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Wang B, Zhang B, Yu Z, Ianniello C, Lakshmanan K, Paska J, Madelin G, Cloos M, Brown R. A radially interleaved sodium and proton coil array for brain MRI at 7 T. NMR IN BIOMEDICINE 2021; 34:e4608. [PMID: 34476861 PMCID: PMC9362999 DOI: 10.1002/nbm.4608] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/09/2021] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
The objective of the current study was to design and build a dual-tuned coil array for simultaneous 23 Na/1 H MRI of the human brain at 7 T. Quality factor, experimental B1+ measurements, and electromagnetic simulations in prototypes showed that setups consisting of geometrically interleaved 1 H and 23 Na loops performed better than or similar to 1 H or 23 Na loops in isolation. Based on these preliminary findings, we built a transmit/receive eight-channel 23 Na loop array that was geometrically interleaved with a transmit/receive eight-channel 1 H loop array. We assessed the performance of the manufactured array with mononuclear signal-to-noise ratio (SNR) and B1+ measurements, along with multinuclear magnetic resonance fingerprinting maps and images. The 23 Na array within the developed dual-tuned device provided more than 50% gain in peripheral SNR and similar B1+ uniformity and coverage as a reference birdcage coil of similar size. The 1 H array provided good B1+ uniformity in the brain, excluding the cerebellum and brain stem. The integrated 23 Na and 1 H arrays were used to demonstrate truly simultaneous quantitative 1 H mapping and 23 Na imaging.
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Affiliation(s)
- Bili Wang
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Bei Zhang
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Advanced Imaging Research Center, Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Zidan Yu
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Vilcek Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York, USA
| | - Carlotta Ianniello
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Vilcek Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York, USA
| | - Karthik Lakshmanan
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Jan Paska
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Guillaume Madelin
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Vilcek Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York, USA
| | - Martijn Cloos
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Vilcek Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York, USA
- Centre for Advanced Imaging, The University of Queensland, St Lucia, Brisbane, Queensland, Australia
| | - Ryan Brown
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Vilcek Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York, USA
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Platt T, Ladd ME, Paech D. 7 Tesla and Beyond: Advanced Methods and Clinical Applications in Magnetic Resonance Imaging. Invest Radiol 2021; 56:705-725. [PMID: 34510098 PMCID: PMC8505159 DOI: 10.1097/rli.0000000000000820] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 08/07/2021] [Accepted: 08/07/2021] [Indexed: 12/15/2022]
Abstract
ABSTRACT Ultrahigh magnetic fields offer significantly higher signal-to-noise ratio, and several magnetic resonance applications additionally benefit from a higher contrast-to-noise ratio, with static magnetic field strengths of B0 ≥ 7 T currently being referred to as ultrahigh fields (UHFs). The advantages of UHF can be used to resolve structures more precisely or to visualize physiological/pathophysiological effects that would be difficult or even impossible to detect at lower field strengths. However, with these advantages also come challenges, such as inhomogeneities applying standard radiofrequency excitation techniques, higher energy deposition in the human body, and enhanced B0 field inhomogeneities. The advantages but also the challenges of UHF as well as promising advanced methodological developments and clinical applications that particularly benefit from UHF are discussed in this review article.
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Affiliation(s)
- Tanja Platt
- From the Medical Physics in Radiology, German Cancer Research Center (DKFZ)
| | - Mark E. Ladd
- From the Medical Physics in Radiology, German Cancer Research Center (DKFZ)
- Faculty of Physics and Astronomy
- Faculty of Medicine, University of Heidelberg, Heidelberg
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen
| | - Daniel Paech
- Division of Radiology, German Cancer Research Center (DKFZ), Heidelberg
- Clinic for Neuroradiology, University of Bonn, Bonn, Germany
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Bogner W, Otazo R, Henning A. Accelerated MR spectroscopic imaging-a review of current and emerging techniques. NMR IN BIOMEDICINE 2021; 34:e4314. [PMID: 32399974 PMCID: PMC8244067 DOI: 10.1002/nbm.4314] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/24/2020] [Accepted: 03/30/2020] [Indexed: 05/14/2023]
Abstract
Over more than 30 years in vivo MR spectroscopic imaging (MRSI) has undergone an enormous evolution from theoretical concepts in the early 1980s to the robust imaging technique that it is today. The development of both fast and efficient sampling and reconstruction techniques has played a fundamental role in this process. State-of-the-art MRSI has grown from a slow purely phase-encoded acquisition technique to a method that today combines the benefits of different acceleration techniques. These include shortening of repetition times, spatial-spectral encoding, undersampling of k-space and time domain, and use of spatial-spectral prior knowledge in the reconstruction. In this way in vivo MRSI has considerably advanced in terms of spatial coverage, spatial resolution, acquisition speed, artifact suppression, number of detectable metabolites and quantification precision. Acceleration not only has been the enabling factor in high-resolution whole-brain 1 H-MRSI, but today is also common in non-proton MRSI (31 P, 2 H and 13 C) and applied in many different organs. In this process, MRSI techniques had to constantly adapt, but have also benefitted from the significant increase of magnetic field strength boosting the signal-to-noise ratio along with high gradient fidelity and high-density receive arrays. In combination with recent trends in image reconstruction and much improved computation power, these advances led to a number of novel developments with respect to MRSI acceleration. Today MRSI allows for non-invasive and non-ionizing mapping of the spatial distribution of various metabolites' tissue concentrations in animals or humans, is applied for clinical diagnostics and has been established as an important tool for neuro-scientific and metabolism research. This review highlights the developments of the last five years and puts them into the context of earlier MRSI acceleration techniques. In addition to 1 H-MRSI it also includes other relevant nuclei and is not limited to certain body regions or specific applications.
