A5088526460- Advanced MRI Techniques and Applications
- Atomic and Subatomic Physics Research
- Medical Imaging Techniques and Applications
- Advanced Neuroimaging Techniques and Applications
- Functional Brain Connectivity Studies
- NMR spectroscopy and applications
- Advanced NMR Techniques and Applications
- Advanced Radiotherapy Techniques
- Radiomics and Machine Learning in Medical Imaging
- Tensor decomposition and applications
- Epilepsy research and treatment
- Neuroscience and Neuropharmacology Research
- Photoacoustic and Ultrasonic Imaging
- Neural dynamics and brain function
- Spectroscopy Techniques in Biomedical and Chemical Research
- Photoreceptor and optogenetics research
- Electrical and Bioimpedance Tomography
- Neuroscience and Neural Engineering
- Retinal Development and Disorders
- Energy Harvesting in Wireless Networks
- MRI in cancer diagnosis
- Lanthanide and Transition Metal Complexes
- Characterization and Applications of Magnetic Nanoparticles
- Neonatal and fetal brain pathology
- Fish biology, ecology, and behavior
University Medical Center Utrecht
2020-2024
Utrecht University
1997-2020
Delft University of Technology
2018
Abstract Purpose We present a novel silent echo‐planar spectroscopic imaging (EPSI) readout, which uses an ultrasonic gradient insert to accelerate MRSI while producing high spectral bandwidth (20 kHz) and low sound level. Methods The consisted of single‐axis (z‐direction) plug‐and‐play coil, powered by audio amplifier, produced 40 mT/m at 20 kHz. EPSI readout was implemented in phase‐encoded acquisition. Here, the additional spatial encoding provided this used reduce number phase‐encoding...
<h3>BACKGROUND AND PURPOSE:</h3> Cerebral MR imaging in infants is usually performed with a field strength of up to 3T. In adults, growing number studies have shown added diagnostic value 7T imaging. might be additional unexplained seizures, for example. The aim this study was investigate the feasibility infants. We provide information about safety preparations and show first images at 7T. <h3>MATERIALS METHODS:</h3> Specific absorption rate levels during were simulated Sim4life using infant...
Purpose A novel silent imaging method is proposed that combines a gradient insert oscillating at the inaudible frequency 20 kHz with slew rate‐limited waveforms to form axis enable quiet and fast imaging. Methods The consisted of plug‐and‐play (45 kg) single z ‐gradient, which operated as an additional fourth axis. This was made resonant using capacitors combined audio amplifier allow for operation kHz. field characterized measurements physiological effects operating were explored peripheral...
Purpose To characterize the acceleration capabilities of a silent head insert gradient axis that operates at inaudible frequency 20 kHz and maximum amplitude 40 mT/m without inducing peripheral nerve stimulation. Methods The axis' acquisitions feature an oscillating in phase‐encoding direction is played out on top cartesian readout, similarly as done Wave‐CAIPI. additional spatial encoding fills k‐space readout lanes allowing for acquisition fewer steps increasing aliasing artifacts. Fully...
The goal of this study was to introduce and evaluate the performance a lightweight, high‐performance, single‐axis (z‐axis) gradient insert design primarily intended for high‐resolution functional magnetic resonance imaging, aimed at providing both ease use boost in spatiotemporal resolution. optimal winding positions coil were obtained using genetic algorithm with cost function that balanced (minimum 0.30 mT/m/A) field linearity (≥16 cm linear region). These parameters verified distribution...
Abstract Magnetic Resonance Spin TomogrAphy in Time‐domain (MR‐STAT) is a multiparametric quantitative MR framework, which allows for simultaneously acquiring tissue parameters such as T1, T2, and proton density from one single short scan. A typical two‐dimensional (2D) MR‐STAT acquisition uses gradient‐spoiled, gradient‐echo sequence with slowly varying RF flip‐angle train Cartesian readouts, the maps are reconstructed by an iterative, model‐based optimization algorithm. In this work, we...
