Publications
431 results found
Lota A, Wassall R, Scott A, et al., 2017, T2 mapping by cardiovasular magnetic resonance in acute and recovered myocarditis: potential role in clinical surveillance, European Journal of Heart Failure, Supplement, Vol: 19, Pages: 258-258, ISSN: 1567-4215
Giannakidis A, Kamnitsas K, Spadotto V, et al., 2017, Fast fully automatic segmentation of the severely abnormal human right ventricle from cardiovascular magnetic resonance images using a multi-scale 3D convolutional neural network, 12th International Conference on Signal-Image Technology and Internet-Based Systems (SITIS), Publisher: IEEE, Pages: 42-46
Cardiac magnetic resonance (CMR) is regarded as the reference examination for cardiac morphology in tetralogy of Fallot (ToF) patients allowing images of high spatial resolution and high contrast. The detailed knowledge of the right ventricular anatomy is critical in ToF management. The segmentation of the right ventricle (RV) in CMR images from ToF patients is a challenging task due to the high shape and image quality variability. In this paper we propose a fully automatic deep learning-based framework to segment the RV from CMR anatomical images of the whole heart. We adopt a 3D multi-scale deep convolutional neural network to identify pixels that belong to the RV. Our robust segmentation framework was tested on 26 ToF patients achieving a Dice similarity coefficient of 0.8281±0.1010 with reference to manual annotations performed by expert cardiologists. The proposed technique is also computationally efficient, which may further facilitate its adoption in the clinical routine.
Lota AS, Wassall R, Scott AD, et al., 2017, T2 MAPPING IN ACUTE AND RECOVERED MYOCARDITIS: POTENTIAL ROLE IN CLINICAL SURVEILLANCE, 12th Annual Meeting of the British-Society-of-Cardiovascular-Magnetic-Resonance (BSCMR), Publisher: BMJ PUBLISHING GROUP, Pages: A22-A24, ISSN: 1355-6037
Khalique Z, Ferreira PF, Scott AD, et al., 2017, DT-CMR IMAGING OF DERANGED MICROSTRUCTURE IN SITUS INVERSUS TOTALIS, 24th Great Wall International Congress of Cardiology / Asia Pacific Heart Congress / International Congress of Cardiovascular Prevention and Rehabilitation, Publisher: BMJ PUBLISHING GROUP, Pages: A15-A16, ISSN: 1355-6037
Giannakidis A, Oktay O, Keegan J, et al., 2017, Super-resolution Reconstruction of Late Gadolinium Cardiovascular Magnetic Resonance Images using a Residual Convolutional Neural Network, The 25th Scientific Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM 2017)
Lota A, Baksi J, Tsao A, et al., 2017, Cardiovascular magnetic resonance in survivors of sudden cardiac arrest: 14 year experience from a tertiary referral centre in the United Kingdom, JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY, Vol: 69, Pages: 491-491, ISSN: 0735-1097
Nielles-Vallespin S, Khalique Z, Ferreira PF, et al., 2017, Assessment of myocardial microstructural dynamics by in vivo diffusion tensor cardiac magnetic resonance, Journal of the American College of Cardiology, Vol: 69, Pages: 661-676, ISSN: 0735-1097
BackgroundCardiomyocytes are organized in microstructures termed sheetlets that reorientate during left ventricular thickening. Diffusion tensor cardiac magnetic resonance (DT-CMR) may enable noninvasive interrogation of in vivo cardiac microstructural dynamics. Dilated cardiomyopathy (DCM) is a condition of abnormal myocardium with unknown sheetlet function.ObjectivesThis study sought to validate in vivo DT-CMR measures of cardiac microstructure against histology, characterize microstructural dynamics during left ventricular wall thickening, and apply the technique in hypertrophic cardiomyopathy (HCM) and DCM.MethodsIn vivo DT-CMR was acquired throughout the cardiac cycle in healthy swine, followed by in situ and ex vivo DT-CMR, then validated against histology. In vivo DT-CMR was performed in 19 control subjects, 19 DCM, and 13 HCM patients.ResultsIn swine, a DT-CMR index of sheetlet reorientation (E2A) changed substantially (E2A mobility ∼46°). E2A changes correlated with wall thickness changes (in vivo r2 = 0.75; in situ r2 = 0.89), were consistently observed under all experimental conditions, and accorded closely with histological analyses in both relaxed and contracted states. The potential contribution of cyclical strain effects to in vivo E2A was ∼17%. In healthy human control subjects, E2A increased from diastole (18°) to systole (65°; p < 0.001; E2A mobility = 45°). HCM patients showed significantly greater E2A in diastole than control subjects did (48°; p < 0.001) with impaired E2A mobility (23°; p < 0.001). In DCM, E2A was similar to control subjects in diastole, but systolic values were markedly lower (40°; p < 0.001) with impaired E2A mobility (20°; p < 0.001).ConclusionsMyocardial microstructure dynamics can be characterized by in vivo DT-CMR. Sheetlet function was abnormal in DCM with altered systolic conformation and reduced mobility, contrasting with HCM, which showed reduced mobility with alte
