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Dudysheva N, Mauconduit F, Abdeddaim R, Gapais PF, Hosseinnezhadian S, Dubois M, Amadon A, Boulant N, Hertz-Pannier L, Vignaud A. The restricted SAR protocol: A method to assess MRI coil prototypes in an unconditionally safe manner. Magn Reson Med 2024; 91:1723-1734. [PMID: 38084471 DOI: 10.1002/mrm.29962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 10/24/2023] [Accepted: 11/17/2023] [Indexed: 02/03/2024]
Abstract
PURPOSE Testing an RF coil prototype on subjects involves laborious verifications to ensure its safety. In particular, it requires preliminary electromagnetic simulations and their validations on phantoms to accurately predict the specific absorption rate (SAR). For coil design validation with a simpler safety procedure, the restricted SAR (rS) mode is proposed, enabling representative first experiments in vivo. The goal of the developed approach is to accelerate the transition of a custom coil system from prototype to clinical use. METHODS The restricted specific absorption rate (SAR) (rS) mode imposes a radical limitation on the transmitted RF power based on a worst-case scenario of local RF power absorption. The limitations used are independent of the SAR spatial distribution, making this approach unconditionally safe. The developed rS protocol contains the sequences required for coil evaluation and satisfies the imposed rS conditions. It provides a quantitative characterization of the coil transmission and reception profiles and a qualitative evaluation of the anatomical images. Protocol validation was performed on commercial and pre-industrial prototype coils on a small cohort of healthy volunteers. RESULTS The proposed rS protocol enables coil evaluation within an acquisition time compatible with common clinical protocol duration. The total time of all evaluation steps does not exceed 17 min. At the same time, the global SAR remains 100 times less than the International Electrotechnical Commission safety limit for played sequences. CONCLUSION The rS protocol allows characterizing and comparing coil prototypes on volunteers without extensive electromagnetic calculations and phantom validations in an unconditionally safe way.
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Affiliation(s)
- Natalia Dudysheva
- Paris-Saclay University, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
- Multiwave Imaging, Marseille, France
| | - Franck Mauconduit
- Paris-Saclay University, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Redha Abdeddaim
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, Institut Marseille Imaging, Marseille, France
| | | | | | | | - Alexis Amadon
- Paris-Saclay University, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Nicolas Boulant
- Paris-Saclay University, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Lucie Hertz-Pannier
- Paris-Saclay University, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Alexandre Vignaud
- Paris-Saclay University, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
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2
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Boulant N, Le Ster C, Amadon A, Aubert G, Beckett A, Belorgey J, Bonnelye C, Bosch D, Brunner DO, Dilasser G, Dubois O, Ehses P, Feinberg D, Feizollah S, Gras V, Gross S, Guihard Q, Lannou H, Le Bihan D, Mauconduit F, Molinié F, Nunio F, Pruessmann K, Quettier L, Scheffler K, Stöcker T, Tardif C, Ugurbil K, Vignaud A, Vu A, Wu X. The possible influence of third-order shim coils on gradient-magnet interactions: an inter-field and inter-site study. MAGMA 2024; 37:169-183. [PMID: 38197908 PMCID: PMC10995016 DOI: 10.1007/s10334-023-01138-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 11/28/2023] [Accepted: 11/30/2023] [Indexed: 01/11/2024]
Abstract
OBJECTIVE To assess the possible influence of third-order shim coils on the behavior of the gradient field and in gradient-magnet interactions at 7 T and above. MATERIALS AND METHODS Gradient impulse response function measurements were performed at 5 sites spanning field strengths from 7 to 11.7 T, all of them sharing the same exact whole-body gradient coil design. Mechanical fixation and boundary conditions of the gradient coil were altered in several ways at one site to study the impact of mechanical coupling with the magnet on the field perturbations. Vibrations, power deposition in the He bath, and field dynamics were characterized at 11.7 T with the third-order shim coils connected and disconnected inside the Faraday cage. RESULTS For the same whole-body gradient coil design, all measurements differed greatly based on the third-order shim coil configuration (connected or not). Vibrations and gradient transfer function peaks could be affected by a factor of 2 or more, depending on the resonances. Disconnecting the third-order shim coils at 11.7 T also suppressed almost completely power deposition peaks at some frequencies. DISCUSSION Third-order shim coil configurations can have major impact in gradient-magnet interactions with consequences on potential hardware damage, magnet heating, and image quality going beyond EPI acquisitions.
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Affiliation(s)
- Nicolas Boulant
- CEA, CNRS, BAOBAB, NeuroSpin, University Paris-Saclay, 91191, Gif Sur Yvette Cedex, France.
| | - Caroline Le Ster
- CEA, CNRS, BAOBAB, NeuroSpin, University Paris-Saclay, 91191, Gif Sur Yvette Cedex, France
| | - Alexis Amadon
- CEA, CNRS, BAOBAB, NeuroSpin, University Paris-Saclay, 91191, Gif Sur Yvette Cedex, France
| | - Guy Aubert
- CEA, Irfu, DACM, University Paris-Saclay, Gif Sur Yvette, France
| | - Alexander Beckett
- Brain Imaging Center and Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA
- Advanced MRI Technologies, Sebastopol, CA, USA
| | - Jean Belorgey
- CEA, Irfu, DIS, University Paris-Saclay, Gif Sur Yvette, France
| | - Cédric Bonnelye
- CEA, CNRS, BAOBAB, NeuroSpin, University Paris-Saclay, 91191, Gif Sur Yvette Cedex, France
| | - Dario Bosch
- Department for Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | | | | | - Olivier Dubois
- CEA, Irfu, DIS, University Paris-Saclay, Gif Sur Yvette, France
| | | | - David Feinberg
- Brain Imaging Center and Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA
- Advanced MRI Technologies, Sebastopol, CA, USA
| | - Sajjad Feizollah
- Montreal Neurological Institute-Hospital, McGill University, Montreal, QC, Canada
| | - Vincent Gras
- CEA, CNRS, BAOBAB, NeuroSpin, University Paris-Saclay, 91191, Gif Sur Yvette Cedex, France
| | | | - Quentin Guihard
- CEA, Irfu, DIS, University Paris-Saclay, Gif Sur Yvette, France
| | - Hervé Lannou
- CEA, Irfu, DACM, University Paris-Saclay, Gif Sur Yvette, France
| | - Denis Le Bihan
- CEA, CNRS, BAOBAB, NeuroSpin, University Paris-Saclay, 91191, Gif Sur Yvette Cedex, France
| | - Franck Mauconduit
- CEA, CNRS, BAOBAB, NeuroSpin, University Paris-Saclay, 91191, Gif Sur Yvette Cedex, France
| | | | - François Nunio
- CEA, Irfu, DIS, University Paris-Saclay, Gif Sur Yvette, France
| | | | - Lionel Quettier
- CEA, Irfu, DACM, University Paris-Saclay, Gif Sur Yvette, France
| | - Klaus Scheffler
- Department for Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Tony Stöcker
- Center for Neurogenerative Diseases, Bonn, Germany
| | - Christine Tardif
- Montreal Neurological Institute-Hospital, McGill University, Montreal, QC, Canada
| | - Kamil Ugurbil
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | - Alexandre Vignaud
- CEA, CNRS, BAOBAB, NeuroSpin, University Paris-Saclay, 91191, Gif Sur Yvette Cedex, France
| | - An Vu
- University of California, San Francisco, CA, USA
- San Francisco VA Health Care System, San Francisco, CA, USA
| | - Xiaoping Wu
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
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Gapais PF, Luong M, Nizery F, Maitre G, Giacomini E, Guillot J, Vignaud A, Berrahou D, Dubois M, Abdeddaim R, Georget E, Hosseinnezhadian S, Amadon A. Efficiently building receive arrays with electromagnetic simulations and additive manufacturing: A two-layer, 32-channel prototype for 7T brain MRI. Magn Reson Med 2024; 91:1254-1267. [PMID: 37986237 DOI: 10.1002/mrm.29931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 10/26/2023] [Accepted: 10/30/2023] [Indexed: 11/22/2023]
Abstract
PURPOSE We propose a comprehensive workflow to design and build fully customized dense receive arrays for MRI, providing prediction of SNR and g-factor. Combined with additive manufacturing, this method allows an efficient implementation for any arbitrary loop configuration. To demonstrate the methodology, an innovative two-layer, 32-channel receive array is proposed. METHODS The design workflow is based on numerical simulations using a commercial 3D electromagnetic software associated with circuit model co-simulations to provide the most accurate results in an efficient time. A model to compute the noise covariance matrix from circuit model scattering parameters is proposed. A 32-channel receive array at 7 T is simulated and fabricated with a two-layer design made of non-geometrically decoupled loops. Decoupling between loops is achieved using home-built direct high-impedance preamplifiers. The loops are 3D-printed with a new additive manufacturing technique to speed up integration while preserving the detailed geometry as simulated. The SNR and parallel-imaging performances of the proposed design are compared with a commercial coil, and in vivo images are acquired. RESULTS The comparison of SNR and g-factors showed a good agreement between simulations and measurements. Experimental values are comparable with the ones measured on the commercial coil. Preliminary in vivo images also ensured the absence of any unexpected artifacts. CONCLUSION A new design and performance analysis workflow is proposed and tested with a non-conventional 32-channel prototype at 7 T. Additive manufacturing of dense arrays of loops for brain imaging at ultrahigh field is validated for clinical use.
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Affiliation(s)
- Paul-François Gapais
- Université Paris-Saclay, CEA, CNRS, Joliot, NeuroSpin, BAOBAB, Gif-sur-Yvette, France
- Multiwave Imaging SAS, Marseille, France
| | - Michel Luong
- Université Paris-Saclay, CEA, Irfu, DACM, Gif-sur-Yvette, France
| | - François Nizery
- Université Paris-Saclay, CEA, Irfu, LCAP, Gif-sur-Yvette, France
| | - Gabriel Maitre
- Université Paris-Saclay, CEA, Irfu, LCAP, Gif-sur-Yvette, France
| | - Eric Giacomini
- Université Paris-Saclay, CEA, CNRS, Joliot, NeuroSpin, BAOBAB, Gif-sur-Yvette, France
| | - Jules Guillot
- Université Paris-Saclay, CEA, CNRS, Joliot, NeuroSpin, BAOBAB, Gif-sur-Yvette, France
| | - Alexandre Vignaud
- Université Paris-Saclay, CEA, CNRS, Joliot, NeuroSpin, BAOBAB, Gif-sur-Yvette, France
| | | | | | - Redha Abdeddaim
- Aix-Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, Marseille, France
| | | | | | - Alexis Amadon
- Université Paris-Saclay, CEA, CNRS, Joliot, NeuroSpin, BAOBAB, Gif-sur-Yvette, France
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4
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Mazancieux A, Mauconduit F, Amadon A, Willem de Gee J, Donner TH, Meyniel F. Brainstem fMRI signaling of surprise across different types of deviant stimuli. Cell Rep 2023; 42:113405. [PMID: 37950868 PMCID: PMC10698303 DOI: 10.1016/j.celrep.2023.113405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/10/2023] [Accepted: 10/24/2023] [Indexed: 11/13/2023] Open
Abstract
Detection of deviant stimuli is crucial to orient and adapt our behavior. Previous work shows that deviant stimuli elicit phasic activation of the locus coeruleus (LC), which releases noradrenaline and controls central arousal. However, it is unclear whether the detection of behaviorally relevant deviant stimuli selectively triggers LC responses or other neuromodulatory systems (dopamine, serotonin, and acetylcholine). We combine human functional MRI (fMRI) recordings optimized for brainstem imaging with pupillometry to perform a mapping of deviant-related responses in subcortical structures. Participants have to detect deviant items in a "local-global" paradigm that distinguishes between deviance based on the stimulus probability and the sequence structure. fMRI responses to deviant stimuli are distributed in many cortical areas. Both types of deviance elicit responses in the pupil, LC, and other neuromodulatory systems. Our results reveal that the detection of task-relevant deviant items recruits the same multiple subcortical systems across computationally different types of deviance.
