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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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Amor Z, Le Ster C, Gr C, Daval-Frérot G, Boulant N, Mauconduit F, Thirion B, Ciuciu P, Vignaud A. Impact of B 0 $$ {\mathrm{B}}_0 $$ field imperfections correction on BOLD sensitivity in 3D-SPARKLING fMRI data. Magn Reson Med 2024; 91:1434-1448. [PMID: 38156952 DOI: 10.1002/mrm.29943] [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: 08/09/2023] [Revised: 10/07/2023] [Accepted: 11/09/2023] [Indexed: 01/03/2024]
Abstract
PURPOSE Static and dynamicB 0 $$ {\mathrm{B}}_0 $$ field imperfections are detrimental to functional MRI (fMRI) applications, especially at ultra-high magnetic fields (UHF). In this work, a field camera is used to assess the benefits of retrospectively correctingB 0 $$ {\mathrm{B}}_0 $$ field perturbations on Blood Oxygen Level Dependent (BOLD) sensitivity in non-Cartesian three-dimensional (3D)-SPARKLING fMRI acquisitions. METHODS fMRI data were acquired at 1 mm3 $$ {}^3 $$ and for a 2.4s-TR while concurrently monitoring in real-time field perturbations using a Skope Clip-on field camera in a novel experimental setting involving a shorter TR than the required minimal TR of the field probes. Measurements of the dynamic field deviations were used along with a staticΔ B 0 $$ \Delta {\mathrm{B}}_0 $$ map to retrospectively correct static and dynamic field imperfections, respectively. In order to evaluate the impact of such a correction on fMRI volumes, a comparative study was conducted on healthy volunteers. RESULTS Correction ofB 0 $$ {\mathrm{B}}_0 $$ deviations improved image quality and yielded between 20% and 30% increase in median temporal signal-to-noise ratio (tSNR).Using fMRI data collected during a retinotopic mapping experiment, we demonstrated a significant increase in sensitivity to the BOLD contrast and improved accuracy of the BOLD phase maps: 44% (resp., 159%) more activated voxels were retrieved when using a significance control level based on a p-value of 0.001 without correcting for multiple comparisons (resp., 0.05 with a false discovery rate correction). CONCLUSION 3D-SPARKLING fMRI hugely benefits from static and dynamicB 0 $$ {\mathrm{B}}_0 $$ imperfections correction. However, the proposed experimental protocol is flexible enough to be deployed on a large spectrum of encoding schemes, including arbitrary non-Cartesian readouts.
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Affiliation(s)
- Zaineb Amor
- CEA, NeuroSpin, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Caroline Le Ster
- CEA, NeuroSpin, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Chaithya Gr
- CEA, NeuroSpin, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- Inria, MIND, Palaiseau, France
| | - Guillaume Daval-Frérot
- CEA, NeuroSpin, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- Inria, MIND, Palaiseau, France
- Siemens Healthineers, Courbevoie, France
| | - Nicolas Boulant
- CEA, NeuroSpin, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Franck Mauconduit
- CEA, NeuroSpin, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Bertrand Thirion
- CEA, NeuroSpin, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- Inria, MIND, Palaiseau, France
| | - Philippe Ciuciu
- CEA, NeuroSpin, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- Inria, MIND, Palaiseau, France
| | - Alexandre Vignaud
- CEA, NeuroSpin, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
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Le Ster C, Selingue E, Poirier R, Edeline JM, Mériaux S, Boulant N. Behavioral and functional assessment of mice inner ear after chronic exposure to an ultrahigh B 0 field of 11.7 T or 17.2 T. Magn Reson Med 2023; 90:699-707. [PMID: 37036024 DOI: 10.1002/mrm.29659] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/03/2023] [Accepted: 03/16/2023] [Indexed: 04/11/2023]
Abstract
