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Lopez Rios N, Pouliot P, Papoutsis K, Foias A, Stikov N, Lesage F, Dehaes M, Cohen-Adad J. Design and construction of an optimized transmit/receive hybrid birdcage resonator to improve full body images of medium-sized animals in 7T scanner. PLoS One 2018; 13:e0192035. [PMID: 29390005 PMCID: PMC5794134 DOI: 10.1371/journal.pone.0192035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 01/16/2018] [Indexed: 11/18/2022] Open
Abstract
The purpose of this work was to develop an optimized transmit/receive birdcage coil to extend the possibilities of a 7T preclinical MRI system to conduct improved full body imaging in medium-sized animals, such as large New Zealand rabbits. The coil was designed by combining calculation and electromagnetic simulation tools. The construction was based on precise mechanical design and careful building practice. A 16-leg, 20 cm long, 16 cm inner diameter, shielded quadrature hybrid structure was selected. Coil parameters were assessed on the bench and images were acquired on phantoms and rabbits. The results were compared to simulations and data obtained with an available commercial coil. An inexpensive assembly with an increase of 2 cm in useful inner diameter and 50 Ω matching with larger animals was achieved. A reduction in radiofrequency (RF) power demand of 31.8%, an improvement in image uniformity of 18.5 percentage points and an increase in signal-to-noise ratio of up to 42.2% were revealed by phantom image acquisitions, which was confirmed by in vivo studies. In conclusion, the proposed coil extended the possibilities of a preclinical 7T system as it improved image studies in relatively large animals by reducing the RF power demand, and increasing image uniformity and signal-to-noise ratio. Shorter scans and time under anesthesia or reduced RF exposure, resulting in better images and lower animal health risk during in vivo experiments, were achieved.
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Affiliation(s)
- Nibardo Lopez Rios
- Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada
- Sainte-Justine Hospital University Center, Montreal, Canada
- Medical Biophysics Center, University of Oriente, Santiago de Cuba, Cuba
- * E-mail:
| | - Philippe Pouliot
- Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada
- Research Center, Montreal Heart Institute, Montreal, QC, Canada
| | - Konstantinos Papoutsis
- Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada
- FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Alexandru Foias
- Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada
| | - Nikola Stikov
- Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada
- Research Center, Montreal Heart Institute, Montreal, QC, Canada
| | - Frédéric Lesage
- Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada
- Research Center, Montreal Heart Institute, Montreal, QC, Canada
| | - Mathieu Dehaes
- Sainte-Justine Hospital University Center, Montreal, Canada
- Department of Radiology, Radio-oncology and Nuclear Medicine, University of Montreal, Montreal, Canada
- Institute of Biomedical Engineering, University of Montreal, Montreal, Canada
| | - Julien Cohen-Adad
- Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada
- Functional Neuroimaging Unit, CRIUGM, University of Montreal, Montreal, QC, Canada
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Lakshmanan K, Brown R, Madelin G, Qian Y, Boada F, Wiggins GC. An eight-channel sodium/proton coil for brain MRI at 3 T. NMR IN BIOMEDICINE 2018; 31:10.1002/nbm.3867. [PMID: 29280204 PMCID: PMC5779625 DOI: 10.1002/nbm.3867] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 10/27/2017] [Accepted: 10/31/2017] [Indexed: 06/07/2023]
Abstract
The purpose of this work is to illustrate a new coil decoupling strategy and its application to a transmit/receive sodium/proton phased array for magnetic resonance imaging (MRI) of the human brain. We implemented an array of eight triangular coils that encircled the head. The ensemble of coils was arranged to form a modified degenerate mode birdcage whose eight shared rungs were offset from the z-axis at interleaved angles of ±30°. This key geometric modification resulted in triangular elements whose vertices were shared between next-nearest neighbors, which provided a convenient location for counter-wound decoupling inductors, whilst nearest-neighbor decoupling was addressed with shared capacitors along the rungs. This decoupling strategy alleviated the strong interaction that is characteristic of array coils at low frequency (32.6 MHz in this case) and allowed the coil to operate efficiently in transceive mode. The sodium array provided a 1.6-fold signal-to-noise ratio advantage over a dual-nuclei birdcage coil in the center of the head and up to 2.3-fold gain in the periphery. The array enabled sodium MRI of the brain with 5-mm isotropic resolution in approximately 13 min, thus helping to overcome low sodium MR sensitivity and improving quantification in neurological studies. An eight-channel proton array was integrated into the sodium array to enable anatomical imaging.
