ORCID Profile
0000-0002-6160-6079
Current Organisation
University of Oxford
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Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 15-11-2022
DOI: 10.1161/CIRCULATIONAHA.122.060137
Abstract: Myocardial scars are assessed noninvasively using cardiovascular magnetic resonance late gadolinium enhancement (LGE) as an imaging gold standard. A contrast-free approach would provide many advantages, including a faster and cheaper scan without contrast-associated problems. Virtual native enhancement (VNE) is a novel technology that can produce virtual LGE-like images without the need for contrast. VNE combines cine imaging and native T1 maps to produce LGE-like images using artificial intelligence. VNE was developed for patients with previous myocardial infarction from 4271 data sets (912 patients) each data set comprises slice position-matched cine, T1 maps, and LGE images. After quality control, 3002 data sets (775 patients) were used for development and 291 data sets (68 patients) for testing. The VNE generator was trained using generative adversarial networks, using 2 adversarial discriminators to improve the image quality. The left ventricle was contoured semiautomatically. Myocardial scar volume was quantified using the full width at half maximum method. Scar transmurality was measured using the centerline chord method and visualized on bull’s-eye plots. Lesion quantification by VNE and LGE was compared using linear regression, Pearson correlation ( R ), and intraclass correlation coefficients. Proof-of-principle histopathologic comparison of VNE in a porcine model of myocardial infarction also was performed. VNE provided significantly better image quality than LGE on blinded analysis by 5 independent operators on 291 data sets (all P .001). VNE correlated strongly with LGE in quantifying scar size ( R , 0.89 intraclass correlation coefficient, 0.94) and transmurality ( R , 0.84 intraclass correlation coefficient, 0.90) in 66 patients (277 test data sets). Two cardiovascular magnetic resonance experts reviewed all test image slices and reported an overall accuracy of 84% for VNE in detecting scars when compared with LGE, with specificity of 100% and sensitivity of 77%. VNE also showed excellent visuospatial agreement with histopathology in 2 cases of a porcine model of myocardial infarction. VNE demonstrated high agreement with LGE cardiovascular magnetic resonance for myocardial scar assessment in patients with previous myocardial infarction in visuospatial distribution and lesion quantification with superior image quality. VNE is a potentially transformative artificial intelligence–based technology with promise in reducing scan times and costs, increasing clinical throughput, and improving the accessibility of cardiovascular magnetic resonance in the near future.
Publisher: Oxford University Press (OUP)
Date: 27-09-2017
DOI: 10.1093/EHJCI/JEW207
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.HLC.2017.09.008
Abstract: Revascularisation of left main coronary artery (LMCA) disease can be potentially managed with percutaneous coronary intervention (PCI) or coronary artery bypass graft surgery (CABG). Recent randomised controlled trial (RCT) data have added to the literature on this subject and this meta-analysis aims to assess the state of the data to assist in guiding patient treatment decisions. A systematic literature search of Cochrane Library, EMBASE, OVID, and PubMed Medline was performed. Randomised controlled trials of patients with LMCA disease undergoing PCI with drug eluting stents or CABG were included. Clinical outcomes and adverse events were assessed and analysed. Four suitable RCTs of adequate quality and follow-up were identified. The incidence of major adverse cardiac and cerebrovascular events (MACCE) at 3 to 5 years of follow-up was significantly increased with PCI compared to CABG (23.3% vs 18.2%, OR 1.37 95% CI: 1.18-1.58 p=<0.0001 I Coronary artery bypass grafting and PCI both represent reasonable treatment modalities for LMCA disease in appropriately selected patients. However, where CABG is feasible it offers superior long-term freedom from repeat revascularisation. Longer-term follow-up is required to further clarify the durability of mortality outcomes, especially in patients treated with PCI.
