Imperial College London

DrDeclanO'Regan

Faculty of MedicineInstitute of Clinical Sciences

Reader in Imaging Sciences
 
 
 
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Contact

 

+44 (0)20 3313 1510declan.oregan

 
 
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Location

 

Imaging Sciences DepartmentHammersmith HospitalHammersmith Campus

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Summary

 

Publications

Publication Type
Year
to

124 results found

Marvao AD, Meyer HV, Dawes TJ, Shi W, Bai W, Rueckert D, Birney E, O'Regan DP, Cook Set al., 2016, Genome wide association analysis of the heart using high-resolution 3D cardiac MRI identifies new genetic loci underlying cardiac structure and function., Journal of Cardiovascular Magnetic Resonance, Vol: 18, ISSN: 1097-6647

Journal article

Jaijee S, Quinlan M, Tokarczuk P, Statton B, Diamond T, Howard LS, O'Regan D, Gibbs JSet al., 2016, Cardiac Magnetic Resonance Imaging In Healthy Volunteers In Normoxic And Hypoxic Exercise, International Conference of the American-Thoracic-Society (ATS), Publisher: AMER THORACIC SOC, ISSN: 1073-449X

Conference paper

Oktay O, Tarroni G, Bai W, de Marvao A, O'Regan D, Cook S, Rueckert Det al., 2016, Respiratory Motion Correction for 2D Cine Cardiac MR Images using Probabilistic Edge Maps, 43rd Computing in Cardiology Conference (CinC), Publisher: IEEE, Pages: 129-132, ISSN: 2325-8861

Conference paper

Alenaini W, O'Regan DP, de Marvao A, Dawes TJ, Shi W, Cook SAet al., 2015, Three dimensional modelling of the effect of arterial pulse wave velocity and body size on left ventricular geometry, Journal of Cardiovascular Magnetic Resonance, Vol: 17

Journal article

Jaijee SK, Ariff B, Howard L, O'Regan DP, Gin-Sing W, Davies R, Gibbs JSet al., 2015, Left main bronchus compression due to main pulmonary artery dilatation in pulmonary hypertension: two case reports, Pulmonary Circulation, Vol: 5, Pages: 723-725, ISSN: 2045-8940

Pulmonary arterial dilatation associated with pulmonary hypertension may result in significant compression of local structures. Left main coronary artery and left recurrent laryngeal nerve compression have been described. Tracheobronchial compression from pulmonary arterial dilatation is rare in adults, and there are no reports in the literature of its occurrence in idiopathic pulmonary arterial hypertension. Compression in infants with congenital heart disease has been well described. We report 2 cases of tracheobronchial compression: first, an adult patient with idiopathic pulmonary arterial hypertension who presents with symptomatic left main bronchus compression, and second, an adult patient with Eisenmenger ventricular septal defect and right-sided aortic arch, with progressive intermedius and right middle lobe bronchi compression in association with enlarged pulmonary arteries.

Journal article

de Marvao A, Dawes TJW, Shi W, Durighel G, Rueckert D, Cook SA, O'Regan DPet al., 2015, Precursors of the hypertensive heart phenotype develop in normotensive adults: a high resolution 3D MRI study, JACC: Cardiovascular Imaging, Vol: 8, Pages: 1260-1269, ISSN: 1936-878X