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Affiliation(s)
- 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
| | - 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
| | - 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
| | - Yongxian Qian
- 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
| | - Fernando Boada
- 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
| | - Graham C. Wiggins
- 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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53
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Liu J, Shao Q, Wang Y, Adriany G, Bischof J, Van de Moortele PF, He B. In vivo imaging of electrical properties of an animal tumor model with an 8-channel transceiver array at 7 T using electrical properties tomography. Magn Reson Med 2017; 78:2157-2169. [PMID: 28112824 PMCID: PMC5522781 DOI: 10.1002/mrm.26609] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 12/20/2016] [Accepted: 12/22/2016] [Indexed: 02/02/2023]
Abstract
PURPOSE To develop and evaluate a technique for imaging electrical properties ((EPs), conductivity and permittivity) of an animal tumor model in vivo using MRI. METHODS Electrical properties were reconstructed from the calculated EP gradient, which was derived using two sets of measured transmit B1 magnitude and relative phase maps with the sample and radiofrequency (RF) coil oriented in the positive and negative z-directions, respectively. An eight-channel transceiver microstrip array RF coil fitting the size of the animal was developed for generating and mapping B1 fields to reconstruct EPs. The technique was evaluated at 7 tesla using a physical phantom and in vivo on two Copenhagen rats with subcutaneously implanted AT-1 rat prostate cancer on a hind limb. RESULTS The reconstructed EPs in the phantom experiment was in good agreement with the target EP map determined by a dielectric probe. Reconstructed conductivity map of the animals revealed the boundary between tumor and healthy tissue consistent with the boundary indicated by T1 -weighted MRI. CONCLUSION A technique for imaging EP of an animal tumor model using MRI has been developed with high sensitivity, accuracy, and resolution, as demonstrated in the phantom experiment. Further animal experiments are needed to demonstrate its translational value for tumor diagnosis. Magn Reson Med 78:2157-2169, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Jiaen Liu
- Department of Biomedical Engineering, University of
Minnesota, Minneapolis, MN, U.S
| | - Qi Shao
- Department of Biomedical Engineering, University of
Minnesota, Minneapolis, MN, U.S
| | - Yicun Wang
- Department of Biomedical Engineering, University of
Minnesota, Minneapolis, MN, U.S
| | - Gregor Adriany
- Center for Magnetic Resonance Research, University of
Minnesota, Minneapolis, MN, U.S
| | - John Bischof
- Department of Biomedical Engineering, University of
Minnesota, Minneapolis, MN, U.S
- Department of Mechanical Engineering, University of
Minnesota, Minneapolis, Minnesota, MN, U.S
- Institute for Engineering in Medicine, University of
Minnesota, Minneapolis, MN, U.S
| | | | - Bin He
- Department of Biomedical Engineering, University of
Minnesota, Minneapolis, MN, U.S
- Institute for Engineering in Medicine, University of
Minnesota, Minneapolis, MN, U.S
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Ianniello C, de Zwart JA, Duan Q, Deniz CM, Alon L, Lee JS, Lattanzi R, Brown R. Synthesized tissue-equivalent dielectric phantoms using salt and polyvinylpyrrolidone solutions. Magn Reson Med 2017; 80:413-419. [PMID: 29159985 DOI: 10.1002/mrm.27005] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 10/03/2017] [Accepted: 10/23/2017] [Indexed: 11/11/2022]
Abstract
