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Shang Y, Simegn GL, Gillen K, Yang HJ, Han H. Advancements in MR hardware systems and magnetic field control: B 0 shimming, RF coils, and gradient techniques for enhancing magnetic resonance imaging and spectroscopy. PSYCHORADIOLOGY 2024; 4:kkae013. [PMID: 39258223 PMCID: PMC11384915 DOI: 10.1093/psyrad/kkae013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 07/02/2024] [Accepted: 08/12/2024] [Indexed: 09/12/2024]
Abstract
High magnetic field homogeneity is critical for magnetic resonance imaging (MRI), functional MRI, and magnetic resonance spectroscopy (MRS) applications. B0 inhomogeneity during MR scans is a long-standing problem resulting from magnet imperfections and site conditions, with the main issue being the inhomogeneity across the human body caused by differences in magnetic susceptibilities between tissues, resulting in signal loss, image distortion, and poor spectral resolution. Through a combination of passive and active shim techniques, as well as technological advances employing multi-coil techniques, optimal coil design, motion tracking, and real-time modifications, improved field homogeneity and image quality have been achieved in MRI/MRS. The integration of RF and shim coils brings a high shim efficiency due to the proximity of participants. This technique will potentially be applied to high-density RF coils with a high-density shim array for improved B0 homogeneity. Simultaneous shimming and image encoding can be achieved using multi-coil array, which also enables the development of novel encoding methods using advanced magnetic field control. Field monitoring enables the capture and real-time compensation for dynamic field perturbance beyond the static background inhomogeneity. These advancements have the potential to better use the scanner performance to enhance diagnostic capabilities and broaden applications of MRI/MRS in a variety of clinical and research settings. The purpose of this paper is to provide an overview of the latest advances in B0 magnetic field shimming and magnetic field control techniques as well as MR hardware, and to emphasize their significance and potential impact on improving the data quality of MRI/MRS.
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Affiliation(s)
- Yun Shang
- Department of Radiology, Weill Medical College of Cornell University, New York, NY 10065, United States
| | - Gizeaddis Lamesgin Simegn
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205, United States
| | - Kelly Gillen
- Department of Radiology, Weill Medical College of Cornell University, New York, NY 10065, United States
| | - Hsin-Jung Yang
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Biomedical Imaging Research Institute, Los Angeles, CA 90048, United States
| | - Hui Han
- Department of Radiology, Weill Medical College of Cornell University, New York, NY 10065, United States
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Overson DK, Darnell D, Robb F, Song AW, Truong TK. Flexible multi-purpose integrated RF/shim coil array for MRI and localized B 0 shimming. Magn Reson Med 2024; 91:842-849. [PMID: 37849021 PMCID: PMC10842526 DOI: 10.1002/mrm.29891] [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: 05/02/2023] [Revised: 09/22/2023] [Accepted: 09/27/2023] [Indexed: 10/19/2023]
Abstract
PURPOSE To develop a flexible, lightweight, and multi-purpose integrated parallel reception, excitation, and shimming (iPRES) coil array that can conform to the subject's anatomy and perform MR imaging and localized B0 shimming in different anatomical regions with a high SNR, shimming performance, ease of positioning, and subject comfort. METHODS A four-channel flexible iPRES coil array was constructed by enabling RF and direct currents to flow on the same flexible coil elements for imaging and shimming, respectively. Shimming experiments were performed with the coil array wrapped around the knee or neck of healthy subjects to demonstrate its high shimming performance and versatility. Additionally, its SNR and shimming performance in the knee were compared to those obtained with the coil array wrapped around a larger rigid tube designed to fit most knee sizes. RESULTS Shimming with the coil array wrapped around the knee or neck resulted in an average reduction in B0 RMSE of 50.1% and 40.5% relative to first-order and second-order spherical harmonic shimming, respectively, and substantially reduced distortions in DWI images. In contrast, shimming the knee with the coil array wrapped around the rigid tube only provided a 29.6% reduction in B0 RMSE, whereas the SNR was reduced by 58.7%. CONCLUSION The flexible iPRES coil array can conform to different anatomical regions and perform imaging and localized B0 shimming with a higher SNR, shimming performance, ease of positioning, and comfort compared to a rigid iPRES coil array, which should be valuable for many applications throughout the human body.
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Affiliation(s)
- Devon Karl Overson
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
- Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Dean Darnell
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
- Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | | | - Allen W Song
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
- Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Trong-Kha Truong
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
- Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
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Sun K, Chen Z, Dan G, Luo Q, Yan L, Liu F, Zhou XJ. Three-dimensional echo-shifted EPI with simultaneous blip-up and blip-down acquisitions for correcting geometric distortion. Magn Reson Med 2023; 90:2375-2387. [PMID: 37667533 PMCID: PMC10903279 DOI: 10.1002/mrm.29828] [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: 01/18/2023] [Revised: 07/08/2023] [Accepted: 07/25/2023] [Indexed: 09/06/2023]
Abstract
PURPOSE EPI with blip-up/down acquisition (BUDA) can provide high-quality images with minimal distortions by using two readout trains with opposing phase-encoding gradients. Because of the need for two separate acquisitions, BUDA doubles the scan time and degrades the temporal resolution when compared to single-shot EPI, presenting a major challenge for many applications, particularly fMRI. This study aims at overcoming this challenge by developing an echo-shifted EPI BUDA (esEPI-BUDA) technique to acquire both blip-up and blip-down datasets in a single shot. METHODS A 3D esEPI-BUDA pulse sequence was designed by using an echo-shifting strategy to produce two EPI readout trains. These readout trains produced a pair of k-space datasets whose k-space trajectories were interleaved with opposite phase-encoding gradient directions. The two k-space datasets were separately reconstructed using a 3D SENSE algorithm, from which time-resolved B0 -field maps were derived using TOPUP in FSL and then input into a forward model of joint parallel imaging reconstruction to correct for geometric distortion. In addition, Hankel structured low-rank constraint was incorporated into the reconstruction framework to improve image quality by mitigating the phase errors between the two interleaved k-space datasets. RESULTS The 3D esEPI-BUDA technique was demonstrated in a phantom and an fMRI study on healthy human subjects. Geometric distortions were effectively corrected in both phantom and human brain images. In the fMRI study, the visual activation volumes and their BOLD responses were comparable to those from conventional 3D echo-planar images. CONCLUSION The improved imaging efficiency and dynamic distortion correction capability afforded by 3D esEPI-BUDA are expected to benefit many EPI applications.