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Affiliation(s)
- Audrey Mazancieux
- Cognitive Neuroimaging Unit, Institut National de la Santé et de la Recherche Médicale, Commissariat à l'Energie Atomique et aux énergies alternatives, Centre national de la recherche scientifique, Université Paris-Saclay, NeuroSpin center, 91191 Gif/Yvette, France.
| | - Franck Mauconduit
- NeuroSpin, CEA, CNRS, BAOBAB, Université Paris-Saclay, Gif-Sur-Yvette, France
| | - Alexis Amadon
- NeuroSpin, CEA, CNRS, BAOBAB, Université Paris-Saclay, Gif-Sur-Yvette, France
| | - Jan Willem de Gee
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Tobias H Donner
- Section Computational Cognitive Neuroscience, Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Florent Meyniel
- Cognitive Neuroimaging Unit, Institut National de la Santé et de la Recherche Médicale, Commissariat à l'Energie Atomique et aux énergies alternatives, Centre national de la recherche scientifique, Université Paris-Saclay, NeuroSpin center, 91191 Gif/Yvette, France; Institut de neuromodulation, GHU Paris, psychiatrie et neurosciences, centre hospitalier Sainte-Anne, pôle hospitalo-universitaire 15, Université Paris Cité, Paris, France.
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5
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Meneses BP, Stockmann JP, Arango N, Gapais PF, Giacomini E, Mauconduit F, Gras V, Boulant N, Vignaud A, Luong M, Amadon A. Shim Coils Tailored for Correcting B0 Inhomogeneity in the Human Brain (SCOTCH): Design Methodology and 48-Channel Prototype Assessment in 7-Tesla MRI. Neuroimage 2022; 261:119498. [PMID: 35917918 DOI: 10.1016/j.neuroimage.2022.119498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 06/30/2022] [Accepted: 07/19/2022] [Indexed: 10/31/2022] Open
Abstract
Increased static field inhomogeneities are a burden for human brain MRI at Ultra-High-Field. In particular they cause enhanced Echo-Planar image distortions and signal losses due to magnetic susceptibility gradients at air-tissue interfaces in the subject's head. In the past decade, Multi-Coil Arrays (MCA) have been proposed to shim the field in the brain better than the 2nd or 3rd order Spherical Harmonic (SH) coils usually offered by MRI manufacturers. Here we present a novel MCA, named SCOTCH, optimized for whole brain shimming. Based on a cylindrical structure, it features several layers of small coils whose shape, size and location are found from a principal component analysis of ideal stream functions computed from an internal 100-brain fieldmap database. From an Open-Access external database of 126 brains, our SCOTCH implementation is shown to be equivalent to a partial 7th-order SH system with unlimited power, outperforming all known existing MCA prototypes. This result is further confirmed by a low-cost 30-cm diameter SCOTCH prototype built with 48 coils on 3 layers, and tested on 7 volunteers at 7T with a parallel-transmit RF coil made to be inserted in SCOTCH. Echo-Planar images of the subject brains before and after SCOTCH shimming show large signal recoveries, especially in the prefrontal cortex.
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Affiliation(s)
- Bruno Pinho Meneses
- Universite Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191 Gif-sur-Yvette, France
| | - Jason P Stockmann
- Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, 02129, USA
| | - Nicolas Arango
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Paul-François Gapais
- Universite Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191 Gif-sur-Yvette, France
| | - Eric Giacomini
- Universite Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191 Gif-sur-Yvette, France
| | - Franck Mauconduit
- Universite Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191 Gif-sur-Yvette, France
| | - Vincent Gras
- Universite Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191 Gif-sur-Yvette, France
| | - Nicolas Boulant
- Universite Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191 Gif-sur-Yvette, France
| | - Alexandre Vignaud
- Universite Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191 Gif-sur-Yvette, France
| | - Michel Luong
- Universite Paris-Saclay, CEA, IRFU, DACM, Gif-sur-Yvette 91191, France
| | - Alexis Amadon
- Universite Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191 Gif-sur-Yvette, France.
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6
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Meneses BP, Amadon A. Physical limits to human brain B0 shimming with spherical harmonics, engineering implications thereof. MAGMA 2022; 35:923-941. [PMID: 35829793 DOI: 10.1007/s10334-022-01025-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 06/17/2022] [Accepted: 06/22/2022] [Indexed: 01/07/2023]
Abstract
OBJECTIVE As the MRI main magnetic field rises for improved signal-to-noise ratio, susceptibility-induced B0-inhomogeneity increases proportionally, aggravating related artifacts. Considering only susceptibility disparities between air and biological tissue, we explore the topological conditions for which perfect shimming could be performed in a Region of Interest (ROI) such as the human brain or part thereof. MATERIALS AND METHODS After theoretical considerations for perfect shimming, spherical harmonic (SH) shimming simulations of very high degree are performed, based on a 100-subject database of 1.7-mm-resolved brain fieldmaps acquired at 3T . In addition to the whole brain, shimmed ROIs include slabs targeting the prefrontal cortex, both or single temporal lobes, or spheres in the frontal brain above the nasal sinus. RESULTS AND DISCUSSION We show "perfect" SH shimming is possible only if the ROI can be contained in a sphere that does not enclose sources of magnetic field inhomogeneity, which are gathered at the air-tissue interface. We establish a [Formula: see text]Hz inhomogeneity hard shim limit at 7T for whole brain SH shimming, that can only be attained at shimming degree higher than 90. On the other hand, under limited power and SH degree resources, 3D region-specific shimming is shown to greatly improve homogeneity in critical zones such as the prefrontal cortex and around ear canals.
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Affiliation(s)
- Bruno Pinho Meneses
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191, Gif-sur-Yvette, France
| | - Alexis Amadon
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191, Gif-sur-Yvette, France.
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Abstract
We exploit the inter-subject similarity of inhomogeneous static magnetic field patterns arising in the human brain under MRI examination to design a small set of shim coils providing performance equivalent to numerous coils based on high-order Spherical Harmonics corrections. A hundred brain B 0-maps were first collected at 3 T. Ideal subject-specific electric current density stream functions are then computed with low power constraints, on a cylindrical surface. This step is repeated over tens of brain maps so that a Principal Component Analysis can be applied to the stream functions; the main components result in the small set of coils. Both 50-subject hold-out and 10-fold cross-validation are employed to evaluate consistency of the proposed system performance over a posteriori subjects. Simulations show that only three cylindrical coils manage to capture the principal magnetic field profiles in the human brain, thus providing a better static field inhomogeneity mitigation than that obtained from 16 unlimited-power high-order Spherical Harmonics coils, with inhomogeneity greatly reduced in the pre-frontal cortex compared to 2nd-order shimmed baseline field acquisitions. The approach provides a very reduced channel count system for mitigating complex B 0-inhomogeneity patterns. Thus, a compact, cost-effective system could be conceived and driven by relatively low-budget electronics. The method should therefore have a strong impact in both ultra-high and portable low-field MRI/MRS. Moreover, this technique can be applied to the design of shim coils addressing anatomies other than the brain.
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Affiliation(s)
- Bruno Pinho Meneses
- Universite Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191 Gif-sur-Yvette, France
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8
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Pinho AL, Amadon A, Fabre M, Dohmatob E, Denghien I, Torre JJ, Ginisty C, Becuwe-Desmidt S, Roger S, Laurier L, Joly-Testault V, Médiouni-Cloarec G, Doublé C, Martins B, Pinel P, Eger E, Varoquaux G, Pallier C, Dehaene S, Hertz-Pannier L, Thirion B. Subject-specific segregation of functional territories based on deep phenotyping. Hum Brain Mapp 2020; 42:841-870. [PMID: 33368868 PMCID: PMC7856658 DOI: 10.1002/hbm.25189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 07/11/2020] [Accepted: 08/04/2020] [Indexed: 11/08/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) has opened the possibility to investigate how brain activity is modulated by behavior. Most studies so far are bound to one single task, in which functional responses to a handful of contrasts are analyzed and reported as a group average brain map. Contrariwise, recent data-collection efforts have started to target a systematic spatial representation of multiple mental functions. In this paper, we leverage the Individual Brain Charting (IBC) dataset-a high-resolution task-fMRI dataset acquired in a fixed environment-in order to study the feasibility of individual mapping. First, we verify that the IBC brain maps reproduce those obtained from previous, large-scale datasets using the same tasks. Second, we confirm that the elementary spatial components, inferred across all tasks, are consistently mapped within and, to a lesser extent, across participants. Third, we demonstrate the relevance of the topographic information of the individual contrast maps, showing that contrasts from one task can be predicted by contrasts from other tasks. At last, we showcase the benefit of contrast accumulation for the fine functional characterization of brain regions within a prespecified network. To this end, we analyze the cognitive profile of functional territories pertaining to the language network and prove that these profiles generalize across participants.