PURPOSE To explore the use of polyvinylpyrrolidone (PVP) for simulated materials with tissue-equivalent dielectric properties. METHODS PVP and salt were used to control, respectively, relative permittivity and electrical conductivity in a collection of 63 samples with a range of solute concentrations. Their dielectric properties were measured with a commercial probe and fitted to a 3D polynomial in order to establish an empirical recipe. The material's thermal properties and MR spectra were measured. RESULTS The empirical polynomial recipe (available at https://www.amri.ninds.nih.gov/cgi-bin/phantomrecipe) provides the PVP and salt concentrations required for dielectric materials with permittivity and electrical conductivity values between approximately 45 and 78, and 0.1 to 2 siemens per meter, respectively, from 50 MHz to 4.5 GHz. The second- (solute concentrations) and seventh- (frequency) order polynomial recipe provided less than 2.5% relative error between the measured and target properties. PVP side peaks in the spectra were minor and unaffected by temperature changes. CONCLUSION PVP-based phantoms are easy to prepare and nontoxic, and their semitransparency makes air bubbles easy to identify. The polymer can be used to create simulated material with a range of dielectric properties, negligible spectral side peaks, and long T2 relaxation time, which are favorable in many MR applications. Magn Reson Med 80:413-419, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Carlotta Ianniello
- Center for Advanced Imaging Innovation and Research (CAI2R) and Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.,The Sackler Institute of Graduate Biomedical Science, New York University School of Medicine, New York, New York, USA
| | - Jacco A de Zwart
- Laboratory of Functional and Molecular Imaging, NINDS, National Institutes of Health, Bethesda, Maryland, USA
| | - Qi Duan
- Laboratory of Functional and Molecular Imaging, NINDS, National Institutes of Health, Bethesda, Maryland, USA
| | - Cem M Deniz
- Center for Advanced Imaging Innovation and Research (CAI2R) and Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA
| | - Leeor Alon
- Center for Advanced Imaging Innovation and Research (CAI2R) and Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA
| | - Jae-Seung Lee
- Center for Advanced Imaging Innovation and Research (CAI2R) and Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA
| | - Riccardo Lattanzi
- Center for Advanced Imaging Innovation and Research (CAI2R) and Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.,The Sackler Institute of Graduate Biomedical Science, New York University School of Medicine, New York, New York, USA
| | - Ryan Brown
- Center for Advanced Imaging Innovation and Research (CAI2R) and Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA
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55
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Vaidya MV, Deniz CM, Collins CM, Sodickson DK, Lattanzi R. Manipulating transmit and receive sensitivities of radiofrequency surface coils using shielded and unshielded high-permittivity materials. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2017; 31:355-366. [PMID: 29110240 DOI: 10.1007/s10334-017-0657-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 09/29/2017] [Accepted: 10/02/2017] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To use high-permittivity materials (HPM) positioned near radiofrequency (RF) surface coils to manipulate transmit/receive field patterns. MATERIALS AND METHODS A large HPM pad was placed below the RF coil to extend the field of view (FOV). The resulting signal-to-noise ratio (SNR) was compared with that of other coil configurations covering the same FOV in simulations and experiments at 7 T. Transmit/receive efficiency was evaluated when HPM discs with or without a partial shield were positioned at a distance from the coil. Finally, we evaluated the increase in transmit homogeneity for a four-channel array with HPM discs interposed between adjacent coil elements. RESULTS Various configurations of HPM increased SNR, transmit/receive efficiency, excitation/reception sensitivity overlap, and FOV when positioned near a surface coil. For a four-channel array driven in quadrature, shielded HPM discs enhanced the field below the discs as well as at the center of the sample as compared with other configurations with or without unshielded HPM discs. CONCLUSION Strategically positioning HPM at a distance from a surface coil or array can increase the overlap between excitation/reception sensitivities, and extend the FOV of a single coil for reduction of the number of channels in an array while minimally affecting the SNR.