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Affiliation(s)
- Kaibao Sun
- Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, IL, United States
| | - Zhifeng Chen
- USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Department of Data Science and AI, Faculty of IT, Monash University, Clayton, VIC, Australia
| | - Guangyu Dan
- Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, IL, United States
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Qingfei Luo
- Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, IL, United States
| | - Lirong Yan
- USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Feng Liu
- School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, Queensland, Australia
| | - Xiaohong Joe Zhou
- Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, IL, United States
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
- Departments of Radiology and Neurosurgery, University of Illinois at Chicago, Chicago, IL, United States
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Theilenberg S, Shang Y, Ghazouani J, Kumaragamage C, Nixon TW, McIntyre S, Vaughan JT, Parkinson B, Garwood M, de Graaf RA, Juchem C. Design and realization of a multi-coil array for B 0 field control in a compact 1.5T head-only MRI scanner. Magn Reson Med 2023; 90:1228-1241. [PMID: 37145035 PMCID: PMC10330274 DOI: 10.1002/mrm.29692] [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: 12/17/2022] [Revised: 03/27/2023] [Accepted: 04/14/2023] [Indexed: 05/06/2023]
Abstract
PURPOSE To design and implement a multi-coil (MC) array for B0 field generation for image encoding and simultaneous advanced shimming in a novel 1.5T head-only MRI scanner. METHODS A 31-channel MC array was designed following the unique constraints of this scanner design: The vertically oriented magnet is very short, stopping shortly above the shoulders of a sitting subject, and includes a window for the subject to see through. Key characteristics of the MC hardware, the B0 field generation capabilities, and thermal behavior, were optimized in simulations prior to its construction. The unit was characterized via bench testing. B0 field generation capabilities were validated on a human 4T MR scanner by analysis of experimental B0 fields and by comparing images for several MRI sequences acquired with the MC array to those acquired with the system's linear gradients. RESULTS The MC system was designed to produce a multitude of linear and nonlinear magnetic fields including linear gradients of up to 10 kHz/cm (23.5 mT/m) with MC currents of 5 A per channel. With water cooling it can be driven with a duty cycle of up to 74% and ramp times of 500 μs. MR imaging experiments encoded with the developed multi-coil hardware were largely artifact-free; residual imperfections were predictable, and correctable. CONCLUSION The presented compact multi-coil array is capable of generating image encoding fields with amplitudes and quality comparable to clinical systems at very high duty cycles, while additionally enabling high-order B0 shimming capabilities and the potential for nonlinear encoding fields.
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Affiliation(s)
- Sebastian Theilenberg
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
| | - Yun Shang
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
| | - Jalal Ghazouani
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
| | - Chathura Kumaragamage
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, United States
| | - Terence W. Nixon
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, United States
| | - Scott McIntyre
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, United States
| | - J. Thomas Vaughan
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
- Department of Radiology, Columbia University Medical Center, New York, NY, United States
| | - Ben Parkinson
- Robinson Research Institute, Victoria University of Wellington, Wellington, New Zealand
| | - Mike Garwood
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States
| | - Robin A. de Graaf
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, United States
| | - Christoph Juchem
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
- Department of Radiology, Columbia University Medical Center, New York, NY, United States
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Haskell MW, Nielsen JF, Noll DC. Off-resonance artifact correction for MRI: A review. NMR IN BIOMEDICINE 2023; 36:e4867. [PMID: 36326709 PMCID: PMC10284460 DOI: 10.1002/nbm.4867] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 09/25/2022] [Accepted: 11/01/2022] [Indexed: 06/06/2023]
Abstract
In magnetic resonance imaging (MRI), inhomogeneity in the main magnetic field used for imaging, referred to as off-resonance, can lead to image artifacts ranging from mild to severe depending on the application. Off-resonance artifacts, such as signal loss, geometric distortions, and blurring, can compromise the clinical and scientific utility of MR images. In this review, we describe sources of off-resonance in MRI, how off-resonance affects images, and strategies to prevent and correct for off-resonance. Given recent advances and the great potential of low-field and/or portable MRI, we also highlight the advantages and challenges of imaging at low field with respect to off-resonance.