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Affiliation(s)
| | - Alexis Amadon
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Murielle Fabre
- Cognitive Neuroimaging Unit, INSERM, CEA, Université Paris-Saclay, NeuroSpin center, Gif-sur-Yvette, 91191, France
| | - Elvis Dohmatob
- Université Paris-Saclay, Inria, CEA, Palaiseau, France.,Criteo AI Lab, Paris, France
| | - Isabelle Denghien
- Cognitive Neuroimaging Unit, INSERM, CEA, Université Paris-Saclay, NeuroSpin center, Gif-sur-Yvette, 91191, France
| | | | | | | | | | | | | | | | | | | | - Philippe Pinel
- Cognitive Neuroimaging Unit, INSERM, CEA, Université Paris-Saclay, NeuroSpin center, Gif-sur-Yvette, 91191, France
| | - Evelyn Eger
- Cognitive Neuroimaging Unit, INSERM, CEA, Université Paris-Saclay, NeuroSpin center, Gif-sur-Yvette, 91191, France
| | | | - Christophe Pallier
- Cognitive Neuroimaging Unit, INSERM, CEA, Université Paris-Saclay, NeuroSpin center, Gif-sur-Yvette, 91191, France
| | - Stanislas Dehaene
- Cognitive Neuroimaging Unit, INSERM, CEA, Université Paris-Saclay, NeuroSpin center, Gif-sur-Yvette, 91191, France.,Collège de France, Paris, France
| | - Lucie Hertz-Pannier
- CEA Saclay/DRF/IFJ/NeuroSpin/UNIACT, Paris, France.,UMR 1141, NeuroDiderot, Université de Paris, Paris, France
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9
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Tasserie J, Grigis A, Uhrig L, Dupont M, Amadon A, Jarraya B. Pypreclin: An automatic pipeline for macaque functional MRI preprocessing. Neuroimage 2020; 207:116353. [DOI: 10.1016/j.neuroimage.2019.116353] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/08/2019] [Accepted: 11/10/2019] [Indexed: 12/12/2022] Open
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10
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Saib G, Gras V, Mauconduit F, Boulant N, Vignaud A, Brugières P, Le Bihan D, Le Brusquet L, Amadon A. Time-of-flight angiography at 7T using TONE double spokes with parallel transmission. Magn Reson Imaging 2019; 61:104-115. [DOI: 10.1016/j.mri.2019.05.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 04/23/2019] [Accepted: 05/14/2019] [Indexed: 12/29/2022]
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11
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Tomi‐Tricot R, Gras V, Thirion B, Mauconduit F, Boulant N, Cherkaoui H, Zerbib P, Vignaud A, Luciani A, Amadon A. SmartPulse, a machine learning approach for calibration‐free dynamic RF shimming: Preliminary study in a clinical environment. Magn Reson Med 2019; 82:2016-2031. [DOI: 10.1002/mrm.27870] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 05/23/2019] [Accepted: 05/26/2019] [Indexed: 12/16/2022]
Affiliation(s)
| | - Vincent Gras
- NeuroSpin, CEA, Université Paris‐Saclay Gif‐sur‐Yvette France
| | | | | | - Nicolas Boulant
- NeuroSpin, CEA, Université Paris‐Saclay Gif‐sur‐Yvette France
| | - Hamza Cherkaoui
- Parietal, Inria Université Paris‐Saclay Gif‐sur‐Yvette France
| | - Pierre Zerbib
- Department of Radiology AP‐HP, CHU Henri Mondor Créteil France
| | | | - Alain Luciani
- Department of Radiology AP‐HP, CHU Henri Mondor Créteil France
- Université Paris‐Est Créteil Val de Marne Créteil France
- INSERM U955, Team 18, Molecular Virology and Immunology – Physiopathology and Therapeutic of Chronic Viral Hepatitis Créteil France
| | - Alexis Amadon
- NeuroSpin, CEA, Université Paris‐Saclay Gif‐sur‐Yvette France
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12
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Pinho AL, Amadon A, Ruest T, Fabre M, Dohmatob E, Denghien I, Ginisty C, Becuwe-Desmidt S, Roger S, Laurier L, Joly-Testault V, Médiouni-Cloarec G, Doublé C, Martins B, Pinel P, Eger E, Varoquaux G, Pallier C, Dehaene S, Hertz-Pannier L, Thirion B. Individual Brain Charting, a high-resolution fMRI dataset for cognitive mapping. Sci Data 2018; 5:180105. [PMID: 29893753 PMCID: PMC5996851 DOI: 10.1038/sdata.2018.105] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 02/23/2018] [Indexed: 01/11/2023] Open
Abstract
Functional Magnetic Resonance Imaging (fMRI) has furthered brain mapping on perceptual, motor, as well as higher-level cognitive functions. However, to date, no data collection has systematically addressed the functional mapping of cognitive mechanisms at a fine spatial scale. The Individual Brain Charting (IBC) project stands for a high-resolution multi-task fMRI dataset that intends to provide the objective basis toward a comprehensive functional atlas of the human brain. The data refer to a cohort of 12 participants performing many different tasks. The large amount of task-fMRI data on the same subjects yields a precise mapping of the underlying functions, free from both inter-subject and inter-site variability. The present article gives a detailed description of the first release of the IBC dataset. It comprises a dozen of tasks, addressing both low- and high- level cognitive functions. This openly available dataset is thus intended to become a reference for cognitive brain mapping.
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Affiliation(s)
- Ana Luísa Pinho
- Parietal Team, Inria, Saclay, France
- Neurospin, CEA, Saclay, France
- Paris-Saclay University, Paris, France
| | | | - Torsten Ruest
- Parietal Team, Inria, Saclay, France
- Neurospin, CEA, Saclay, France
- Paris-Saclay University, Paris, France
| | - Murielle Fabre
- Neurospin, CEA, Saclay, France
- Paris-Saclay University, Paris, France
- Cognitive Neuroimaging Unit, Saclay, France
- INSERM, Paris, France
- Paris-Sud University, Paris, France
| | - Elvis Dohmatob
- Parietal Team, Inria, Saclay, France
- Neurospin, CEA, Saclay, France
- Paris-Saclay University, Paris, France
| | - Isabelle Denghien
- Neurospin, CEA, Saclay, France
- Paris-Saclay University, Paris, France
- Cognitive Neuroimaging Unit, Saclay, France
- INSERM, Paris, France
- Paris-Sud University, Paris, France
| | | | | | - Séverine Roger
- Neurospin, CEA, Saclay, France
- UNIACT-U1129, Paris, France
| | | | | | | | | | | | | | - Evelyn Eger
- Neurospin, CEA, Saclay, France
- Paris-Saclay University, Paris, France
- Cognitive Neuroimaging Unit, Saclay, France
- INSERM, Paris, France
- Paris-Sud University, Paris, France
| | - Gaël Varoquaux
- Parietal Team, Inria, Saclay, France
- Neurospin, CEA, Saclay, France
- Paris-Saclay University, Paris, France
| | - Christophe Pallier
- Neurospin, CEA, Saclay, France
- Paris-Saclay University, Paris, France
- Cognitive Neuroimaging Unit, Saclay, France
- INSERM, Paris, France
- Paris-Sud University, Paris, France
| | - Stanislas Dehaene
- Neurospin, CEA, Saclay, France
- Paris-Saclay University, Paris, France
- Cognitive Neuroimaging Unit, Saclay, France
- INSERM, Paris, France
- Paris-Sud University, Paris, France
- Collège de France, Paris, France
| | - Lucie Hertz-Pannier
- Neurospin, CEA, Saclay, France
- INSERM, Paris, France
- UNIACT-U1129, Paris, France
- Paris Descartes University, Paris, France
| | - Bertrand Thirion
- Parietal Team, Inria, Saclay, France
- Neurospin, CEA, Saclay, France
- Paris-Saclay University, Paris, France
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13
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Gras V, Mauconduit F, Vignaud A, Amadon A, Le Bihan D, Stöcker T, Boulant N. Design of universal parallel-transmit refocusing k T -point pulses and application to 3D T 2 -weighted imaging at 7T. Magn Reson Med 2017; 80:53-65. [PMID: 29193250 DOI: 10.1002/mrm.27001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 10/02/2017] [Accepted: 10/16/2017] [Indexed: 12/18/2022]
Abstract
PURPOSE T2 -weighted sequences are particularly sensitive to the radiofrequency (RF) field inhomogeneity problem at ultra-high-field because of the errors accumulated by the imperfections of the train of refocusing pulses. As parallel transmission (pTx) has proved particularly useful to counteract RF heterogeneities, universal pulses were recently demonstrated to save precious time and computational efforts by skipping B1 calibration and online RF pulse tailoring. Here, we report a universal RF pulse design for non-selective refocusing pulses to mitigate the RF inhomogeneity problem at 7T in turbo spin-echo sequences with variable flip angles. METHOD Average Hamiltonian theory was used to synthetize a single non-selective refocusing pulse with pTx while optimizing its scaling properties in the presence of static field offsets. The design was performed under explicit power and specific absorption rate constraints on a database of 10 subjects using a 8Tx-32Rx commercial coil at 7T. To validate the proposed design, the RF pulses were tested in simulation and applied in vivo on 5 additional test subjects. RESULTS The root-mean-square rotation angle error (RA-NRMSE) evaluation and experimental data demonstrated great improvement with the proposed universal pulses (RA-NRMSE ∼8%) compared to the standard circularly polarized mode of excitation (RA-NRMSE ∼26%). CONCLUSION This work further completes the spectrum of 3D universal pulses to mitigate RF field inhomogeneity throughout all 3D MRI sequences without any pTx calibration. The approach returns a single pulse that can be scaled to match the desired flip angle train, thereby increasing the modularity of the proposed plug and play approach. Magn Reson Med 80:53-65, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Vincent Gras
- CEA, DRF, Joliot, NeuroSpin, Unirs, CEA Saclay, Gif sur Yvette, France
| | | | - Alexandre Vignaud
- CEA, DRF, Joliot, NeuroSpin, Unirs, CEA Saclay, Gif sur Yvette, France
| | - Alexis Amadon
- CEA, DRF, Joliot, NeuroSpin, Unirs, CEA Saclay, Gif sur Yvette, France
| | - Denis Le Bihan
- CEA, DRF, Joliot, NeuroSpin, Unirs, CEA Saclay, Gif sur Yvette, France
| | - Tony Stöcker
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Nicolas Boulant
- CEA, DRF, Joliot, NeuroSpin, Unirs, CEA Saclay, Gif sur Yvette, France
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14
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Tomi-Tricot R, Gras V, Mauconduit F, Legou F, Boulant N, Gebhardt M, Ritter D, Kiefer B, Zerbib P, Rahmouni A, Vignaud A, Luciani A, Amadon A. B1
artifact reduction in abdominal DCE-MRI using kT
-points: First clinical assessment of dynamic RF shimming at 3T. J Magn Reson Imaging 2017; 47:1562-1571. [DOI: 10.1002/jmri.25908] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 11/09/2017] [Indexed: 11/05/2022] Open
Affiliation(s)
| | - Vincent Gras
- NeuroSpin/UNIRS, CEA, Paris-Saclay; Gif-sur-Yvette Cedex France
| | | | - François Legou
- Department of Radiology; AP-HP, CHU Henri Mondor; Cedex France
| | - Nicolas Boulant
- NeuroSpin/UNIRS, CEA, Paris-Saclay; Gif-sur-Yvette Cedex France
| | | | | | | | - Pierre Zerbib
- Department of Radiology; AP-HP, CHU Henri Mondor; Cedex France
| | - Alain Rahmouni
- Department of Radiology; AP-HP, CHU Henri Mondor; Cedex France
- Université Paris-Est Créteil Val de Marne; Créteil Cedex France
| | | | - Alain Luciani
- Department of Radiology; AP-HP, CHU Henri Mondor; Cedex France
- Université Paris-Est Créteil Val de Marne; Créteil Cedex France
- INSERM Unité U955, Equipe 18, Molecular Virology and Immunology - Physiopathology and Therapeutic of Chronic Viral Hepatitis; Créteil France
| | - Alexis Amadon
- NeuroSpin/UNIRS, CEA, Paris-Saclay; Gif-sur-Yvette Cedex France
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15
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Gras V, Boland M, Vignaud A, Ferrand G, Amadon A, Mauconduit F, Le Bihan D, Stöcker T, Boulant N. Homogeneous non-selective and slice-selective parallel-transmit excitations at 7 Tesla with universal pulses: A validation study on two commercial RF coils. PLoS One 2017; 12:e0183562. [PMID: 28827835 PMCID: PMC5565195 DOI: 10.1371/journal.pone.0183562] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/07/2017] [Indexed: 11/21/2022] Open
Abstract
Parallel transmission (pTx) technology, despite its great potential to mitigate the transmit field inhomogeneity problem in magnetic resonance imaging at ultra-high field (UHF), suffers from a cumbersome calibration procedure, thereby making the approach problematic for routine use. The purpose of this work is to demonstrate on two different 7T systems respectively equipped with 8-transmit-channel RF coils from two different suppliers (Rapid-Biomed and Nova Medical), the benefit of so-called universal pulses (UP), optimized to produce uniform excitations in the brain in a population of adults and making unnecessary the calibration procedures mentioned above. Non-selective and slice-selective UPs were designed to return homogeneous excitation profiles throughout the brain simultaneously on a group of ten subjects, which then were subsequently tested on ten additional volunteers in magnetization prepared rapid gradient echo (MPRAGE) and multi-slice gradient echo (2D GRE) protocols. The results were additionally compared experimentally with the standard non-pTx circularly-polarized (CP) mode, and in simulation with subject-specific tailored excitations. For both pulse types and both coils, the UP mode returned a better signal and contrast homogeneity than the CP mode. Retrospective analysis of the flip angle (FA) suggests that the FA deviation from the nominal FA on average over a healthy adult population does not exceed 11% with the calibration-free parallel-transmit pulses whereas it goes beyond 25% with the CP mode. As a result the universal pulses designed in this work confirm their relevance in 3D and 2D protocols with commercially available equipment. Plug-and-play pTx implementations henceforth become accessible to exploit with more flexibility the potential of UHF for brain imaging.