Yang G, Zhuang X, Khan H, et al., 2017, Differentiation of Pre-ablation and Post-ablation Late Gadolinium-enhanced Cardiac MRI Scans of Longstanding Persistent Atrial Fibrillation Patients
Yang G, Zhuang X, Khan H, et al., 2017, Multi-atlas Propagation based Left Atrium Segmentation Coupled with Super-voxel based Pulmonary Veins Delineation in Late Gadolinium-enhanced Cardiac MRI
Raphael CE, Keegan J, Parker KH, et al., 2016, Feasibility of cardiovascular magnetic resonance derived coronary wave intensity analysis, Journal of Cardiovascular Magnetic Resonance, Vol: 18, ISSN: 1532-429X
BackgroundWave intensity analysis (WIA) of the coronary arteries allows description of the predominant mechanisms influencing coronary flow over the cardiac cycle. The data are traditionally derived from pressure and velocity changes measured invasively in the coronary artery. Cardiovascular magnetic resonance (CMR) allows measurement of coronary velocities using phase velocity mapping and derivation of central aortic pressure from aortic distension. We assessed the feasibility of WIA of the coronary arteries using CMR and compared this to invasive data.MethodsCMR scans were undertaken in a serial cohort of patients who had undergone invasive WIA. Velocity maps were acquired in the proximal left anterior descending and proximal right coronary artery using a retrospectively-gated breath-hold spiral phase velocity mapping sequence with high temporal resolution (19 ms). A breath-hold segmented gradient echo sequence was used to acquire through-plane cross sectional area changes in the proximal ascending aorta which were used as a surrogate of an aortic pressure waveform after calibration with brachial blood pressure measured with a sphygmomanometer. CMR-derived aortic pressures and CMR-measured velocities were used to derive wave intensity. The CMR-derived wave intensities were compared to invasive data in 12 coronary arteries (8 left, 4 right). Waves were presented as absolute values and as a % of total wave intensity. Intra-study reproducibility of invasive and non-invasive WIA was assessed using Bland-Altman analysis and the intraclass correlation coefficient (ICC).ResultsThe combination of the CMR-derived pressure and velocity data produced the expected pattern of forward and backward compression and expansion waves. The intra-study reproducibility of the CMR derived wave intensities as a % of the total wave intensity (mean ± standard deviation of differences) was 0.0 ± 6.8%, ICC = 0.91. Intra-study reproducib
Pennell DJ, Baksi AJ, Prasad SK, et al., 2016, Review of Journal of Cardiovascular Magnetic Resonance 2015, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 86-86, ISSN: 1097-6647
There were 116 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2015, which is a 14 % increase on the 102 articles published in 2014. The quality of the submissions continues to increase. The 2015 JCMR Impact Factor (which is published in June 2016) rose to 5.75 from 4.72 for 2014 (as published in June 2015), which is the highest impact factor ever recorded for JCMR. The 2015 impact factor means that the JCMR papers that were published in 2013 and 2014 were cited on average 5.75 times in 2015. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, the progress of the journal's impact over the last 5 years has been impressive. Our acceptance rate is < 25 % and has been falling because the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors have felt that it is useful once per calendar year to summarize the papers for the readership into broad areas of interest or theme, so that areas of interest can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality papers to JCMR for publication.