ObjectivesThis study used high-resolution 3-dimensional cardiac magnetic resonance to define the anatomical and functional left ventricular (LV) properties associated with increasing systolic blood pressure (SBP) in a drug-naïve cohort.BackgroundLV hypertrophy and remodeling occur in response to hemodynamic stress but little is known about how these phenotypic changes are initiated in the general population.MethodsIn this study, 1,258 volunteers (54% women, mean age 40.6 ± 12.8 years) without self-reported cardiovascular disease underwent 3-dimensional cardiac magnetic resonance combined with computational modeling. The relationship between SBP and wall thickness (WT), relative WT, end-systolic wall stress (WS), and fractional wall thickening were analyzed using 3-dimensional regression models adjusted for body surface area, sex, race, age, and multiple testing. Significantly associated points in the LV model (p < 0.05) were identified and the relationship with SBP reported as mean β coefficients.ResultsThere was a continuous relationship between SBP and asymmetric concentric hypertrophic adaptation of the septum and anterior wall that was associated with normalization of wall stress. In the lateral wall an increase in wall stress with rising SBP was not balanced by a commensurate hypertrophic relationship. In normotensives, SBP was positively associated with WT (β = 0.09) and relative WT (β = 0.07) in the septal and anterior walls, and this regional hypertrophic relationship was progressively stronger among pre-hypertensives (β = 0.10) and hypertensives (β = 0.30).ConclusionsThese findings show that the precursors of the hypertensive heart phenotype can be traced to healthy normotensive adults and that an independent and continuous relationship exists between adverse LV remodeling and SBP in a low-risk population. These adaptations show distinct regional variations with concentric hypertrophy of the septum and eccentric hyper

Journal article

Cheng Z, Kidher E, Jarral OA, O'Regan DP, Wood NB, Athanasiou T, Xu XYet al., 2015, Assessment of hemodynamic conditions in the aorta following root replacement with composite valve-conduit graft, Annals of Biomedical Engineering, Vol: 44, Pages: 1392-1404, ISSN: 0090-6964

This paper presents the analysis of detailed hemodynamics in the aortas of four patients following replacement with a composite bio-prosthetic valve-conduit. Magnetic resonance image-based computational models were set up for each patient with boundary conditions comprising subject-specific three-dimensional inflow velocity profiles at the aortic root and central pressure waveform at the model outlet. Two normal subjects were also included for comparison. The purpose of the study was to investigate the effects of the valve-conduit on flow in the proximal and distal aorta. The results suggested that following the composite valve-conduit implantation, the vortical flow structure and hemodynamic parameters in the aorta were altered, with slightly reduced helical flow index, elevated wall shear stress and higher non-uniformity in wall shear compared to normal aortas. Inter-individual analysis revealed different hemodynamic conditions among the patients depending on the conduit configuration in the ascending aorta, which is a key factor in determining post-operative aortic flow. Introducing a natural curvature in the conduit to create a smooth transition between the conduit and native aorta may help prevent the occurrence of retrograde and recirculating flow in the aortic arch, which is particularly important when a large portion or the entire ascending aorta needs to be replaced.

Journal article

Bai W, Shi W, de Marvao A, Dawes TJW, O'Regan DP, Cook SA, Rueckert Det al., 2015, A bi-ventricular cardiac atlas built from 1000+ high resolution MR images of healthy subjects and an analysis of shape and motion, Medical Image Analysis, Vol: 26, Pages: 133-145, ISSN: 1361-8423

Atlases encode valuable anatomical and functional information from a population. In this work, a bi-ventricular cardiac atlas was built from a unique data set, which consists of high resolution cardiac MR images of 1000+ normal subjects. Based on the atlas, statistical methods were used to study the variation of cardiac shapes and the distribution of cardiac motion across the spatio-temporal domain. We have shown how statistical parametric mapping (SPM) can be combined with a general linear model to study the impact of gender and age on regional myocardial wall thickness. Finally, we have also investigated the influence of the population size on atlas construction and atlas-based analysis. The high resolution atlas, the statistical models and the SPM method will benefit more studies on cardiac anatomy and function analysis in the future.