PURPOSE Assess short-term and long-term effects of chronic exposure to an ultrahigh static magnetic (B0 ) field on mice inner ear in the context of MR safety of human scanning at 11.7 T. METHODS Mice were chronically exposed to a B0 field of 11.7 T or 17.2 T during ten 2-h exposure sessions evenly distributed over a period of 5 weeks, resulting in a total of 20 h of exposure per mouse. During exposure sessions, mice were anesthetized and positioned either parallel or antiparallel to B0 . Before, during, and 2 weeks after the magnetic-field exposure period, mice performed behavioral tests (balance beam, rotarod, and swim tests) to evaluate their short-term and long-term motor coordination and balance. An auditory brainstem response (ABR) test was finally performed to assess the functional integrity of mice cochlea, 2 weeks after the last exposure. RESULTS After awaking from anesthesia following B0 exposures at 11.7 Tor 17.2 T, mice displayed a transient (<5 min) rotating behavior. The behavioral tests did not show any difference between the exposed and the control mice at any time point. Determination of ABR thresholds did not reveal an impairment of cochlea hair cells resulting from chronic B0 exposure. CONCLUSION Despite the transient disturbance of mice vestibular system observed immediately after B0 exposure, no short-term nor long-term alteration was detected with behavioral and ABR tests.
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Affiliation(s)
- Caroline Le Ster
- University of Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Erwan Selingue
- University of Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | | | | | - Sébastien Mériaux
- University of Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Nicolas Boulant
- University of Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
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Le Ster C, Grant A, Van de Moortele PF, Monreal-Madrigal A, Adriany G, Vignaud A, Mauconduit F, Rabrait-Lerman C, Poser BA, Uğurbil K, Boulant N. Magnetic field strength dependent SNR gain at the center of a spherical phantom and up to 11.7T. Magn Reson Med 2022; 88:2131-2138. [PMID: 35849739 PMCID: PMC9420790 DOI: 10.1002/mrm.29391] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [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: 04/02/2022] [Revised: 06/06/2022] [Accepted: 06/27/2022] [Indexed: 02/05/2023]
Abstract
PURPOSE The SNR at the center of a spherical phantom of known electrical properties was measured in quasi-identical experimental conditions as a function of magnetic field strength between 3 T and 11.7 T. METHODS The SNR was measured at the center of a spherical water saline phantom with a gradient recalled echo sequence. Measurements were performed at NeuroSpin at 3, 7, and 11.7 T. The phantom was then shipped to Maastricht University and then to the University of Minnesota for additional data points at 7, 9.4, and 10.5 T. Experiments were carried out with the exact same type of birdcage volume coil (except at 3 T, where a similar coil was used) to attempt at isolating the evolution of SNR with field strength alone. Phantom electrical properties were characterized over the corresponding frequency range. RESULTS Electrical properties were found to barely vary over the frequency range. Removing the influence of the flip-angle excitation inhomogeneity was crucial, as expected. After such correction, measurements revealed a gain of SNR growing as B0 1.94 ± 0.16 compared with B0 2.13 according to ultimate intrinsic SNR theory. CONCLUSIONS By using quasi-identical experimental setups (RF volume coil, phantom, electrical properties, and protocol), this work reports experimental data between 3 T and 11.7 T, enabling the comparison with SNR theories in which conductivity and permittivity can be assumed to be constant with respect to field strength. According to ultimate SNR theory, these results can be reasonably extrapolated to the performance of receive arrays with greater than about 32 elements for central SNR in the same spherical phantom.