Serbanovic-Canic J, de Luca A, Warboys C, et al., 2016, Zebrafish model for functional screening of flow-responsive genes, Arteriosclerosis Thrombosis and Vascular Biology, Vol: 36, ISSN: 1524-4636
OBJECTIVE: Atherosclerosis is initiated at branches and bends of arteries exposed to disturbed blood flow that generates low shear stress. This mechanical environment promotes lesions by inducing endothelial cell (EC) apoptosis and dysfunction via mechanisms that are incompletely understood. Although transcriptome-based studies have identified multiple shear-responsive genes, most of them have an unknown function. To address this, we investigated whether zebrafish embryos can be used for functional screening of mechanosensitive genes that regulate EC apoptosis in mammalian arteries. APPROACH AND RESULTS: First, we demonstrated that flow regulates EC apoptosis in developing zebrafish vasculature. Specifically, suppression of blood flow in zebrafish embryos (by targeting cardiac troponin) enhanced that rate of EC apoptosis (≈10%) compared with controls exposed to flow (≈1%). A panel of candidate regulators of apoptosis were identified by transcriptome profiling of ECs from high and low shear stress regions of the porcine aorta. Genes that displayed the greatest differential expression and possessed 1 to 2 zebrafish orthologues were screened for the regulation of apoptosis in zebrafish vasculature exposed to flow or no-flow conditions using a knockdown approach. A phenotypic change was observed in 4 genes; p53-related protein (PERP) and programmed cell death 2-like protein functioned as positive regulators of apoptosis, whereas angiopoietin-like 4 and cadherin 13 were negative regulators. The regulation of perp, cdh13, angptl4, and pdcd2l by shear stress and the effects of perp and cdh13 on EC apoptosis were confirmed by studies of cultured EC exposed to flow. CONCLUSIONS: We conclude that a zebrafish model of flow manipulation coupled to gene knockdown can be used for functional screening of mechanosensitive genes in vascular ECs, thus providing potential therapeutic targets to prevent or treat endothelial injury at atheroprone sites.
Vassiliou VS, Heng EL, Gatehouse PD, et al., 2016, Magnetic resonance imaging phantoms for quality-control of myocardial T1 and ECV mapping: specific formulation, long-term stability and variation with heart rate and temperature, Journal of Cardiovascular Magnetic Resonance, Vol: 18, ISSN: 1532-429X
BACKGROUND: Magnetic resonance imaging (MRI) phantoms are routinely used for quality assurance in MRI centres; however their long term stability for verification of myocardial T1/ extracellular volume fraction (ECV) mapping has never been investigated. METHODS: Nickel-chloride agarose gel phantoms were formulated in a reproducible laboratory procedure to mimic blood and myocardial T1 and T2 values, native and late after Gadolinium administration as used in T1/ECV mapping. The phantoms were imaged weekly with an 11 heart beat MOLLI sequence for T1 and long TR spin-echo sequences for T2, in a carefully controlled reproducible manner for 12 months. RESULTS: There were only small relative changes seen in all the native and post gadolinium T1 values (up to 9.0 % maximal relative change in T1 values) or phantom ECV (up to 8.3 % maximal relative change of ECV, up to 2.2 % maximal absolute change in ECV) during this period. All native and post gadolinium T2 values remained stable over time with <2 % change. Temperature sensitivity testing showed MOLLI T1 values in the long T1 phantoms increasing by 23.9 ms per degree increase and short T1 phantoms increasing by 0.3 ms per degree increase. There was a small absolute increase in ECV of 0.069 % (~0.22 % relative increase in ECV) per degree increase. Variation in heart rate testing showed a 0.13 % absolute increase in ECV (~0.45 % relative increase in ECV) per 10 heart rate increase. CONCLUSIONS: These are the first phantoms reported in the literature modeling T1 and T2 values for blood and myocardium specifically for the T1mapping/ECV mapping application, with stability tested rigorously over a 12 month period. This work has significant implications for the utility of such phantoms in improving the accuracy of serial scans for myocardial tissue characterisation by T1 mapping methods and in multicentre work.