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Affiliation(s)
- Wolfgang Bogner
- High‐Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
| | - Ricardo Otazo
- Department of Medical PhysicsMemorial Sloan Kettering Cancer CenterNew York, New YorkUSA
| | - Anke Henning
- Max Planck Institute for Biological CyberneticsTübingenGermany
- Advanced Imaging Research Center, UT Southwestern Medical CenterDallasTexasUSA
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Rowland BC, Driver ID, Tachrount M, Klomp DWJ, Rivera D, Forner R, Pham A, Italiaander M, Wise RG. Whole brain 31 P MRSI at 7T with a dual-tuned receive array. Magn Reson Med 2020; 83:765-775. [PMID: 31441537 PMCID: PMC7614292 DOI: 10.1002/mrm.27953] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 12/24/2022]
Abstract
PURPOSE The design and performance of a novel head coil setup for 31 P spectroscopy at ultra-high field strengths (7T) is presented. The described system supports measurements at both the 1 H and 31 P resonance frequencies. METHODS The novel coil consists of 2, actively detunable, coaxial birdcage coils to give homogeneous transmit, combined with a double resonant 30 channel receive array. This allows for anatomical imaging combined with 31 P acquisitions over the whole head, without changing coils or disturbing the subject. A phosphate buffer phantom and 3 healthy volunteers were scanned with a pulse acquire CSI sequence using both the novel array coil and a conventional transceiver birdcage. Four different methods of combining the array channels were compared at 3 different levels of SNR. RESULTS The novel coil setup delivers significantly increased 31 P SNR in the peripheral regions of the brain, reaching up to factor 8, while maintaining comparable performance relative to the birdcage in the center. CONCLUSIONS The new system offers the potential to acquire whole brain 31 P MRSI with superior signal relative to the standard options.
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Affiliation(s)
- Benjamin C. Rowland
- Division of Cancer Science, University of Manchester, Manchester, UK
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, UK
| | - Ian D. Driver
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, UK
| | - Mohamed Tachrount
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, UK
| | - Dennis W. J. Klomp
- Radiology, UMC Utrecht, Utrecht, Netherlands
- MR Coils, Zaltbommel, Netherlands
| | | | | | - Anh Pham
- MR Coils, Zaltbommel, Netherlands
| | | | - Richard G. Wise
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, UK
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5
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van Rijssel MJ, Pluim JPW, Chan HSM, van den Wildenberg L, Schmitz AMT, Luijten PR, Gilhuijs KGA, Klomp DWJ. Correcting time-intensity curves in dynamic contrast-enhanced breast MRI for inhomogeneous excitation fields at 7T. Magn Reson Med 2019; 84:1000-1010. [PMID: 31880346 PMCID: PMC7217168 DOI: 10.1002/mrm.28147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 12/13/2022]
Abstract
Purpose Inhomogeneous excitation at ultrahigh field strengths (7T and above) compromises the reliability of quantified dynamic contrast‐enhanced breast MRI. This can hamper the introduction of ultrahigh field MRI into the clinic. Compensation for this non‐uniformity effect can consist of both hardware improvements and post‐acquisition corrections. This paper investigated the correctable radiofrequency transmit (B1+) range post‐acquisition in both simulations and patient data for 7T MRI. Methods Simulations were conducted to determine the minimum B1+ level at which corrections were still beneficial because of noise amplification. Two correction strategies leading to differences in noise amplification were tested. The effect of the corrections on a 7T patient data set (N = 38) with a wide range of B1+ levels was investigated in terms of time‐intensity curve types as well as washin, washout and peak enhancement values. Results In simulations assuming a common amount of T1 saturation, the lowest B1+ level at which the SNR of the corrected images was at least that of the original precontrast image was 43% of the nominal angle. After correction, time‐intensity curve types changed in 24% of included patients, and the distribution of curve types corresponded better to the distribution found in literature. Additionally, the overlap between the distributions of washin, washout, and peak enhancement values for grade 1 and grade 2 tumors was slightly reduced. Conclusion Although the correctable range varies with the amount of T1 saturation, post‐acquisition correction for inhomogeneous excitation was feasible down to B1+ levels of 43% of the nominal angle in vivo.
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Affiliation(s)
| | - Josien P W Pluim
- Center for Image Sciences, UMC Utrecht, Utrecht, The Netherlands.,Department of Biomedical Engineering, Technische Universiteit Eindhoven, Eindhoven, The Netherlands
| | - Hui-Shan M Chan
- Center for Image Sciences, UMC Utrecht, Utrecht, The Netherlands
| | | | | | - Peter R Luijten
- Center for Image Sciences, UMC Utrecht, Utrecht, The Netherlands
| | | | - Dennis W J Klomp
- Center for Image Sciences, UMC Utrecht, Utrecht, The Netherlands
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6
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Sonkar K, Ayyappan V, Tressler CM, Adelaja O, Cai R, Cheng M, Glunde K. Focus on the glycerophosphocholine pathway in choline phospholipid metabolism of cancer. NMR IN BIOMEDICINE 2019; 32:e4112. [PMID: 31184789 PMCID: PMC6803034 DOI: 10.1002/nbm.4112] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 04/16/2019] [Accepted: 04/20/2019] [Indexed: 05/02/2023]
Abstract
Activated choline metabolism is a hallmark of carcinogenesis and tumor progression, which leads to elevated levels of phosphocholine and glycerophosphocholine in all types of cancer tested so far. Magnetic resonance spectroscopy applications have played a key role in detecting these elevated choline phospholipid metabolites. To date, the majority of cancer-related studies have focused on phosphocholine and the Kennedy pathway, which constitutes the biosynthesis pathway for membrane phosphatidylcholine. Fewer and more recent studies have reported on the importance of glycerophosphocholine in cancer. In this review article, we summarize the recent literature on glycerophosphocholine metabolism with respect to its cancer biology and its detection by magnetic resonance spectroscopy applications.