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.HLC.2016.07.011
Abstract: Aortic valve replacement is indicated in patients with severe symptomatic aortic stenosis (AS). Transcatheter aortic valve replacement (TAVR) has evolved as a potential strategy in a growing proportion of patients in preference to surgical aortic valve replacement (SAVR). This meta-analysis aims to assess the differential outcomes of TAVR and SAVR in patients enrolled in published randomised controlled trials (RCTs). A systematic literature search of Cochrane Library, EMBASE, OVID, and PubMed MEDLINE was performed. Randomised controlled trials of patients with severe AS undergoing TAVR compared with SAVR were included. Clinical outcomes and procedural complications were assessed. Five RCTs with a total of 3,828 patients (1,928 TAVR and 1,900 SAVR) were analysed. There was no statistically significant difference in combined rates of all-cause mortality and stroke at 30-days for TAVR vs SAVR (6.3% vs 7.5% OR 0.83 95% CI: 0.64-1.08 P=0.17) or at 12 months (17.2% vs 19.2% OR 0.87 95% CI: 0.73-1.03 P=0.29). No statistically significant difference was seen for death or stroke separately at any time point although a numerical trend in favour of TAVR for both was recorded. Length of in-patient stay was significantly less with TAVR vs SAVR (9.6 +/- 7.7 days vs 12.2 +/- 8.8 days OR -2.94 95% CI: -4.64 to -1.24 P=0.0007). Major vascular complications were more frequent in patients undergoing TAVR vs SAVR (8.2% vs. 4.0% OR 2.15 95% CI: 1.62-2.86 P <0.00001) but major bleeding was more common among SAVR patients (20.5% vs 44.2% OR 0.34 95% CI: 0.22-0.52 P=<0.00001). Transcatheter aortic valve replacement and SAVR are associated with overall similar rates of death and stroke among patients in intermediate to high-risk cohorts but with reduced length of in-patient hospital stay.
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.EJRAD.2019.06.001
Abstract: There is a direct reverse dose-effect relationship between the amount of physical activity and cardiovascular risk. It is unknown whether this is true for extreme, persistent endurance training. The aim of the study was to assess structural changes of the heart in long-time ultra-marathon runners with special focus on myocardial fibrosis using parametric mapping. We studied a group of 30 healthy, male ultra-marathon runners (mean age 40.9 ± 6.6 yrs, median 9 yrs of running with frequent competitions) and 10 matched controls not engaged in any regular activities. All of them underwent cardiovascular magnetic resonance (CMR) with 3 T scanner including T1-mapping, late gadolinium enhancement (LGE) and extracellular volume (ECV) quantification. Athletes demonstrated significantly larger heart chambers and left ventricular (LV) mass. LV systolic function was unchanged. 73.3% of athletes fulfilled volumetric criteria for dilated cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy. Non-ischemic, small volume LGE was found in 8 athletes and in 1 control (27% vs. 10%, p = 0.40). It was localised at insertion points (5 athletes, 1 control) or in the septum or infero-lateral wall (3 athletes). Athletes with insertion point LGE had higher right ventricular end-diastolic volume index in comparison to athletes without LGE (p = 0.04), which suggests its relation to volume overload. There were no differences between athletes and non-athletes in terms of ECV values (26.1% vs. 25%, p = 0.29). Ultra-marathon runner's hearts demonstrate a high degree of structural remodelling, but there is no significant increase in focal or diffuse myocardial fibrosis.
Publisher: Elsevier BV
Date: 10-2021
Publisher: Elsevier BV
Date: 02-2018
Publisher: Elsevier BV
Date: 06-2021
Publisher: MDPI AG
Date: 03-2021
DOI: 10.3390/JCM10050946
Abstract: Coronary artery disease (CAD) is highly prevalent in patients with severe aortic stenosis (AS). The management of CAD is a central aspect of the work-up of patients undergoing transcatheter aortic valve implantation (TAVI), but few data are available on this field and the best percutaneous coronary intervention (PCI) practice is yet to be determined. A major challenge is the ability to elucidate the severity of bystander coronary stenosis independently of the severity of aortic valve stenosis and subsequent impact on blood flow. The prognostic role of CAD in patients undergoing TAVI is being still debated and the benefits and the best timing of PCI in this context are currently under evaluation. Additionally, PCI in the setting of advanced AS poses some technical challenges, due to the complex anatomy, risk of hemodynamic instability, and the increased risk of bleeding complications. This review aims to provide a comprehensive synthesis of the available literature on myocardial revascularization in patients with severe AS undergoing TAVI. This work can assist the Heart Team in in idualizing decisions about myocardial revascularization, taking into account available diagnostic tools as well as the risks and benefits.
