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
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97 results found

Biffi C, de Marvao A, Attard MI, Dawes TJW, Whiffin N, Bai W, Shi W, Francis C, Meyer H, Buchan R, Cook SA, Rueckert D, O'Regan DPet al., 2018, Three-dimensional cardiovascular imaging-genetics: a mass univariate framework, BIOINFORMATICS, Vol: 34, Pages: 97-103, ISSN: 1367-4803

JOURNAL ARTICLE

Dawes TJW, Cai J, Quinlan M, de Marvao A, Ostrowski PJ, Tokarczuk PF, Watson GMJ, Wharton J, Howard LSGE, Gibbs JSR, Cook SA, Wilkins MR, O'Regan DPet al., 2018, Fractal Analysis of Right Ventricular Trabeculae in Pulmonary Hypertension., Radiology

Purpose To measure right ventricular (RV) trabecular complexity by its fractal dimension (FD) in healthy subjects and patients with pulmonary hypertension (PH) and to assess its relationship with hemodynamic and functional parameters and future cardiovascular events. Materials and Methods This retrospective study used data acquired from May 2004 to October 2013 in 256 patients with newly diagnosed PH who underwent cardiac MRI, right-sided heart catheterization, and 6-minute walk distance testing, with median follow-up of 4.0 years. A total of 256 healthy control subjects underwent cardiac MRI only. Biventricular FD, volumes, and function were assessed on short-axis cine images. Reproducibility was assessed with the intraclass correlation coefficient, correlation between variables was assessed with the Pearson correlation test, and mortality prediction was compared by using uni- and multivariable Cox regression analyses. Results RV FD reproducibility had an intraclass correlation coefficient of 0.97 (95% confidence interval [CI]: 0.96, 0.98). RV FD was higher in patients with PH (median, 1.310; interquartile range [IQR], 1.281-1.341) than in healthy subjects (median, 1.264; IQR, 1.242-1.295; P < .001), with the greatest difference near the apex. RV FD was associated with pulmonary vascular resistance (r = 0.30, P < .001). At univariable Cox regression analysis, RV FD was a significant predictor of death (hazard ratio [HR], 1.256; 95% CI: 1.011, 1.560; P = .04); however, at multivariable analysis, RV FD did not enable prediction of survival independently of conventional parameters of RV remodeling (HR, 1.179; 95% CI: 0.871, 1.596; P = .29). Conclusion Fractal analysis of RV trabecular complexity is a highly reproducible measure of remodeling in patients with PH that is associated with afterload, although the gain in survival prediction over traditional markers is not significant. Published under a CC BY 4.0 license. Online supplemental material is available for

JOURNAL ARTICLE

Jaijee SK, Quinlan M, Tokarczuk P, Clemence M, Howard LS, Gibbs JSR, O'Regan Det al., 2018, Exercise cardiac MRI unmasks right ventricular dysfunction in acute hypoxia and chronic pulmonary arterial hypertension., Am J Physiol Heart Circ Physiol

Background - Coupling of right ventricular (RV) contractility to afterload is maintained at rest in the early stages of pulmonary arterial hypertension (PAH), but exercise may unmask depleted contractile reserves. We assessed whether elevated afterload reduces RV contractile reserve despite compensated resting function using non-invasive exercise imaging. Methods and Results - Fourteen patients with PAH (mean age 39.1 years, 10 females) and 34 healthy control subjects (mean age 35.6 years, 17 females) completed real-time cardiac magnetic resonance imaging during sub-maximal exercise breathing room-air. Controls were then also exercised during acute normobaric hypoxia (FiO2 12%). RV contractile reserve was assessed by the effect of exercise on ejection fraction (RVEF). In control subjects the increase in RVEF on exercise was less during hypoxia (P=0.017), but the response of left ventricular ejection fraction to exercise did not change. Patients with PAH had impaired RV reserve with half demonstrating a fall in RVEF on exercise despite comparable resting function to controls (PAH: rest 53.6{plus minus}4.3% vs exercise 51.4{plus minus}10.7%; controls: rest 57.1{plus minus}5.2% vs exercise 69.6{plus minus}6.1%, P<0.0001). In control subjects the increase in stroke volume index (SVi) on exercise was driven by reduced RV end-systolic volume, whereas PAH patients did not augment SVi, with increases in both end-diastolic and end-systolic volumes. From baseline hemodynamic and exercise capacity variables only VE/VCO2 was an independent predictor of RV functional reserve (P=0.021). Conclusions - Non-invasive cardiac imaging during exercise unmasks depleted RV contractile reserves in healthy adults under hypoxic conditions and PAH patients under normoxic conditions despite preserved ejection fraction.