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Affiliation(s)
- Kanchan Sonkar
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of Cancer Imaging Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Vinay Ayyappan
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of Cancer Imaging Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Caitlin M. Tressler
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of Cancer Imaging Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Oluwatobi Adelaja
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of Cancer Imaging Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Ruoqing Cai
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of Cancer Imaging Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Menglin Cheng
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of Cancer Imaging Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Kristine Glunde
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of Cancer Imaging Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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7
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Orzada S, Solbach K, Gratz M, Brunheim S, Fiedler TM, Johst S, Bitz AK, Shooshtary S, Abuelhaija A, Voelker MN, Rietsch SHG, Kraff O, Maderwald S, Flöser M, Oehmigen M, Quick HH, Ladd ME. A 32-channel parallel transmit system add-on for 7T MRI. PLoS One 2019; 14:e0222452. [PMID: 31513637 PMCID: PMC6742215 DOI: 10.1371/journal.pone.0222452] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 08/29/2019] [Indexed: 02/07/2023] Open
Abstract
PURPOSE A 32-channel parallel transmit (pTx) add-on for 7 Tesla whole-body imaging is presented. First results are shown for phantom and in-vivo imaging. METHODS The add-on system consists of a large number of hardware components, including modulators, amplifiers, SAR supervision, peripheral devices, a control computer, and an integrated 32-channel transmit/receive body array. B1+ maps in a phantom as well as B1+ maps and structural images in large volunteers are acquired to demonstrate the functionality of the system. EM simulations are used to ensure safe operation. RESULTS Good agreement between simulation and experiment is shown. Phantom and in-vivo acquisitions show a field of view of up to 50 cm in z-direction. Selective excitation with 100 kHz sampling rate is possible. The add-on system does not affect the quality of the original single-channel system. CONCLUSION The presented 32-channel parallel transmit system shows promising performance for ultra-high field whole-body imaging.
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Affiliation(s)
- Stephan Orzada
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany
- * E-mail:
| | - Klaus Solbach
- RF & Microwave Technology, University of Duisburg-Essen, Duisburg, Germany
| | - Marcel Gratz
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany
- High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | - Sascha Brunheim
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany
- High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | - Thomas M. Fiedler
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Sören Johst
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany
| | - Andreas K. Bitz
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Electromagnetic Theory and Applied Mathematics, Faculty of Electrical Engineering and Information Technology, FH Aachen – University of Applied Sciences, Aachen, Germany
| | - Samaneh Shooshtary
- RF & Microwave Technology, University of Duisburg-Essen, Duisburg, Germany
| | - Ashraf Abuelhaija
- RF & Microwave Technology, University of Duisburg-Essen, Duisburg, Germany
| | - Maximilian N. Voelker
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany
- High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | - Stefan H. G. Rietsch
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany
- High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | - Oliver Kraff
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany
| | - Stefan Maderwald
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany
| | - Martina Flöser
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Mark Oehmigen
- High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | - Harald H. Quick
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany
- High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | - Mark E. Ladd
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Physics and Astronomy and Faculty of Medicine, University of Heidelberg, Heidelberg, Germany
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8
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Lee BY, Zhu XH, Chen W. Quantitative analysis of spatial averaging effect on chemical shift imaging SNR and noise coherence with k-space sampling schemes. Magn Reson Imaging 2019; 60:85-92. [PMID: 30943436 DOI: 10.1016/j.mri.2019.03.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 03/25/2019] [Accepted: 03/27/2019] [Indexed: 01/19/2023]
Abstract
Spatial averaging of multiple voxels from high-resolution chemical shift imaging (hrCSI) is a common strategy for in vivo metabolic studies to achieve a better signal-to-noise ratio (SNR) for a region-of-interest. However, the mechanism about how the spatial averaging approach influences the respective spectral signal and noise and its relevance to the k-space sampling schemes remains unclear. Using three-dimension 17O CSI technique with the weighted k-space sampling method of Fourier series window, we performed quantitative SNR comparisons between a single low-resolution CSI (lrCSI) voxel (being 27 times larger than the hrCSI voxel size) and the spatially averaged hrCSI voxels with matched sampling volume and location. We demonstrated that the averaged hrCSI voxel spectrum had a large SNR loss (> 4 times) compared to the lrCSI voxel, which was resulted from unmatched increases in signal (~1.9 fold) and noise (~9.3 fold). The signal increase was caused by the spatial overlapping between the adjacent hrCSI voxels. The substantial noise increase was mainly attributed to the strong noise coherence among hrCSI voxels acquired with the weighted k-space sampling. This study presents a quantitative relation between the k-space sampling schemes to an apparent SNR penalty of the spatial averaging approach. The information could be useful for designing CSI acquisition method and determination of optimal spatial resolution for in vivo metabolic imaging studies.
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Affiliation(s)
- Byeong-Yeul Lee
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, MN, USA.
| | - Xiao-Hong Zhu
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, MN, USA
| | - Wei Chen
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, MN, USA.
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9
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Vidya Shankar R, Chang JC, Hu HH, Kodibagkar VD. Fast data acquisition techniques in magnetic resonance spectroscopic imaging. NMR IN BIOMEDICINE 2019; 32:e4046. [PMID: 30637822 DOI: 10.1002/nbm.4046] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 10/30/2018] [Accepted: 10/31/2018] [Indexed: 06/09/2023]
Abstract
Magnetic resonance spectroscopic imaging (MRSI) is an important technique for assessing the spatial variation of metabolites in vivo. The long scan times in MRSI limit clinical applicability due to patient discomfort, increased costs, motion artifacts, and limited protocol flexibility. Faster acquisition strategies can address these limitations and could potentially facilitate increased adoption of MRSI into routine clinical protocols with minimal addition to the current anatomical and functional acquisition protocols in terms of imaging time. Not surprisingly, a lot of effort has been devoted to the development of faster MRSI techniques that aim to capture the same underlying metabolic information (relative metabolite peak areas and spatial distribution) as obtained by conventional MRSI, in greatly reduced time. The gain in imaging time results, in some cases, in a loss of signal-to-noise ratio and/or in spatial and spectral blurring. This review examines the current techniques and advances in fast MRSI in two and three spatial dimensions and their applications. This review categorizes the acceleration techniques according to their strategy for acquisition of the k-space. Techniques such as fast/turbo-spin echo MRSI, echo-planar spectroscopic imaging, and non-Cartesian MRSI effectively cover the full k-space in a more efficient manner per TR . On the other hand, techniques such as parallel imaging and compressed sensing acquire fewer k-space points and employ advanced reconstruction algorithms to recreate the spatial-spectral information, which maintains statistical fidelity in test conditions (ie no statistically significant differences on voxel-wise comparisions) with the fully sampled data. The advantages and limitations of each state-of-the-art technique are reviewed in detail, concluding with a note on future directions and challenges in the field of fast spectroscopic imaging.