Journal article

Dawes T, De Marvao A, Shi W, Rueckert D, Watson G, Howard L, Gibbs S, Cook S, Wilkins M, O'Regan Det al., 2015, Prognostic value of right heart adaptation to pulmonary arterial hypertension: a prospective cohort study, Congress of the European-Society-of-Cardiology (ESC), Publisher: OXFORD UNIV PRESS, Pages: 708-709, ISSN: 0195-668X

Conference paper

De Marvao A, Dawes T, Shi W, Rueckert D, Cook S, O'Regan Det al., 2015, Rising systolic blood pressure leads to a continuous progression towards hypertensive heart disease: a prospective population study, Congress of the European-Society-of-Cardiology (ESC), Publisher: OXFORD UNIV PRESS, Pages: 191-191, ISSN: 0195-668X

Conference paper

Buyandelger B, Mansfield C, Kostin S, Choi O, Roberts AM, Ware JS, Mazzarotto F, Pesce F, Buchan R, Isaacson RL, Vouffo J, Gunkel S, Knöll G, McSweeney SJ, Wei H, Perrot A, Pfeiffer C, Toliat MR, Ilieva K, Krysztofinska E, López-Olañeta MM, Gómez-Salinero JM, Schmidt A, Ng KE, Teucher N, Chen J, Teichmann M, Eilers M, Haverkamp W, Regitz-Zagrosek V, Hasenfuss G, Braun T, Pennell DJ, Gould I, Barton PJ, Lara-Pezzi E, Schafer S, Hübner N, Felkin LE, O'Regan DP, Petretto E, Brand T, Milting H, Nürnberg P, Schneider MD, Prasad S, Knöll Ret al., 2015, ZBTB17 (MIZ1) Is Important for the Cardiac Stress Response and a Novel Candidate Gene for Cardiomyopathy and Heart Failure., Circulation. Cardiovascular Genetics, Vol: 8, Pages: 643-652, ISSN: 1942-3268

BACKGROUND: -Mutations in sarcomeric and cytoskeletal proteins are a major cause of hereditary cardiomyopathies, but our knowledge remains incomplete as to how the genetic defects execute their effects. METHODS AND RESULTS: -We used cysteine and glycine-rich protein 3 (CSRP3), a known cardiomyopathy gene, in a yeast two-hybrid screen and identified zinc finger and BTB domain containing protein 17 (ZBTB17) as a novel interacting partner. ZBTB17 is a transcription factor that contains the peak association signal (rs10927875) at the replicated 1p36 cardiomyopathy locus. ZBTB17 expression protected cardiac myocytes from apoptosis in vitro and in a mouse model with cardiac myocyte-specific deletion of Zbtb17, which develops cardiomyopathy and fibrosis after biomechanical stress. ZBTB17 also regulated cardiac myocyte hypertrophy in vitro and in vivo in a calcineurin-dependent manner. CONCLUSIONS: -We revealed new functions for ZBTB17 in the heart, a transcription factor which may play a role as a novel cardiomyopathy gene.

Journal article

Francis C, de Marvao A, O'Regan DP, Dawes TJW, Alenaini W, Gandhi A, Quinlan M, Buchan R, Barton PJ, Walsh R, John S, Cook SAet al., 2015, AORTOPATHY-CAUSING MUTATIONS INCREASE AORTIC STIFFNESS IN HEALTHY INDIVIDUALS, British-Cardiac-Society (BCS) Annual Conference on Hearts and Genes, Publisher: BMJ PUBLISHING GROUP, Pages: A99-A99, ISSN: 1355-6037

Conference paper

Roberts AM, Ware JS, Herman DS, Schafer S, Baksi J, Bick AG, Buchan RJ, Walsh R, John S, Wilkinson S, Mazzarotto F, Felkin LE, Gong S, L MacArthur JA, Cunningham F, Flannick J, Gabriel SB, Altshuler DM, Macdonald PS, Heinig M, Keogh AM, Hayward CS, Banner NR, Pennell DJ, O'Regan DP, San TR, de Marvao A, W Dawes TJ, Gulati A, Birks EJ, Yacoub MH, Radke M, Gotthardt M, Wilson JG, O'Donnell CJ, Prasad SK, Barton PJ, Fatkin D, Hubner N, Seidman JG, Seidman CE, Cook SAet al., 2015, Integrated allelic, transcriptional, and phenomic dissection of the cardiac effects of titin truncations in health and disease., Sci Transl Med, Vol: 7