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Affiliation(s)
- Caroline Le Ster
- University of Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif sur Yvette, France
| | - Andrea Grant
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | | | | | - Gregor Adriany
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Alexandre Vignaud
- University of Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif sur Yvette, France
| | - Franck Mauconduit
- University of Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif sur Yvette, France
| | | | - Benedikt A Poser
- Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Kâmil Uğurbil
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Nicolas Boulant
- University of Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif sur Yvette, France
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Le Ster C, Mauconduit F, Massire A, Boulant N, Gras V. Standardized universal pulse: A fast RF calibration approach to improve flip angle accuracy in parallel transmission. Magn Reson Med 2022; 87:2839-2850. [PMID: 35122302 DOI: 10.1002/mrm.29180] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 08/06/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 11/09/2022]
Abstract
PURPOSE In parallel transmission (pTX), subject-tailored RF pulses allow achieving excellent flip angle (FA) accuracy but often require computationally extensive online optimizations, precise characterization of the static field ( Δ B 0 ), and the transmit RF field ( B 1 + ) distributions. This costs time and requires expertise from the MR user. Universal pulses (UPs) have been proposed to reduce this burden, yet, with a penalty in FA accuracy. This study introduces the concept of standardized universal pulses (SUPs), where pulses are designed offline and adjusted to the subject through a fast online calibration scan. METHODS A SUP is designed offline using a so-called standardized database, wherein each B 1 + map has been normalized to a reference transmit RF field distribution. When scanning a new subject, a 3-slice B 1 + acquisition (scan time < 10 s) is performed and used to adjust the SUP to the subject through a linear transform. SUP performance was assessed at 7T with simulations by computing the FA-normalized root mean square error (FA-NRMSE) and the FA pattern stability as measured by the average and coefficient of variation of the FA across 15 control subjects, along with in vivo experiments using an MP2RAGE sequence implementing the SUP variant for the FLASH readout. RESULTS Adjusted SUP improved the FA-NRMSE (8.8 % for UP vs. 7.1 % for adjusted SUP). Experimentally in vivo, this translated in an improved signal homogeneity and more accurate T 1 quantification using MP2RAGE. CONCLUSION The proposed SUP approach improves excitation accuracy (FA-NRMSE) while preserving the same offline pulse design principle as offered by UPs.
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Affiliation(s)
- Caroline Le Ster
- NeuroSpin, CEA, CNRS, BAOBAB, Université Paris-Saclay, Gif-Sur-Yvette, France
| | - Franck Mauconduit
- NeuroSpin, CEA, CNRS, BAOBAB, Université Paris-Saclay, Gif-Sur-Yvette, France
| | | | - Nicolas Boulant
- NeuroSpin, CEA, CNRS, BAOBAB, Université Paris-Saclay, Gif-Sur-Yvette, France
| | - Vincent Gras
- NeuroSpin, CEA, CNRS, BAOBAB, Université Paris-Saclay, Gif-Sur-Yvette, France
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Jamil R, Mauconduit F, Le Ster C, Ehses P, Poser BA, Vignaud A, Boulant N. Temporal SNR optimization through RF coil combination in fMRI: The more, the better? PLoS One 2021; 16:e0259592. [PMID: 34748584 PMCID: PMC8575292 DOI: 10.1371/journal.pone.0259592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 05/25/2021] [Accepted: 10/21/2021] [Indexed: 11/19/2022] Open
Abstract
For functional MRI with a multi-channel receiver RF coil, images are often reconstructed channel by channel, resulting into multiple images per time frame. The final image to analyze usually is the result of the covariance Sum-of-Squares (covSoS) combination across these channels. Although this reconstruction is quasi-optimal in SNR, it is not necessarily the case in terms of temporal SNR (tSNR) of the time series, which is yet a more relevant metric for fMRI data quality. In this work, we investigated tSNR optimality through voxel-wise RF coil combination and its effects on BOLD sensitivity. An analytical solution for an optimal RF coil combination is described, which is somewhat tied to the extended Krueger-Glover model involving both thermal and physiological noise covariance matrices. Compared experimentally to covSOS on four volunteers at 7T, the method yielded great improvement of tSNR but, surprisingly, did not result into higher BOLD sensitivity. Solutions to improve the method such as for example the t-score for the mean recently proposed are also explored, but result into similar observations once the statistics are corrected properly. Overall, the work shows that data-driven RF coil combinations based on tSNR considerations alone should be avoided unless additional and unbiased assumptions can be made.