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Affiliation(s)
- Rohini Vidya Shankar
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
| | - John C Chang
- Banner M D Anderson Cancer Center, Gilbert, AZ, USA
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Houchun H Hu
- Department of Radiology and Medical Imaging, Phoenix Children's Hospital, Phoenix, AZ, USA
| | - Vikram D Kodibagkar
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
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10
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Krikken E, Steensma BR, Voogt IJ, Luijten PR, Klomp DW, Raaijmakers AJ, Wijnen JP. Homogeneous B 1+ for bilateral breast imaging at 7 T using a five dipole transmit array merged with a high density receive loop array. NMR IN BIOMEDICINE 2019; 32:e4039. [PMID: 30489661 PMCID: PMC6587506 DOI: 10.1002/nbm.4039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 09/24/2018] [Accepted: 10/12/2018] [Indexed: 06/09/2023]
Abstract
To explore the use of five meandering dipole antennas in a multi-transmit setup, combined with a high density receive array for breast imaging at 7 T for improved penetration depth and more homogeneous B1 field. Five meandering dipole antennas and 30 receiver loops were positioned on two cups around the breasts. Finite difference time domain simulations were performed to evaluate RF safety limits of the transmit setup. Scattering parameters of the transmit setup and coupling between the antennas and the detuned loops were measured. In vivo parallel imaging performance was investigated for various acceleration factors. After RF shimming, a B1 map, a T1 -weighted image, and a T2 -weighted image were acquired to assess B1 efficiency, uniformity in contrast weighting, and imaging performance in clinical applications. The maximum achievable local SAR10g value was 7.0 W/kg for 5 × 1 W accepted power. The dipoles were tuned and matched to a maximum reflection of -11.8 dB, and a maximum inter-element coupling of -14.2 dB. The maximum coupling between the antennas and the receive loops was -18.2 dB and the mean noise correlation for the 30 receive loops 7.83 ± 8.69%. In vivo measurements showed an increased field of view, which reached to the axilla, and a high transmit efficiency. This coil enabled the acquisition of T1 -weighted images with a high spatial resolution of 0.7 mm3 isotropic and T2 -weighted spin echo images with uniformly weighted contrast.
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Affiliation(s)
- Erwin Krikken
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Bart R. Steensma
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Ingmar J. Voogt
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Peter R. Luijten
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Dennis W.J. Klomp
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Alexander J.E. Raaijmakers
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
- Department of Biomedical EngineeringEindhoven University of TechnologyEindhovenThe Netherlands
| | - Jannie P. Wijnen
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
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11
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Li X, Rispoli JV. Toward 7T breast MRI clinical study: safety assessment using simulation of heterogeneous breast models in RF exposure. Magn Reson Med 2018; 81:1307-1321. [PMID: 30216530 DOI: 10.1002/mrm.27395] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 04/19/2018] [Accepted: 05/17/2018] [Indexed: 12/27/2022]
Abstract
PURPOSE To facilitate assessment of RF power deposition and temperature rise within the breast, we present a method to seamlessly join heterogeneous breast models with standard whole-body models and demonstrate simulations at 7 T. METHODS Finite-difference time-domain electromagnetic and bioheat simulations are performed to analyze the specific absorption rate (SAR) and temperature rise distributions in 36 Breast Imaging Reporting and Data System (BI-RADS) categorized breast models fused to 2 female whole-body models while transmitting from a 7T breast volume coil. The breast models are uncompressed in the prone position and feature heterogeneous tissue contents; fusion with human models uses affine transformation and the level-set method. RESULTS The fusion method produces a continuous transient from the chest region to the posterior portion of breast models while preserving the original volume and shape of breast models. Simulation results of both Ella and Hanako models indicate that the maximum local SAR, partial body SAR, and local tissue temperature rise are positively correlated with both breast density and the highest BI-RADS density classification. Additionally, maximum local tissue temperature rise is positively correlated with maximum 10-g SAR values. CONCLUSION Fibroglandular tissue content plays an important role in the distribution of SAR and temperature rise within breast tissue. The combined body-breast models preserve the integrity of breast models while concurrently exhibiting the loading of whole-body human models. The procedures presented in this simulation study facilitate safety assessments for breast MRI across the population at both clinical and ultrahigh field strengths.