The recent discovery of heterozygous human mutations that truncate full-length titin (TTN, an abundant structural, sensory, and signaling filament in muscle) as a common cause of end-stage dilated cardiomyopathy (DCM) promises new prospects for improving heart failure management. However, realization of this opportunity has been hindered by the burden of TTN-truncating variants (TTNtv) in the general population and uncertainty about their consequences in health or disease. To elucidate the effects of TTNtv, we coupled TTN gene sequencing with cardiac phenotyping in 5267 individuals across the spectrum of cardiac physiology and integrated these data with RNA and protein analyses of human heart tissues. We report diversity of TTN isoform expression in the heart, define the relative inclusion of TTN exons in different isoforms (using the TTN transcript annotations available at http://cardiodb.org/titin), and demonstrate that these data, coupled with the position of the TTNtv, provide a robust strategy to discriminate pathogenic from benign TTNtv. We show that TTNtv is the most common genetic cause of DCM in ambulant patients in the community, identify clinically important manifestations of TTNtv-positive DCM, and define the penetrance and outcomes of TTNtv in the general population. By integrating genetic, transcriptome, and protein analyses, we provide evidence for a length-dependent mechanism of disease. These data inform diagnostic criteria and management strategies for TTNtv-positive DCM patients and for TTNtv that are identified as incidental findings.

Journal article

Bai W, Peressutti D, Oktay O, Shi W, O'Regan DP, King AP, Rueckert Det al., 2015, Learning a Global Descriptor of Cardiac Motion from a Large Cohort of 1000+Normal Subjects, 8th International Conference on Functional Imaging and Modeling of the Heart(FIMH), Publisher: SPRINGER-VERLAG BERLIN, Pages: 1-9, ISSN: 0302-9743

Conference paper

Wang H, Shi W, Bai W, de Marvao AMSM, Dawes TJW, O'Regan DP, Edwards P, Cook S, Rueckert Det al., 2015, Prediction of Clinical Information from Cardiac MRI Using Manifold Learning, 8th International Conference on Functional Imaging and Modeling of the Heart(FIMH), Publisher: SPRINGER-VERLAG BERLIN, Pages: 91-98, ISSN: 0302-9743

Conference paper

de Marvao A, Dawes TJ, Shi W, Durighel G, Rueckert D, Cook SA, O'Regan DPet al., 2015, Adverse changes in left ventricular structure begin at normotensive systolic blood pressures: a high resolution MRI study., Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, Vol: 17, Pages: M11-M11, ISSN: 1097-6647

Journal article

Kidher E, Cheng Z, Jarral OA, O'Regan DP, Xu XY, Athanasiou Tet al., 2014, In-vivo assessment of the morphology and hemodynamic functions of the BioValsalva (TM) composite valve-conduit graft using cardiac magnetic resonance imaging and computational modelling technology, Journal of Cardiothoracic Surgery, Vol: 9, ISSN: 1749-8090

Background: The evaluation of any new cardiac valvular prosthesis should go beyond the classical morbidityand mortality rates and involve hemodynamic assessment. As a proof of concept, the objective of this study wasto characterise for the first time the hemodynamics and the blood flow profiles at the aortic root in patientsimplanted with BioValsalva™ composite valve-conduit using comprehensive MRI and computer technologies.Methods: Four male patients implanted with BioValsalva™ and 2 age-matched normal controls (NC) underwent cardiacmagnetic resonance imaging (MRI). Phase-contrast imaging with velocity-mapping in 3 orthogonal directions wasperformed at the level of the aortic root and descending thoracic aorta. Computational fluid dynamic (CFD) simulationswere performed for all the subjects with patient-specific flow information derived from phase-contrast MR data.Results: The maximum and mean flow rates throughout the cardiac cycle at the aortic root level were very comparablebetween NC and BioValsalva™ patients (541 ± 199 vs. 567 ± 75 ml/s) and (95 ± 46 vs. 96 ± 10 ml/s), respectively.The maximum velocity (cm/s) was higher in patients (314 ± 49 vs. 223 ± 20; P = 0.06) due to relatively smaller effectiveorifice area (EOA), 2.99 ± 0.47 vs. 4.40 ± 0.24 cm2 (P = 0.06), however, the BioValsalva™ EOA was comparable to otherreported prosthesis. The cross-sectional area and maximum diameter at the root were comparable between the twogroups. BioValsalva™ conduit was stiffer than the native aortic wall, compliance (mm2 • mmHg−1 • 10−3) values were(12.6 ± 4.2 vs 25.3 ± 0.4.; P = 0.06). The maximum time-averaged wall shear stress (Pa), at the ascending aorta wasequivalent between the two groups, 17.17 ± 2.7 (NC) vs. 17.33 ± 4.7 (BioValsalva™ ). Flow streamlines at the root andascending aorta were also similar between the two groups apa