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Affiliation(s)
- Manushka V Vaidya
- Center for Advanced Imaging Innovation and Research and the Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, 660 First Ave, Fourth Floor, New York, NY, 10016, USA. .,The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, 550 First Avenue, New York, NY, 10016, USA. .,NYU WIRELESS, 2 Metro Tech Center, Brooklyn, NY, 11201, USA.
| | - Cem M Deniz
- Center for Advanced Imaging Innovation and Research and the Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, 660 First Ave, Fourth Floor, New York, NY, 10016, USA.,NYU WIRELESS, 2 Metro Tech Center, Brooklyn, NY, 11201, USA
| | - Christopher M Collins
- Center for Advanced Imaging Innovation and Research and the Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, 660 First Ave, Fourth Floor, New York, NY, 10016, USA.,The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, 550 First Avenue, New York, NY, 10016, USA.,NYU WIRELESS, 2 Metro Tech Center, Brooklyn, NY, 11201, USA
| | - Daniel K Sodickson
- Center for Advanced Imaging Innovation and Research and the Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, 660 First Ave, Fourth Floor, New York, NY, 10016, USA.,The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, 550 First Avenue, New York, NY, 10016, USA.,NYU WIRELESS, 2 Metro Tech Center, Brooklyn, NY, 11201, USA
| | - Riccardo Lattanzi
- Center for Advanced Imaging Innovation and Research and the Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, 660 First Ave, Fourth Floor, New York, NY, 10016, USA.,The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, 550 First Avenue, New York, NY, 10016, USA.,NYU WIRELESS, 2 Metro Tech Center, Brooklyn, NY, 11201, USA
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56
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Gudino N, de Zwart JA, Duan Q, Dodd SJ, Murphy-Boesch J, van Gelderen P, Duyn JH. Optically controlled on-coil amplifier with RF monitoring feedback. Magn Reson Med 2017; 79:2833-2841. [PMID: 28905426 DOI: 10.1002/mrm.26916] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 08/18/2017] [Accepted: 08/18/2017] [Indexed: 12/27/2022]
Abstract
PURPOSE To develop a new optically controlled on-coil amplifier that facilitates safe use of multi-channel radiofrequency (RF) transmission in MRI by real-time monitoring of signal phase and amplitude. METHODS Monitoring was carried out with a 4-channel prototype system by sensing, down sampling, digitizing, and optically transmitting the RF transmit signal to a remote PC to control the amplifiers. Performance was evaluated with benchtop and 7 T MRI experiments. RESULTS Monitored amplitude and phase were stable across repetitions and had standard deviations of 0.061 μT and 0.0073 rad, respectively. The feedback system allowed inter-channel phase and B1 amplitude to be adjusted within two iterations. MRI experiments demonstrated the feasibility of this approach to perform safe and accurate multi-channel RF transmission and monitoring at high field. CONCLUSION We demonstrated a 4-channel transceiver system based on optically controlled on-coil amplifiers with RF signal monitoring and feedback control. The approach allows the safe and precise control of RF transmission fields, required to achieve uniform excitation at high field. Magn Reson Med 79:2833-2841, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Natalia Gudino
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Jacco A de Zwart
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Qi Duan
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Stephen J Dodd
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Joe Murphy-Boesch
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Peter van Gelderen
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Jeff H Duyn
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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Neves AL, Georget E, Cochinaire N, Sabouroux P. Real-time microwave sensor system for detection of polluting substances in pure water. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:084706. [PMID: 28863705 DOI: 10.1063/1.4998982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
In the present work, a real-time coaxial sensor for detecting foreign substances in aqueous solutions was developed and tested. This tool, based on a coaxial propagation line for determining the electromagnetic parameters of materials, was updated into a liquid permittivity monitoring sensor of continuous flow. A few solutions of different nature were tested, and while adding a liquid or electrolyte substance, named "pollutant," variations in the base solution were documented. Ethanol and water mixtures were used as reference, while the ability of the system to detect emulsions (such as oil in water solutions) was also evaluated. The system shows great potential for the quantification and qualification of liquid mixtures, having a threshold of reduced volume/volume fractions of foreign substances or pollutants, a property which is shown to be extremely useful in an analogue of high glycaemia (diabetes disease)-thus, opening the possibilities of monitoring biological liquids.
