A5101687745- Advanced Neuroimaging Techniques and Applications
- Advanced MRI Techniques and Applications
- MRI in cancer diagnosis
- NMR spectroscopy and applications
- Functional Brain Connectivity Studies
- Medical Imaging Techniques and Applications
- Fetal and Pediatric Neurological Disorders
- Biomedical Text Mining and Ontologies
- Electron Spin Resonance Studies
- Ultrasound Imaging and Elastography
- RNA and protein synthesis mechanisms
- Elasticity and Material Modeling
- Radiomics and Machine Learning in Medical Imaging
- Advancements in Photolithography Techniques
- Photoacoustic and Ultrasonic Imaging
- Advancements in Semiconductor Devices and Circuit Design
- Gene expression and cancer classification
- Semiconductor materials and devices
University of Leeds
2022-2025
Cardiff University
2021-2023
Heidelberg University
2015
German Cancer Research Center
2015
This work reports for the first time on implementation and application of cardiac diffusion-weighted MRI a Connectom MR scanner with maximum gradient strength 300 mT/m. It evaluates benefits increased performance investigation myocardial microstructure.
Purpose: Diffusion tensor imaging (DTI) is commonly used in cardiac diffusion magnetic resonance (dMRI). However, the tissue's microstructure (cells, membranes, etc.) restricts movement of water molecules, making spin displacements deviate from Gaussian behaviour. This effect may be observed with kurtosis (DKI) using sufficiently high b-values (b > 450 s/mm 2 ), which are presently outside realm routine dMRI due to limited gradient strength clinical scanners. The Connectom scanner G max =...
Abstract This paper introduces the Welsh Advanced Neuroimaging Database (WAND), a multi-scale, multi-modal imaging dataset comprising in vivo brain data from 170 healthy volunteers (aged 18–63 years), including 3 Tesla (3 T) magnetic resonance (MRI) with ultra-strong (300 mT/m) field gradients, structural and functional MRI nuclear spectroscopy at T 7 T, magnetoencephalography (MEG), transcranial stimulation (TMS), together trait questionnaire cognitive data. Data are organised using Brain...
Summary: Robust estimation with convexity constraints significantly improves signal fitting for in vivo human cardiac diffusion kurtosis imaging. Purpose: Cardiac tensor imaging (cDTI) is an emerging technique to investigate the microstructure of heart tissue. At sufficiently high b-values, additional information on can be observed, but data require a representation beyond DTI such as (DKI). cDTI highly prone image corruption, which researchers usually attempt handle shot-rejection. However,...
Although both relaxation and diffusion imaging are sensitive to tissue microstructure, studies have reported limited sensitivity robustness of using or conventional alone characterize microstructure. Recently, it has been shown that tensor-valued encoding joint relaxation-diffusion quantification enable more reliable compartment-specific microstructural properties. However, scan times acquire such data can be prohibitive. Here, we aim simultaneously quantify MR fingerprinting (MRF) b-tensor...
Motivation: Advances in MRI have increased our understanding of the human brain but are frequently limited by single modality study designs. Combining data from multiple modalities/MR contrasts can enhance complex multi-scale neural relationships that underpin behaviour. Goal(s): Our goal was to create an open-access multi-scale, multi-modal imaging database healthy brain. Approach: The Welsh Advanced Neuroimaging Database (WAND) includes micro and macro-structural, functional spectroscopic...
Abstract Purpose The characterization of tissue microstructure using diffusion MRI (dMRI) signals is rapidly evolving, with increasing sophistication signal representations and models. However, this progress often requires to be acquired very high b ‐values (e.g., > 30 ms/μm 2 ), along many directions, multiple ‐values, leading long scan times extremely low SNR in dMRI images. purpose work boost the efficiency by combining three particularly efficient spatial encoding techniques utilizing...
Abstract Purpose To address key issues of low SNR and image distortions in prostate diffusion MRI (dMRI) by means using strong gradients, single‐shot spiral readouts an expanded encoding model for reconstruction. Methods Diffusion‐weighted spin echo imaging with EPI is performed on a whole‐body system equipped gradients (up to 250 mT/m). An including static off‐resonance, coil sensitivities, magnetic field dynamics employed The acquisitions are phantom vivo (one healthy volunteer one patient...
Purpose: Eddy currents might lead to image distortions in diffusion weighted echo planar imaging. A method is proposed reduce their effects on double encoding (DDE) MRI experiments and the thereby derived microscopic fractional anisotropy (\mu FA) . Methods: The twice refocused spin scheme was adapted for DDE measurements. To assess effect of individual encodings distortions, measurements a grid plastic rods water were performed. eddy current compensation \mu FA evaluated brains six healthy...
Diffusion-weighted magnetic resonance imaging (DW-MRI) is a non-invasive technique to probe tissue microstructure. Conventional Stejskal–Tanner diffusion encoding (i.e., along single axis), unable disentangle different microstructural features within voxel; If voxel contains microcompartments that vary in more than one attribute (e.g., size, shape, orientation), it can be difficult quantify of those attributes isolation using encoding. Multidimensional encoding, which the water encoded...