JOURNAL ARTICLE

Oktay O, Ferrante E, Kamnitsas K, Heinrich M, Bai W, Caballero J, Cook SA, de Marvao A, Dawes T, O'Regan DP, Kainz B, Glocker B, Rueckert Det al., 2018, Anatomically Constrained Neural Networks (ACNNs): Application to Cardiac Image Enhancement and Segmentation, IEEE TRANSACTIONS ON MEDICAL IMAGING, Vol: 37, Pages: 384-395, ISSN: 0278-0062

JOURNAL ARTICLE

Pirola S, Jarral OA, O'Regan DP, Asimakopoulos G, Anderson JR, Pepper JR, Athanasiou T, Xu XYet al., 2018, Computational study of aortic hemodynamics for patients with an abnormal aortic valve: The importance of secondary flow at the ascending aorta inlet, APL Bioengineering, Vol: 2, Pages: 026101-026101

JOURNAL ARTICLE

Shirvani S, Tokarczuk P, Statton B, Quinlan M, Berry A, Tomlinson J, Weale P, Kühn B, O'Regan DPet al., 2018, Motion-corrected multiparametric renal arterial spin labelling at 3 T: reproducibility and effect of vasodilator challenge., Eur Radiol

OBJECTIVES: We investigated the feasibility and reproducibility of free-breathing motion-corrected multiple inversion time (multi-TI) pulsed renal arterial spin labelling (PASL), with general kinetic model parametric mapping, to simultaneously quantify renal perfusion (RBF), bolus arrival time (BAT) and tissue T1. METHODS: In a study approved by the Health Research Authority, 12 healthy volunteers (mean age, 27.6 ± 18.5 years; 5 male) gave informed consent for renal imaging at 3 T using multi-TI ASL and conventional single-TI ASL. Glyceryl trinitrate (GTN) was used as a vasodilator challenge in six subjects. Flow-sensitive alternating inversion recovery (FAIR) preparation was used with background suppression and 3D-GRASE (gradient and spin echo) read-out, and images were motion-corrected. Parametric maps of RBF, BAT and T1 were derived for both kidneys. Agreement was assessed using Pearson correlation and Bland-Altman plots. RESULTS: Inter-study correlation of whole-kidney RBF was good for both single-TI (r2 = 0.90), and multi-TI ASL (r2 = 0.92). Single-TI ASL gave a higher estimate of whole-kidney RBF compared to multi-TI ASL (mean bias, 29.3 ml/min/100 g; p <0.001). Using multi-TI ASL, the median T1 of renal cortex was shorter than that of medulla (799.6 ms vs 807.1 ms, p = 0.01), and mean whole-kidney BAT was 269.7 ± 56.5 ms. GTN had an effect on systolic blood pressure (p < 0.05) but the change in RBF was not significant. CONCLUSIONS: Free-breathing multi-TI renal ASL is feasible and reproducible at 3 T, providing simultaneous measurement of renal perfusion, haemodynamic parameters and tissue characteristics at baseline and during pharmacological challenge. KEY POINTS: • Multiple inversion time arterial spin labelling (ASL) of the kidneys is feasible and reproducible at 3 T. • This approach allows simultaneous mapping of renal perfusion, bolus arrival time and tissue T 1 during free breathing. • This technique enables repeated