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Affiliation(s)
- Xin Li
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
| | - Joseph V Rispoli
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana.,School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana.,Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana
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12
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Krikken E, Khlebnikov V, Zaiss M, Jibodh RA, van Diest PJ, Luijten PR, Klomp DWJ, van Laarhoven HWM, Wijnen JP. Amide chemical exchange saturation transfer at 7 T: a possible biomarker for detecting early response to neoadjuvant chemotherapy in breast cancer patients. Breast Cancer Res 2018; 20:51. [PMID: 29898745 PMCID: PMC6001024 DOI: 10.1186/s13058-018-0982-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 05/10/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The purpose of this work was to investigate noninvasive early detection of treatment response of breast cancer patients to neoadjuvant chemotherapy (NAC) using chemical exchange saturation transfer (CEST) measurements sensitive to amide proton transfer (APT) at 7 T. METHODS CEST images were acquired in 10 tumors of nine breast cancer patients treated with NAC. APT signals in the tumor, before and after the first cycle of NAC, were quantified using a three-pool Lorentzian fit of the z-spectra in the region of interest. The changes in APT were subsequently related to pathological response after surgery defined by the Miller-Payne system. RESULTS Significant differences (P < 0.05, unpaired Mann-Whitney test) were found in the APT signal before and after the first cycle of NAC in six out of 10 lesions, of which two showed a pathological complete response. Of the remaining four lesions, one showed a pathological complete response. No significant difference in changes of APT signal were found between the different pathological responses to NAC treatment (P > 0.05, Kruskal-Wallis test). CONCLUSIONS This preliminary study shows the feasibility of using APT CEST magnetic resonance imaging as a noninvasive biomarker to assess the effect of NAC in an early stage of NAC treatment of breast cancer patients. TRIAL REGISTRATION Registration number, NL49333.041.14/ NTR4980 . Registered on 16 October 2014.
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Affiliation(s)
- Erwin Krikken
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Vitaliy Khlebnikov
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Moritz Zaiss
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Rajni A. Jibodh
- Department of Medical Oncology, Academic Medical Centre Amsterdam, Amsterdam, The Netherlands
| | - Paul J. van Diest
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Peter R. Luijten
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Dennis W. J. Klomp
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Jannie P. Wijnen
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
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13
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van Rijssel MJ, Pluim JPW, Luijten PR, Gilhuijs KGA, Raaijmakers AJE, Klomp DWJ. Estimating B 1+ in the breast at 7 T using a generic template. NMR IN BIOMEDICINE 2018; 31:e3911. [PMID: 29570887 PMCID: PMC5947628 DOI: 10.1002/nbm.3911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 01/30/2018] [Accepted: 01/30/2018] [Indexed: 06/08/2023]
Abstract
Dynamic contrast-enhanced MRI is the workhorse of breast MRI, where the diagnosis of lesions is largely based on the enhancement curve shape. However, this curve shape is biased by RF transmit (B1+ ) field inhomogeneities. B1+ field information is required in order to correct these. The use of a generic, coil-specific B1+ template is proposed and tested. Finite-difference time-domain simulations for B1+ were performed for healthy female volunteers with a wide range of breast anatomies. A generic B1+ template was constructed by averaging simulations based on four volunteers. Three-dimensional B1+ maps were acquired in 15 other volunteers. Root mean square error (RMSE) metrics were calculated between individual simulations and the template, and between individual measurements and the template. The agreement between the proposed template approach and a B1+ mapping method was compared against the agreement between acquisition and reacquisition using the same mapping protocol. RMSE values (% of nominal flip angle) comparing individual simulations with the template were in the range 2.00-4.01%, with mean 2.68%. RMSE values comparing individual measurements with the template were in the range8.1-16%, with mean 11.7%. The agreement between the proposed template approach and a B1+ mapping method was only slightly worse than the agreement between two consecutive acquisitions using the same mapping protocol in one volunteer: the range of agreement increased from ±16% of the nominal angle for repeated measurement to ±22% for the B1+ template. With local RF transmit coils, intersubject differences in B1+ fields of the breast are comparable to the accuracy of B1+ mapping methods, even at 7 T. Consequently, a single generic B1+ template suits subjects over a wide range of breast anatomies, eliminating the need for a time-consuming B1+ mapping protocol.
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14
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Schmitz AMT, Veldhuis WB, Menke-Pluijmers MBE, van der Kemp WJM, van der Velden TA, Viergever MA, Mali WPTM, Kock MCJM, Westenend PJ, Klomp DWJ, Gilhuijs KGA. Preoperative indication for systemic therapy extended to patients with early-stage breast cancer using multiparametric 7-tesla breast MRI. PLoS One 2017; 12:e0183855. [PMID: 28949967 PMCID: PMC5614529 DOI: 10.1371/journal.pone.0183855] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 08/11/2017] [Indexed: 11/19/2022] Open
Abstract
Purpose To establish a preoperative decision model for accurate indication of systemic therapy in early-stage breast cancer using multiparametric MRI at 7-tesla field strength. Materials and methods Patients eligible for breast-conserving therapy were consecutively included. Patients underwent conventional diagnostic workup and one preoperative multiparametric 7-tesla breast MRI. The postoperative (gold standard) indication for systemic therapy was established from resected tumor and lymph-node tissue, based on 10-year risk-estimates of breast cancer mortality and relapse using Adjuvant! Online. Preoperative indication was estimated using similar guidelines, but from conventional diagnostic workup. Agreement was established between preoperative and postoperative indication, and MRI-characteristics used to improve agreement. MRI-characteristics included phospomonoester/phosphodiester (PME/PDE) ratio on 31-phosphorus spectroscopy (31P-MRS), apparent diffusion coefficients on diffusion-weighted imaging, and tumor size on dynamic contrast-enhanced (DCE)-MRI. A decision model was built to estimate the postoperative indication from preoperatively available data. Results We included 46 women (age: 43-74yrs) with 48 invasive carcinomas. Postoperatively, 20 patients (43%) had positive, and 26 patients (57%) negative indication for systemic therapy. Using conventional workup, positive preoperative indication agreed excellently with positive postoperative indication (N = 8/8; 100%). Negative preoperative indication was correct in only 26/38 (68%) patients. However, 31P-MRS score (p = 0.030) and tumor size (p = 0.002) were associated with the postoperative indication. The decision model shows that negative indication is correct in 21/22 (96%) patients when exempting tumors larger than 2.0cm on DCE-MRI or with PME>PDE ratios at 31P-MRS. Conclusions Preoperatively, positive indication for systemic therapy is highly accurate. Negative indication is highly accurate (96%) for tumors sized ≤2,0cm on DCE-MRI and with PME≤PDE ratios on 31P-MRS.
