A5084899945- Advanced MRI Techniques and Applications
- Advanced Neuroimaging Techniques and Applications
- Cardiac Imaging and Diagnostics
- Cardiovascular Function and Risk Factors
- MRI in cancer diagnosis
- Atomic and Subatomic Physics Research
- Medical Imaging Techniques and Applications
- NMR spectroscopy and applications
- Cardiomyopathy and Myosin Studies
- Cardiac electrophysiology and arrhythmias
- Electron Spin Resonance Studies
- Medical Image Segmentation Techniques
- Elasticity and Material Modeling
- Cardiovascular Disease and Adiposity
- Seismic Imaging and Inversion Techniques
- Cardiac Structural Anomalies and Repair
- Functional Brain Connectivity Studies
- Advanced NMR Techniques and Applications
- Cerebrovascular and Carotid Artery Diseases
- Cardiac Valve Diseases and Treatments
- Advanced X-ray and CT Imaging
- Image and Signal Denoising Methods
- Congenital Heart Disease Studies
- Ultrasound Imaging and Elastography
- Amyloidosis: Diagnosis, Treatment, Outcomes
Royal Brompton Hospital
2015-2025
Imperial College London
2014-2025
Guy's and St Thomas' NHS Foundation Trust
2022-2025
Harefield Hospital
2022-2024
Lung Institute
2023-2024
British Lung Foundation
2024
Royal Brompton & Harefield NHS Foundation Trust
1996-2021
National Institutes of Health
2013-2018
National Heart Lung and Blood Institute
2013-2018
National Health Service
2017
Quantification of myocardial blood flow requires knowledge the amount contrast agent in tissue and arterial input function (AIF) driving delivery this agent. Accurate quantification is challenged by lack linearity between measured signal concentration. This work characterizes sources non-linearity presents a systematic approach to accurate measurements concentration both myocardium.
Cardiomyocytes are organized in microstructures termed sheetlets that reorientate during left ventricular thickening. Diffusion tensor cardiac magnetic resonance (DT-CMR) may enable noninvasive interrogation of vivo microstructural dynamics. Dilated cardiomyopathy (DCM) is a condition abnormal myocardium with unknown sheetlet function.This study sought to validate DT-CMR measures microstructure against histology, characterize dynamics wall thickening, and apply the technique hypertrophic...
Abstract 23 Na MRI has the potential to noninvasively detect sodium (Na) content changes in vivo. The goal of this study was implement a clinical setting for neurooncological and muscular imaging. Due biexponential T 2 decay tissue signal with short component, which ranges between 0.5–8 ms, measurement total requires imaging techniques echo times (TEs) below 0.5 ms. A 3D radial pulse sequence TE 0.2 ms at spatial resolution 4 × mm 3 developed that allows acquisition presentation images on...
The aim of this study was to implement a quantitative in vivo cardiac diffusion tensor imaging (DTI) technique that robust, reproducible, and feasible perform patients with cardiovascular disease. A stimulated‐echo single‐shot echo‐planar (EPI) sequence zonal excitation parallel implemented, together novel modification the prospective navigator (NAV) combined biofeedback mechanism. Ten volunteers were scanned on two different days, each time both multiple breath‐hold (MBH) NAV multislice...
Cardiac diffusion tensor imaging (cDTI) measures the magnitudes and directions of intramyocardial water diffusion. Assuming cross-myocyte components to be constrained by laminar microstructures myocardium, we hypothesized that cDTI at two cardiac phases might identify any abnormalities orientation mobility in hypertrophic cardiomyopathy (HCM). We performed vivo 3 Tesla end-systole late diastole 11 healthy controls patients with HCM, as well gadolinium enhancement (LGE) for detection regional...
Abstract While radial 3D acquisition has been discussed in cardiac MRI for its excellent results with undersampling, the self‐navigating properties of trajectory need yet to be exploited. Hence, interleaved such that first readout every interleave starts at top sphere, which represents shell covering all readouts. If this is done sub‐optimally, image quality might degraded by eddy current effects, and advanced density compensation needed. In work, an innovative based on a natural spiral...
Abstract Free‐breathing three‐dimensional whole‐heart coronary MRI is a noninvasive alternative to X‐ray angiography. However, the existing navigator‐gated approaches do not meet requirements of clinical practice, as they perform with suboptimal accuracy and require prolonged acquisition times. Self‐navigated techniques, applied bright‐blood imaging sequences, promise detect position blood pool directly in readouts acquired for imaging. Hence, respiratory displacement heart can be calculated...
The navigator gating and slice tracking approach currently used for respiratory motion compensation during free-breathing coronary magnetic resonance angiography (MRA) has low imaging efficiency (typically 30–50%), resulting in long times. In this work, a novel correction technique with 100% scan was developed whole-heart MRA. signal as reference to segment the data into six bins. 3D projection reconstruction k-space sampling acquisition enabled of resolution images within each bin. between...