JOURNAL ARTICLE

Ware JS, Amor-Salamanca A, Tayal U, Govind R, Serrano I, Salazar-Mendiguchia J, Manuel Garcia-Pinilla J, Pascual-Figal DA, Nunez J, Guzzo-Merello G, Gonzalez-Vioque E, Bardaji A, Manito N, Lopez-Garrido MA, Padron-Barthe L, Edwards E, Whiffin N, Walsh R, Buchan RJ, Midwinter W, Wilk A, Prasad S, Pantazis A, Baski J, O'Regan DP, Alonso-Pulpon L, Cook SA, Lara-Pezzi E, Barton PJ, Garcia-Pavia Pet al., 2018, Genetic Etiology for Alcohol-Induced Cardiac Toxicity, JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY, Vol: 71, Pages: 2293-2302, ISSN: 0735-1097

JOURNAL ARTICLE

Whiffin N, Walsh R, Govind R, Edwards M, Ahmad M, Zhang X, Tayal U, Buchan R, Midwinter W, Wilk AE, Najgebauer H, Francis C, Wilkinson S, Monk T, Brett L, O'Regan DP, Prasad SK, Morris-Rosendahl DJ, Barton PJR, Edwards E, Ware JS, Cook SAet al., 2018, CardioClassifier: disease- and gene-specific computational decision support for clinical genome interpretation., Genet Med

PurposeInternationally adopted variant interpretation guidelines from the American College of Medical Genetics and Genomics (ACMG) are generic and require disease-specific refinement. Here we developed CardioClassifier (http://www.cardioclassifier.org), a semiautomated decision-support tool for inherited cardiac conditions (ICCs).MethodsCardioClassifier integrates data retrieved from multiple sources with user-input case-specific information, through an interactive interface, to support variant interpretation. Combining disease- and gene-specific knowledge with variant observations in large cohorts of cases and controls, we refined 14 computational ACMG criteria and created three ICC-specific rules.ResultsWe benchmarked CardioClassifier on 57 expertly curated variants and show full retrieval of all computational data, concordantly activating 87.3% of rules. A generic annotation tool identified fewer than half as many clinically actionable variants (64/219 vs. 156/219, Fisher's P = 1.1  ×  10-18), with important false positives, illustrating the critical importance of disease and gene-specific annotations. CardioClassifier identified putatively disease-causing variants in 33.7% of 327 cardiomyopathy cases, comparable with leading ICC laboratories. Through addition of manually curated data, variants found in over 40% of cardiomyopathy cases are fully annotated, without requiring additional user-input data.ConclusionCardioClassifier is an ICC-specific decision-support tool that integrates expertly curated computational annotations with case-specific data to generate fast, reproducible, and interactive variant pathogenicity reports, according to best practice guidelines.GENETICS in MEDICINE advance online publication, 25 January 2018; doi:10.1038/gim.2017.258.

JOURNAL ARTICLE

de Marvao A, Biffi C, Walsh R, Doumou G, Dawes T, Shi W, Bai W, Berry A, Buchan R, Pierce I, Tokarczuk P, Statton B, Francis C, Duan J, Quinlan M, Felkin L, Le T-T, Bhuva A, Tang HC, Barton P, Chin CW-L, Rueckert D, Ware J, Prasad S, O'Regan DP, Cook SAet al., 2018, DEFINING THE EFFECTS OF GENETIC VARIATION USING MACHINE LEARNING ANALYSIS OF CMRS: A STUDY IN HYPERTROPHIC CARDIOMYOPATHY AND IN A HEALTHY POPULATION, Joint Meeting of the British-Society-of-Cardiovascular-Imaging/British-Society-of-Cardiovascular-CT, British-Society-of-Cardiovascular-Magnetic-Resonance and British-Nuclear-Cardiac-Society on British Cardiovascular Imaging, Publisher: BMJ PUBLISHING GROUP, Pages: A7-A8, ISSN: 1355-6037