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Affiliation(s)
- Vincent Gras
- CEA/DRF/Joliot/NeuroSpin/Unirs, Gif sur Yvette, France
| | - Markus Boland
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | | | | | - Alexis Amadon
- CEA/DRF/Joliot/NeuroSpin/Unirs, Gif sur Yvette, France
| | | | | | - Tony Stöcker
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Nicolas Boulant
- CEA/DRF/Joliot/NeuroSpin/Unirs, Gif sur Yvette, France
- * E-mail:
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Georget E, Luong M, Vignaud A, Giacomini E, Chazel E, Ferrand G, Amadon A, Mauconduit F, Enoch S, Tayeb G, Bonod N, Poupon C, Abdeddaim R. Stacked magnetic resonators for MRI RF coils decoupling. J Magn Reson 2017; 275:11-18. [PMID: 27951426 DOI: 10.1016/j.jmr.2016.11.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 11/01/2016] [Accepted: 11/20/2016] [Indexed: 06/06/2023]
Abstract
Parallel transmission is a very promising method to tackle B1+ field inhomogeneities at ultrahigh field in magnetic resonant imaging (MRI). This technique is however limited by the mutual coupling between the radiating elements. Here we propose to solve this problem by designing a passive magneto-electric resonator that we here refer to as stacked magnetic resonator (SMR). By combining numerical and experimental methodologies, we prove that this novelty passive solution allows an efficient decoupling of elements of a phased-array coil. We demonstrate the ability of this technique to significantly reduce by more than 10dB the coupling preserving the quality of images compared to ideally isolated linear resonators on a spherical salty agar gel phantom in a 7T MRI scanner.
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Affiliation(s)
- Elodie Georget
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | - Michel Luong
- Université Paris-Saclay, CEA-Saclay, DRF/IRFU/SACM, 91191 Gif-sur-Yvette Cedex, France.
| | - Alexandre Vignaud
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | - Eric Giacomini
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | - Edouard Chazel
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | - Guillaume Ferrand
- Université Paris-Saclay, CEA-Saclay, DRF/IRFU/SACM, 91191 Gif-sur-Yvette Cedex, France.
| | - Alexis Amadon
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | | | - Stefan Enoch
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France.
| | - Gérard Tayeb
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France.
| | - Nicolas Bonod
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France.
| | - Cyril Poupon
- Université Paris-Saclay, CEA-Saclay, DRF/I2BM/Neurospin/UNIRS, 91191 Gif-sur-Yvette Cedex, France.
| | - Redha Abdeddaim
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France.
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17
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Gras V, Vignaud A, Amadon A, Mauconduit F, Le Bihan D, Boulant N. New method to characterize and correct with sub-µs precision gradient delays in bipolar multispoke RF pulses. Magn Reson Med 2017; 78:2194-2202. [PMID: 28112827 DOI: 10.1002/mrm.26614] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 12/28/2016] [Accepted: 12/28/2016] [Indexed: 11/07/2022]
Abstract
PURPOSE Small gradient delays with respect to radiofrequency (RF) events can have disastrous effects on the performance of bipolar spokes RF pulses used in parallel transmission (pTx). In this work, we propose a new method to characterize and correct this delay with sub-µs precision. METHODS By determining experimentally the phase Δφ producing a 0 ° flip angle excitation in a α0°-α180°+Δφ bipolar two-spoke pulse configuration at multiple slice locations, we demonstrate the possibility of deducing the underlying gradient delay with precision. The technique also suggests prospectively compensating for the same delay by altering the phase of the second pulse. The approach was tested with a multislice gradient echo sequence on a phantom and on one healthy volunteer at 7 Tesla. RESULTS Application of the method returned an accuracy of approximately 50 ns on the gradient delay measurement, a performance shown in fact to be desirable for high-performance pTx 2D applications. Phase corrections of up to 180 ° on the second spoke RF pulse in the bipolar configuration allowed us to obtain similar performance as for unipolar designs, yet with significantly shorter excitations. CONCLUSIONS A simple and accurate gradient-delay calibration method was proposed that offers the possibility of using bipolar multispoke pulses in multislice protocols. Magn Reson Med 78:2194-2202, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Vincent Gras
- CEA, DRF, I2BM, NeuroSpin, Unirs, Gif-sur-Yvette, Cedex, France
| | | | - Alexis Amadon
- CEA, DRF, I2BM, NeuroSpin, Unirs, Gif-sur-Yvette, Cedex, France
| | | | - Denis Le Bihan
- CEA, DRF, I2BM, NeuroSpin, Unirs, Gif-sur-Yvette, Cedex, France
| | - Nicolas Boulant
- CEA, DRF, I2BM, NeuroSpin, Unirs, Gif-sur-Yvette, Cedex, France
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18
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Borghesani V, Pedregosa F, Buiatti M, Amadon A, Eger E, Piazza M. Word meaning in the ventral visual path: a perceptual to conceptual gradient of semantic coding. Neuroimage 2016; 143:128-140. [DOI: 10.1016/j.neuroimage.2016.08.068] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 08/29/2016] [Accepted: 08/31/2016] [Indexed: 10/21/2022] Open
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19
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Gras V, Vignaud A, Amadon A, Mauconduit F, Le Bihan D, Boulant N. In vivo demonstration of whole-brain multislice multispoke parallel transmit radiofrequency pulse design in the small and large flip angle regimes at 7 Tesla. Magn Reson Med 2016; 78:1009-1019. [PMID: 27774653 DOI: 10.1002/mrm.26491] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 09/07/2016] [Accepted: 09/12/2016] [Indexed: 11/07/2022]
Abstract
PURPOSE A multispoke specific absorption rate (SAR) -aware pulse design approach for homogeneous multiple-slice small and large flip angle (FA) excitations with parallel transmission is proposed. The approach aims at optimizing in a slice-specific manner the spokes locations and radiofrequency pulses. METHODS The problem is posed as a set of slice-specific magnitude-least-squares problems, linked together by hardware and SAR constraints, and solved jointly using an active-set algorithm. Average Hamiltonian theory is exploited in the large FA case to greatly reduce the computational burden. The approach is validated numerically by means of simulations and experimentally on two volunteers at 7 Tesla through application of a high-resolution T2*-weighted brain imaging protocol. RESULTS The optimization of up to 1300 variables under 745 explicit constraints could be performed in less than 1 and 4 min for the small and large FA cases, respectively. The joint design proves valuable for SAR demanding protocols. Compared with the conventional circularly polarized mode, the designed pulses increased the signal by more than 40% in 70% of the voxels. CONCLUSION The B1+ inhomogeneity problem was mitigated efficiently in a multislice near whole-brain coverage protocol in the small and large FA regimes using a rapid slice-specific pulse design algorithm where the pulses were optimized jointly. Magn Reson Med 78:1009-1019, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Gras V, Vignaud A, Amadon A, Le Bihan D, Boulant N. Universal pulses: A new concept for calibration-free parallel transmission. Magn Reson Med 2016; 77:635-643. [PMID: 26888654 DOI: 10.1002/mrm.26148] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 01/11/2016] [Accepted: 01/13/2016] [Indexed: 11/12/2022]
Abstract
PURPOSE A calibration-free parallel transmission method is investigated to mitigate the radiofrequency (RF) field inhomogeneity problem in brain imaging at 7 Tesla (T). THEORY AND METHODS Six volunteers were scanned to build a representative database of RF and static field maps at 7T. Small-tip-angle and inversion pulses were designed with joint kT -points trajectory optimization to work robustly on all six subjects. The returned "universal" pulses were then inserted in an MPRAGE sequence implemented on six additional volunteers without further field measurements and pulse optimizations. Similar acquisitions were performed in the circularly polarized mode and with subject-based optimizations for comparison. Performance of the different approaches was evaluated by means of image analysis and computation of the flip angle normalized root mean square errors (NRMSE). RESULTS For both the excitation and inversion, the universal pulses (NRMSE∼11%) outperformed the circularly polarized (NRMSE∼28%) and RF shim modes (NRMSE∼20%) across all volunteers and returned slightly worse results than for subject-based optimized pulses (NRMSE∼7%). CONCLUSION RF pulses can be designed to robustly mitigate the RF field inhomogeneity problem over a population class. This appears as a first step toward another plug and play parallel transmission solution where the pulse design can be done offline and without measuring subject-specific field maps. Magn Reson Med 77:635-643, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Vincent Gras
- NeuroSpin, CEA, DSV, Gif sur Yvette, Cedex, France
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21
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Gras V, Luong M, Amadon A, Boulant N. Joint design of kT-points trajectories and RF pulses under explicit SAR and power constraints in the large flip angle regime. J Magn Reson 2015; 261:181-189. [PMID: 26619073 DOI: 10.1016/j.jmr.2015.10.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 10/16/2015] [Accepted: 10/25/2015] [Indexed: 06/05/2023]
Abstract
In Magnetic Resonance Imaging at ultra-high field, kT-points radiofrequency pulses combined with parallel transmission are a promising technique to mitigate the B1 field inhomogeneity in 3D imaging applications. The optimization of the corresponding k-space trajectory for its slice-selective counterpart, i.e. the spokes method, has been shown in various studies to be very valuable but also dependent on the hardware and specific absorption rate constraints. Due to the larger number of degrees of freedom than for spokes excitations, joint design techniques based on the fine discretization (gridding) of the parameter space become hardly tractable for kT-points pulses. In this article, we thus investigate the simultaneous optimization of the 3D blipped k-space trajectory and of the kT-points RF pulses, using a magnitude least squares cost-function, with explicit constraints and in the large flip angle regime. A second-order active-set algorithm is employed due to its demonstrated success and robustness in similar problems. An analysis of global optimality and of the structure of the returned trajectories is proposed. The improvement provided by the k-space trajectory optimization is validated experimentally by measuring the flip angle on a spherical water phantom at 7T and via Quantum Process Tomography.
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Affiliation(s)
- Vincent Gras
- CEA, I2BM, NeuroSpin, UNIRS, Gif sur Yvette 91191 Cedex, France
| | - Michel Luong
- CEA, DSM, Irfu, SACM, Gif sur Yvette 91191 Cedex, France
| | - Alexis Amadon
- CEA, I2BM, NeuroSpin, UNIRS, Gif sur Yvette 91191 Cedex, France
| | - Nicolas Boulant
- CEA, I2BM, NeuroSpin, UNIRS, Gif sur Yvette 91191 Cedex, France.