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Affiliation(s)
- Melissa W Haskell
- Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, USA
- Hyperfine Research, Guilford, Connecticut, USA
| | | | - Douglas C Noll
- Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
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He H, Wei S, Wang H, Yang W. Analysis of coil element distribution and dimension for matrix gradient coils. MAGMA (NEW YORK, N.Y.) 2022; 35:967-980. [PMID: 35689695 DOI: 10.1007/s10334-022-01021-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 05/11/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
OBJECTIVE The goal of this work is to analyze the influence of the distributions and dimensions of the coil elements and to present a method for improving the performance of the matrix gradient coil. METHODS Three typical models (five structures in total) are presented, and a double-layer biplanar matrix gradient coil is used to install coil elements. Two metrics, namely, the role of coil elements and mutual inductance between coil elements, are proposed to assess the performance of coil systems. An optimization approach to design matrix gradient coils is introduced based on analyzing the distributions and dimensions of coil elements. The flexibility of the magnetic field generation of the designed coil structure is demonstrated by generating full third-order spherical harmonic fields and different oblique gradient fields. RESULTS Matrix gradient coils with suitable distributions are capable of generating target magnetic fields. The role of coil elements quantitatively illustrates that the coil elements have different impacts on generating magnetic fields. Increasing the coil element dimension within a certain range can reduce the mutual inductance between coil elements and improve the performance of the coil system. The designed novel double-layer biplanar matrix gradient coil achieves an acceptable performance in generating different magnetic fields. CONCLUSIONS The proposed metrics can provide theoretical support for designing matrix gradient coils and evaluating their performance. The role of coil elements contributes to analyzing the distributions of coil elements to decrease the number of coil elements and power amplifiers. The mutual inductance between coil elements can be a reference for designing the dimensions of coil elements.
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Affiliation(s)
- Hongyan He
- Institute of Electrical of Engineering, Chinese Academy of Sciences, Beijing, 100190, China
- Chinese Academy of Sciences, Beijing, 100049, China
- School of Information and Electrical Engineering, Hebei University of Engineering, Handan, 056038, China
| | - Shufeng Wei
- Institute of Electrical of Engineering, Chinese Academy of Sciences, Beijing, 100190, China
| | - Huixian Wang
- Institute of Electrical of Engineering, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wenhui Yang
- Institute of Electrical of Engineering, Chinese Academy of Sciences, Beijing, 100190, China.
- Chinese Academy of Sciences, Beijing, 100049, China.
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Chen Q, Luo C, Tie C, Cheng C, Zou C, Zhang X, Liu X, Zheng H, Li Y. A 5‐channel local B
0
shimming coil combined with a 3‐channel RF receiver coil for rat brain imaging at 3 T. Magn Reson Med 2022; 89:477-486. [DOI: 10.1002/mrm.29458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/22/2022] [Accepted: 08/22/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Qiaoyan Chen
- Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences Shenzhen China
- Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province Shenzhen China
| | - Chao Luo
- Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences Shenzhen China
- Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province Shenzhen China
| | - Changjun Tie
- Institute of Computing Technology, Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
- Peng Cheng Laboratory Shenzhen China
| | - Chuanli Cheng
- Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences Shenzhen China
- Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province Shenzhen China
| | - Chao Zou
- Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences Shenzhen China
- Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province Shenzhen China
| | - Xiaoliang Zhang
- Department of Biomedical Engineering State University of New York at Buffalo Buffalo New York USA
| | - Xin Liu
- Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences Shenzhen China
- Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province Shenzhen China
| | - Hairong Zheng
- Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences Shenzhen China
- Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province Shenzhen China
| | - Ye Li
- Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences Shenzhen China
- Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province Shenzhen China
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Cuthbertson JD, Truong TK, Stormont R, Robb F, Song AW, Darnell D. An iPRES-W Coil Array for Simultaneous Imaging and Wireless Localized B 0 Shimming of the Cervical Spinal Cord. Magn Reson Med 2022; 88:1002-1014. [PMID: 35468243 PMCID: PMC10445458 DOI: 10.1002/mrm.29257] [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: 01/07/2022] [Revised: 02/13/2022] [Accepted: 03/11/2022] [Indexed: 11/07/2022]
Abstract
PURPOSE To develop a wireless integrated parallel reception, excitation, and shimming (iPRES-W) coil array for simultaneous imaging and wireless localized B0 shimming, and to demonstrate its ability to correct for distortions in DTI of the spinal cord in vivo. METHODS A 4-channel coil array was modified to allow an RF current at the Larmor frequency and a direct current to flow on each coil element, enabling imaging and localized B0 shimming, respectively. One coil element was further modified to allow additional RF currents within a wireless communication band to flow on it to wirelessly control the direct currents for shimming, which were supplied from a battery pack within the scanner bore. The RF signals for imaging were transferred via conventional wired connections. Experiments were conducted to evaluate the RF, B0 shimming, and wireless performance of this coil design. RESULTS The coil modifications did not degrade the SNR. Wireless localized B0 shimming with the iPRES-W coil array substantially reduced the B0 RMSE (-57.5% on average) and DTI distortions in the spinal cord. The antenna radiation efficiency, antenna gain pattern, and battery power consumption of an iPRES-W coil measured in an anechoic chamber were minimally impacted by the introduction of a saline phantom representing tissue. CONCLUSION The iPRES-W coil array can perform imaging and wireless localized B0 shimming of the spinal cord with no SNR degradation, with minimal change in wireless performance and without any scanner modifications or additional antenna systems within the scanner bore.