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Affiliation(s)
- A. M. T. Schmitz
- Department of Radiology / Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands
- * E-mail:
| | - W. B. Veldhuis
- Department of Radiology / Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands
| | | | - W. J. M. van der Kemp
- Department of Radiology / Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands
| | - T. A. van der Velden
- Department of Radiology / Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands
| | - M. A. Viergever
- Department of Radiology / Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands
| | - W. P. T. M. Mali
- Department of Radiology / Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands
| | - M. C. J. M. Kock
- Department of Radiology, Albert Schweitzer Hospital, Dordrecht, the Netherlands
| | - P. J. Westenend
- Department of Pathology, Albert Schweitzer Hospital, Dordrecht, the Netherlands
| | - D. W. J. Klomp
- Department of Radiology / Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands
| | - K. G. A. Gilhuijs
- Department of Radiology / Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands
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15
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Kraff O, Quick HH. 7T: Physics, safety, and potential clinical applications. J Magn Reson Imaging 2017; 46:1573-1589. [DOI: 10.1002/jmri.25723] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 03/17/2017] [Indexed: 12/19/2022] Open
Affiliation(s)
- Oliver Kraff
- Erwin L. Hahn Institute for MR Imaging; University of Duisburg-Essen; Essen Germany
| | - Harald H. Quick
- Erwin L. Hahn Institute for MR Imaging; University of Duisburg-Essen; Essen Germany
- High Field and Hybrid MR Imaging; University Hospital Essen; Essen Germany
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16
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van der Velden TA, Luijten PR, Klomp DW. Improved fat suppression of the breast using discretized frequency shimming. Magn Reson Med 2017; 79:593-599. [DOI: 10.1002/mrm.26651] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 01/24/2017] [Accepted: 01/27/2017] [Indexed: 11/12/2022]
Affiliation(s)
- Tijl A. van der Velden
- Department of Radiology; University Medical Centre Utrecht; 3584CX Utrecht the Netherlands
| | - Peter R. Luijten
- Department of Radiology; University Medical Centre Utrecht; 3584CX Utrecht the Netherlands
| | - Dennis W.J. Klomp
- Department of Radiology; University Medical Centre Utrecht; 3584CX Utrecht the Netherlands
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17
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Rispoli JV, Wright SM, Malloy CR, McDougall MP. Automated modification and fusion of voxel models to construct body phantoms with heterogeneous breast tissue: Application to MRI simulations. ACTA ACUST UNITED AC 2017; 7:1-7. [PMID: 28798837 DOI: 10.5430/jbgc.v7n1p1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Human voxel models incorporating detailed anatomical features are vital tools for the computational evaluation of electromagnetic (EM) fields within the body. Besides whole-body human voxel models, phantoms representing smaller heterogeneous anatomical features are often employed; for example, localized breast voxel models incorporating fatty and fibroglandular tissues have been developed for a variety of EM applications including mammography simulation and dosimetry, magnetic resonance imaging (MRI), and ultra-wideband microwave imaging. However, considering wavelength effects, electromagnetic modeling of the breast at sub-microwave frequencies necessitates detailed breast phantoms in conjunction with whole-body voxel models. METHODS Heterogeneous breast phantoms are sized to fit within radiofrequency coil hardware, modified by voxel-wise extrusion, and fused to whole-body models using voxel-wise, tissue-dependent logical operators. To illustrate the utility of this method, finite-difference time-domain simulations are performed using a whole-body model integrated with a variety of available breast phantoms spanning the standard four tissue density classifications representing the majority of the population. RESULTS The software library uses a combination of voxel operations to seamlessly size, modify, and fuse eleven breast phantoms to whole-body voxel models. The software is publicly available on GitHub and is linked to the file exchange at MATLAB® Central. Simulations confirm the proportions of fatty and fibroglandular tissues in breast phantoms have significant yet predictable implications on projected power deposition in tissue. CONCLUSIONS Breast phantoms may be modified and fused to whole-body voxel models using the software presented in this work; user considerations for the open-source software and resultant phantoms are discussed. Furthermore, results indicate simulating breast models as predominantly fatty tissue can considerably underestimate the potential for tissue heating in women with substantial fibroglandular tissue.
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Affiliation(s)
- Joseph V Rispoli
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, United States of America.,Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America.,School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Steven M Wright
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, United States of America.,Department of Electrical & Computer Engineering, Texas A&M University, College Station, Texas, United States of America
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Mary P McDougall
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, United States of America.,Department of Electrical & Computer Engineering, Texas A&M University, College Station, Texas, United States of America
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18
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Kim J, Santini T, Bae KT, Krishnamurthy N, Zhao Y, Zhao T, Ibrahim TS. Development of a 7 T RF coil system for breast imaging. NMR IN BIOMEDICINE 2017; 30:10.1002/nbm.3664. [PMID: 27859861 PMCID: PMC5943082 DOI: 10.1002/nbm.3664] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 09/23/2016] [Accepted: 10/06/2016] [Indexed: 06/06/2023]
Abstract
In ultrahigh-field MRI, such as 7 T, the signal-to-noise ratio (SNR) increases while transmit (Tx) field (B1+ ) can be degraded due to inhomogeneity and elevated specific absorption rate (SAR). By applying new array coil concepts to both Tx and receive (Rx) coils, the B1+ homogeneity and SNR can be improved. In this study, we developed and tested in vivo a new RF coil system for 7 T breast MRI. An RF coil system composed of an eight-channel Tx-only array based on a tic-tac-toe design (can be combined to operate in single-Tx mode) in conjunction with an eight-channel Rx-only insert was developed. Characterizations of the B1+ field and associated SAR generated by the developed RF coil system were numerically calculated and empirically measured using an anatomically detailed breast model, phantom and human breasts. In vivo comparisons between 3 T (using standard commercial solutions) and 7 T (using the newly developed coil system) breast imaging were made. At 7 T, about 20% B1+ inhomogeneity (standard deviation over the mean) was measured within the breast tissue for both the RF simulations and 7 T experiments. The addition of the Rx-only array enhances the SNR by a factor of about three. High-quality MR images of human breast were acquired in vivo at 7 T. For the in vivo comparisons between 3 T and 7 T, an approximately fourfold increase of SNR was measured with 7 T imaging. The B1+ field distributions in the breast model, phantom and in vivo were in reasonable agreement. High-quality 7 T in vivo breast MRI was successfully acquired at 0.6 mm isotropic resolution using the newly developed RF coil system.