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Affiliation(s)
- Redouane Jamil
- CEA, CNRS, BAOBAB, NeuroSpin, Paris-Saclay University, Gif-sur-Yvette, France
| | - Franck Mauconduit
- CEA, CNRS, BAOBAB, NeuroSpin, Paris-Saclay University, Gif-sur-Yvette, France
| | - Caroline Le Ster
- CEA, CNRS, BAOBAB, NeuroSpin, Paris-Saclay University, Gif-sur-Yvette, France
| | - Philipp Ehses
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Benedikt A. Poser
- Department of Cognitive Neuroscience, Maastricht Brain Imaging Centre, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Alexandre Vignaud
- CEA, CNRS, BAOBAB, NeuroSpin, Paris-Saclay University, Gif-sur-Yvette, France
| | - Nicolas Boulant
- CEA, CNRS, BAOBAB, NeuroSpin, Paris-Saclay University, Gif-sur-Yvette, France
- * E-mail:
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Le Ster C, Mauconduit F, Mirkes C, Vignaud A, Boulant N. Measuring radiofrequency field-induced temperature variations in brain MRI exams with motion compensated MR thermometry and field monitoring. Magn Reson Med 2021; 87:1390-1400. [PMID: 34687068 DOI: 10.1002/mrm.29058] [Citation(s) in RCA: 4] [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: 07/30/2021] [Revised: 09/23/2021] [Accepted: 10/08/2021] [Indexed: 11/08/2022]
Abstract
PURPOSE An MR thermometry (MRT) method with motion and field fluctuation compensation is proposed to measure non-invasively sub-degree brain temperature variations occurring through radiofrequency (RF) power deposition during MR exams. METHODS MRT at 7T with a multi-slice echo planar imaging (EPI) sequence and concurrent field monitoring was first tested in vitro to assess accuracy in the presence of external field perturbations, an optical probe being used for ground truth. In vivo, this strategy was complemented by a motion compensation scheme based on a dictionary pre-scan, as reported in some previous work, and was adapted to the human brain. Precision reached with this scheme was assessed on eight volunteers with a 5 minute-long low specific absorption rate (SAR) scan. Finally, temperature rise in the brain was measured twice on the same volunteers and with the same strategy, this time by employing a 20-minutes scan at the maximum SAR delivered with a commercial volume head coil. RESULTS In vitro, the root mean square (RMS) error between optical probe and MRT measurements was 0.02°C with field sensor correction. In vivo, the low SAR scan returned a precision in temperature change measurement with field monitoring and motion compensation of 0.05°C. The 20-minutes maximum SAR scan returned a temperature rise throughout the inner-brain in the range of 0-0.2°C. Brain periphery remained too sensitive with respect to motion to lead to equally conclusive results. CONCLUSION Sub-degree temperature rise in the inner human brain was characterized experimentally throughout RF exposure. Potential applications include improvement of human thermal models and revision of safety margins.