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Affiliation(s)
- Jonathan D. Cuthbertson
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina
- Medical Physics Graduate Program, Duke University, Durham, North Carolina
| | - Trong-Kha Truong
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina
- Medical Physics Graduate Program, Duke University, Durham, North Carolina
| | | | | | - Allen W. Song
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina
- Medical Physics Graduate Program, Duke University, Durham, North Carolina
| | - Dean Darnell
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina
- Medical Physics Graduate Program, Duke University, Durham, North Carolina
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Boer VO, Pedersen JO, Arango N, Kuang I, Stockmann J, Petersen ET. Improving brain B0 shimming using an easy and accessible multi-coil shim array at ultra-high field. MAGNETIC RESONANCE MATERIALS IN PHYSICS, BIOLOGY AND MEDICINE 2022; 35:943-951. [PMID: 35511312 PMCID: PMC9596507 DOI: 10.1007/s10334-022-01014-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 03/16/2022] [Accepted: 04/11/2022] [Indexed: 12/03/2022]
Abstract
Object Improve shimming capabilities of ultra-high field systems, with addition of an accessible low-complexity B0 shim array for head MRI at 7 T. Materials and methods An eight channel B0 shim coil array was designed as a tradeoff between shimming improvement and construction complexity, to provide an easy to use shim array that can be employed with the standard 7 T head coil. The array was interfaced using an open-source eight-channel shim amplifier rack. Improvements in field homogeneity for whole-brain and slice-based shimming were compared to standard second-order shimming, and to more complex higher order dynamic shimming and shim arrays with 32 and 48 channels. Results The eight-channel shim array provided 12% improvement in whole brain static shimming and provided 33% improvement when using slice-based shimming. With this, the eight-channel array performed similar to third-order dynamic shimming (without the need for higher order eddy current compensation). More complex shim arrays with 32 and 48 channels performed better, but require a dedicated RF coil. Discussion The designed eight-channel shim array provides a low-complexity and low-cost approach for improving B0 field shimming on an ultra-high field system. In both static and dynamic shimming, it provides improved B0 homogeneity over standard shimming.
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Affiliation(s)
- Vincent Oltman Boer
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, section 714, Kettegård Allé 30, 2650, Hvidovre, Hvidovre, Denmark.
| | | | - Nick Arango
- Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Irene Kuang
- Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jason Stockmann
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Esben Thade Petersen
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, section 714, Kettegård Allé 30, 2650, Hvidovre, Hvidovre, Denmark
- Department of Health Technology, Centre for Magnetic Resonance, Technical University of Denmark, Kgs. Lyngby, Denmark
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Darnell D, Truong TK, Song AW. Recent Advances in Radio-Frequency Coil Technologies: Flexible, Wireless, and Integrated Coil Arrays. J Magn Reson Imaging 2022; 55:1026-1042. [PMID: 34324753 PMCID: PMC10494287 DOI: 10.1002/jmri.27865] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/19/2021] [Accepted: 07/19/2021] [Indexed: 12/25/2022] Open
Abstract
Radio-frequency (RF) coils are to magnetic resonance imaging (MRI) scanners what eyes are to the human body. Because of their critical importance, there have been constant innovations driving the rapid development of RF coil technologies. Over the past four decades, the breadth and depth of the RF coil technology evolution have far exceeded the space allowed for this review article. However, these past developments have laid the very foundation on which some of the recent technical breakthroughs are built upon. Here, we narrow our focus on some of the most recent RF coil advances, specifically, on flexible, wireless, and integrated coil arrays. To provide a detailed review, we discuss the theoretical underpinnings, experimental implementations, promising results, as well as future outlooks covering these exciting topics. These recent innovations have greatly improved patient comfort and ease of scan, while also increasing the signal-to-noise ratio, image resolution, temporal throughput, and diagnostic and treatment accuracy. Together with advances in other MRI subfields, they will undoubtedly continue to drive the field forward and lead us to an ever more exciting future. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Dean Darnell
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
| | - Trong-Kha Truong
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
| | - Allen W. Song
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
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11
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Stockmann JP, Arango NS, Witzel T, Mareyam A, Sappo C, Zhou J, Jenkins L, Craven-Brightman L, Milshteyn E, Davids M, Hoge WS, Sliwiak M, Nasr S, Keil B, Adalsteinsson E, Guerin B, White JK, Setsompop K, Polimeni JR, Wald LL. A 31-channel integrated "AC/DC" B 0 shim and radiofrequency receive array coil for improved 7T MRI. Magn Reson Med 2022; 87:1074-1092. [PMID: 34632626 PMCID: PMC9899096 DOI: 10.1002/mrm.29022] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 08/30/2021] [Accepted: 09/04/2021] [Indexed: 02/06/2023]
Abstract
PURPOSE To test an integrated "AC/DC" array approach at 7T, where B0 inhomogeneity poses an obstacle for functional imaging, diffusion-weighted MRI, MR spectroscopy, and other applications. METHODS A close-fitting 7T 31-channel (31-ch) brain array was constructed and tested using combined Rx and ΔB0 shim channels driven by a set of rapidly switchable current amplifiers. The coil was compared to a shape-matched 31-ch reference receive-only array for RF safety, signal-to-noise ratio (SNR), and inter-element noise correlation. We characterize the coil array's ability to provide global and dynamic (slice-optimized) shimming using ΔB0 field maps and echo planar imaging (EPI) acquisitions. RESULTS The SNR and average noise correlation were similar to the 31-ch reference array. Global and slice-optimized shimming provide 11% and 40% improvements respectively compared to baseline second-order spherical harmonic shimming. Birdcage transmit coil efficiency was similar for the reference and AC/DC array setups. CONCLUSION Adding ΔB0 shim capability to a 31-ch 7T receive array can significantly boost 7T brain B0 homogeneity without sacrificing the array's rdiofrequency performance, potentially improving ultra-high field neuroimaging applications that are vulnerable to off-resonance effects.