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22
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Gras V, Vignaud A, Mauconduit F, Luong M, Amadon A, Le Bihan D, Boulant N. Signal-domain optimization metrics for MPRAGE RF pulse design in parallel transmission at 7 tesla. Magn Reson Med 2015; 76:1431-1442. [PMID: 26599411 DOI: 10.1002/mrm.26043] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 10/19/2015] [Accepted: 10/20/2015] [Indexed: 12/13/2022]
Abstract
PURPOSE Standard radiofrequency pulse design strategies focus on minimizing the deviation of the flip angle from a target value, which is sufficient but not necessary for signal homogeneity. An alternative approach, based directly on the signal, here is proposed for the MPRAGE sequence, and is developed in the parallel transmission framework with the use of the kT -points parametrization. METHODS The flip angle-homogenizing and the proposed methods were investigated numerically under explicit power and specific absorption rate constraints and tested experimentally in vivo on a 7 T parallel transmission system enabling real time local specific absorption rate monitoring. Radiofrequency pulse performance was assessed by a careful analysis of the signal and contrast between white and gray matter. RESULTS Despite a slight reduction of the flip angle uniformity, an improved signal and contrast homogeneity with a significant reduction of the specific absorption rate was achieved with the proposed metric in comparison with standard pulse designs. CONCLUSION The proposed joint optimization of the inversion and excitation pulses enables significant reduction of the specific absorption rate in the MPRAGE sequence while preserving image quality. The work reported thus unveils a possible direction to increase the potential of ultra-high field MRI and parallel transmission. Magn Reson Med 76:1431-1442, 2016. © 2015 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- V Gras
- CEA, I2BM, Neurospin, UNIRS, Gif sur Yvette 91191 Cedex, France
| | - A Vignaud
- CEA, I2BM, Neurospin, UNIRS, Gif sur Yvette 91191 Cedex, France
| | | | - M Luong
- CEA, DSM, Irfu, SACM, Gif sur Yvette 91191 Cedex, France
| | - A Amadon
- CEA, I2BM, Neurospin, UNIRS, Gif sur Yvette 91191 Cedex, France
| | - D Le Bihan
- CEA, I2BM, Neurospin, UNIRS, Gif sur Yvette 91191 Cedex, France
| | - N Boulant
- CEA, I2BM, Neurospin, UNIRS, Gif sur Yvette 91191 Cedex, France.
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23
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Dupas L, Massire A, Amadon A, Vignaud A, Boulant N. Two-spoke placement optimization under explicit specific absorption rate and power constraints in parallel transmission at ultra-high field. J Magn Reson 2015; 255:59-67. [PMID: 25912342 DOI: 10.1016/j.jmr.2015.03.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 03/17/2015] [Accepted: 03/19/2015] [Indexed: 06/04/2023]
Abstract
The spokes method combined with parallel transmission is a promising technique to mitigate the B1(+) inhomogeneity at ultra-high field in 2D imaging. To date however, the spokes placement optimization combined with the magnitude least squares pulse design has never been done in direct conjunction with the explicit Specific Absorption Rate (SAR) and hardware constraints. In this work, the joint optimization of 2-spoke trajectories and RF subpulse weights is performed under these constraints explicitly and in the small tip angle regime. The problem is first considerably simplified by making the observation that only the vector between the 2 spokes is relevant in the magnitude least squares cost-function, thereby reducing the size of the parameter space and allowing a more exhaustive search. The algorithm starts from a set of initial k-space candidates and performs in parallel for all of them optimizations of the RF subpulse weights and the k-space locations simultaneously, under explicit SAR and power constraints, using an active-set algorithm. The dimensionality of the spoke placement parameter space being low, the RF pulse performance is computed for every location in k-space to study the robustness of the proposed approach with respect to initialization, by looking at the probability to converge towards a possible global minimum. Moreover, the optimization of the spoke placement is repeated with an increased pulse bandwidth in order to investigate the impact of the constraints on the result. Bloch simulations and in vivo T2(∗)-weighted images acquired at 7 T validate the approach. The algorithm returns simulated normalized root mean square errors systematically smaller than 5% in 10 s.
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Affiliation(s)
- Laura Dupas
- CEA, DSV, I2BM, NeuroSpin, UNIRS, 91191 Gif-sur-Yvette, France.
| | | | - Alexis Amadon
- CEA, DSV, I2BM, NeuroSpin, UNIRS, 91191 Gif-sur-Yvette, France
| | | | - Nicolas Boulant
- CEA, DSV, I2BM, NeuroSpin, UNIRS, 91191 Gif-sur-Yvette, France
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Carlier PG, Azzabou N, de Sousa PL, Hicks A, Boisserie JM, Amadon A, Carlier RY, Wary C, Orlikowski D, Laforêt P. Skeletal muscle quantitative nuclear magnetic resonance imaging follow-up of adult Pompe patients. J Inherit Metab Dis 2015; 38:565-72. [PMID: 25749708 PMCID: PMC4432102 DOI: 10.1007/s10545-015-9825-9] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/03/2015] [Accepted: 02/10/2015] [Indexed: 12/25/2022]
Abstract
Adult late-onset Pompe disease is most often a slowly progressive limb-girdle and spine extensor muscle dystrophy, due to defective lysosomal acid maltase. With the exception of the few patients who present with a dramatically accelerated clinical course, standard diagnostic imaging fail to detect and evaluate disease progression between two successive visits. In muscle dystrophy of very rapid evolution, like the Duchenne disease, quantitative NMR imaging has successfully demonstrated its capacity to objectivate both disease activity and degenerative changes progression over short follow-up periods. The purpose of this retrospective monocentric open-label study was to investigate whether quantitative NMR imaging can monitor disease progression in adult Pompe patients despite its very slow nature. Quantitative imaging of Pompe patients succeeded in demonstrating that muscle fatty infiltration increased on average by 0.9%/year, with the hamstring and adductor muscles showing the fastest degradation. Muscle water T2 mapping revealed that 32% of all muscles had abnormally high T2 in at least one of two successive examinations. When muscle water T2 was abnormal, fatty degenerative changes were further increased by 0.61%/year. Enzyme replacement therapy resulted in 0.68%/year slowdown of the muscle fatty infiltration, in both muscles with normal and high T2s.
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Affiliation(s)
- Pierre G Carlier
- Institut de Myologie and CEA, DSV, IBM, MIRCen, Laboratoire de RMN, Pitie-Salpetriere University Hospital, Bd de l'Hôpital, 75651, Paris Cedex 13, France,
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Boulant N, Bottlaender M, Uhrig L, Giacomini E, Luong M, Amadon A, Massire A, Larrat B, Vignaud A. FID navigator-based MR thermometry method to monitor small temperature changes in the brain of ventilated animals. NMR Biomed 2015; 28:101-107. [PMID: 25388870 DOI: 10.1002/nbm.3232] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 10/07/2014] [Accepted: 10/08/2014] [Indexed: 06/04/2023]
Abstract
An MR thermometry method is proposed for measuring in vivo small temperature changes engendered by external RF heat sources. The method relies on reproducible and stable respiration and therefore currently applies to ventilated animals whose breathing is carefully controlled. It first consists in characterizing the stability of the main magnetic field as well as the variations induced by breathing during a first monitoring stage. Second, RF heating is applied while the phase and thus temperature evolutions are continuously measured, the corrections due to breathing and field drift being made thanks to the data accumulated during the first period. The RF heat source is finally stopped and the temperature rise likewise is continuously monitored during a third and last stage to observe the animal cooling down and to validate the assumptions made for correcting for the main field variation and the physiological noise. Experiments were performed with a clinical 7 T scanner on an anesthetized baboon and with a dedicated RF heating setup. Analysis of the data reveals a precision around 0.1°C, which allows us to reliably measure sub-degree temperature rises in the muscle and in the brain of the animal.
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Affiliation(s)
- Nicolas Boulant
- CEA/DSV/I2BM/NeuroSpin/UNIRS, CEA Saclay, 91191, Gif sur Yvette, France
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Fujiwara S, Uhrig L, Amadon A, Jarraya B, Le Bihan D. Quantification of iron in the non-human primate brain with diffusion-weighted magnetic resonance imaging. Neuroimage 2014; 102 Pt 2:789-97. [PMID: 25192653 DOI: 10.1016/j.neuroimage.2014.08.049] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 08/23/2014] [Accepted: 08/26/2014] [Indexed: 01/12/2023] Open
Abstract
Pathological iron deposits in the brain, especially within basal ganglia, are linked to severe neurodegenerative disorders like Parkinson's disease. As iron induces local changes in magnetic susceptibility, its presence can be visualized with magnetic resonance imaging (MRI). The usual approach, based on iron induced changes in magnetic relaxation (T2/T2'), is often prone, however, to confounding artifacts and lacks specificity. Here, we propose a new method to quantify and map iron deposits using water diffusion MRI. This method is based on the differential sensitivity of two image acquisition schemes to the local magnetic field gradients induced by iron deposits and their cross-term with gradient pulses used for diffusion encoding. Iron concentration could be imaged and estimated with high accuracy in the brain cortex, the thalamus, the substantia nigra and the globus pallidus of macaques, showing iron distributions in agreement with literature. Additionally, iron maps could clearly show a dramatic increase in iron content upon injection of an UltraSmall Particle Iron Oxide (USPIO) contrast agent, notably in the cortex and the thalamus, reflecting regional differences in blood volume. The method will benefit clinical investigations on the effect of iron deposits in the brain or other organs, as iron deposits are increasingly seen as a biomarker for a wide range of diseases, notably, neurodegenerative diseases in the pre-symptomatic stage. It also has the potential for quantifying variations in blood volume induced by brain activation in fMRI studies using USPIOs.
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Affiliation(s)
- Shunro Fujiwara
- Neurospin, Bâtiment 145, CEA-Saclay, Gif-sur-Yvette, 91191 Gif-sur-Yvette, France; Department of Neurosurgery, Iwate Medical University, 19-1 Uchimaru, Morioka, 0208505 Iwate, Japan
| | - Lynn Uhrig
- Neurospin, Bâtiment 145, CEA-Saclay, Gif-sur-Yvette, 91191 Gif-sur-Yvette, France; Equipe Avenir INSERM Bettencourt Schueller, Institut Fédératif de Recherche n°49, NeuroSpin, Bât. 145, CEA-Saclay, Gif-sur-Yvette, 91191 Gif-sur-Yvette, France
| | - Alexis Amadon
- Neurospin, Bâtiment 145, CEA-Saclay, Gif-sur-Yvette, 91191 Gif-sur-Yvette, France
| | - Béchir Jarraya
- Neurospin, Bâtiment 145, CEA-Saclay, Gif-sur-Yvette, 91191 Gif-sur-Yvette, France; Equipe Avenir INSERM Bettencourt Schueller, Institut Fédératif de Recherche n°49, NeuroSpin, Bât. 145, CEA-Saclay, Gif-sur-Yvette, 91191 Gif-sur-Yvette, France; Department of Neurosurgery, Neuromodulation unit, Foch Hospital, University of Versailles-Saint Quentin, 40 rue Worth, 92150 Suresnes, France
| | - Denis Le Bihan
- Neurospin, Bâtiment 145, CEA-Saclay, Gif-sur-Yvette, 91191 Gif-sur-Yvette, France.
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Ferrand G, Luong M, Cloos MA, Amadon A, Wackernagel H. Accelerating parallel transmit array B1 mapping in high field MRI with slice undersampling and interpolation by kriging. IEEE Trans Med Imaging 2014; 33:1726-1734. [PMID: 24816550 DOI: 10.1109/tmi.2014.2322440] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Transmit arrays have been developed to mitigate the RF field inhomogeneity commonly observed in high field magnetic resonance imaging (MRI), typically above 3T. To this end, the knowledge of the RF complex-valued B1 transmit-sensitivities of each independent radiating element has become essential. This paper details a method to speed up a currently available B1-calibration method. The principle relies on slice undersampling, slice and channel interleaving and kriging, an interpolation method developed in geostatistics and applicable in many domains. It has been demonstrated that, under certain conditions, kriging gives the best estimator of a field in a region of interest. The resulting accelerated sequence allows mapping a complete set of eight volumetric field maps of the human head in about 1 min. For validation, the accuracy of kriging is first evaluated against a well-known interpolation technique based on Fourier transform as well as to a B1-maps interpolation method presented in the literature. This analysis is carried out on simulated and decimated experimental B1 maps. Finally, the accelerated sequence is compared to the standard sequence on a phantom and a volunteer. The new sequence provides B1 maps three times faster with a loss of accuracy limited potentially to about 5%.