Alam MH, Auger D, McGill LA, et al., 2016, Comparison of 3 T and 1.5 T for T2* magnetic resonance of tissue iron, Journal of Cardiovascular Magnetic Resonance, Vol: 18, ISSN: 1532-429X
BACKGROUND: T2* magnetic resonance of tissue iron concentration has improved the outcome of transfusion dependant anaemia patients. Clinical evaluation is performed at 1.5 T but scanners operating at 3 T are increasing in numbers. There is a paucity of data on the relative merits of iron quantification at 3 T vs 1.5 T. METHODS: A total of 104 transfusion dependent anaemia patients and 20 normal volunteers were prospectively recruited to undergo cardiac and liver T2* assessment at both 1.5 T and 3 T. Intra-observer, inter-observer and inter-study reproducibility analysis were performed on 20 randomly selected patients for cardiac and liver T2*. RESULTS: Association between heart and liver T2* at 1.5 T and 3 T was non-linear with good fit (R (2) = 0.954, p < 0.001 for heart white-blood (WB) imaging; R (2) = 0.931, p < 0.001 for heart black-blood (BB) imaging; R (2) = 0.993, p < 0.001 for liver imaging). R2* approximately doubled between 1.5 T and 3 T with linear fits for both heart and liver (94, 94 and 105 % respectively). Coefficients of variation for intra- and inter-observer reproducibility, as well as inter-study reproducibility trended to be less good at 3 T (3.5 to 6.5 %) than at 1.5 T (1.4 to 5.7 %) for both heart and liver T2*. Artefact scores for the heart were significantly worse with the 3 T BB sequence (median 4, IQR 2-5) compared with the 1.5 T BB sequence (4 [3-5], p = 0.007). CONCLUSION: Heart and liver T2* and R2* at 3 T show close association with 1.5 T values, but there were more artefacts at 3 T and trends to lower reproducibility causing difficulty in quantifying low T2* values with high tissue iron. Therefore T2* imaging at 1.5 T remains the gold standard for clinical practice. However, in centres where only 3 T is available, equival
McGill L-A, Ferreira P, Scott A, et al., 2016, Non-invasive Interrogation of Myocardial Disarray in Hypertrophic Cardiomyopathy, Annual Conference of the British Cardiovascular Society (BCS) on Prediction and Prevention, Publisher: BMJ Publishing Group, Pages: A96-A96, ISSN: 1355-6037
Firmin D, 2016, Abstracts, 14th Annual Meeting of the European Association of Cardiovascular Imaging, a registered branch of the ESC, Pages: i1-i80, ISSN: 2047-2404
Alam MH, He T, Auger D, et al., 2016, Validation of T2* In-line Analysis for Tissue Iron Quantification at 1.5T, Journal of Cardiovascular Magnetic Resonance, Vol: 18, ISSN: 1532-429X
Background: There is a need for improved worldwide access to tissue iron quantification using T2* cardiovascular magnetic resonance (CMR). One route to facilitate this would be simple in-line T2* analysis widely available on MR scanners. We therefore compared our clinically validated and established T2* method at Royal Brompton Hospital (RBH T2*) against a novel work-in-progress (WIP) sequence with in-line T2* measurement from Siemens (WIP T2*).Methods: Healthy volunteers (n=22) and patients with iron overload (n=78) were recruited (53 males, median age 34 years). A 1.5T study (Magnetom Avanto, Siemens) was performed on all subjects. The same mid-ventricular short axis cardiac slice and transaxial slice through the liver were used to acquire both RBH T2* images and WIP T2* maps for each participant. Cardiac white blood (WB) and black blood (BB) sequences were acquired. Intraobserver, interobserver and interstudy reproducibility were measured on the same data from a subset of 20 participants. Results: Liver T2* values ranged from 0.8-35.7ms (median 5.1ms) and cardiac T2* values from 6.0-52.3ms (median 31ms). The coefficient of variance (CoV) values for direct comparison of T2* values by RBH and WIP were 6.1%-7.8% across techniques. Accurate delineation of the septum was difficult on