Myocardial disarray is an important histological feature of hypertrophic cardiomyopathy (HCM) which has been studied post-mortem, but its in-vivo prevalence and extent unknown. Cardiac Diffusion Tensor Imaging (cDTI) provides information on mean intravoxel myocyte orientation potentially myocardial disarray. Recent technical advances have improved cDTI, the aim this study was to assess interstudy reproducibility quantitative cDTI in patients with HCM.
Stimulated-echo (STEAM) and, more recently, motion-compensated spin-echo (M2-SE) techniques have been used for in-vivo diffusion tensor cardiovascular magnetic resonance (DT-CMR) assessment of cardiac microstructure. The two differ in the length scales interrogated, their signal-to-noise ratio efficiency and sensitivity to both motion strain. Previous comparisons high performance gradients at 1.5 T a single phase. However, recent work using STEAM has demonstrated novel findings microscopic...
Background Cardiac amyloidosis (CA) is a disease of interstitial myocardial infiltration, usually by light chains or transthyretin. We used diffusion tensor cardiovascular magnetic resonance (DT-CMR) to noninvasively assess the effects amyloid infiltration on cardiac microstructure. Methods DT-CMR was performed at diastole and systole in 20 CA, 11 hypertrophic cardiomyopathy, 10 control subjects with calculation mean diffusivity, fractional anisotropy, sheetlet orientation (secondary...
Cine Displacement Encoding with Stimulated Echoes (DENSE) facilitates the quantification of myocardial deformation, by encoding tissue displacements in cardiovascular magnetic resonance (CMR) image phase, from which strain can be estimated high accuracy and reproducibility. Current methods for analyzing DENSE images still heavily rely on user input, making this process time-consuming subject to inter-observer variability. The present study sought develop a spatio-temporal deep learning model...
Muscle channelopathies such as paramyotonia, hyperkalemic periodic paralysis, and potassium-aggravated myotonia are caused by gain-of-function Na+ channel mutations.Methods: Implementation of a three-dimensional radial 23Na magnetic resonance (MR) sequence with ultra-short echo times allowed the authors to quantify changes in total muscular signal intensity. By this technique T2-weighted 1H MRI, studied whether affected muscles take up water during episodes myotonic stiffness or cold-...
Purpose To investigate the influence of diffusion weighting on in vivo cardiac tensor imaging (cDTI) and obtain optimal parameters. Methods Ten subjects were scanned using stimulated echo acquisition mode planar with six b‐values, from 50 to 950 s·mm −2 , plus b = 15 reference. The relationship between b‐value both signal loss signal‐to‐noise ratio measures was investigated. Mean diffusivity, fractional anisotropy, helical angle maps calculated all possible pairs effects main reference data....
Abstract Background and Aims Microstructural disturbances underlie dysfunctional contraction adverse left ventricular (LV) remodelling after ST-elevation myocardial infarction (STEMI). Biphasic diffusion tensor cardiovascular magnetic resonance (DT-CMR) quantifies dynamic reorientation of sheetlets (E2A) from diastole to systole during thickening, markers tissue integrity [mean diffusivity (MD) fractional anisotropy (FA)]. This study investigated whether microstructural alterations...
Diffusion tensor cardiac magnetic resonance (DT-CMR) enables probing of the microarchitecture myocardium, but apparent diffusion coefficient (ADC) and fractional anisotropy (FA) reported in healthy volunteers have been inconsistent. The aim this study was to validate a stimulated-echo sequence using phantoms, assess intercentre reproducibility in-vivo measures sequence.
There is growing interest in cardiac diffusion tensor imaging (cDTI), but, unlike other MRI applications, there has been little investigation of the effects noise on parameters typically derived. One method mitigating floor when are multiple image averages, as cDTI, to average complex rather than magnitude data, but phase contains contributions from bulk motion, which must be removed first. The mean diffusivity (MD), fractional anisotropy (FA), helical angle (HA) and absolute secondary...
Quantitative saturation-recovery based T1 mapping sequences are less sensitive to systematic errors than the Modified Look-Locker Inversion recovery (MOLLI) technique but require high performance saturation pulses. We propose optimize adiabatic and pulse train pulses for quantitative have <1 % absolute residual longitudinal magnetization (|MZ/M0|) over ranges of B0 $$ {\widehat{B}}_1 (B1 scale factor) inhomogeneity found at 1.5 T 3 T. Design parameters an BIR4-90 were optimized improved...
Quantitative myocardial perfusion mapping has advantages over qualitative assessment, including the ability to detect global flow reduction. However, it is not clinically available and remains as a research tool. Building upon previously described imaging sequence, this paper presents algorithm implementation of an automated solution for inline with step by performance characterization. An workflow proposed demonstrated on normal volunteers. Initial evaluation demonstrates fully respiratory...