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Affiliation(s)
- Jason P Stockmann
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Nicolas S Arango
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Thomas Witzel
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Azma Mareyam
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Charlotte Sappo
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Jiazheng Zhou
- Max-Planck Institute for Biological Cybernetics, High-Field Magnetic Resonance, Tübingen, Germany
| | - Lucas Jenkins
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Lincoln Craven-Brightman
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Eugene Milshteyn
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Mathias Davids
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - W Scott Hoge
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
- Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Monika Sliwiak
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Shahin Nasr
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Boris Keil
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Elfar Adalsteinsson
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Bastien Guerin
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Jacob K White
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Kawin Setsompop
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Jonathan R Polimeni
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Lawrence L Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
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12
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Willey D, Darnell D, Song AW, Truong TK. Application of an integrated radio-frequency/shim coil technology for signal recovery in fMRI. Magn Reson Med 2021; 86:3067-3081. [PMID: 34288086 DOI: 10.1002/mrm.28925] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 05/26/2021] [Accepted: 06/23/2021] [Indexed: 01/07/2023]
Abstract
PURPOSE Gradient-echo echo-planar imaging (EPI), which is typically used for blood oxygenation level-dependent (BOLD) functional MRI (fMRI), suffers from distortions and signal loss caused by localized B0 inhomogeneities. Such artifacts cannot be effectively corrected for with the low-order spherical harmonic (SH) shim coils available on most scanners. The integrated parallel reception, excitation, and shimming (iPRES) coil technology allows radiofrequency (RF) and direct currents to flow on each coil element, enabling imaging and localized B0 shimming with one coil array. iPRES was previously used to correct for distortions in spin-echo EPI and is further developed here to also recover signal loss in gradient-echo EPI. METHODS The cost function in the shim optimization, which typically uses a single term representing the B0 inhomogeneity, was modified to include a second term representing the signal loss, with an adjustable weight to optimize the trade-off between distortion correction and signal recovery. Simulations and experiments were performed to investigate the shimming performance. RESULTS Slice-optimized shimming with iPRES and the proposed cost function substantially reduced the signal loss in the inferior frontal and temporal brain regions compared to shimming with iPRES and the original cost function or 2nd -order SH shimming with either cost function. In breath-holding fMRI experiments, the ΔB0 and signal loss root-mean-square errors decreased by -34.3% and -56.2%, whereas the EPI signal intensity and number of activated voxels increased by 60.3% and 174.0% in the inferior frontal brain region. CONCLUSION iPRES can recover signal loss in gradient-echo EPI, which is expected to improve BOLD fMRI studies in brain regions suffering from signal loss.
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Affiliation(s)
- Devin Willey
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Dean Darnell
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Allen W Song
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Trong-Kha Truong
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
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13
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Juchem C, Theilenberg S, Kumaragamage C, Mullen M, DelaBarre L, Adriany G, Brown PB, McIntyre S, Nixon TW, Garwood M, de Graaf RA. Dynamic multicoil technique (DYNAMITE) MRI on human brain. Magn Reson Med 2020; 84:2953-2963. [PMID: 32544274 DOI: 10.1002/mrm.28323] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/23/2020] [Accepted: 04/23/2020] [Indexed: 12/14/2022]
Abstract
PURPOSE Spatial encoding for MRI is generally based on linear x, y, and z magnetic field gradients generated by a set of dedicated gradient coils. We recently introduced the dynamic multicoil technique (DYNAMITE) for B0 field control and demonstrated DYNAMITE MRI in a preclinical MR environment. In this study, we report the first realization of DYNAMITE MRI of the in vivo human head. METHODS Gradient fields for DYNAMITE MRI were generated with a 28-channel multicoil hardware arranged in 4 rows of 7 coils on a cylindrical surface (length 359 mm, diameter 344 mm, maximum 5 A per coil). DYNAMITE MRIs of a resolution phantom and in vivo human heads were acquired with multislice gradient-echo, multislice spin-echo, and 3D gradient-echo sequences. The resultant image fidelity was compared to that obtained with conventional gradient coil technology. RESULTS DYNAMITE field control enabled the realization of all imaging sequences with average gradient errors ≤ 1%. DYNAMITE MRI provided image quality and sensitivity comparable to conventional gradient technology without any obvious artifacts. Some minor geometric deformations were noticed primarily in the image periphery as the result of regional field imperfections. The imperfections can be readily approximated theoretically through numerical integration of the Biot-Savart law and removed through image distortion correction. CONCLUSION The first realization of DYNAMITE MRI of the in vivo human head has been presented. The obtained image fidelity is comparable to MRI with conventional gradient coils, paving the way for full-fledged DYNAMITE MRI and B0 shim systems for human applications.
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Affiliation(s)
- Christoph Juchem
- Department of Biomedical Engineering, Columbia University, New York, New York, USA.,Department of Radiology, Columbia University, New York, New York, USA
| | | | - Chathura Kumaragamage
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Michael Mullen
- Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Lance DelaBarre
- Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Gregor Adriany
- Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Peter B Brown
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Scott McIntyre
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Terence W Nixon
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Michael Garwood
- Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Robin A de Graaf
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
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14
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Zhou J, Stockmann JP, Arango N, Witzel T, Scheffler K, Wald LL, Lin FH. An orthogonal shim coil for 3T brain imaging. Magn Reson Med 2020; 83:1499-1511. [PMID: 31631391 PMCID: PMC7360482 DOI: 10.1002/mrm.28010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 09/03/2019] [Accepted: 09/03/2019] [Indexed: 01/07/2023]
Abstract
PURPOSE We designed and implemented an orthogonal shim array consisting of shim coils with their planes perpendicular to the planes of neighboring RF coils. This shim coil improves the magnetic field homogeneity by minimizing the interference to RF coils. METHODS Using realistic off-resonance maps of the human brain, we first evaluated the performance of shim coils in different orientations. Based on simulations, we developed a 7-channel orthogonal shim array, whose coil plan was perpendicular to neighboring RF coils, at the forehead. A programmable open-source current driver supplied shim currents. RESULTS The 7-channel orthogonal shim array caused only marginal SNR loss to the integrated 32-channel RF-shim array. The 7-channel orthogonal shim array itself improved the magnetic field homogeneity by 30% in slice-optimized shimming, comparable to the baseline shimming offered by the scanner's 2nd order spherical harmonic shimming. CONCLUSION Orthogonal shim coils can improve the field homogeneity while maintaining high image SNR.