some WIP T2* maps due to artefacts. The inability to manually correct for noise by truncation of erroneous later echo times led to some overestimation of T2* using WIP T2* compared with the RBH T2*. Reproducibility CoV results for RBH T2* ranged from 1.5%–5.7% which were better than the reproducibility of WIP T2* values of 4.1%–16.6%. Conclusions: Iron estimation using the T2* CMR sequence in combination with Siemens’ in-line data processing is generally satisfactory and may help facilitate global access to tissue iron assessment. The current automated T2* map technique is less good for tissue iron assessment with noisy data at low T2* values.
Giannakidis A, Gullberg GT, Pennell DJ, et al., 2016, Value of formalin fixation for the prolonged preservation of rodent myocardial microanatomical organization: Evidence by MR diffusion tensor imaging., Anatomical Record, Vol: 299, Pages: 878-887, ISSN: 0749-3002
Previous ex vivo diffusion tensor imaging (DTI) studies on formalin fixed myocardial tissue assumed that, after some initial changes in the first 48 hours since the start of fixation, DTI parameters remain stable over time. Prolonged preservation of cardiac tissue in formalin prior to imaging has been seen many times in the DTI literature as it is considered orderly. Our objective is to define the effects of the prolonged cardiac tissue exposure to formalin on tissue microanatomical organization, as this is assessed by DTI parameters. DTI experiments were conducted on eight excised rodent hearts that were fixed by immersion in formalin. The samples were randomly divided into two equinumerous groups corresponding to shorter (∼2 weeks) and more prolonged (∼ 6-8 weeks) durations of tissue exposure to formalin prior to imaging. We found that when the duration of cardiac tissue exposure to formalin before imaging increased, water diffusion became less restricted, helix angle (HA) histograms flattened out and exhibited heavier tails (even though the classic HA transmural variation was preserved), and a significant loss of inter-voxel primary diffusion orientation integrity was introduced. The prolonged preservation of cardiac tissue in formalin profoundly affected its microstructural organization, as this was assessed by DTI parameters. The accurate interpretation of diffusivity profiles necessitates awareness of the pitfalls of prolonged cardiac tissue exposure duration to formalin. The acquired knowledge works to the advantage of a proper experimental design of DTI studies of fixed hearts. This article is protected by copyright. All rights reserved.
Yang G, Ye X, Slabaugh G, et al., 2016, Combined self-learning based single-image super-resolution and dual-tree complex wavelet transform denoising for medical images, Medical Imaging 2016: Image Processing, Publisher: Society of Photo Optical Instrumentation Engineers
In this paper, we propose a novel self-learning based single-image super-resolution (SR) method, which is coupled with dual-tree complex wavelet transform (DTCWT) based denoising to better recover high-resolution (HR) medical images. Unlike previous methods, this self-learning based SR approach enables us to reconstruct HR medical images from a single low-resolution (LR) image without extra training on HR image datasets in advance. The relationships between the given image and its scaled down versions are modeled using support vector regression with sparse coding and dictionary learning, without explicitly assuming reoccurrence or self-similarity across image scales. In addition, we perform DTCWT based denoising to initialize the HR images at each scale instead of simple bicubic interpolation. We evaluate our method on a variety of medical images. Both quantitative and qualitative results show that the proposed approach outperforms bicubic interpolation and state-of-the-art single-image SR methods while effectively removing noise.