Multidimensional Magnetic Resonance Imaging (MRI) is a versatile tool for microstructure mapping. We use diffusion weighted inversion recovery spin echo (DW-IR-SE) sequence with spiral readouts at ultra-strong gradients to acquire rich diffusion-relaxation data set sensitivity myelin water. reconstruct 1D and 2D spectra two-step convex optimization approach investigate variety of multidimensional MRI methods, including multi-component relaxometry, diffusometry, relaxation correlation...
Cardiac Diffusion Tensor Imaging (cDTI) is prone to imaging artefacts including distortion, signal dropout, and misregistration even after post-processing. We developed a method for image rejection based on comparison between the observed images corresponding set of predicted generated by tensor models fit data. A threshold exclude from subsequent refitting model can be chosen user with simple graphical method.
Cardiac diffusion Magnetic Resonance Imaging (cardiac dMRI) allows to non-invasively assess the microstructure of heart. motion typically necessitates use motion-compensated gradients. Here we report for first time on application cardiac dMRI a Connectom MR scanner with gradient strength 300 mT/m using spin echo (SE) sequence EPI readout and up third order (M3) The results show benefits applying higher compensation in human heart scanner.
Conventional spin-echo based cardiac diffusion tensor imaging (DTI) has a relatively limited range of encoding frequencies, and hence sensitivity to at different length scales. Here, we explored the feasibility applying broader frequencies evaluate effects time-dependent diffusion. We employed waveforms with up 4th order motion-compensation in cohort healthy volunteers, report trends decreasing MD FA increasing frequencies. The availability higher enhances DTI shorter scales, may be more...
Using spiral trajectories instead of EPI can reduce the echo time in diffusion weighted MRI. The feasibility for cardiac DTI has recently been demonstrated, but larger object size (i.e torso vs. example skull) may require an inner volume excitation to keep readout at useable duration. Here we examine use undersampled with SENSE reconstruction and standard slice selective pulses. We show that MD FA derived from yield comparable values being higher than one measured EPI.
Motivation: Diffusion tensor modeling, which is based on Gaussian diffusion, commonly used in cardiac diffusion MRI (dMRI). However, the tissue's microstructure (cells, membranes, etc.) restricts water molecules and deviates signal from behavior. Goal(s): This effect may be observed for higher b-values, are presently outside realm of routine dMRI due to limited gradient strength clinical scanners. Approach: Cardiac-gated, second-order motion-compensated were performed with...
Motivation: Tensor-valued diffusion encoding has been shown to provide more information on tissue microstructure than conventional weighting/tensor imaging. Goal(s): Quantifying microscopic anisotropy, isotropic and anisotropic kurtosis in a human heart vivo with TE commonly used for DTI. Approach: We strong gradients ($$$\mathrm{G_{max}=300\,mT/m}$$$) combination linear, planar, spherical tensor up second-order motion compensation achieve $$$\mathrm{b_{max} = 1500\,s/mm^2}$$$ of 74 ms....
Motivation: Cardiac diffusion tensor imaging (cDTI) with echo-planar (EPI) requires long readouts to avoid aliasing artefacts if 2D-selective rf-pulses are not available. These prolong the echo time (TE) and increasing sensitivity off-resonance artefacts. Goal(s): The reduction of excited refocused field view in phase direction reduce TE image cDTI. Approach: We combine ZOnally-magnified Oblique Multi-slice (ZOOM) EPI (i.e. tilting slice orientation refocussing rf-pulse) ultra-strong...
Motivation: Oscillating gradient spin-echo (OGSE) diffusion MRI provides information about the cardiac microstructure that is complementary to conventional pulsed spin echo (PGSE). Goal(s): Using waveforms with different frequencies enables assessment of at sub-cellular length scales. Approach: OGSE tensor imaging (DTI) was applied in ex vivo mouse heart investigate ability disentangle hypertrophic from healthy hearts. Results: Our results show hearts exhibited significantly parameters (8...
Diffusion-weighted magnetic resonance spectroscopy (DW-MRS) offers improved cellular specificity to microstructure-compared water-based methods alone-but spatial resolution and SNR is severely reduced slow-diffusing metabolites necessitate higher b-values accurately characterize their diffusion properties. Ultra-strong gradients allow access per-unit time, for a given b-value, shorter times, but introduce additional challenges such as eddy-current artefacts, gradient non-uniformity,...
Diffusion weighted imaging techniques permit us to infer microstructural detail in biological tissue vivo and noninvasively. Modern sequences are based on advanced diffusion encoding schemes, allowing probing of more revealing measures microstructure than the standard apparent coefficient or fractional anisotropy. Though these methods may result faster acquisitions, they generally demand prior knowledge sequence-specific parameters for which there is no accepted sharing standard. Here, we...