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Massire A, Vignaud A, Robert B, Le Bihan D, Boulant N, Amadon A. Parallel-transmission-enabled three-dimensional T2-weighted imaging of the human brain at 7 Tesla. Magn Reson Med 2014; 73:2195-203. [DOI: 10.1002/mrm.25353] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 06/02/2014] [Accepted: 06/13/2014] [Indexed: 11/09/2022]
Affiliation(s)
| | | | | | | | | | - Alexis Amadon
- CEA, DSV, I2BM, NeuroSpin; UNIRS Gif-sur-Yvette France
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Hoyos-Idrobo A, Weiss P, Massire A, Amadon A, Boulant N. On variant strategies to solve the magnitude least squares optimization problem in parallel transmission pulse design and under strict SAR and power constraints. IEEE Trans Med Imaging 2014; 33:739-748. [PMID: 24595346 DOI: 10.1109/tmi.2013.2295465] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Parallel transmission is a very promising candidate technology to mitigate the inevitable radio-frequency (RF) field inhomogeneity in magnetic resonance imaging at ultra-high field. For the first few years, pulse design utilizing this technique was expressed as a least squares problem with crude power regularizations aimed at controlling the specific absorption rate (SAR), hence the patient safety. This approach being suboptimal for many applications sensitive mostly to the magnitude of the spin excitation, and not its phase, the magnitude least squares (MLS) problem then was first formulated in 2007. Despite its importance and the availability of other powerful numerical optimization methods, the MLS problem yet has been faced almost exclusively by the pulse designer with the so-called variable exchange method. In this paper, we investigate various two-stage strategies consisting of different initializations and nonlinear programming approaches, and incorporate directly the strict SAR and hardware constraints. Several schemes such as sequential quadratic programming, interior point methods, semidefinite programming and magnitude squared least squares relaxations are studied both in the small and large tip angle regimes with RF and static field maps obtained in vivo on a human brain at 7T. Convergence and robustness of the different approaches are analyzed, and recommendations to tackle this specific problem are finally given. Small tip angle and inversion pulses are returned in a few seconds and in under a minute respectively while respecting the constraints, allowing the use of the proposed approach in routine.
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Boulant N, Massire A, Amadon A, Vignaud A. Radiofrequency pulse design in parallel transmission under strict temperature constraints. Magn Reson Med 2013; 72:679-88. [DOI: 10.1002/mrm.24974] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 09/06/2013] [Accepted: 09/08/2013] [Indexed: 11/08/2022]
Affiliation(s)
| | | | - Alexis Amadon
- CEA Saclay; I2BM, NeuroSpin, UNIRS; Gif sur Yvette France
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Massire A, Cloos MA, Vignaud A, Le Bihan D, Amadon A, Boulant N. Design of non-selective refocusing pulses with phase-free rotation axis by gradient ascent pulse engineering algorithm in parallel transmission at 7T. J Magn Reson 2013; 230:76-83. [PMID: 23454576 DOI: 10.1016/j.jmr.2013.01.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 01/09/2013] [Accepted: 01/15/2013] [Indexed: 06/01/2023]
Abstract
At ultra-high magnetic field (≥ 7T), B1 and ΔB0 non-uniformities cause undesired inhomogeneities in image signal and contrast. Tailored radiofrequency pulses exploiting parallel transmission have been shown to mitigate these phenomena. However, the design of large flip angle excitations, a prerequisite for many clinical applications, remains challenging due the non-linearity of the Bloch equation. In this work, we explore the potential of gradient ascent pulse engineering to design non-selective spin-echo refocusing pulses that simultaneously mitigate severe B1 and ΔB0 non-uniformities. The originality of the method lays in the optimization of the rotation matrices themselves as opposed to magnetization states. Consequently, the commonly used linear class of large tip angle approximation can be eliminated from the optimization procedure. This approach, combined with optimal control, provides additional degrees of freedom by relaxing the phase constraint on the rotation axis, and allows the derivative of the performance criterion to be found analytically. The method was experimentally validated on an 8-channel transmit array at 7T, using a water phantom with B1 and ΔB0 inhomogeneities similar to those encountered in the human brain. For the first time in MRI, the rotation matrix itself on every voxel was measured by using Quantum Process Tomography. The results are complemented with a series of spin-echo measurements comparing the proposed method against commonly used alternatives. Both experiments confirm very good performance, while simultaneously maintaining a low energy deposition and pulse duration compared to well-known adiabatic solutions.
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Affiliation(s)
- Aurélien Massire
- CEA, DSV, I2BM, NeuroSpin, LRMN, Gif-sur-Yvette Cedex 91191, France
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Streicher MN, Schäfer A, Ivanov D, Müller DK, Amadon A, Reimer E, Huber L, Dhital B, Rivera D, Kögler C, Trampel R, Pampel A, Turner R. Fast accurate MR thermometry using phase referenced asymmetric spin-echo EPI at high field. Magn Reson Med 2013; 71:524-33. [DOI: 10.1002/mrm.24681] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Markus N. Streicher
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Andreas Schäfer
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Dimo Ivanov
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Dirk K. Müller
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Alexis Amadon
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Enrico Reimer
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Laurentius Huber
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Bibek Dhital
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Debra Rivera
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Carsten Kögler
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Robert Trampel
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - André Pampel
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
| | - Robert Turner
- Max Planck Institute for Human Cognitive and Brain Sciences; Stephanstr. Leipzig Germany
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Cloos MA, Boulant N, Luong M, Ferrand G, Giacomini E, Hang MF, Wiggins CJ, Le Bihan D, Amadon A. Parallel-transmission-enabled magnetization-prepared rapid gradient-echo T1-weighted imaging of the human brain at 7 T. Neuroimage 2012; 62:2140-50. [PMID: 22659484 DOI: 10.1016/j.neuroimage.2012.05.068] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 04/20/2012] [Accepted: 05/24/2012] [Indexed: 12/26/2022] Open
Abstract
One of the promises of Ultra High Field (UHF) MRI scanners is to bring finer spatial resolution in the human brain images due to an increased signal to noise ratio. However, at such field strengths, the spatial non-uniformity of the Radio Frequency (RF) transmit profiles challenges the applicability of most MRI sequences, where the signal and contrast levels strongly depend on the flip angle (FA) homogeneity. In particular, the MP-RAGE sequence, one of the most commonly employed 3D sequences to obtain T1-weighted anatomical images of the brain, is highly sensitive to these spatial variations. These cause deterioration in image quality and complicate subsequent image post-processing such as automated tissue segmentation at UHF. In this work, we evaluate the potential of parallel-transmission (pTx) to obtain high-quality MP-RAGE images of the human brain at 7 T. To this end, non-selective transmit-SENSE pulses were individually tailored for each of 8 subjects under study, and applied to an 8-channel transmit-array. Such RF pulses were designed both for the low-FA excitation train and the 180° inversion preparation involved in the sequence, both utilizing the recently introduced k(T)-point trajectory. The resulting images were compared with those obtained from the conventional method and from subject-specific RF-shimmed excitations. In addition, four of the volunteers were scanned at 3 T for benchmarking purposes (clinical setup without pTx). Subsequently, automated tissue classification was performed to provide a more quantitative measure of the final image quality. Results indicated that pTx could already significantly improve image quality at 7 T by adopting a suitable RF-Shim. Exploiting the full potential of the pTx-setup, the proposed k(T)-point method provided excellent inversion fidelity, comparable to what is commonly only achievable at 3 T with energy intensive adiabatic pulses. Furthermore, the cumulative energy deposition was simultaneously reduced by over 40% compared to the conventional adiabatic inversions. Regarding the low-FA k(T)-point based excitations, the FA uniformity achieved at 7 T surpassed what is typically obtained at 3 T. Subsequently, automated white and gray matter segmentation not only confirmed the expected improvements in image quality, but also suggests that care should be taken to properly account for the strong local susceptibility effects near cranial cavities. Overall, these findings indicate that the k(T)-point-based pTx solution is an excellent candidate for UHF 3D imaging, where patient safety is a major concern due to the increase of specific absorption rates.
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Affiliation(s)
- M A Cloos
- CEA, DSV, I2BM, NeuroSpin, LRMN, Gif-sur-Yvette, France.
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Massire A, Cloos MA, Luong M, Amadon A, Vignaud A, Wiggins CJ, Boulant N. Thermal simulations in the human head for high field MRI using parallel transmission. J Magn Reson Imaging 2012; 35:1312-21. [PMID: 22241685 DOI: 10.1002/jmri.23542] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 11/28/2011] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To investigate, via numerical simulations, the compliance of the specific absorption rate (SAR) versus temperature guidelines for the human head in magnetic resonance imaging procedures utilizing parallel transmission at high field. MATERIALS AND METHODS A combination of finite element and finite-difference time-domain methods was used to calculate the evolution of the temperature distribution in the human head for a large number of parallel transmission scenarios. The computations were performed on a new model containing 20 anatomical structures. RESULTS Among all the radiofrequency field exposure schemes simulated, the recommended 39°C maximum local temperature was never exceeded when the local 10-g average SAR threshold was reached. On the other hand, the maximum temperature barely complied with its guideline when the global SAR reached 3.2 W/kg. The maximal temperature in the eye could very well rise by more than 1°C in both cases. CONCLUSION Considering parallel transmission, the recommended values of local 10-g SAR may remain a relevant metric to ensure that the local temperature inside the human head never exceeds 39°C, although it can lead to rises larger than 1°C in the eye. Monitoring temperature instead of SAR can provide increased flexibility in pulse design for parallel transmission.
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Ferrand G, Luong M, Amadon A, Cloos MA, Giacomini E, Darrasse L. Generalized double-acquisition imaging for radiofrequency inhomogeneity mitigation in high-field MRI: Experimental proof and performance analysis. Magn Reson Med 2011; 67:175-82. [DOI: 10.1002/mrm.23006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 04/05/2011] [Accepted: 04/23/2011] [Indexed: 11/08/2022]
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Cloos MA, Boulant N, Luong M, Ferrand G, Giacomini E, Le Bihan D, Amadon A. kT -points: short three-dimensional tailored RF pulses for flip-angle homogenization over an extended volume. Magn Reson Med 2011; 67:72-80. [PMID: 21590724 DOI: 10.1002/mrm.22978] [Citation(s) in RCA: 159] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 04/02/2011] [Accepted: 04/05/2011] [Indexed: 01/17/2023]
Abstract
With Transmit SENSE, we demonstrate the feasibility of uniformly exciting a volume such as the human brain at 7T through the use of an original minimalist transmit k-space coverage, referred to as "k(T) -points." Radio-frequency energy is deposited only at a limited number of k-space locations in the vicinity of the center to counteract transmit sensitivity inhomogeneities. The resulting nonselective pulses are short and need little energy compared to adiabatic or other B 1+-robust pulses available in the literature, making them good candidates for short-repetition time 3D sequences at high field. Experimental verification was performed on three human volunteers at 7T by means of an 8-channel transmit array system. On average, whereas the standard circularly polarized excitation resulted in a 33%-flip angle spread (standard deviation over mean) throughout the brain, and a static radio-frequency shim showed flip angle variations of 17% and up, application of k(T) -point-based excitations demonstrated excellent flip angle uniformity (8%) for a small target flip angle and with sub-millisecond durations.