CONFERENCE PAPER

Cai J, Bryant JA, Thu-Thao L, Su B, de Marvao A, O'Regan DP, Cook SA, Chin CW-Let al., 2017, Fractal analysis of left ventricular trabeculations is associated with impaired myocardial deformation in healthy Chinese, JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE, Vol: 19, ISSN: 1097-6647

JOURNAL ARTICLE

Dawes T, de Marvao A, Shi W, Rueckert D, Cook S, O'Regan Det al., 2017, Systolic motion of the basal right ventricular freewall is the strongest predictor of global function: a high resolution 3D imaging study, Association-of-Anaesthetists-of-Great-Britain-and-Ireland (AAGBI) GAT Annual Scientific Meeting, Publisher: WILEY, Pages: 77-77, ISSN: 0003-2409

CONFERENCE PAPER

Dawes TJW, de Marvao A, Shi W, Fletcher T, Watson GMJ, Wharton J, Rhodes CJ, Howard LSGE, Gibbs JSR, Rueckert D, Cook SA, Wilkins MR, O'Regan DPet al., 2017, Machine Learning of Three-dimensional Right Ventricular Motion Enables Outcome Prediction in Pulmonary Hypertension: A Cardiac MR Imaging Study, RADIOLOGY, Vol: 283, Pages: 381-390, ISSN: 0033-8419

JOURNAL ARTICLE

Esslinger U, Garnier S, Korniat A, Proust C, Kararigas G, Mueller-Nurasyid M, Empana J-P, Morley MP, Perret C, Stark K, Bick AG, Prasad SK, Kriebel J, Li J, Tiret L, Strauch K, O'Regan DP, Marguiles KB, Seidman JG, Boutouyrie P, Lacolley P, Jouven X, Hengstenberg C, Komajda M, Hakonarson H, Isnard R, Arbustini E, Grallert H, Cook SA, Seidman CE, Regitz-Zagrosek V, Cappola TP, Charron P, Cambien F, Villard Eet al., 2017, Exome-wide association study reveals novel susceptibility genes to sporadic dilated cardiomyopathy, PLOS ONE, Vol: 12, ISSN: 1932-6203

JOURNAL ARTICLE

Le T-T, Bryant JA, Ting AE, Ho PY, Su B, Teo RCC, Gan JS-J, Chung Y-C, O'Regan DP, Cook SA, Chin CW-Let al., 2017, Assessing exercise cardiac reserve using real-time cardiovascular magnetic resonance, JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE, Vol: 19, ISSN: 1097-6647

JOURNAL ARTICLE

Michelakis ED, Gurtu V, Webster L, Barnes G, Watson G, Howard L, Cupitt J, Paterson I, Thompson RB, Chow K, O'Regan DP, Zhao L, Wharton J, Kiely DG, Kinnaird A, Boukouris AE, White C, Nagendran J, Freed DH, Wort SJ, Gibbs JSR, Wilkins MRet al., 2017, Inhibition of pyruvate dehydrogenase kinase improves pulmonary arterial hypertension in genetically susceptible patients, SCIENCE TRANSLATIONAL MEDICINE, Vol: 9, ISSN: 1946-6234

JOURNAL ARTICLE

Oktay O, Bai W, Guerrero R, Rajchl M, de Marvao A, O'Regan DP, Cook SA, Heinrich MP, Glocker B, Rueckert Det al., 2017, Stratified Decision Forests for Accurate Anatomical Landmark Localization in Cardiac Images, IEEE TRANSACTIONS ON MEDICAL IMAGING, Vol: 36, Pages: 332-342, ISSN: 0278-0062

JOURNAL ARTICLE

Pirola S, Cheng Z, Jarral OA, O'Regan DP, Pepper JR, Athanasiou T, Xu XYet al., 2017, On the choice of outlet boundary conditions for patient-specific analysis of aortic flow using computational fluid dynamics, JOURNAL OF BIOMECHANICS, Vol: 60, Pages: 15-21, ISSN: 0021-9290