Journal article

de Marvao A, Dawes TJW, Shi W, Minas C, Keenan NG, Diamond T, Durighel G, Montana G, Rueckert D, Cook SA, O'Regan DPet al., 2014, Population-based studies of myocardial hypertrophy: high resolution cardiovascular magnetic resonance atlases improve statistical power, Journal of Cardiovascular Magnetic Resonance, Vol: 16, ISSN: 1532-429X

Background: Cardiac phenotypes, such as left ventricular (LV) mass, demonstrate high heritability although mostgenes associated with these complex traits remain unidentified. Genome-wide association studies (GWAS) haverelied on conventional 2D cardiovascular magnetic resonance (CMR) as the gold-standard for phenotyping.However this technique is insensitive to the regional variations in wall thickness which are often associated with leftventricular hypertrophy and require large cohorts to reach significance. Here we test whether automated cardiacphenotyping using high spatial resolution CMR atlases can achieve improved precision for mapping wall thicknessin healthy populations and whether smaller sample sizes are required compared to conventional methods.Methods: LV short-axis cine images were acquired in 138 healthy volunteers using standard 2D imaging and 3Dhigh spatial resolution CMR. A multi-atlas technique was used to segment and co-register each image. Theagreement between methods for end-diastolic volume and mass was made using Bland-Altman analysis in 20subjects. The 3D and 2D segmentations of the LV were compared to manual labeling by the proportion ofconcordant voxels (Dice coefficient) and the distances separating corresponding points. Parametric andnonparametric data were analysed with paired t-tests and Wilcoxon signed-rank test respectively. Voxelwise powercalculations used the interstudy variances of wall thickness.Results: The 3D volumetric measurements showed no bias compared to 2D imaging. The segmented 3D imageswere more accurate than 2D images for defining the epicardium (Dice: 0.95 vs 0.93, P < 0.001; mean error 1.3 mmvs 2.2 mm, P < 0.001) and endocardium (Dice 0.95 vs 0.93, P < 0.001; mean error 1.1 mm vs 2.0 mm, P < 0.001). The3D technique resulted in significant differences in wall thickness assessment at the base, septum and apex of theLV compared to 2D (P < 0.001). Fewer subjects were required for 3D imaging to detect a 1 mm d

Journal article

Shi W, Lombaert H, Bai W, Ledig C, Zhuang X, Marvao A, Dawes T, O'Regan D, Rueckert Det al., 2014, Multi-atlas Spectral PatchMatch: Application to Cardiac Image Segmentation, 17th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI), Publisher: SPRINGER INTERNATIONAL PUBLISHING AG, Pages: 348-+, ISSN: 0302-9743

Conference paper

Pabari P, Konstantinou K, Sutaria N, O'Regan DP, Bhattacharyya S, Keenan NG, Chapman N, Ariff Bet al., 2014, Comprehensive cardiovascular MRI in hypertension: a UK single centre experience, Journal of Cardiovascular Magnetic Resonance, Vol: 16