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Affiliation(s)
- Jiazheng Zhou
- High-Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen. Germany
- Graduate Training Center of Neuroscience, IMPRS, University of Tübingen, Tübingen, Germany
| | - Jason P Stockmann
- A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Nicolas Arango
- A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
- Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Thomas Witzel
- A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Klaus Scheffler
- High-Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen. Germany
- Biomedical Magnetic Resonance, University Hospital Tübingen (UKT), Tübingen, Germany
| | - Lawrence L Wald
- A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Fa-Hsuan Lin
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Canada
- Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland
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15
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Aghaeifar A, Bause J, Leks E, Grodd W, Scheffler K. Dynamic B
0
shimming of the motor cortex and cerebellum with a multicoil shim setup for BOLD fMRI at 9.4T. Magn Reson Med 2019; 83:1730-1740. [DOI: 10.1002/mrm.28044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 09/20/2019] [Accepted: 09/25/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Ali Aghaeifar
- High‐Field Magnetic Resonance Center Max Planck Institute for Biological Cybernetics Tuebingen Germany
- IMPRS for Cognitive and Systems Neuroscience University of Tuebingen Tuebingen Germany
| | - Jonas Bause
- High‐Field Magnetic Resonance Center Max Planck Institute for Biological Cybernetics Tuebingen Germany
- IMPRS for Cognitive and Systems Neuroscience University of Tuebingen Tuebingen Germany
- Department of Biomedical Magnetic Resonance University of Tuebingen Tuebingen Germany
| | - Edyta Leks
- High‐Field Magnetic Resonance Center Max Planck Institute for Biological Cybernetics Tuebingen Germany
- IMPRS for Cognitive and Systems Neuroscience University of Tuebingen Tuebingen Germany
- Department of Biomedical Magnetic Resonance University of Tuebingen Tuebingen Germany
| | - Wolfgang Grodd
- High‐Field Magnetic Resonance Center Max Planck Institute for Biological Cybernetics Tuebingen Germany
| | - Klaus Scheffler
- High‐Field Magnetic Resonance Center Max Planck Institute for Biological Cybernetics Tuebingen Germany
- Department of Biomedical Magnetic Resonance University of Tuebingen Tuebingen Germany
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16
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Sharma U, Jagannathan NR. In vivo MR spectroscopy for breast cancer diagnosis. BJR Open 2019; 1:20180040. [PMID: 33178927 PMCID: PMC7592438 DOI: 10.1259/bjro.20180040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 05/02/2019] [Accepted: 06/14/2019] [Indexed: 12/23/2022] Open
Abstract
Breast cancer is a significant health concern in females, worldwide. In vivo proton (1H) MR spectroscopy (MRS) has evolved as a non-invasive tool for diagnosis and for biochemical characterization of breast cancer. Water-to-fat ratio, fat and water fractions and choline containing compounds (tCho) have been identified as diagnostic biomarkers of malignancy. Detection of tCho in normal breast tissue of volunteers and in lactating females limits the use of tCho as a diagnostic marker. Technological developments like high-field scanners, multi channel coils, pulse sequences with water and fat suppression facilitated easy detection of tCho. Also, quantification of tCho and its cut-off for objective assessment of malignancy have been reported. Meta-analysis of in vivo 1H MRS studies have documented the pooled sensitivities and the specificities in the range of 71-74% and 78-88%, respectively. Inclusion of MRS has been shown to enhance the diagnostic specificity of MRI, however, detection of tCho in small sized lesions (≤1 cm) is challenging even at high magnetic fields. Potential of MRS in monitoring the effect of chemotherapy in breast cancer has also been reported. This review briefly presents the potential clinical role of in vivo 1H MRS in the diagnosis of breast cancer, its current status and future developments.
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Affiliation(s)
- Uma Sharma
- Department of NMR & MRI Facility, All India Institute of Medical Sciences , New Delhi, India
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17
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Fardanesh R, Marino MA, Avendano D, Leithner D, Pinker K, Thakur SB. Proton MR spectroscopy in the breast: Technical innovations and clinical applications. J Magn Reson Imaging 2019; 50:1033-1046. [PMID: 30848037 DOI: 10.1002/jmri.26700] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 02/20/2019] [Indexed: 01/27/2023] Open
Abstract
Proton magnetic resonance spectroscopy (MRS) is a promising noninvasive diagnostic technique for investigation of breast cancer metabolism. Spectroscopic imaging data may be obtained following contrast-enhanced MRI by applying the point-resolved spectroscopy sequence (PRESS) or the stimulated echo acquisition mode (STEAM) sequence from the MR voxel encompassing the breast lesion. Total choline signal (tCho) measured in vivo using either a qualitative or quantitative approach has been used as a diagnostic test in the workup of malignant breast lesions. In addition to tCho metabolites, other relevant metabolites, including multiple lipids, can be detected and monitored. MRS has been heavily investigated as an adjunct to morphologic and dynamic MRI to improve diagnostic accuracy in breast cancer, obviating unnecessary benign biopsies. Besides its use in the staging of breast cancer, other promising applications have been recently investigated, including the assessment of treatment response and therapy monitoring. This review provides guidance on spectroscopic acquisition and quantification methods and highlights current and evolving clinical applications of proton MRS. Level of Evidence 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019.