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Affiliation(s)
- A L Neves
- Aix Marseille University, CNRS, Centrale Marseille, Institut Fresnel, F-13013 Marseille, France
| | - E Georget
- CEA-Saclay, DRF/I2BM/Neurospin, 91191 Gif-sur-Yvette Cedex, France
| | - N Cochinaire
- Aix Marseille University, CNRS, Centrale Marseille, Institut Fresnel, F-13013 Marseille, France
| | - P Sabouroux
- Aix Marseille University, CNRS, Centrale Marseille, Institut Fresnel, F-13013 Marseille, France
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58
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Ipek Ö. Radio-frequency coils for ultra-high field magnetic resonance. Anal Biochem 2017; 529:10-16. [DOI: 10.1016/j.ab.2017.03.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 03/24/2017] [Accepted: 03/27/2017] [Indexed: 10/19/2022]
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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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60
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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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61
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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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62
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Gudino N, Duan Q, de Zwart JA, Murphy-Boesch J, Dodd SJ, Merkle H, van Gelderen P, Duyn JH. Optically controlled switch-mode current-source amplifiers for on-coil implementation in high-field parallel transmission. Magn Reson Med 2015; 76:340-9. [PMID: 26256671 DOI: 10.1002/mrm.25857] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 06/23/2015] [Accepted: 07/12/2015] [Indexed: 01/20/2023]
Abstract
PURPOSE We tested the feasibility of implementing parallel transmission (pTX) for high-field MRI using a radiofrequency (RF) amplifier design to be located on or in the immediate vicinity of an RF transmit coil. METHOD We designed a current-source switch-mode amplifier based on miniaturized, nonmagnetic electronics. Optical RF carrier and envelope signals to control the amplifier were derived, through a custom-built interface, from the RF source accessible in the scanner control. Amplifier performance was tested by benchtop measurements as well as with imaging at 7T (300 MHz) and 11.7 T (500 MHz). The ability to perform pTX was evaluated by measuring interchannel coupling and phase adjustment in a two-channel setup. RESULTS The amplifier delivered in excess of 44 W RF power and caused minimal interference with MRI. The interface derived accurate optical control signals with carrier frequencies ranging from 64 to 750 MHz. Decoupling better than 14 dB was obtained between two coil loops separated by only 1 cm. Application to MRI was demonstrated by acquiring artifact-free images at 7 T and 11.7 T. CONCLUSION We propose an optically controlled miniaturized RF amplifier for on-coil implementation at high fields that should facilitate implementation of high-density pTX arrays. Magn Reson Med 76:340-349, 2016. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Natalia Gudino
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Qi Duan
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Jacco A de Zwart
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Joe Murphy-Boesch
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Stephen J Dodd
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Hellmut Merkle
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Peter van Gelderen
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Jeff H Duyn
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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63
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Graessl A, Ruehle A, Waiczies H, Resetar A, Hoffmann SH, Rieger J, Wetterling F, Winter L, Nagel AM, Niendorf T. Sodium MRI of the human heart at 7.0 T: preliminary results. NMR IN BIOMEDICINE 2015; 29:1131-44. [PMID: 26082025 DOI: 10.1002/nbm.3290] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 02/25/2015] [Accepted: 02/25/2015] [Indexed: 05/05/2023]
Abstract