Publisher: Springer Science and Business Media LLC
Date: 30-06-2021
DOI: 10.1038/S41598-021-92923-4
Abstract: Stress and rest T1-mapping may assess for myocardial ischemia and extracellular volume (ECV). However, the stress T1 response is method-dependent, and underestimation may lead to misdiagnosis. Further, ECV quantification may be affected by time, as well as the number and dosage of gadolinium (Gd) contrast administered. We compared two commonly available T1-mapping approaches in their stress T1 response and ECV measurement stability. Healthy subjects (n = 10, 50% female, 35 ± 8 years) underwent regadenoson stress CMR (1.5 T) on two separate days. Prototype ShMOLLI 5(1)1(1)1 sequence was used to acquire consecutive mid-ventricular T1-maps at rest, stress and post-Gd contrast to track the T1 time evolution. For comparison, standard MOLLI sequences were used: MOLLI 5(3)3 Low (256 matrix) & High (192 matrix) Heart Rate (HR) to acquire rest and stress T1-maps, and MOLLI 4(1)3(1)2 Low & High HR for post-contrast T1-maps. Stress and rest myocardial blood flow (MBF) maps were acquired after IV Gd contrast (0.05 mmol/kg each). Stress T1 reactivity (delta T1) was defined as the relative percentage increase in native T1 between rest and stress. Myocardial T1 values for delta T1 (dT1) and ECV were calculated. Residuals from the identified time dependencies were used to assess intra-method variability. ShMOLLI achieved a greater stress T1 response compared to MOLLI Low and High HR (peak dT1 = 6.4 ± 1.7% vs. 4.8 ± 1.3% vs. 3.8 ± 1.0%, respectively both p 0.0001). ShMOLLI dT1 correlated strongly with stress MBF (r = 0.77, p 0.001), compared to MOLLI Low HR (r = 0.65, p 0.01) and MOLLI High HR (r = 0.43, p = 0.07). ShMOLLI ECV was more stable to gadolinium dose with less time drift (0.006–0.04% per minute) than MOLLI variants. Overall, ShMOLLI demonstrated less intra-in idual variability than MOLLI variants for stress T1 and ECV quantification. Power calculations indicate up to a fourfold (stress T1) and 7.5-fold (ECV) advantage in s le-size reduction using ShMOLLI. Our results indicate that ShMOLLI correlates strongly with increased MBF during regadenoson stress and achieves a significantly higher stress T1 response, greater effect size, and greater ECV measurement stability compared with the MOLLI variants tested.