Abstract Purpose Current three‐dimensional (3D) MR Spin TomogrAphy in Time‐Domain (MR‐STAT) protocols use transient‐state, gradient‐spoiled gradient‐echo sequences that are prone to cerebrospinal fluid (CSF) pulsation artifacts when applied the brain. This study aims develop a 3D MR‐STAT protocol for whole‐brain relaxometry overcomes challenges posed by CSF‐induced ghosting artifacts. Method We optimized flip‐angle train within Cartesian framework achieve two objectives: (1) minimization of...
Abstract Objectives Acoustic noise in magnetic resonance imaging (MRI) negatively impacts patients. We assessed a silent gradient coil switched at 20 kHz combined with T 1 -weighted magnetisation prepared rapid gradient-echo (MPRAGE) sequence 7 T. Methods Five healthy subjects (21–29 years; three females) without previous 7-T MRI experience underwent both quiet MPRAGE (Q-MPRAGE) and conventional (C-MPRAGE) twice. Image quality was quantitatively, qualitatively by two neuroradiologists. Sound...
The restricted bore diameter of current simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) systems can be an impediment to achieving similar patient positioning during PET/MRI planning and radiotherapy. Our goal was evaluate the B1 transmit (B1+) uniformity, B1+ efficiency, specific absorption rate (SAR) a novel radiofrequency (RF) body coil design, in which RF shielded PET detectors were integrated with aim enabling wide-bore system.We designed constructed...
Motivation: For silent whole-body MRI using ultrasonic encoding at 20kHz, very high slew rates will be experienced by body parts such as the torso with PNS risk. However, thresholds for these frequencies are not well known. Goal(s): To estimate 20kHz. Approach: We test volunteers in a gradient coil driven 20kHz to determine when occurs and compare simulations current IEC guidelines. Results: much higher dB/dt values than predicted guidelines where we found mean threshold value of 1316T/s...
Motivation: Advancing MRI sequence development by integrating parallel transmit capabilities with the open-source and widely-used Pulseq framework. Goal(s): To integrate pTx into framework, facilitating design of universal pulses that enhance imaging homogeneity quality. Approach: Development 'pTx-Pulseq' as a backwards-compatible extension, validated through single-channel control complex operation, culminating in hybrid enhances native MP-RAGE flexibility. Results: Effective channels using...
Motivation: High performance gradients enable fast and high-resolution imaging but are costly cumbersome to install in an existing MRI-systemGoal(s): Present a wireless (resonant) gradient coil setup that yields additional without needing dedicated amplifierApproach: The increased was measured using field camera measurements acceleration assessed retrospectively phantom experimentsResults: yielded factor 23 improvement slew rate (from 125 T/m/s 2900 T/m/s) 28-fold retrospective resulted...
Motivation: MR-STAT is a framework that enables simultaneous T1, T2 and proton-density mapping. Currently, acquires slices sequentially which relatively inefficient in terms of SNR time. Goal(s): Increase the scan-efficiency while limiting motion-sensitivity Approach: We use multi-slice (SMS) acquisition to increase scan efficiency two-step approach for reconstruction: an SMS-SENSE reconstruction followed by conventional slice-by-slice reconstruction. Results: Phantom in-vivo results showed...
Motivation: To enable silent whole-body MRI using ultrasonic encoding, an additional low inductance gradient coil can be integrated between the RF-rods and RF-shield of a bore coil. However, resulting effect on RF efficiency is unclear. Goal(s): demonstrate feasibility placing under without affecting efficiency. Approach: A Maxwell was into We measured field compared with extra gradient. Results: successfully induced greatly For validations, volunteer images were obtained Impact: Placing...
Motivation: Cerebrospinal fluid (CSF) pulsation artifacts using 3D unbalanced gradient-echo sequences hinder the accuracy of whole-brain relaxometry measurements. Goal(s): To develop a CSF-suppressed MR-STAT sequence and eliminate CSF artifacts, allowing for fast, high-resolution with enhanced image quality. Approach: The time-varying RF flip-angle train is optimized an additional suppression constraint to achieve both high quantitative parameter encoding capability low signal intensity....
