Commissioning Completion of the Iseult Whole Body 11.7 T MRI System

Quettier, L.; Aubert, G.; Belorgey, J.; Berriaud, Christophe; Brédy, P.; Dilasser, Guillaume; Dubois, Olivier; Gilgrass, G.; Guihard, Q.; Jannot, Vincent; Juster, F.P.; Lannou, H.; Molinié, F.; Nunio, F.; Roger, Arnaud; Schild, T.; Scola, L.; Sinanna, A.; Stepanov, V.; Védrine, P.

doi:10.1109/tasc.2020.2983702

Cited by 22 publications

(14 citation statements)

References 6 publications

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“…The project was officially endorsed in April 2004 by French President Jacques Chirac and German Chancelor Gerhard Schröder. Due to the complexity of this unique MRI system and the associated technical challenges to be addressed, 5 years of extensive R&D efforts and prototyping activities were required to define the final design and validate the technical choices used to design the magnet [13][14][15][16]. After seven years of fabrication at Belfort by GE Power (Ex-Alstom) [12], the Iseult magnet was delivered to CEA in June 2017, its connection with the cryogenic plant and all the ancillary equipment was completed in October 2018.…”

Section: History Of the Iseult-inumac Projectmentioning

confidence: 99%

“…As the main coil magnet is designed to be cryostable [16], a local quench cannot theoretically propagate. Obviously, this does not mean that a quench is impossible, e.g., resulting from a heat overload from interactions with the gradient system which could go above the Gorter-Mellink limitation where He super-fluidity vanishes and thus provides less heat dissipation [18].…”

Section: Quench Protectionmentioning

confidence: 99%

“…Therefore, as a safety measure, some magnet protection mechanism had to be implemented in the event of a quench. The complexity of the overall Iseult magnet operation, taking into account electrical and cryogenic requirements for field stability, magnet and patient safety, led us to design a Magnet Control System (MCS) and a Magnet Safety System (MSS) relying on a high availability programmable logic controller [16,19]. MCS is permanently monitoring and controlling more than 300 devices located in the magnet cryostat and in its cryogenic and electrical ancillary (programmable logic controllers, valves, current transducers, temperature and pressure sensors).…”

Section: Quench Protectionmentioning

confidence: 99%

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Commissioning of the Iseult CEA 11.7 T whole-body MRI: current status, gradient–magnet interaction tests and first imaging experience

Boulant

Quettier

Aubert³

et al. 2023

Magn Reson Mater Phy

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Objectives The Iseult MRI is an actively shielded whole-body magnet providing a homogeneous and stable magnetic field of 11.7 T. After nearly 20 years of research and development, the magnet successfully reached its target field strength for the first time in 2019. This article reviews its commissioning status, the gradient–magnet interaction test results and first imaging experience. Materials and methods Vibration, acoustics, power deposition in the He bath, and field monitoring measurements were carried out. Magnet safety system was tested against outer magnetic perturbations, and calibrated to define a safe operation of the gradient coil. First measurements using parallel transmission were also performed on an ex-vivo brain to mitigate the RF field inhomogeneity effect. Results Acoustics measurements show promising results with sound pressure levels slightly above the enforced limits only at certain frequency intervals. Vibrations of the gradient coil revealed a linear trend with the B0 field only in the worst case. Field monitoring revealed some resonances at some frequencies that are still under investigation. Discussion Gradient-magnet interaction tests at up to 11.7 T are concluded. The scanner is now kept permanently at field and the final calibrations are on-going to pave the road towards the first acquisitions on volunteers.

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Section: History Of the Iseult-inumac Projectmentioning

confidence: 99%

Section: Quench Protectionmentioning

confidence: 99%

Section: Quench Protectionmentioning

confidence: 99%

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Commissioning of the Iseult CEA 11.7 T whole-body MRI: current status, gradient–magnet interaction tests and first imaging experience

Boulant

Quettier

Aubert³

et al. 2023

Magn Reson Mater Phy

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“…Research on the development of extremely ultrahigh-field (EUHF) MRI above 11.7 T has started worldwide [75]. The increased intensity of magnetic field will allow the acquisition of anatomical and functional information at high resolution.…”

Section: Resultsmentioning

confidence: 99%

A Preliminary Study for Reference RF Coil at 11.7 T MRI: Based on Electromagnetic Field Simulation of Hybrid-BC RF Coil According to Diameter and Length at 3.0, 7.0 and 11.7 T

Seo

Chung

2022

Sensors

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Magnetic resonance imaging (MRI) systems must undergo quantitative evaluation through daily and periodic performance assessments. In general, the reference or standard radiofrequency (RF) coils for these performance assessments of 1.5 to 7.0 T MRI systems have been low-pass-type birdcage (LP-BC) RF coils. However, LP-BC RF coils are inappropriate for use as reference RF coils because of their relatively lower magnetic field (B1-field) sensitivity than other types of BC RF coils, especially in ultrahigh-field (UHF) MRI systems above 3.0 T. Herein, we propose a hybrid-type BC (Hybrid-BC) RF coil as a reference RF coil with improved B1-field sensitivity in UHF MRI system and applied it to an 11.7 T MRI system. An electromagnetic field (EM-field) analysis on the Hybrid-BC RF coil was performed to provide the proper dimensions for its use as a reference RF coil. Commercial finite difference time-domain program was used in EM-field simulation, and home-made analysis programs were used in analysis. The optimal specifications of the proposed Hybrid-BC RF coils for them to qualify as reference RF coils are proposed based on their B1+-field sensitivity under unnormalized conditions, as well as by considering their B1+-field uniformity and RF safety under normalized conditions.

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“…With the current trend of increasing magnetic field intensity of clinical and research MRI scanners (7 T Siemens Terra, 10.5 T at the Center for Magnetic Resonance Research (CMRR) [18], 11.7 T Iseult project [19]) to achieve 2 higher SNR and Constrast-to-Noise Ratio (CNR), susceptibility-induced inhomogeneity rises proportionally to the main field. High performance static field shimming becomes crucial for these scanners to deliver their full potential in applications such as functional MRI (fMRI) [20].…”

Section: Introductionmentioning

confidence: 99%

Physical limits to human brain B0 shimming with spherical harmonics, engineering implications thereof

Meneses

Amadon

2022

Magn Reson Mater Phy

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Objective As the MRI main magnetic field rises for improved Signalto-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-mmresolved brain fieldmaps acquired at 3 T . 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 DiscussionWe 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 13Hz inhomogeneity hard shim limit at 7 T 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 regionspecific shimming is shown to greatly improve homogeneity in critical zones such as the prefrontal cortex and around ear canals.

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Commissioning Completion of the Iseult Whole Body 11.7 T MRI System

Cited by 22 publications

References 6 publications

Commissioning of the Iseult CEA 11.7 T whole-body MRI: current status, gradient–magnet interaction tests and first imaging experience

Commissioning of the Iseult CEA 11.7 T whole-body MRI: current status, gradient–magnet interaction tests and first imaging experience

A Preliminary Study for Reference RF Coil at 11.7 T MRI: Based on Electromagnetic Field Simulation of Hybrid-BC RF Coil According to Diameter and Length at 3.0, 7.0 and 11.7 T

Physical limits to human brain B0 shimming with spherical harmonics, engineering implications thereof

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