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Affiliation(s)
- Reza Fardanesh
- Department of Radiology, Breast Imaging Service, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Maria Adele Marino
- Department of Radiology, Breast Imaging Service, Memorial Sloan Kettering Cancer Center, New York, New York, USA.,Department of Biomedical Sciences and Morphologic and Functional Imaging, Policlinico Universitario G. Martino, University of Messina, Italy
| | - Daly Avendano
- Department of Radiology, Breast Imaging Service, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Doris Leithner
- Department of Radiology, Breast Imaging Service, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Katja Pinker
- Department of Radiology, Breast Imaging Service, Memorial Sloan Kettering Cancer Center, New York, New York, USA.,Department of Biomedical Imaging and Image-guided Therapy, Division of Molecular and Gender Imaging, Medical University of Vienna, Vienna, Austria
| | - Sunitha B Thakur
- Department of Radiology, Breast Imaging Service, Memorial Sloan Kettering Cancer Center, New York, New York, USA.,Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA
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18
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Darnell D, Cuthbertson J, Robb F, Song AW, Truong TK. Integrated radio-frequency/wireless coil design for simultaneous MR image acquisition and wireless communication. Magn Reson Med 2018; 81:2176-2183. [PMID: 30277273 DOI: 10.1002/mrm.27513] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/27/2018] [Accepted: 08/08/2018] [Indexed: 01/07/2023]
Abstract
PURPOSE An innovative radio-frequency (RF) coil design that allows RF currents both at the Larmor frequency and in a wireless communication band to flow on the same coil is proposed to enable simultaneous MRI signal reception and wireless data transfer, thereby minimizing the number of wired connections in the scanner without requiring any modifications or additional hardware within the scanner bore. METHODS As a first application, the proposed integrated RF/wireless coil design was further combined with an integrated RF/shim coil design to perform not only MR image acquisition and wireless data transfer, but also localized B0 shimming with a single coil. Proof-of-concept phantom experiments were conducted with such a coil to demonstrate its ability to simultaneously perform these three functions, while maintaining the RF performance, wireless data integrity, and B0 shimming performance. RESULTS Performing wirelessly controlled shimming of localized B0 inhomogeneities with the coil substantially reduced the B0 root-mean-square error (>70%) and geometric distortions in echo-planar images without degrading the image quality, signal-to-noise ratio (<1.7%), or wireless data throughput (maximum variance = 0.04 Mbps) of the coil. CONCLUSIONS The RF/wireless coil design can provide a solution for wireless data transfer that can be easily integrated into existing MRI scanners for a variety of applications.
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Affiliation(s)
- Dean Darnell
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina
| | - Jonathan Cuthbertson
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina
- Medical Physics Graduate Program, Duke University, Durham, North Carolina
| | | | - Allen W Song
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina
- Medical Physics Graduate Program, Duke University, Durham, North Carolina
| | - Trong-Kha Truong
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina
- Medical Physics Graduate Program, Duke University, Durham, North Carolina
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19
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Stockmann JP, Wald LL. In vivo B 0 field shimming methods for MRI at 7T. Neuroimage 2018; 168:71-87. [PMID: 28602943 PMCID: PMC5760477 DOI: 10.1016/j.neuroimage.2017.06.013] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 05/19/2017] [Accepted: 06/06/2017] [Indexed: 01/12/2023] Open
Abstract
Functional MRI (fMRI) at 7T and above provides improved Signal-to-Noise Ratio and Contrast-to-Noise Ratio compared to 3T acquisitions. In addition to the beneficial effects on spin polarization and magnetization of deoxyhemoglobin, the increased applied field also further magnetizes air and tissue. While the magnets themselves typically provide a static B0 field with sufficient spatial homogeneity, the diamagnetism of tissue and the paramagnetism of air causes local field deviations inside the human head. These spatially-varying field offsets (ΔB0) cause image artifacts, especially in single shot EPI, including geometric distortion, signal dropout, and blurring. These effects are particularly strong near air-tissue interfaces such as the frontal sinus, and ear canals. Furthermore, if the field offsets are dynamically modulated through physiological processes such as respiration or motion, then the effect on the image time-series can be even more problematic. While post-processing methods have been developed to mitigate these effects, the ideal solution would be to reduce the ΔB0 variations at their source. Typically 7T scanners contain 2nd and some 3rd order spherical harmonic shim coil terms to cancel static ΔB0 variations of low spatial order. In this article, we will motivate the need for improved, higher-order compensation for B0 inhomogeneity and potentially add dynamic control of these fields. We discuss and compare several promising hardware approaches for static and dynamic B0 shimming using either higher-order spherical harmonic shim coils or multi-coil shim arrays as well as passive shimming approaches, and active variants such and adaptive current networks.
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Affiliation(s)
- Jason P Stockmann
- A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, United States.