Motivation: Conventional MRI vendor-specific sequence development limits research transferability and reproducibility. Harmonized frameworks, like Pulseq, overcome these limitations - but Pulseq was not supported yet on Philips scanners. Goal(s): To develop a fully-compliant interpreter for systems, facilitating the use of open-source sequences previously incompatible with platforms. Approach: Custom adaptation R5.4 platform, followed by validation standard imaging using field camera...
Abstract Purpose To demonstrate the feasibility and robustness of Magnetic Resonance Spin TomogrAphy in Time‐domain (MR‐STAT) framework for fast, high SNR relaxometry at 7T. Methods deploy MR‐STAT on 7T‐systems, we designed optimized flip‐angles using BLAKJac‐framework that incorporates SAR‐constraints. Transmit RF‐inhomogeneities were mitigated by including a measured ‐map reconstruction. Experiments performed gel‐phantom five volunteers to explore sequence its sensitivity inhomogeneities....
Purpose: Current 3D Magnetic Resonance Spin TomogrAphy in Time-domain (MR-STAT) protocols use transient-state, gradient-spoiled gradient-echo sequences that are prone to cerebrospinal fluid (CSF) pulsation artifacts when applied the brain. This study aims at developing a MR-STAT protocol for whole-brain relaxometry overcomes challenges posed by CSF-induced ghosting artifacts. Method: We optimized flip-angle train within Cartesian framework achieve two objectives: (1) minimization of noise...
To demonstrate the feasibility of using a nonlinear gradient field for spatial encoding at ultrasonic switching frequency 20 kHz and present framework to reconstruct data acquired in this way.
We combined quantitative susceptibility mapping (QSM) and single voxel (SV) 1H magnetic resonance spectroscopy (MRS) at 7 tesla (7T) with the aim to characterize mesial temporal lobe epilepsy (mTLE). discovered in 9 patients that distribution of quantified susceptibly is negatively skewed epileptogenic hippocampi compared contralateral hippocampi, meaning more positive values: an indicator for iron deposition. No differences metabolite ratios could be seen between however our small sample...
MR-STAT is a framework for simultaneously acquiring multi-parametric quantitative maps from one single short scan. In this work, we design new 3D sequence and the corresponding two-step reconstruction strategy based on previous work. The improved by designing faster acquisition framework, more accurate signal modeling reconstruction. proposed takes 7 minutes after retrospectively undersampling, validated in phantom experiment. Furthermore, apply first time musculoskeletal applications. Knee...
MR-STAT is a framework that enables the estimation of multi-parametric quantitative MR-maps from single short scan. Quantitative imaging at 7T can be used to probe brain’s microstructure high resolution. We show first results and SAR-limitations B1+-inhomogeneities successfully addressed by designing low-SAR flip angle train using B1+-prior during reconstruction. In addition, we use increased SNR achieve two-fold acceleration acquisition quality parameters obtained both on gel-phantom...
Acoustic noise in MRI scans can be reduced by utilising gradient switching frequencies at 20kHz. High slew rates required to achieve such high-frequency lead peripheral nerve stimulation (PNS), adding difficulty for application whole-body gradients. Instead, nonlinear encoding gradients have been shown limit PNS while achieving desired rates. In this work, we show the feasibility of using a silent spatial employing PSF-based reconstruction and investigate image fidelity on 4-fold accelerated...
Large dB/dt swings in gradient coils can induce peripheral nerve stimulation (PNS) the human body. This limits slew rates used whole-body MRI reducing scan speeds and spatial resolution. Ultrasonic head gradients enable fast silent imaging, however extension to is challenging due required larger swings. In this work, we present a body coil which be investigate PNS induction at an ultrasonic driving frequency of 20kHz.