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Affiliation(s)
- Junghwan Kim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tales Santini
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kyongtae Ty Bae
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Yujuan Zhao
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tiejun Zhao
- MR Research Support, Siemens Healthcare, Pittsburgh, PA, USA
| | - Tamer S. Ibrahim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
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19
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Kim J, Krishnamurthy N, Santini T, Zhao Y, Zhao T, Bae KT, Ibrahim TS. Experimental and numerical analysis of B1(+) field and SAR with a new transmit array design for 7T breast MRI. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 269:55-64. [PMID: 27240143 PMCID: PMC4979605 DOI: 10.1016/j.jmr.2016.04.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 04/20/2016] [Accepted: 04/21/2016] [Indexed: 05/15/2023]
Abstract
Developing a radiofrequency (RF) coil system that produces a uniform B1(+) field (circularly polarized component of the transverse magnetic field responsible for excitation) and low specific absorption rate (SAR) is critical for high performance ultrahigh field human imaging. In this study, we provide the design of a new eight channel radiofrequency (RF) transmit (Tx) array for breast MRI at 7T. A numerical analysis utilizing an in-house finite difference time domain (FDTD) package was carried out in (1) four breast models, (2) homogeneous spherical model and (3) full body model to calculate the B1(+) intensity (μT) and homogeneity represented by coefficient of variation (CoV=standard deviation/mean) in the proposed RF array design. The numerical results were compared with that measured in breast phantom (Bphantom) and homogeneous spherical phantom at 7T MRI and showed very good agreement. Average and peak SARs were also calculated in the four breast models and the temperature rises due to the operation of the RF array were also measured in the Bphantom. The proposed RF array; which can operate in a single or multi transmit modes, demonstrates homogeneous RF field excitation with acceptable local/average SAR levels for breast MRI at 7T.
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Affiliation(s)
- Junghwan Kim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | | | - Tales Santini
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Yujuan Zhao
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Tiejun Zhao
- MR Research Support, Siemens Healthcare, Pittsburgh, PA 15213, USA
| | - Kyongtae Ty Bae
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Tamer S Ibrahim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA; Department of Radiology, University of Pittsburgh, Pittsburgh, PA 15213, USA.
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20
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Magnetic Resonance Imaging of Phosphocreatine and Determination of BOLD Kinetics in Lower Extremity Muscles using a Dual-Frequency Coil Array. Sci Rep 2016; 6:30568. [PMID: 27465636 PMCID: PMC4964597 DOI: 10.1038/srep30568] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/01/2016] [Indexed: 01/17/2023] Open
Abstract
Magnetic resonance imaging (MRI) provides the unique ability to study metabolic and microvasculature functions in skeletal muscle using phosphorus and proton measurements. However, the low sensitivity of these techniques can make it difficult to capture dynamic muscle activity due to the temporal resolution required for kinetic measurements during and after exercise tasks. Here, we report the design of a dual-nuclei coil array that enables proton and phosphorus MRI of the human lower extremities with high spatial and temporal resolution. We developed an array with whole-volume coverage of the calf and a phosphorus signal-to-noise ratio of more than double that of a birdcage coil in the gastrocnemius muscles. This enabled the local assessment of phosphocreatine recovery kinetics following a plantar flexion exercise using an efficient sampling scheme with a 6 s temporal resolution. The integrated proton array demonstrated image quality approximately equal to that of a clinical state-of-the-art knee coil, which enabled fat quantification and dynamic blood oxygen level-dependent measurements that reflect microvasculature function. The developed array and time-efficient pulse sequences were combined to create a localized assessment of calf metabolism using phosphorus measurements and vasculature function using proton measurements, which could provide new insights into muscle function.
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21
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Menezes GLG, Stehouwer BL, Klomp DWJ, van der Velden TA, van den Bosch MAAJ, Knuttel FM, Boer VO, van der Kemp WJM, Luijten PR, Veldhuis WB. Dynamic contrast-enhanced breast MRI at 7T and 3T: an intra-individual comparison study. SPRINGERPLUS 2016; 5:13. [PMID: 26759752 PMCID: PMC4700043 DOI: 10.1186/s40064-015-1654-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 12/21/2015] [Indexed: 01/01/2023]
Abstract
The aim of this study is to compare the current state of lesion identification, the BI-RADS classification and the contrast-enhancement behavior at 7T and 3T breast MRI in the same patient group. Twenty-seven patients with thirty suspicious lesions were selected for this prospective study and underwent both 7T and 3T MRI. All examinations were rated by two radiologists (R1 and R2) independently on image quality, lesion identification and BI-RADS classification. We assessed sensitivity, specificity, NPV and PPV, observer agreement, lesion sizes, and contrast-enhancement-to-noise ratios (CENRs) of mass lesions. Fifteen of seventeen histopathological proven malignant lesions were detected at both field strengths. Image quality of the dynamic series was good at 7T, and excellent at 3T (P = 0.001 for R1 and P = 0.88 for R2). R1 found higher rates of specificity, NPV and PPV at 7T when compared to 3T, while R2 found the same results for sensitivity, specificity, NPV and PPV for both field strengths. The observers showed excellent agreement for BI-RADS categories at 7T (κ = 0.86) and 3T (κ = 0.93). CENRs were higher at 7T (P = 0.015). Lesion sizes were bigger at 7T according to R2 (P = 0.039). Our comparison study shows that 7T MRI allows BI-RADS conform analysis. Technical improvements, such as acquisition of T2w sequences and adjustment of B1+ field inhomogeneity, are still necessary to allow clinical use of 7T breast MRI.
