A5038267374- Advanced MRI Techniques and Applications
- Medical Imaging Techniques and Applications
- Advanced Neuroimaging Techniques and Applications
- Cardiac Imaging and Diagnostics
- Atomic and Subatomic Physics Research
- Fetal and Pediatric Neurological Disorders
- MRI in cancer diagnosis
- Electron Spin Resonance Studies
- NMR spectroscopy and applications
- Epilepsy research and treatment
- Ear and Head Tumors
- Hearing Loss and Rehabilitation
- Ion channel regulation and function
- Advanced Radiotherapy Techniques
- Functional Brain Connectivity Studies
- Ear Surgery and Otitis Media
- Traumatic Brain Injury Research
- Neuroscience and Neuropharmacology Research
- Advanced NMR Techniques and Applications
- Ultrasound Imaging and Elastography
- Nuclear Physics and Applications
- Reconstructive Facial Surgery Techniques
- Domain Adaptation and Few-Shot Learning
- Ultrasound and Hyperthermia Applications
King's College London
2022-2024
St Thomas' Hospital
2022-2023
Institute of Biomedical Science
2023
Abstract Purpose To improve motion robustness of functional fetal MRI scans by developing an intrinsic real‐time correction method. provides ideal tool to characterize brain development and growth. It is, however, a relatively slow imaging technique therefore extremely susceptible subject motion, particularly in experiments acquiring multiple Echo‐Planar‐Imaging‐based repetitions, for example, diffusion or blood‐oxygen‐level‐dependency MRI. Methods A 3D UNet was trained on 125 datasets track...
Purpose To develop a fully data‐driven retrospective intrascan motion‐correction framework for volumetric brain MRI at ultrahigh field (7 Tesla) that includes modeling of pose‐dependent changes in polarizing magnetic (B 0 ) fields. Theory and Methods Tissue susceptibility induces spatially varying B distributions the head, which change with pose. A physics‐inspired model has been deployed to variations head was validated vivo. This is integrated into forward parallel imaging presence motion....
Purpose This work proposes a novel RF pulse design for parallel transmit (pTx) systems to obtain uniform saturation of semisolid magnetization transfer (MT) contrast in the presence field inhomogeneities. The is usually modeled as being purely longitudinal, with applied saturating but not rotating its magnetization; thus, standard pTx methods do apply. Theory and Methods Pulse homogeneity (PUSH) optimizes pulses by considering uniformity root‐mean squared , which relates rate saturation....
Purpose The MP2RAGE sequence is typically optimized for either T 1 ‐weighted uniform image (UNI) or gray matter–dominant fluid and white matter suppression (FLAWS) contrast images. Here, the purpose was to optimize an protocol at 7 Tesla provide UNI FLAWS images simultaneously in a clinically applicable acquisition time <0.7 mm isotropic resolution. Methods Using extended phase graph formalism, signal evolution of simulated incorporating 2 relaxation, diffusion, RF spoiling, B +...
A fast B1+ mapping sequence such as saturation-prepared turbo FLASH (satTFL) is desirable for online pulse design at ultra-high field, but it often results in inaccuracies. Previous work performed linear fitting of the magnitude obtained with satTFL over that longer more accurate Actual Flip angle Imaging (AFI) to obtain calibration parameters would correct on fly brain imaging. In this we introduce a new machine-learning-based method uses additional features create precise and less...
MRI provides an ideal tool for characterising fetal brain development and growth. It is, however, a relatively slow imaging technique therefore extremely susceptible to subject motion. To address this challenge, we are developing intrinsically motion-robust deep-learning-based method achieve real-time head tracking update the acquisition geometry prospectively. Our uses Gadgetron reconstruction of scans 3D UNet position location motion estimation. Real-time correction functional was...
We demonstrated that applying a fast implementation of an RF phase shimming method enabled the acquisition localized MR spectra in different regions human brain including B1 challenging areas, such as hippocampus and prefrontal cortex, using commercially available pTx coil on clinical platform at 7T. efficiency was increased by ~100% cerebellum PFC while ~50-75% for pons hippocampus. The most favorable flip angle distributions were obtained cortex. Fast with advanced MRS methodology enables...
Abstract Introduction Quantitative MRI is important for non-invasive tissue characterisation. In previous work we developed a clinically feasible multi-contrast protocol T 1 -weighted imaging based on the MP2RAGE sequence that was optimised both children and adults. It demonstrated range of Fluid And White Matter Suppression (FLAWS) related contrasts could be produced while maintaining uniform image (UNI) quality, challenge at higher field strengths. Here introduce an approach to use these...