Journal article

Shi W, Lombaert H, Bai W, Ledig C, Zhuang X, Marvao A, Dawes T, O'Regan D, O'Regan Det al., 2014, Multi-atlas spectral PatchMatch: application to cardiac image segmentation., Pages: 348-355

The automatic segmentation of cardiac magnetic resonance images poses many challenges arising from the large variation between different anatomies, scanners and acquisition protocols. In this paper, we address these challenges with a global graph search method and a novel spectral embedding of the images. Firstly, we propose the use of an approximate graph search approach to initialize patch correspondences between the image to be segmented and a database of labelled atlases, Then, we propose an innovative spectral embedding using a multi-layered graph of the images in order to capture global shape properties. Finally, we estimate the patch correspondences based on a joint spectral representation of the image and atlases. We evaluated the proposed approach using 155 images from the recent MICCAI SATA segmentation challenge and demonstrated that the proposed algorithm significantly outperforms current state-of-the-art methods on both training and test sets.

Conference paper

Woodbridge M, Fagiolo G, O'Regan DP, 2013, MRIdb: Medical Image Management for Biobank Research, JOURNAL OF DIGITAL IMAGING, Vol: 26, Pages: 886-890, ISSN: 0897-1889

Journal article

Corden B, Keenan NG, Dawes TJW, De Marvao ASM, Durighel G, Diamond T, Cook SA, O'Regan DPet al., 2013, Lean mass, fat mass and eccentric left ventricular remodelling in obesity, Congress of the European-Society-of-Cardiology (ESC), Publisher: OXFORD UNIV PRESS, Pages: 145-146, ISSN: 0195-668X

Conference paper

Childs AS, Malik SJ, O'Regan DP, Hajnal JVet al., 2013, Impact of number of channels on RF shimming at 3T, MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE, Vol: 26, Pages: 401-410, ISSN: 0968-5243

Journal article

Corden B, Keenan NG, De Marvao ASM, Dawes TJW, Diamond T, Durighel G, Cook SA, O'Regan DPet al., 2013, Sex differences in the relationship between adiposity and left ventricular morphology, Congress of the European-Society-of-Cardiology (ESC), Publisher: OXFORD UNIV PRESS, Pages: 150-150, ISSN: 0195-668X

Conference paper

O'Regan DP, Harden SP, Cook SA, 2013, RATIONAL IMAGING Investigating stable chest pain of suspected cardiac origin, BMJ-BRITISH MEDICAL JOURNAL, Vol: 347, ISSN: 1756-1833

Journal article

Bai W, Shi W, O'Regan DP, Tong T, Wang H, Jamil-Copley S, Peters NS, Rueckert Det al., 2013, A Probabilistic Patch-Based Label Fusion Model for Multi-Atlas Segmentation With Registration Refinement: Application to Cardiac MR Images, IEEE TRANSACTIONS ON MEDICAL IMAGING, Vol: 32, Pages: 1302-1315, ISSN: 0278-0062

Journal article

Corden B, Keenan NG, de Marvao ASM, Dawes TJW, DeCesare A, Diamond T, Durighel G, Hughes AD, Cook SA, O'Regan DPet al., 2013, Body Fat Is Associated With Reduced Aortic Stiffness Until Middle Age, HYPERTENSION, Vol: 61, Pages: 1322-1327, ISSN: 0194-911X

Journal article

Shi W, Jantsch M, Aljabar P, Pizarro L, Bai W, Wang H, O'Regan D, Zhuang X, Rueckert Det al., 2013, Temporal sparse free-form deformations, Medical Image Analysis

Journal article

Grapsa J, Cabrita IZ, Durighel G, Dawson D, O'regan D, Gin-Sing W, Howard LS, Gibbs S, Nihoyannopoulos Pet al., 2013, Right heart failure and clinical deterioration: the study of idiopathic pulmonary arterial hypertensive patients, EUROPEAN JOURNAL OF HEART FAILURE, Vol: 12, Pages: S280-S280, ISSN: 1388-9842

Journal article

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