The objective of this work was to examine the feasibility of three-dimensional (3D) and whole heart coverage (23)Na cardiac MRI at 7.0 T including single-cardiac-phase and cinematic (cine) regimes. A four-channel transceiver RF coil array tailored for (23)Na MRI of the heart at 7.0 T (f = 78.5 MHz) is proposed. An integrated bow-tie antenna building block is used for (1)H MR to support shimming, localization and planning in a clinical workflow. Signal absorption rate simulations and assessment of RF power deposition were performed to meet the RF safety requirements. (23) Na cardiac MR was conducted in an in vivo feasibility study. 3D gradient echo (GRE) imaging in conjunction with Cartesian phase encoding (total acquisition time T(AQ) = 6 min 16 s) and whole heart coverage imaging employing a density-adapted 3D radial acquisition technique (T(AQ) = 18 min 20 s) were used. For 3D GRE-based (23)Na MRI, acquisition of standard views of the heart using a nominal in-plane resolution of (5.0 × 5.0) mm(2) and a slice thickness of 15 mm were feasible. For whole heart coverage 3D density-adapted radial (23)Na acquisitions a nominal isotropic spatial resolution of 6 mm was accomplished. This improvement versus 3D conventional GRE acquisitions reduced partial volume effects along the slice direction and enabled retrospective image reconstruction of standard or arbitrary views of the heart. Sodium cine imaging capabilities were achieved with the proposed RF coil configuration in conjunction with 3D radial acquisitions and cardiac gating. Cardiac-gated reconstruction provided an enhancement in blood-myocardium contrast of 20% versus the same data reconstructed without cardiac gating. The proposed transceiver array enables (23)Na MR of the human heart at 7.0 T within clinical acceptable scan times. This capability is in positive alignment with the needs of explorations that are designed to examine the potential of (23)Na MRI for the assessment of cardiovascular and metabolic diseases.
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Affiliation(s)
- Andreas Graessl
- Berlin Ultrahigh Field Facility (BUFF), Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany
| | - Anjuli Ruehle
- Berlin Ultrahigh Field Facility (BUFF), Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany
| | | | - Ana Resetar
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Stefan H Hoffmann
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | | | | | - Lukas Winter
- Berlin Ultrahigh Field Facility (BUFF), Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany
| | - Armin M Nagel
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Thoralf Niendorf
- Berlin Ultrahigh Field Facility (BUFF), Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany
- Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
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64
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Duan Q, Nair G, Gudino N, de Zwart JA, van Gelderen P, Murphy-Boesch J, Reich DS, Duyn JH, Merkle H. A 7T spine array based on electric dipole transmitters. Magn Reson Med 2015; 74:1189-97. [PMID: 26190585 DOI: 10.1002/mrm.25817] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/30/2015] [Accepted: 05/27/2015] [Indexed: 11/10/2022]
Abstract
PURPOSE The goal of this study was to explore the feasibility of using an array of electric dipole antennas for RF transmission in spine MRI at high fields. METHOD A two-channel transmit array based on an electric dipole design was quantitatively optimized for 7T spine imaging and integrated with a receive array combining eight loop coils. Using B1+ mapping, the transmit efficiency of the dipole array was compared with a design using quadrature loop pairs. The radiofrequency energy deposition for each array was measured using a home-built dielectric phantom and MR thermometry. The performance of the proposed array was qualitatively demonstrated in human studies. RESULTS The results indicate dramatically improved transmit efficiency for the dipole design compared with the loop excitation. A gain of up to 76% was achieved within the spinal region. CONCLUSION For imaging of the spine, electric dipole-based transmitters provide an attractive alternative to the traditional loop-based design. Easy integration with existing receive array technology facilitates practical use at high fields.
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Affiliation(s)
- Qi Duan
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Govind Nair
- Division of Neuroimmunology and Neurovirology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Natalia Gudino
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Jacco A de Zwart
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Peter van Gelderen
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Joe Murphy-Boesch
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Daniel S Reich
- Division of Neuroimmunology and Neurovirology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Jeff H Duyn
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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