A5022262514- Advanced MRI Techniques and Applications
- Atomic and Subatomic Physics Research
- Advanced NMR Techniques and Applications
- Medical Imaging Techniques and Applications
- Functional Brain Connectivity Studies
- Advanced Neuroimaging Techniques and Applications
- Electron Spin Resonance Studies
- Lanthanide and Transition Metal Complexes
- Ultrasound and Hyperthermia Applications
- MRI in cancer diagnosis
- Sparse and Compressive Sensing Techniques
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Neural dynamics and brain function
- Photoacoustic and Ultrasonic Imaging
- Radiomics and Machine Learning in Medical Imaging
- NMR spectroscopy and applications
- Cardiac Imaging and Diagnostics
- Radio Frequency Integrated Circuit Design
- Cardiovascular Function and Risk Factors
- Acoustic Wave Resonator Technologies
- Neurogenesis and neuroplasticity mechanisms
- Microwave and Dielectric Measurement Techniques
- Ferroelectric and Piezoelectric Materials
- Advanced Power Amplifier Design
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2011-2025
Université Paris-Saclay
2019-2025
Centre National de la Recherche Scientifique
2020-2025
CEA Paris-Saclay
2019-2024
Direction de la Recherche Fondamentale
2019-2024
NeuroSpine Institute
2019-2023
Laboratoire de Biométrie et Biologie Evolutive
2023
Siemens (France)
2015-2020
Siemens Healthcare (Germany)
2016-2019
Inserm
2011-2019
To present a new optimition-driven design of optimal k-space trajectories in the context compressed sensing: Spreading Projection Algorithm for Rapid K-space sampLING (SPARKLING).The SPARKLING algorithm is versatile method inspired from stippling techniques that automatically generates optimized sampling patterns compatible with MR hardware constraints on maximum gradient amplitude and slew rate. These non-Cartesian curves are designed to comply key criteria sampling: controlled distribution...
Purpose The SNR at the center of a spherical phantom known electrical properties was measured in quasi‐identical experimental conditions as function magnetic field strength between 3 T and 11.7 T. Methods water saline with gradient‐recalled echo sequence. Measurements were performed NeuroSpin 3, 7, then shipped to Maastricht University Minnesota for additional data points 9.4, 10.5 Experiments carried out exact same type birdcage volume coil (except T, where similar used) attempt isolating...
Abstract Objective To assess the possible influence of third-order shim coils on behavior gradient field and in gradient–magnet interactions at 7 T above. Materials methods Gradient impulse response function measurements were performed 5 sites spanning strengths from to 11.7 T, all them sharing same exact whole-body coil design. Mechanical fixation boundary conditions altered several ways one site study impact mechanical coupling with magnet perturbations. Vibrations, power deposition He...
Detection of deviant stimuli is crucial to orient and adapt our behavior. Previous work shows that elicit phasic activation the locus coeruleus (LC), which releases noradrenaline controls central arousal. However, it unclear whether detection behaviorally relevant selectively triggers LC responses or other neuromodulatory systems (dopamine, serotonin, acetylcholine). We combine human functional MRI (fMRI) recordings optimized for brainstem imaging with pupillometry perform a mapping...
Abstract Structural microtubule associated proteins (MAPs) stabilize microtubules, a property that was thought to be essential for development, maintenance and function of neuronal circuits. However, deletion the structural MAPs in mice does not lead major neurodevelopment defects. Here we demonstrate role MAP6 brain wiring is independent binding. We find disrupts connectivity with lack post-commissural fornix fibres. contributes development by regulating axonal elongation induced Semaphorin...
Diffusion tensor imaging (DTI) was used to study traumatic brain injury. The impact–acceleration trauma model in rats. Here, addition diffusivities (mean, axial and radial), fractional anisotropy (FA) used, particular, as a parameter characterize the cerebral tissue early after trauma. DTI implemented at 7 T using fast spiral k ‐space sampling twice‐refocused spin echo radiofrequency sequence for eddy current minimization. method carefully validated on different phantom measurements. of...
Ultrahigh-field (UHF) magnetic resonance imaging (MRI) systems are getting a lot of attention as they ensure high intrinsic signal-to-noise ratio resulting in higher spatial and temporal resolutions well better contrast. This promises improved clinical results with regard to morphological functional metabolic capabilities. Traditionally, MRI relies on volume coils (birdcage) able deliver homogeneous radio frequency field exciting the nuclei spin. However, this strategy is hindered at UHF...
Purpose T 2 ‐weighted sequences are particularly sensitive to the radiofrequency (RF) field inhomogeneity problem at ultra‐high‐field because of errors accumulated by imperfections train refocusing pulses. As parallel transmission (pTx) has proved useful counteract RF heterogeneities, universal pulses were recently demonstrated save precious time and computational efforts skipping B 1 calibration online pulse tailoring. Here, we report a design for non‐selective mitigate 7T in turbo...
Purpose In MRI at ultra‐high field, the ‐point and spiral nonselective (SPINS) pulse design techniques can be advantageously combined with parallel transmission (pTX) universal to create uniform excitation in a calibration‐free manner. However, these approaches, duration is typically increased as compared standard hard pulses, quality regions exhibiting large resonance frequency offsets often suffer. This limitation inherent structure of or SPINS pulse, likely mitigated using...