Publisher: AME Publishing Company
Date: 06-2020
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 24-08-2021
DOI: 10.1161/CIRCULATIONAHA.121.054432
Abstract: Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging is the gold standard for noninvasive myocardial tissue characterization but requires intravenous contrast agent administration. It is highly desired to develop a contrast agent–free technology to replace LGE for faster and cheaper CMR scans. A CMR virtual native enhancement (VNE) imaging technology was developed using artificial intelligence. The deep learning model for generating VNE uses multiple streams of convolutional neural networks to exploit and enhance the existing signals in native T1 maps (pixel-wise maps of tissue T1 relaxation times) and cine imaging of cardiac structure and function, presenting them as LGE-equivalent images. The VNE generator was trained using generative adversarial networks. This technology was first developed on CMR datasets from the multicenter Hypertrophic Cardiomyopathy Registry, using hypertrophic cardiomyopathy as an exemplar. The datasets were randomized into 2 independent groups for deep learning training and testing. The test data of VNE and LGE were scored and contoured by experienced human operators to assess image quality, visuospatial agreement, and myocardial lesion burden quantification. Image quality was compared using a nonparametric Wilcoxon test. Intra- and interobserver agreement was analyzed using intraclass correlation coefficients (ICC). Lesion quantification by VNE and LGE were compared using linear regression and ICC. A total of 1348 hypertrophic cardiomyopathy patients provided 4093 triplets of matched T1 maps, cines, and LGE datasets. After randomization and data quality control, 2695 datasets were used for VNE method development and 345 were used for independent testing. VNE had significantly better image quality than LGE, as assessed by 4 operators (n=345 datasets P .001 [Wilcoxon test]). VNE revealed lesions characteristic of hypertrophic cardiomyopathy in high visuospatial agreement with LGE. In 121 patients (n=326 datasets), VNE correlated with LGE in detecting and quantifying both hyperintensity myocardial lesions ( r =0.77–0.79 ICC=0.77–0.87 P .001) and intermediate-intensity lesions ( r =0.70–0.76 ICC=0.82–0.85 P .001). The native CMR images (cine plus T1 map) required for VNE can be acquired within 15 minutes and producing a VNE image takes less than 1 second. VNE is a new CMR technology that resembles conventional LGE but without the need for contrast administration. VNE achieved high agreement with LGE in the distribution and quantification of lesions, with significantly better image quality.
Publisher: Elsevier BV
Date: 03-2019
Publisher: Elsevier BV
Date: 11-2017
DOI: 10.1016/J.HLC.2016.12.017
Abstract: The uptake of bone-seeking radiotracers in the amyloid heart is well recognised. 99 Patients diagnosed with AL and ATTR (wild-type and inherited) cardiac amyloidosis were prospectively recruited from the Princess Alexandra Hospital Amyloidosis Centre. Patients underwent injection with Twenty-one patients (8 AL and 13 ATTR) completed the study. Median age was 58 and 70 years for AL and ATTR patients respectively, and 19 (90.5%) were male. 99 99
Publisher: BMJ
Date: 20-09-2021
Publisher: Radiological Society of North America (RSNA)
Date: 06-2023
DOI: 10.1148/RYCT.230145
Publisher: SAGE Publications
Date: 06-2014
Publisher: Wiley
Date: 10-09-2022
DOI: 10.1111/IMJ.15832
Abstract: Systemic sclerosis (SSc) associated interstitial lung disease (ILD) is a common complication of SSc, with a high mortality, despite current available treatments. Rituximab has shown some promising, although varied, results for the treatment of SSc-ILD. To determine whether rituximab stabilised or improved pulmonary function at 12 months, in patients with SSc-ILD. A retrospective analysis of patients with SSc-ILD who progressed despite conventional therapy and received rituximab between 2008 and 2019 was performed at two tertiary centres. Baseline percentage forced vital capacity (FVC) and percentage diffusing capacity of carbon monoxide (DLCO) were compared with 1-year post the first dose of rituximab. Mean and median change in FVC (%) and DLCO (%) were calculated. For those with available data, the FVC (%) and DLCO (%) 2 years and 1 year prior to rituximab were compared with the change 12-months post-rituximab. Thirteen patients were included in the analysis. All patients demonstrated stability in their pulmonary function testing at 1-year post-rituximab. The mean FVC (%) was 57.18 (±16.93 standard deviation (SD)) prior to rituximab and 59.75 (±18.83 SD) 12-month post-rituximab, demonstrating an increase of 2.57 (±4.70 SD P-value 0.07). The mean DLCO (%) increased from 37.10 (±18.41 SD) prior to rituximab to 38.03 (±19.83) post-rituximab. The mean change in DLCO (%) was 0.93 (±5.05 SD P-value 0.53). In the 2 years preceding rituximab, the mean FVC (%) and DLCO (%) declined by 9.25 and 9.66 respectively. This case series suggests that rituximab might stabilise pulmonary function tests, and delay deterioration in patients with progressive SSc-ILD. These findings add to the growing body of evidence suggesting a role for rituximab in the treatment of SSc-ILD.