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Affiliation(s)
- M A Cloos
- CEA, DSV, I2BM, NeuroSpin, LRMN, Gif-sur-Yvette, France.
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Szwed M, Dehaene S, Kleinschmidt A, Eger E, Valabrègue R, Amadon A, Cohen L. Specialization for written words over objects in the visual cortex. Neuroimage 2011; 56:330-44. [PMID: 21296170 DOI: 10.1016/j.neuroimage.2011.01.073] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 12/26/2010] [Accepted: 01/28/2011] [Indexed: 10/18/2022] Open
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Cloos MA, Luong M, Ferrand G, Amadon A, Le Bihan D, Boulant N. Local SAR reduction in parallel excitation based on channel-dependent Tikhonov parameters. J Magn Reson Imaging 2011; 32:1209-16. [PMID: 21031527 DOI: 10.1002/jmri.22346] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To reduce the local specific absorption rate (SAR) obtained with tailored pulses using parallel transmission while obtaining homogenous flip angle distributions. MATERIALS AND METHODS Finite-element simulations on a human head model were performed to obtain the individual magnetic and electric field maps for each channel of a parallel transmit array. From those maps, SAR calculations were carried out for "spoke" pulses designed to homogenize the flip angle in an axial slice of a human brain at 7 T. Based on the assumption that the coil element nearest to the maximum local energy deposition is the dominant contributor to the corresponding hot spot, a set of channel-dependent Tikhonov parameters is optimized. Resulting SAR distributions are compared to the ones obtained when using standard pulse design approaches based on a single Tikhonov parameter. RESULTS In both the small- and large-tip-angle domain, the simulations show local SAR reductions by over a factor of 2 (4) for a well-centered (off-centered) head model at the expense of roughly 1% increment in flip-angle spread over the slice. CONCLUSION Significant SAR reductions can be obtained by optimizing channel-dependent Tikhonov parameters based on the relation between coil elements and SAR hot spot positions.
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Affiliation(s)
- Martijn Anton Cloos
- Commissariat à l'Énergie Atomique, Direction des Sciences du Vivant, Institut d'Imagerie Biomédicale, NeuroSpin, Laboratoire de Résonance Magnétique Nucléaire, Gif-sur-Yvette, France.
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Boulant N, Cloos MA, Amadon A. B1 and B0 inhomogeneity mitigation in the human brain at 7 T with selective pulses by using average Hamiltonian theory. Magn Reson Med 2010; 65:680-91. [PMID: 20949589 DOI: 10.1002/mrm.22658] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 08/31/2010] [Accepted: 09/01/2010] [Indexed: 11/08/2022]
Abstract
A novel method based on average Hamiltonian theory to design selective pulses is reported. With this tool, it is first shown how to shape the radiofrequency and gradient pulses to generate a desired rotation matrix, which is independent of the position through the slice of interest. After theoretical examination of the concept, it is applied to the strongly modulating pulses' recipe developed by the same authors and initially designed to be nonselective, to mitigate the amplitude of (excitation) radiofrequency field and amplitude of static (polarizing) field inhomogeneity problems at high field. Two in vivo human brain imaging experiments at 7 T are reported to prove the validity of the technique.
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Affiliation(s)
- N Boulant
- CEA, DSV, I2BM, NeuroSpin, LRMN, Gif sur Yvette Cedex, France.
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Boulant N, Mangin JF, Amadon A. Counteracting radio frequency inhomogeneity in the human brain at 7 Tesla using strongly modulating pulses. Magn Reson Med 2009; 61:1165-72. [DOI: 10.1002/mrm.21955] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Suarez SV, Amadon A, Giacomini E, Wiklund A, Changeux JP, Le Bihan D, Granon S. Brain activation by short-term nicotine exposure in anesthetized wild-type and beta2-nicotinic receptors knockout mice: a BOLD fMRI study. Psychopharmacology (Berl) 2009; 202:599-610. [PMID: 18818904 DOI: 10.1007/s00213-008-1338-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 09/10/2008] [Indexed: 01/08/2023]
Abstract
RATIONALE The behavioral effects of nicotine and the role of the beta2-containing nicotinic receptors in these behaviors are well documented. However, the behaviors altered by nicotine rely on the functioning on multiple brain circuits where the high-affinity beta2-containing nicotinic receptors (beta2*nAChRs) are located. OBJECTIVES We intend to see which brain circuits are activated when nicotine is given in animals naïve for nicotine and whether the beta2*nAChRs are needed for its activation of the blood oxygen level dependent (BOLD) signal in all brain areas. MATERIALS AND METHODS We used functional magnetic resonance imaging (fMRI) to measure the brain activation evoked by nicotine (1 mg/kg delivered at a slow rate for 45 min) in anesthetized C57BL/6J mice and beta2 knockout (KO) mice. RESULTS Acute nicotine injection results in a significant increased activation in anterior frontal, motor, and somatosensory cortices and in the ventral tegmental area and the substantia nigra. Anesthetized mice receiving no nicotine injection exhibited a major decreased activation in all cortical and subcortical structures, likely due to prolonged anesthesia. At a global level, beta2 KO mice were not rescued from the globally declining BOLD signal. However, nicotine still activated regions of a meso-cortico-limbic circuit likely via alpha7 nicotinic receptors. CONCLUSIONS Acute nicotine exposure compensates for the drop in brain activation due to anesthesia through the meso-cortico-limbic network via the action of nicotine on beta2*nAChRs. The developed fMRI method is suitable for comparing responses in wild-type and mutant mice.
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Affiliation(s)
- S V Suarez
- Unité de Neurobiologie Intégrative du Système Cholinergique, URA CNRS 2182, Institut Pasteur, Département de Neuroscience, 25 rue du Dr. Roux, 75015 Paris, France
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Valette J, Guillermier M, Boumezbeur F, Poupon C, Amadon A, Hantraye P, Lebon V. B(0) homogeneity throughout the monkey brain is strongly improved in the sphinx position as compared to the supine position. J Magn Reson Imaging 2006; 23:408-12. [PMID: 16456823 DOI: 10.1002/jmri.20511] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To map B(0) distortions throughout the monkey brain in the two positions commonly used for NMR studies (the prone sphinx position and the supine position) in order to test the hypothesis that B(0) homogeneity in the sphinx position is significantly improved as compared to the supine position. MATERIALS AND METHODS Three macaque monkeys were installed in the two positions in a 3T whole-body MR system without shim correction. B(0) maps were acquired using a 3D gradient double-echo sequence, and field dispersion throughout the brain was quantified. In addition, field maps and localized (1)H spectra were acquired after first-order shimming was performed. RESULTS The field maps collected in the three animals were highly reproducible. B(0) dispersion throughout the brain was typically two to three times greater in the supine position than in the sphinx position. Although first-order shimming proved relatively more efficient in the supine position, B(0) dispersion still remained greater in the supine than in the sphinx position. These findings can be explained by the thickness of outer brain tissues. CONCLUSION This work demonstrates that the sphinx position is highly favorable in terms of B(0) homogeneity. It should prove useful for NMR exploration of the monkey brain, particularly at high fields where B(0) inhomogeneity associated with susceptibility artifacts is increased.
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Affiliation(s)
- Julien Valette
- Comissariat à l'energie atomique, Service hospitalier Frédéric Joliot, 4 Place du Général Leclerc, 91401 Orsay, France
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Abstract
Although over the last 20 years diffusion MRI has become an established technique with a great impact on health care and neurosciences, like any other MRI technique it remains subject to artifacts and pitfalls. In addition to common MRI artifacts, there are specific problems that one may encounter when using MRI scanner gradient hardware for diffusion MRI, especially in terms of eddy currents and sensitivity to motion. In this article we review those artifacts and pitfalls on a qualitative basis, and introduce possible strategies that have been developed to mitigate or overcome them.
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Affiliation(s)
- Denis Le Bihan
- Anatomical and Functional Neuroimaging Laboratory, Service Hospitalier Frédéric Joliot, Commissariat à l'Energie Atomique, Orsay, France.