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Affiliation(s)
- Gisela L G Menezes
- Department of Radiology and Nuclear Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Bertine L Stehouwer
- Department of Radiology and Nuclear Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Dennis W J Klomp
- Department of Radiology and Nuclear Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Tijl A van der Velden
- Department of Radiology and Nuclear Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Maurice A A J van den Bosch
- Department of Radiology and Nuclear Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Floortje M Knuttel
- Department of Radiology and Nuclear Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Vincent O Boer
- Department of Radiology and Nuclear Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Wybe J M van der Kemp
- Department of Radiology and Nuclear Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Peter R Luijten
- Department of Radiology and Nuclear Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Wouter B Veldhuis
- Department of Radiology and Nuclear Medicine, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
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22
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Brown R, Lakshmanan K, Madelin G, Parasoglou P. A nested phosphorus and proton coil array for brain magnetic resonance imaging and spectroscopy. Neuroimage 2016; 124:602-611. [PMID: 26375209 PMCID: PMC4651763 DOI: 10.1016/j.neuroimage.2015.08.066] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/04/2015] [Accepted: 08/28/2015] [Indexed: 02/02/2023] Open
Abstract
A dual-nuclei radiofrequency coil array was constructed for phosphorus and proton magnetic resonance imaging and spectroscopy of the human brain at 7T. An eight-channel transceive degenerate birdcage phosphorus module was implemented to provide whole-brain coverage and significant sensitivity improvement over a standard dual-tuned loop coil. A nested eight-channel proton module provided adequate sensitivity for anatomical localization without substantially sacrificing performance on the phosphorus module. The developed array enabled phosphorus spectroscopy, a saturation transfer technique to calculate the global creatine kinase forward reaction rate, and single-metabolite whole-brain imaging with 1.4cm nominal isotropic resolution in 15min (2.3cm actual resolution), while additionally enabling 1mm isotropic proton imaging. This study demonstrates that a multi-channel array can be utilized for phosphorus and proton applications with improved coverage and/or sensitivity over traditional single-channel coils. The efficient multi-channel coil array, time-efficient pulse sequences, and the enhanced signal strength available at ultra-high fields can be combined to allow volumetric assessment of the brain and could provide new insights into the underlying energy metabolism impairment in several neurodegenerative conditions, such as Alzheimer's and Parkinson's diseases, as well as mental disorders such as schizophrenia.
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Affiliation(s)
- Ryan Brown
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University School of Medicine, New York, NY, USA; NYU WIRELESS, Polytechnic Institute of New York University, 2 Metro Tech Center, Brooklyn, NY 11201, USA.
| | - Karthik Lakshmanan
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University School of Medicine, New York, NY, USA
| | - Guillaume Madelin
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University School of Medicine, New York, NY, USA
| | - Prodromos Parasoglou
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University School of Medicine, New York, NY, USA
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Brown R, Lakshmanan K, Madelin G, Alon L, Chang G, Sodickson DK, Regatte RR, Wiggins GC. A flexible nested sodium and proton coil array with wideband matching for knee cartilage MRI at 3T. Magn Reson Med 2015; 76:1325-34. [PMID: 26502310 DOI: 10.1002/mrm.26017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 08/27/2015] [Accepted: 09/25/2015] [Indexed: 12/11/2022]
Abstract
PURPOSE We describe a 2 × 6 channel sodium/proton array for knee MRI at 3T. Multielement coil arrays are desirable because of well-known signal-to-noise ratio advantages over volume and single-element coils. However, low tissue-coil coupling that is characteristic of coils operating at low frequency can make the potential gains from a phased array difficult to realize. METHODS The issue of low tissue-coil coupling in the developed six-channel sodium receive array was addressed by implementing 1) a mechanically flexible former to minimize the coil-to-tissue distance and reduce the overall diameter of the array and 2) a wideband matching scheme that counteracts preamplifier noise degradation caused by coil coupling and a high-quality factor. The sodium array was complemented with a nested proton array to enable standard MRI. RESULTS The wideband matching scheme and tight-fitting mechanical design contributed to >30% central signal-to-noise ratio gain on the sodium module over a mononuclear sodium birdcage coil, and the performance of the proton module was sufficient for clinical imaging. CONCLUSION We expect the strategies presented in this study to be generally relevant in high-density receive arrays, particularly in x-nuclei or small animal applications. Magn Reson Med 76:1325-1334, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Ryan Brown
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA. .,Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University School of Medicine, New York, New York, USA. .,NYU WIRELESS, Polytechnic Institute of New York University, Brooklyn, New York, USA.
| | - Karthik Lakshmanan
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.,Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University School of Medicine, New York, New York, USA
| | - Guillaume Madelin
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.,Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University School of Medicine, New York, New York, USA
| | - Leeor Alon
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.,Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University School of Medicine, New York, New York, USA.,NYU WIRELESS, Polytechnic Institute of New York University, Brooklyn, New York, USA
| | - Gregory Chang
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.,Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University School of Medicine, New York, New York, USA
| | - Daniel K Sodickson
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.,Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University School of Medicine, New York, New York, USA.,NYU WIRELESS, Polytechnic Institute of New York University, Brooklyn, New York, USA
| | - Ravinder R Regatte
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.,Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University School of Medicine, New York, New York, USA
| | - Graham C Wiggins
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.,Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University School of Medicine, New York, New York, USA
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