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Affiliation(s)
- Caroline Le Ster
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Franck Mauconduit
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | | | - Alexandre Vignaud
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Nicolas Boulant
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
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Le Ster C, Mauconduit F, Mirkes C, Bottlaender M, Boumezbeur F, Djemai B, Vignaud A, Boulant N. RF heating measurement using MR thermometry and field monitoring: Methodological considerations and first in vivo results. Magn Reson Med 2020; 85:1282-1293. [PMID: 32936510 DOI: 10.1002/mrm.28501] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [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: 04/30/2020] [Revised: 07/10/2020] [Accepted: 08/10/2020] [Indexed: 11/11/2022]
Abstract
PURPOSE A MR thermometry (MRT) method with field monitoring is proposed to improve the measurement of small temperature variations induced in brain MRI exams. METHODS MR thermometry experiments were performed at 7 Tesla with concurrent field monitoring and RF heating. Images were reconstructed with nominal k-space trajectories and with first-order spherical harmonics correction. Experiments were performed in vitro with deliberate field disturbances and on an anesthetized macaque in 2 different specific absorption rate regimes, that is, at 50% and 100% of the maximal specific absorption rate level allowed in the International Electrotechnical Commission normal mode of operation. Repeatability was assessed by running a second separate session on the same animal. RESULTS Inclusion of magnetic field fluctuations in the reconstruction improved temperature measurement accuracy in vitro down to 0.02°C. Measurement precision in vivo was on the order of 0.15°C in areas little affected by motion. In the same region, temperature increase reached 0.5 to 0.8°C after 20 min of heating at 100% specific absorption rates and followed a rough factor of 2 with the 50% specific absorption rate scans. A horizontal temperature plateau, as predicted by Pennes bioheat model with thermal constants from the literature and constant blood temperature assumption, was not observed. CONCLUSION Inclusion of field fluctuations in image reconstruction was beneficial for the measurement of small temperature rises encountered in standard brain exams. More work is needed to correct for motion-induced field disturbances to extract reliable temperature maps.
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Affiliation(s)
- Caroline Le Ster
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Franck Mauconduit
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | | | - Michel Bottlaender
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Service Hospitalier Frederic Joliot, Orsay, France.,UNIACT, Neurospin, CEA, Gif-sur-Yvette, France
| | - Fawzi Boumezbeur
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Boucif Djemai
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Alexandre Vignaud
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
| | - Nicolas Boulant
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, Gif-sur-Yvette, France
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Lasbleiz J, Le Ster C, Guillin R, Saint-Jalmes H, Gambarota G. Measurements of Diffusion and Perfusion in Vertebral Bone Marrow Using Intravoxel Incoherent Motion (IVIM) With Multishot, Readout-Segmented (RESOLVE) Echo-Planar Imaging. J Magn Reson Imaging 2018; 49:768-776. [DOI: 10.1002/jmri.26270] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 07/09/2018] [Accepted: 07/10/2018] [Indexed: 12/29/2022] Open
Affiliation(s)
| | - Caroline Le Ster
- Univ Rennes, Inserm, LTSI - UMR 1099; F-35000 Rennes France
- Siemens Healthcare; Saint-Denis France
| | - Raphaël Guillin
- Department of Medical Imaging; Rennes University Hospitals, Sud Hospital; F-35000 Rennes France
| | - Hervé Saint-Jalmes
- Univ Rennes, CLCC Eugène Marquis, Inserm, LTSI - UMR 1099; F-35000 Rennes France
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Le Ster C, Gambarota G, Lasbleiz J, Guillin R, Decaux O, Saint-Jalmes H. Breath-hold MR measurements of fat fraction,T1, andT2* of water and fat in vertebral bone marrow. J Magn Reson Imaging 2016; 44:549-55. [DOI: 10.1002/jmri.25205] [Citation(s) in RCA: 23] [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: 10/23/2015] [Accepted: 02/05/2016] [Indexed: 01/23/2023] Open
Affiliation(s)
- Caroline Le Ster
- INSERM, UMR 1099; Rennes France
- Université de Rennes 1, LTSI; Rennes France
- Siemens Healthcare; Saint-Denis France
| | - Giulio Gambarota
- INSERM, UMR 1099; Rennes France
- Université de Rennes 1, LTSI; Rennes France
| | - Jérémy Lasbleiz
- INSERM, UMR 1099; Rennes France
- Université de Rennes 1, LTSI; Rennes France
| | - Raphaël Guillin
- Department of Imaging; Rennes University Hospital; Rennes France
| | - Olivier Decaux
- Department of Imaging; Rennes University Hospital; Rennes France
| | - Hervé Saint-Jalmes
- INSERM, UMR 1099; Rennes France
- Université de Rennes 1, LTSI; Rennes France
- CRLCC, Centre Eugène Marquis; Rennes France
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