Publisher: Public Library of Science (PLoS)
Date: 15-05-2015
Publisher: Oxford University Press (OUP)
Date: 07-02-2020
Publisher: Elsevier BV
Date: 05-2023
Publisher: Springer Science and Business Media LLC
Date: 26-08-2020
DOI: 10.1007/S11897-020-00481-Z
Abstract: Left ventricular hypertrophy (LVH) is a common presentation encountered in clinical practice with a erse range of potential aetiologies. Differentiation of pathological from physiological hypertrophy can be challenging but is crucial for further management and prognostication. Cardiovascular magnetic resonance (CMR) with advanced myocardial tissue characterisation is a powerful tool that may help to differentiate these aetiologies in the assessment of LVH. The use of CMR for detailed morphological assessment of LVH is well described. More recently, advanced CMR techniques (late gadolinium enhancement, parametric mapping, diffusion tensor imaging, and myocardial strain) have been used. These techniques are highly promising in helping to differentiate key aetiologies of LVH and provide valuable prognostic information. Recent advancements in CMR tissue characterisation, such as parametric mapping, in combination with detailed morphological assessment and late gadolinium enhancement, provide a powerful resource that may help assess and differentiate important causes of LVH.
Publisher: Wiley
Date: 26-06-2022
DOI: 10.1002/EJHF.2574
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 23-11-2021
DOI: 10.1161/CIRCULATIONAHA.121.054858
Abstract: Transient pulmonary congestion during exercise is emerging as an important determinant of reduced exercise capacity in heart failure with preserved ejection fraction (HFpEF). We sought to determine whether an abnormal cardiac energetic state underpins this process. We recruited patients across the spectrum of diastolic dysfunction and HFpEF (controls, n=11 type 2 diabetes, n=9 HFpEF, n=14 and severe diastolic dysfunction attributable to cardiac amyloidosis, n=9). Cardiac energetics were measured using phosphorus spectroscopy to define the myocardial phosphocreatine to ATP ratio. Cardiac function was assessed by cardiovascular magnetic resonance cine imaging and echocardiography and lung water using magnetic resonance proton density mapping. Studies were performed at rest and during submaximal exercise using a magnetic resonance imaging ergometer. Paralleling the stepwise decline in diastolic function across the groups (E/e′ ratio P .001) was an increase in NT-proBNP (N-terminal pro-brain natriuretic peptide P .001) and a reduction in phosphocreatine/ATP ratio (control, 2.15 [2.09, 2.29] type 2 diabetes, 1.71 [1.61, 1.91] HFpEF, 1.66 [1.44, 1.89] cardiac amyloidosis, 1.30 [1.16, 1.53] P .001). During 20-W exercise, lower left ventricular diastolic filling rates (r=0.58 P .001), lower left ventricular diastolic reserve (r=0.55 P .001), left atrial dilatation (r=–0.52 P .001), lower right ventricular contractile reserve (right ventricular ejection fraction change, r=0.57 P .001), and right atrial dilation (r=–0.71 P .001) were all linked to lower phosphocreatine/ATP ratio. Along with these changes, pulmonary proton density mapping revealed transient pulmonary congestion in patients with HFpEF (+4.4% [0.5, 6.4] P =0.002) and cardiac amyloidosis (+6.4% [3.3, 10.0] P =0.004), which was not seen in healthy controls (–0.1% [–1.9, 2.1] P =0.89) or type 2 diabetes without HFpEF (+0.8% [–1.7, 1.9] P =0.82). The development of exercise-induced pulmonary congestion was associated with lower phosphocreatine/ATP ratio (r=–0.43 P =0.004). A gradient of myocardial energetic deficit exists across the spectrum of HFpEF. Even at low workload, this energetic deficit is related to markedly abnormal exercise responses in all 4 cardiac chambers, which is associated with detectable pulmonary congestion. The findings support an energetic basis for transient pulmonary congestion in HFpEF.