| | - Lawrence L Wald
- A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, United States; Harvard Medical School, Boston, MA, United States
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20
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Lee BY, Zhu XH, Woo MK, Adriany G, Schillak S, Chen W. Interleaved 31 P MRS imaging of human frontal and occipital lobes using dual RF coils in combination with single-channel transmitter-receiver and dynamic B 0 shimming. NMR IN BIOMEDICINE 2018; 31:10.1002/nbm.3842. [PMID: 29073724 PMCID: PMC5736151 DOI: 10.1002/nbm.3842] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 09/10/2017] [Accepted: 09/14/2017] [Indexed: 06/01/2023]
Abstract
In vivo 31 P magnetic resonance spectroscopy (MRS) provides a unique tool for the non-invasive study of brain energy metabolism and mitochondrial function. The assessment of bioenergetic impairment in different brain regions is essential to understand the pathophysiology and progression of human brain diseases. This article presents a simple and effective approach which allows the interleaved measurement of 31 P spectra and imaging from two distinct human brain regions of interest with dynamic B0 shimming capability. A transistor-transistor logic controller was employed to actively switch the single-channel X-nuclear radiofrequency (RF) transmitter-receiver between two 31 P RF surface coils, enabling the interleaved acquisition of two 31 P free induction decays (FIDs) from human occipital and frontal lobes within the same repetition time. Linear gradients were incorporated into the RF pulse sequence to perform the first-order dynamic shimming to further improve spectral resolution. The overall results demonstrate that the approach provides a cost-effective and time-efficient solution for reliable 31 P MRS measurement of cerebral phosphate metabolites and adenosine triphosphate (ATP) metabolic fluxes from two human brain regions with high detection sensitivity and spectral quality at 7 T. The same design concept can be extended to acquire multiple spectra from more than two brain regions or can be employed for other magnetic resonance applications beyond the 31 P spin.
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Affiliation(s)
- Byeong-Yeul Lee
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Xiao-Hong Zhu
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Myung Kyun Woo
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Gregor Adriany
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN 55455
| | | | - Wei Chen
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN 55455
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21
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Darnell D, Ma Y, Wang H, Robb F, Song AW, Truong TK. Adaptive integrated parallel reception, excitation, and shimming (iPRES-A) with microelectromechanical systems switches. Magn Reson Med 2017; 80:371-379. [PMID: 29148102 DOI: 10.1002/mrm.27007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 09/20/2017] [Accepted: 10/23/2017] [Indexed: 11/09/2022]
Abstract
PURPOSE Integrated parallel reception, excitation, and shimming coil arrays with N shim loops per radio-frequency (RF) coil element (iPRES(N)) allow an RF current and N direct currents (DC) to flow in each coil element, enabling simultaneous reception/excitation and shimming of highly localized B0 inhomogeneities. The purpose of this work was to reduce the cost and complexity of this design by reducing the number of DC power supplies required by a factor N, while maintaining a high RF and shimming performance. METHODS In the proposed design, termed adaptive iPRES(N) (iPRES(N)-A), each coil element only requires one DC power supply, but uses microelectromechanical systems switches to adaptively distribute the DC current into the appropriate shim loops to generate the desired magnetic field for B0 shimming. Proof-of-concept phantom experiments with an iPRES(2)-A coil and simulations in the human abdomen with an 8-channel iPRES(4)-A body coil array were performed to demonstrate the advantages of this innovative design. RESULTS The iPRES(2)-A coil showed no loss in signal-to-noise ratio and provided a much more effective correction of highly localized B0 inhomogeneities and geometric distortions than an equivalent iPRES(1) coil (88.2% vs. 32.2% lower B0 root-mean-square error). The iPRES(4)-A coil array showed a comparable shimming performance as that of an equivalent iPRES(4) coil array (52.6% vs. 54.2% lower B0 root-mean-square error), while only requiring 8 instead of 32 power supplies. CONCLUSION The iPRES(N)-A design retains the ability of the iPRES(N) design to shim highly localized B0 inhomogeneities, while drastically reducing its cost and complexity. Magn Reson Med 80:371-379, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Dean Darnell
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Yixin Ma
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Hongyuan Wang
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke Kunshan University, Kunshan, China
| | | | - Allen W Song
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Trong-Kha Truong
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke Kunshan University, Kunshan, China
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22
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Bruce IP, Chang HC, Petty C, Chen NK, Song AW. 3D-MB-MUSE: A robust 3D multi-slab, multi-band and multi-shot reconstruction approach for ultrahigh resolution diffusion MRI. Neuroimage 2017; 159:46-56. [PMID: 28732674 PMCID: PMC5676310 DOI: 10.1016/j.neuroimage.2017.07.035] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 07/14/2017] [Accepted: 07/17/2017] [Indexed: 10/19/2022] Open
Abstract
Recent advances in achieving ultrahigh spatial resolution (e.g. sub-millimeter) diffusion MRI (dMRI) data have proven highly beneficial in characterizing tissue microstructures in organs such as the brain. However, the routine acquisition of in-vivo dMRI data at such high spatial resolutions has been largely prohibited by factors that include prolonged acquisition times, motion induced artifacts, and low SNR. To overcome these limitations, we present here a framework for acquiring and reconstructing 3D multi-slab, multi-band and interleaved multi-shot EPI data, termed 3D-MB-MUSE. Through multi-band excitations, the simultaneous acquisition of multiple 3D slabs enables whole brain dMRI volumes to be acquired in-vivo on a 3 T clinical MRI scanner at high spatial resolution within a reasonably short amount of time. Representing a true 3D model, 3D-MB-MUSE reconstructs an entire 3D multi-band, multi-shot dMRI slab at once while simultaneously accounting for coil sensitivity variations across the slab as well as motion induced artifacts commonly associated with both 3D and multi-shot diffusion imaging. Such a reconstruction fully preserves the SNR advantages of both 3D and multi-shot acquisitions in high resolution dMRI images by removing both motion and aliasing artifacts across multiple dimensions. By enabling ultrahigh resolution dMRI for routine use, the 3D-MB-MUSE framework presented here may prove highly valuable in both clinical and research applications.
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Affiliation(s)
- Iain P Bruce
- Duke University Medical Center, Durham, NC, USA.
| | | | | | - Nan-Kuei Chen
- Duke University Medical Center, Durham, NC, USA; University of Arizona, Tuscan, AZ, USA
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