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Abe F, Akimoto H, Akopian A, Albrow MG, Amadon A, Amendolia SR, Amidei D, Antos J, Aota S, Apollinari G, Arisawa T, Asakawa T, Ashmanskas W, Atac M, Azzi-Bacchetta P, Bacchetta N, Bagdasarov S, Bailey MW, de Barbaro P, Barbaro-Galtieri A, Barnes VE, Barnett BA, Barone M, Bauer G, Baumann T, Bedeschi F, Behrends S, Belforte S, Bellettini G, Bellinger J, Benjamin D, Bensinger J, Beretvas A, Berge JP, Berryhill J, Bertolucci S, Bettelli S, Bevensee B, Bhatti A, Biery K, Bigongiari C, Binkley M, Bisello D, Blair RE, Blocker C, Blusk S, Bodek A, Bokhari W, Bolla G, Bonushkin Y, Bortoletto D, Boudreau J, Breccia L, Bromberg C, Bruner N, Brunetti R, Buckley-Geer E, Budd HS, Burkett K, Busetto G, Byon-Wagner A, Byrum KL, Campbell M, Caner A, Carithers W, Carlsmith D, Cassada J, Castro A, Cauz D, Cerri A, Chang PS, Chang PT, Chao HY, Chapman J, Cheng MT, Chertok M, Chiarelli G, Chiou CN, Chlebana F, Christofek L, Chu ML, Cihangir S, Clark AG, Cobal M, Cocca E, Contreras M, Conway J, Cooper J, Cordelli M, Costanzo D, Couyoumtzelis C, Cronin-Hennessy D, Culbertson R, Dagenhart D, Daniels T, DeJongh F, Dell’Agnello S, Dell’Orso M, Demina R, Demortier L, Deninno M, Derwent PF, Devlin T, Dittmann JR, Donati S, Done J, Dorigo T, Eddy N, Einsweiler K, Elias JE, Ely R, Engels E, Erdmann W, Errede D, Errede S, Fan Q, Feild RG, Feng Z, Ferretti C, Fiori I, Flaugher B, Foster GW, Franklin M, Freeman J, Friedman J, Frisch H, Fukui Y, Gadomski S, Galeotti S, Gallinaro M, Ganel O, Garcia-Sciveres M, Garfinkel AF, Gay C, Geer S, Gerdes DW, Giannetti P, Giokaris N, Giromini P, Giusti G, Gold M, Gordon A, Goshaw AT, Gotra Y, Goulianos K, Grassmann H, Groer L, Grosso-Pilcher C, Guillian G, Guimaraes da Costa J, Guo RS, Haber C, Hafen E, Hahn SR, Hamilton R, Handa T, Handler R, Happacher F, Hara K, Hardman AD, Harris RM, Hartmann F, Hauser J, Hayashi E, Heinrich J, Hao W, Hinrichsen B, Hoffman KD, Hohlmann M, Holck C, Hollebeek R, Holloway L, Huang Z, Huffman BT, Hughes R, Huston J, Huth J, Ikeda H, Incagli M, Incandela J, Introzzi G, Iwai J, Iwata Y, James E, Jensen H, Joshi U, Kajfasz E, Kambara H, Kamon T, Kaneko T, Karr K, Kasha H, Kato Y, Keaffaber TA, Kelley K, Kennedy RD, Kephart R, Kestenbaum D, Khazins D, Kikuchi T, Kim BJ, Kim HS, Kim SH, Kim YK, Kirsch L, Klimenko S, Knoblauch D, Koehn P, Köngeter A, Kondo K, Konigsberg J, Kordas K, Korytov A, Kovacs E, Kowald W, Kroll J, Kruse M, Kuhlmann SE, Kuns E, Kurino K, Kuwabara T, Laasanen AT, Nakano I, Lami S, Lammel S, Lamoureux JI, Lancaster M, Lanzoni M, Latino G, LeCompte T, Leone S, Lewis JD, Limon P, Lindgren M, Liss TM, Liu JB, Liu YC, Lockyer N, Long O, Loomis C, Loreti M, Lucchesi D, Lukens P, Lusin S, Lys J, Maeshima K, Maksimovic P, Mangano M, Mariotti M, Marriner JP, Martin A, Matthews JAJ, Mazzanti P, McIntyre P, Melese P, Menguzzato M, Menzione A, Meschi E, Metzler S, Miao C, Miao T, Michail G, Miller R, Minato H, Miscetti S, Mishina M, Miyashita S, Moggi N, Moore E, Morita Y, Mukherjee A, Muller T, Murat P, Murgia S, Nakada H, Nakano I, Nelson C, Neuberger D, Newman-Holmes C, Ngan CYP, Nodulman L, Nomerotski A, Oh SH, Ohmoto T, Ohsugi T, Oishi R, Okabe M, Okusawa T, Olsen J, Pagliarone C, Paoletti R, Papadimitriou V, Pappas SP, Parashar N, Parri A, Patrick J, Pauletta G, Paulini M, Perazzo A, Pescara L, Peters MD, Phillips TJ, Piacentino G, Pillai M, Pitts KT, Plunkett R, Pompos A, Pondrom L, Proudfoot J, Ptohos F, Punzi G, Ragan K, Reher D, Reischl M, Ribon A, Rimondi F, Ristori L, Robertson WJ, Rodrigo T, Rolli S, Rosenson L, Roser R, Saab T, Sakumoto WK, Saltzberg D, Sansoni A, Santi L, Sato H, Schlabach P, Schmidt EE, Schmidt MP, Scott A, Scribano A, Segler S, Seidel S, Seiya Y, Semeria F, Shah T, Shapiro MD, Shaw NM, Shepard PF, Shibayama T, Shimojima M, Shochet M, Siegrist J, Sill A, Sinervo P, Singh P, Sliwa K, Smith C, Snider FD, Spalding J, Speer T, Sphicas P, Spinella F, Spiropulu M, Spiegel L, Stanco L, Steele J, Stefanini A, Ströhmer R, Strologas J, Strumia F, Stuart D, Sumorok K, Suzuki J, Suzuki T, Takahashi T, Takano T, Takashima R, Takikawa K, Tanaka M, Tannenbaum B, Tartarelli F, Taylor W, Tecchio M, Teng PK, Teramoto Y, Terashi K, Tether S, Theriot D, Thomas TL, Thurman-Keup R, Timko M, Tipton P, Titov A, Tkaczyk S, Toback D, Tollefson K, Tollestrup A, Toyoda H, Trischuk W, de Troconiz JF, Truitt S, Tseng J, Turini N, Uchida T, Ukegawa F, Valls J, van den Brink SC, Vejcik S, Velev G, Vidal R, Vilar R, Vucinic D, Wagner RG, Wagner RL, Wahl J, Wallace NB, Walsh AM, Wang C, Wang CH, Wang MJ, Warburton A, Watanabe T, Watts T, Webb R, Wei C, Wenzel H, Wester WC, Wicklund AB, Wicklund E, Wilkinson R, Williams HH, Wilson P, Winer BL, Winn D, Wolinski D, Wolinski J, Worm S, Wu X, Wyss J, Yagil A, Yao W, Yasuoka K, Yeh GP, Yeh P, Yoh J, Yosef C, Yoshida T, Yu I, Zanetti A, Zetti F, Zucchelli S. Search for the rare decayW±→Ds±γinpp¯collisions ats=1.8TeV. Int J Clin Exp Med 1998. [DOI: 10.1103/physrevd.58.091101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abe F, Akimoto H, Akopian A, Albrow MG, Amadon A, Amendolia SR, Amidei D, Antos J, Aota S, Apollinari G, Arisawa T, Asakawa T, Ashmanskas W, Atac M, Azzi-Bacchetta P, Bacchetta N, Bagdasarov S, Bailey MW, de Barbaro P, Barbaro-Galtieri A, Barnes VE, Barnett BA, Barone M, Bauer G, Baumann T, Bedeschi F, Behrends S, Belforte S, Bellettini G, Bellinger J, Benjamin D, Bensinger J, Beretvas A, Berge JP, Berryhill J, Bertolucci S, Bettelli S, Bevensee B, Bhatti A, Biery K, Bigongiari C, Binkley M, Bisello D, Blair RE, Blocker C, Blusk S, Bodek A, Bokhari W, Bolla G, Bonushkin Y, Bortoletto D, Boudreau J, Breccia L, Bromberg C, Bruner N, Brunetti R, Buckley-Geer E, Budd HS, Burkett K, Busetto G, Byon-Wagner A, Byrum KL, Campbell M, Caner A, Carithers W, Carlsmith D, Cassada J, Castro A, Cauz D, Cerri A, Chang PS, Chang PT, Chao HY, Chapman J, Cheng MT, Chertok M, Chiarelli G, Chiou CN, Chlebana F, Christofek L, Chu ML, Cihangir S, Clark AG, Cobal M, Cocca E, Contreras M, Conway J, Cooper J, Cordelli M, Costanzo D, Couyoumtzelis C, Cronin-Hennessy D, Culbertson R, Dagenhart D, Daniels T, DeJongh F, Dell’Agnello S, Dell’Orso M, Demina R, Demortier L, Deninno M, Derwent PF, Devlin T, Dittmann JR, Donati S, Done J, Dorigo T, Eddy N, Einsweiler K, Elias JE, Ely R, Engles E, Erdmann W, Errede D, Errede S, Fan Q, Feild RG, Feng Z, Ferretti C, Fiori I, Flaugher B, Foster GW, Franklin M, Freeman J, Friedman J, Frisch H, Fukui Y, Gadomski S, Galeotti S, Gallinaro M, Ganel O, Garcia-Sciveres M, Garfinkel AF, Gay C, Geer S, Gerdes DW, Giannetti P, Giokaris N, Giromini P, Giusti G, Gold M, Gordon A, Goshaw AT, Gotra Y, Goulianos K, Grassmann H, Groer L, Grosso-Pilcher C, Guillian G, Guimaraes da Costa J, Guo RS, Haber C, Hafen E, Hahn SR, Hamilton R, Handa T, Handler R, Happacher F, Hara K, Hardman AD, Harris RM, Hartmann F, Hauser J, Hayashi E, Heinrich J, Hao W, Hinrichsen B, Hoffman KD, Hohlmann M, Holck C, Hollebeek R, Holloway L, Huang Z, Huffman BT, Hughes R, Huston J, Huth J, Ikeda H, Incagli M, Incandela J, Introzzi G, Iwai J, Iwata Y, James E, Jensen H, Joshi U, Kadel RW, Kajfasz E, Kambara H, Kamon T, Kaneko T, Karr K, Kasha H, Kato Y, Keaffaber TA, Kelley K, Kennedy RD, Kephart R, Kestenbaum D, Khazins D, Kikuchi T, Kim BJ, Kim HS, Kim SH, Kim YK, Kirsch L, Klimenko S, Knoblauch D, Koehn P, Köngeter A, Kondo K, Konigsberg J, Kordas K, Korytov A, Kovacs E, Kowald W, Kroll J, Kruse M, Kuhlmann SE, Kuns E, Kurino K, Kuwabara T, Laasanen AT, Nakano I, Lami S, Lammel S, Lamoureux JI, Lancaster M, Lanzoni M, Latino G, LeCompte T, Leone S, Lewis JD, Limon P, Lindgren M, Liss TM, Liu JB, Liu YC, Lockyer N, Long O, Loomis C, Loreti M, Lucchesi D, Lukens P, Lusin S, Lys J, Maeshima K, Maksimovic P, Mangano M, Mariotti M, Marriner JP, Martin A, Matthews JAJ, Mazzanti P, McIntyre P, Melese P, Menguzzato M, Menzione A, Meschi E, Metzler S, Miao C, Miao T, Michail G, Miller R, Minato H, Miscetti S, Mishina M, Miyashita S, Moggi N, Moore E, Morita Y, Mukherjee A, Muller T, Murat P, Murgia S, Nakada H, Nakano I, Nelson C, Neuberger D, Newman-Holmes C, Ngan CYP, Nodulman L, Nomerotski A, Oh SH, Ohmoto T, Ohsugi T, Oishi R, Okabe M, Okusawa T, Olsen J, Pagliarone C, Paoletti R, Papadimitriou V, Pappas SP, Parashar N, Parri A, Patrick J, Pauletta G, Paulini M, Perazzo A, Pescara L, Peters MD, Phillips TJ, Piacentino G, Pillai M, Pitts KT, Plunkett R, Pompos A, Pondrom L, Proudfoot J, Ptohos F, Punzi G, Ragan K, Reher D, Reischl M, Ribon A, Rimondi F, Ristori L, Robertson WJ, Rodrigo T, Rolli S, Rosenson L, Roser R, Saab T, Sakumoto WK, Saltzberg D, Sansoni A, Santi L, Sato H, Schlabach P, Schmidt EE, Schmidt MP, Scott A, Scribano A, Segler S, Seidel S, Seiya Y, Semeria F, Shah T, Shapiro MD, Shaw NM, Shepard PF, Shibayama T, Shimojima M, Shochet M, Siegrist J, Sill A, Sinervo P, Singh P, Sliwa K, Smith C, Snider FD, Spalding J, Speer T, Sphicas P, Spinella F, Spiropulu M, Spiegel L, Stanco L, Steele J, Stefanini A, Ströhmer R, Strologas J, Strumia F, Stuart D, Sumorok K, Suzuki J, Suzuki T, Takahashi T, Takano T, Takashima R, Takikawa K, Tanaka M, Tannenbaum B, Tartarelli F, Taylor W, Tecchio M, Teng PK, Teramoto Y, Terashi K, Tether S, Theriot D, Thomas TL, Thurman-Keup R, Timko M, Tipton P, Titov A, Tkaczyk S, Toback D, Tollefson K, Tollestrup A, Toyoda H, Trischuk W, de Troconiz JF, Truitt S, Tseng J, Turini N, Uchida T, Ukegawa F, Valls J, van den Brink SC, Vejcik S, Velev G, Vidal R, Vilar R, Vucinic D, Wagner RG, Wagner RL, Wahl J, Wallace NB, Walsh AM, Wang C, Wang CH, Wang MJ, Warburton A, Watanabe T, Watts T, Webb R, Wei C, Wenzel H, Wester WC, Wicklund AB, Wicklund E, Wilkinson R, Williams HH, Wilson P, Winer BL, Winn D, Wolinski D, Wolinski J, Worm S, Wu X, Wyss J, Yagil A, Yao W, Yasuoka K, Yeh GP, Yeh P, Yoh J, Yosef C, Yoshida T, Yu I, Zanetti A, Zetti F, Zucchelli S. Search for the rare decayW±→π±+γin proton-antiproton collisions ats=1.8 TeV. Int J Clin Exp Med 1998. [DOI: 10.1103/physrevd.58.031101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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