Fair M, Gatehouse P, DiBella EVR, et al., 2016, An extended 3D whole-heart myocardial first-pass perfusion sequence: alternate-cycle views with isotropic and high-resolution imaging, Society for Cardiovascular Magnetic Resonance, Publisher: BioMed Central, ISSN: 1532-429X
Simultaneously optimising parameters such as LV cover-age, image resolution and contrast sensitivity is difficultin first-pass perfusion (FPP). 3D FPP shows potential (1)to improve coverage, but“whole-heart”coveragedemands high acceleration forcing compromises such asloss of spatial resolution. 2D FPP shows high diagnosticability with more slices distributed over alternate-RRcycles (2), relaxing acceleration requirements. This workproposes that 3D FPP could interleave two strategieswith different 3D parameters in alternate cycles, in sumapproaching the full set of desired FPP properties. Thiswork also aims to improve specificity against artefactsby imaging the same myocardium with two differentinterleaved 3D scans (distinct from reformatting a single3D FPP scan). Similar confirmation strategies are oftenused in CMR, such as repetition with swapped phase-encode direction in late-enhancement imaging.
Vassiliou V, Wassilew K, Malley T, et al., 2016, Incremental benefit in correlation with histology of native T1 mapping, partition coefficient and extracellular volume fraction in patients with aortic stenosis, Journal of Cardiovascular Magnetic Resonance, Vol: 18, ISSN: 1097-6647
Scott AD, Nielles-Vallespin S, Ferreira P, et al., 2016, In-vivo cardiac DTI: An initial comparison of M012 compensated spin-echo and STEAM, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 1-3, ISSN: 1097-6647
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Jin N, Fernandes JL, Firmin D, et al., 2016, Free-breathing myocardial T2* Mapping using GRE-EPI and MOCO for myocardial and hepatic iron overload assessment: A multi-centre study, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 1-2, ISSN: 1097-6647
Scott AD, Tayal U, Nielles-Vallespin S, et al., 2016, Accelerating cine DENSE using a zonal excitation, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 1-3, ISSN: 1097-6647
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Vassiliou V, Wassilew K, Asimakopoulos G, et al., 2016, Histological validation of a new CMR T1-mapping-based protocol to improve accuracy for fibrosis assessment in patients with aortic stenosis, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 1-3, ISSN: 1097-6647
Scott AD, Ferreira P, Nielles-Vallespin S, et al., 2016, Can we predict the diffusion “sweet-spot” based on a standard cine?, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 1-3, ISSN: 1097-6647
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Fair MJ, Gatehouse P, DiBella EV, et al., 2016, An extended 3D whole-heart myocardial first-pass perfusion sequence: alternate-cycle views with isotropic and high-resolution imaging, Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, Vol: 18, ISSN: 1097-6647
Tunnicliffe EM, Ferreira P, Scott AD, et al., 2016, Intercentre reproducibility of second eigenvector orientation in cardiac diffusion tensor imaging, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: P35-P35, ISSN: 1097-6647
Pierce I, Keegan J, Wage R, et al., 2016, Late Gadolinium Enhancemnet imaging of the Left Ventricle in a single breath-hold using multi-slice spiral PSIR imaging at 3T, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: P304-P304, ISSN: 1097-6647
McGill LA, Ferreira PF, Scott AD, et al., 2016, Relationship between cardiac diffusion tensor imaging parameters and anthropometrics in healthy volunteers, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 2-2
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