Abstract Background and Objectives Epileptogenic lesions in focal epilepsy can be subtle or undetected on conventional brain MRI. Ultra-high field (7T) MRI offers higher spatial resolution, contrast signal-to-noise ratio compared to imaging systems has shown promise the presurgical evaluation of adult epilepsy. However, utility ultra-high paediatric epilepsy, where malformations cortical development are more common, is unclear. This study 7T 3T children with by comparing: (i) scan...
3D FatNavs were used to provide a rapid, robust pre-scan calibrate motion estimation from pilot-tone. The amount of training data required make reliable forward predictions was investigated. This method robustly predicts within dataset and can be applied other datasets with lower accuracy. Improving the accuracy speed this is ongoing work. independent shows promise for rapid calibration as part routine examinations paves way offer correction at ultra-high field where motion-correction...
In spite of the promised increase in signal-to-noise ratio and contrast to noise ratio, 3D whole-heart imaging at 7T remains challenging predominantly due B 1 , 0 inhomogeneity, specific absorption rate limitations coil-depth issues for single transmit. Here, we developed a toolbox optimize adiabatic hyperbolic secant refocusing pulse with respect inhomogeneity typically used T 2 -preparation non-contrast Coronary Magnetic Resonance Angiography (CMRA). We present phantom vivo data CMRA...
We developed an analysis pipeline to explore normative QSM values in children and adolescents at 7T, assessed the feasibility of this approach for detecting tissue-alterations paediatric drug-resistant epilepsy. Normative consistent with previous studies were reported deep brain regions, cortical susceptibility described first time 7T. Finally, sensitivity changes epileptogenic lesions was demonstrated using pipeline.
Since semisolid tissue components are strong determinants of relaxation parameters, estimation properties may lead to more robust and direct characterization tissues than measurement. We have used multiband MR fingerprinting at ultra-high field in an exploratory study towards high resolution quantitative imaging with efficient parameter encoding. To achieve this, two variants a steady-state sequence proposed that employ different cycling nonselective RF pulses: one highlight dipolar order...
A fast and accurate B1+mapping method is essential for making proper use of a parallel transmit array with high number coil elements in clinical setting. The saturation-prepared turbo FLASH offers this capability implemented the fully automated pre-scan adjustments currently only ultra-high magnetic field strength MRI system. However, some methods require an even higher accuracy. This can be achieved by calibrating B1+measurements more but longer method.
The Magnetization Prepared 2 Rapid Acquisition Gradient Echoes (MP2RAGE) sequence is commonly used for 3D structural T 1 -weighted imaging of the brain at 7T and can be optimised to obtain UNI clinically relevant FLuid White Matter Suppression (FLAWS) images within one acquisition. In this study, such a protocol was together with newly derived analytical equations accounting partial Fourier acquisitions, B + maps, in dedicated fitting algorithm produce quantitative arbitrarily scaled...
DISORDER is an established retrospective data driven motion correction approach that uses optimised phase encoding, but otherwise unmodified 3D acquisitions. It highly effective, requires multiple lines of k-space to be grouped together for each state estimated, and this limits temporal resolution. At 7T, head can also detected by &ldquo;Pilot Tone&rdquo;, which injected RF signal picked up coil in the receiver array, a calibration step required. Here we combine Pilot Tone achieve...
Quantitative MRI at 7T has advantages of enhanced resolution and uniform tissue contrast however protocol optimisation can be challenging as B1(+) field variability is increased. We maximized the precision T1 estimation for a dual flip angle SPGR acquisition using Cramer-Rao Lower Bound framework validated results Monte Carlo simulation both phantom in-vivo experiments. For TR 20ms, simulations suggested optimal angles 4&deg; 26&deg; similar to 28&deg;. By accounting other...
Spin tagging perfusion MR imaging allows the movement of blood in human tissue to be visualized and quantified non-invasively contrast agent-free. Velicity-selection Arterial Labeling (VSASL) relies on velocity instead location for tagging. It is less dependent anatomy coil coverage but includes directional dependence can suffer from reduced SNR. POSSUM expands VSASL spherical, directional-independant encoding slice shuffling enable more robust at 7T.
The aim of this study was to gather data from children on their subjective experiences when undergoing high field MRI and compare adult collected with similar questionnaires. Seventeen twenty-six healthy adults had brain imaging at 7T. Their which included: (a) acoustic noise, (b) anxiety, (c) metallic taste (d) vertigo (dizziness) e) involuntary eye movement (nystagmus) or flashing lights were evaluated. We found that scanned 7T reported adults.
3D cardiovascular MR imaging at ultra-high field (7T) is very challenging due to magnetic-field inhomogeneity (B 0 and B 1 ), SAR constraints also the coil-depth issues of surface coils. To our best knowledge this first report demonstrating contrast-free resolution (0.7mm 3 isotropic) free-breathing CMRA images with translational respiratory motion compensation. avoid imposed by use T 2 -preparation pulses, high excitation flip-angles are exploited obtain contrast between coronary arteries...