healthy participants. Multiple consecutive measurements were performed and coil sensitivity maps were combined to form a complete 256‐channel data set. This setup was compared with a standard 32‐channel head coil, in terms of SNR, noise correlation, and acceleration performance (g‐factor). Results In the periphery of the brain, the receive SNR was on average a factor 1.5 higher (ranging up to a factor 2.7 higher) than the 32‐channel coil; in the center of the brain the SNR was comparable or lower, depending on the size of the region of interest, with a factor 1.0 on average (ranging from 0.7 up to a factor of 1.6). The average noise correlation between coil elements was 3% for the 256‐channel coil, and 5% for the 32‐channel coil. At acceptable g‐factors (< 2), the achievable acceleration factor using SENSE and 2D CAIPIRINHA was 24 and 28, respectively, versus 9 and 12 for the 32‐channel coil. Conclusion The receive performance of the simulated 256 channel array was better than the 32‐channel reference. Combined with 2D CAIPIRINHA, a peak acceleration factor of 28 was assessed, showing great potential for high‐density receive arrays.
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Affiliation(s)
- Arjan D Hendriks
- Department of Radiology, Imaging Division, University Medical Center Utrecht, Utrecht, Netherlands
| | - Peter R Luijten
- Department of Radiology, Imaging Division, University Medical Center Utrecht, Utrecht, Netherlands
| | - Dennis W J Klomp
- Department of Radiology, Imaging Division, University Medical Center Utrecht, Utrecht, Netherlands
| | - Natalia Petridou
- Department of Radiology, Imaging Division, University Medical Center Utrecht, Utrecht, Netherlands
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