Parallel transmission (pTx) technology, despite its great potential to mitigate the transmit field inhomogeneity problem in magnetic resonance imaging at ultra-high (UHF), suffers from a cumbersome calibration procedure, thereby making approach problematic for routine use. The purpose of this work is demonstrate on two different 7T systems respectively equipped with 8-transmit-channel RF coils suppliers (Rapid-Biomed and Nova Medical), benefit so-called universal pulses (UP), optimized...
The simultaneous multi-slice EPI (SMS-EPI, a.k.a. MB-EPI) sequence has met immense popularity recently in functional neuroimaging. A still less common alternative is the use of 3D-EPI, which offers similar acceleration capabilities. aim this work was to compare SMS-EPI and 3D-EPI sequences terms sampling strategies for detection task-evoked activations at 7T using theory. To end, spatial temporal resolutions were matched (1.6 mm isotropic resolution, TR = 1200 ms) their excitation profiles...
BackgroundLithium (Li) is a first-line treatment for bipolar disorder (BD). To study its cerebral distribution and association with plasma concentrations, we used 7Li magnetic resonance imaging at 7T in euthymic patients BD treated Li carbonate least 2 years.MethodsThree-dimensional scans (N = 21) were acquired an ultra-short echo-time sequence using non-Cartesian k-space sampling scheme. Lithium concentrations ([Li]) estimated phantom replacement approach accounting differential T1 T2...
To implement parallel transmit (pTx) 7T magnetic resonance imaging (MRI) in the pre-surgical evaluation of 3T-negative patients with drug-resistant focal epilepsy, and to compare quality conventional single (specifically, circularly polarized [CP]) MRI. We implemented a comparative protocol comprising both pTx CP MRI consecutive adult candidates for epilepsy surgery who had negative or equivocal 3T imaging. Here we report outcomes from first 31 patients. acquired T1, T2, fluid-attenuated...
Abstract Purpose The drift in radiofrequency (RF) power amplifiers (RFPAs) is assessed and several contributing factors are investigated. Two approaches for prospective correction of proposed their effectiveness evaluated. Methods RFPA assessment encompasses both intra‐pulse inter‐pulse analyses. Scan protocols with varying flip angle (FA), RF length, pulse repetition time (TR) used to gauge the influence these parameters on drift. Directional couplers (DICOs) monitor forward waveforms...
To investigate the effects of carbamylated erythropoietin, a modified erythropoietin lacking erythropoietic activity, on brain edema and functional recovery in model diffuse traumatic injury.Adult male Wistar rats.Neurosciences physiology laboratories.Thirty minutes after injury (impact-acceleration model), rats were intravenously administered with either saline solution (traumatic injury-saline) or (50 μg/kg; injury-carbamylated erythropoietin). A third group received no insult...
The quantification of bolus-tracking MRI techniques remains challenging. acquisition usually relies on one contrast and the analysis a simplified model various phenomena that arise within voxel, leading to inaccurate perfusion estimates. To evaluate how simplifications in interstitial impact estimates, we propose numerical tool simulate MR signal provided by dynamic enhanced (DCE) experiment. Our encompasses intrinsic relaxations, magnetic field perturbations induced susceptibility...
Abstract In the central nervous system, microtubule-associated protein 6 (MAP6) is expressed at high levels and crucial for cognitive abilities. The large spectrum of social impairments observed in MAP6-KO mice are reminiscent symptoms psychiatric diseases, such as schizophrenia, respond positively to long-term treatment with antipsychotics. have therefore been proposed be a useful animal model these diseases. Here, we explored brain anatomy using spatial resolution 3D MRI, including...
We have recently proposed a new optimization algorithm called SPARKLING (Spreading Projection Algorithm for Rapid K‐space sampLING) to design efficient compressive sampling patterns magnetic resonance imaging (MRI). This method has few advantages over conventional non‐Cartesian trajectories such as radial lines or spirals: i) it allows sample the k‐space along any arbitrary density while other two are restricted densities and ii) optimizes gradient waveforms given readout time. Here, we...
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 (), and transmit () distributions. This costs time requires expertise from MR user. Universal (UPs) have been proposed to reduce this burden, yet, with a penalty in FA accuracy. study introduces concept standardized universal (SUPs), where are designed offline...
Purpose Optimization of transmit array performance is crucial in ultra‐high‐field MRI scanners such as 11.7T because the increased RF losses and nonuniformity. This work presents a new workflow to investigate minimize coil losses, choose optimum configuration for imaging. Methods An 8‐channel transceiver loop‐array was simulated analyze its loss mechanism at 499.415 MHz. A folded‐end shield developed limit radiation improve efficiency. The element length, diameter length were further...
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 aims at optimizing in a slice‐specific manner the spokes locations radiofrequency pulses. Methods problem posed as set of magnitude‐least‐squares problems, linked together by hardware SAR constraints, solved jointly using an active‐set algorithm. Average Hamiltonian theory exploited FA case to...
Purpose Perovskites are greatly used nowadays in many technological applications because of their high permittivity, more specifically the form aqueous solutions, for MRI dielectric shimming. In this study, full characterizations highly concentrated CaTiO 3 /BaTiO water mixtures were carried out and new permittivity maxima was reached. Methods Permittivity measurements done on solutions from 0%v/v to dry powder. The dependence with pressure investigated. Scanning electron microscopy images...