Publisher: Frontiers Media SA
Date: 23-11-2021
Abstract: Background: Quantitative cardiovascular magnetic resonance (CMR) T1 mapping has shown promise for advanced tissue characterisation in routine clinical practise. However, T1 mapping is prone to motion artefacts, which affects its robustness and clinical interpretation. Current methods for motion correction on T1 mapping are model-driven with no guarantee on generalisability, limiting its widespread use. In contrast, emerging data-driven deep learning approaches have shown good performance in general image registration tasks. We propose MOCOnet, a convolutional neural network solution, for generalisable motion artefact correction in T1 maps. Methods: The network architecture employs U-Net for producing distance vector fields and utilises warping layers to apply deformation to the feature maps in a coarse-to-fine manner. Using the UK Biobank imaging dataset scanned at 1.5T, MOCOnet was trained on 1,536 mid-ventricular T1 maps (acquired using the ShMOLLI method) with motion artefacts, generated by a customised deformation procedure, and tested on a different set of 200 s les with a erse range of motion. MOCOnet was compared to a well-validated baseline multi-modal image registration method. Motion reduction was visually assessed by 3 human experts, with motion scores ranging from 0% (strictly no motion) to 100% (very severe motion). Results: MOCOnet achieved fast image registration (& second per T1 map) and successfully suppressed a wide range of motion artefacts. MOCOnet significantly reduced motion scores from 37.1±21.5 to 13.3±10.5 ( p & 0.001), whereas the baseline method reduced it to 15.8±15.6 ( p & 0.001). MOCOnet was significantly better than the baseline method in suppressing motion artefacts and more consistently ( p = 0.007). Conclusion: MOCOnet demonstrated significantly better motion correction performance compared to a traditional image registration approach. Salvaging data affected by motion with robustness and in a time-efficient manner may enable better image quality and reliable images for immediate clinical interpretation.
Publisher: AME Publishing Company
Date: 06-2020
DOI: 10.21037/CDT-20-165
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-07-2022
Abstract: The sympathetic cotransmitter, neuropeptide Y (NPY), is released into the coronary sinus during ST‐segment–elevation myocardial infarction and can constrict the coronary microvasculature. We sought to establish whether peripheral venous (PV) NPY levels, which are easy to obtain and measure, are associated with microvascular obstruction, myocardial recovery, and prognosis. NPY levels were measured immediately after primary percutaneous coronary intervention and compared with angiographic and cardiovascular magnetic resonance indexes of microvascular function. Patients were prospectively followed up for 6.4 (interquartile range, 4.1–8.0) years. PV (n=163) and coronary sinus (n=68) NPY levels were significantly correlated ( r =0.92 P .001) and associated with multiple coronary and imaging parameters of microvascular function and infarct size (such as coronary flow reserve, acute myocardial edema, left ventricular ejection fraction, and late gadolinium enhancement 6 months later). We therefore assessed the prognostic value of PV NPY during follow‐up, where 34 patients (20.7%) developed heart failure or died. Kaplan‐Meier survival analysis demonstrated that high PV NPY levels ( .4 pg/mL by binary recursive partitioning) were associated with increased incidence of heart failure and mortality (hazard ratio, 3.49 [95% CI, 1.65–7.4] P .001). This relationship was maintained after adjustment for age, cardiovascular risk factors, and previous myocardial infarction. Both PV and coronary sinus NPY levels correlate with microvascular function and infarct size after ST‐segment–elevation myocardial infarction. PV NPY levels are associated with the subsequent development of heart failure or mortality and may therefore be a useful prognostic marker. Further research is required to validate these findings.
Publisher: Elsevier BV
Date: 2023
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Kelly Morgan.