JOURNAL ARTICLE

Schafer S, de Marvao A, Adami E, Fiedler LR, Ng B, Khin E, Rackham OJL, van Heesch S, Pua CJ, Kui M, Walsh R, Tayal U, Prasad SK, Dawes TJW, Ko NSJ, Sim D, Chan LLH, Chin CWL, Mazzarotto F, Barton PJ, Kreuchwig F, de Kleijn DPV, Totman T, Biffi C, Tee N, Rueckert D, Schneider V, Faber A, Regitz-Zagrosek V, Seidman JG, Seidman CE, Linke WA, Kovalik J-P, O'Regan D, Ware JS, Hubner N, Cook SAet al., 2017, Titin-truncating variants affect heart function in disease cohorts and the general population, NATURE GENETICS, Vol: 49, Pages: 46-53, ISSN: 1061-4036

JOURNAL ARTICLE

Suzuki H, Gao H, Bai W, Evangelou E, Glocker B, O'Regan DP, Elliott P, Matthews PMet al., 2017, Abnormal brain white matter microstructure is associated with both pre-hypertension and hypertension, PLOS ONE, Vol: 12, ISSN: 1932-6203

JOURNAL ARTICLE

Tarroni G, Oktay O, Bai W, Schuh A, Suzuki H, Passerat-Palmbach J, Glocker B, de Marvao A, O Regan D, Cook S, Rueckert Det al., 2017, Learning-based heart coverage estimation for short-axis cine cardiac MR images, Pages: 73-82, ISSN: 0302-9743

© Springer International Publishing AG 2017. The correct acquisition of short axis (SA) cine cardiac MR image stacks requires the imaging of the full cardiac anatomy between the apex and the mitral valve plane via multiple 2D slices. While in the clinical practice the SA stacks are usually checked qualitatively to ensure full heart coverage, visual inspection can become infeasible for large amounts of imaging data that is routinely acquired, e.g. in population studies such as the UK Biobank (UKBB). Accordingly, we propose a learning-based technique for the fully-automated estimation of the heart coverage for SA image stacks. The technique relies on the identification of cardiac landmarks (i.e. the apex and the mitral valve sides) on two chamber view long axis images and on the comparison of the landmarks’ positions to the volume covered by the SA stack. Landmark detection is performed using a hybrid random forest approach integrating both regression and structured classification models. The technique was applied on 3000 cases from the UKBB and compared to visual assessment. The obtained results (error rate = 2.3%, sens. = 73%, spec. = 90%) indicate that the proposed technique is able to correctly detect the vast majority of the cases with insufficient coverage, suggesting that it could be used as a fully-automated quality control step for CMR SA image stacks.

CONFERENCE PAPER

Cheng Z, Kidher E, Jarral OA, O'Regan DP, Wood NB, Athanasiou T, Xu XYet al., 2016, 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

JOURNAL ARTICLE

Corden B, de Marvao A, Dawes TJ, Shi W, Rueckert D, Cook SA, O'Regan DPet al., 2016, Relationship between body composition and left ventricular geometry using three dimensional cardiovascular magnetic resonance, JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE, Vol: 18, ISSN: 1097-6647

JOURNAL ARTICLE

Dawes T, de Marvao A, Shi W, Fletcher T, Watson G, Wharton J, Rhodes C, Howard L, Gibbs S, Rueckert D, Cook S, Wilkins M, O'Regan Det al., 2016, Use of artificial intelligence to predict survival in pulmonary hypertension, Spring Meeting on Clinician Scientists in Training, Publisher: ELSEVIER SCIENCE INC, Pages: 35-35, ISSN: 0140-6736

CONFERENCE PAPER

Dawes TJW, Corden B, Cotter S, de Marvao A, Walsh R, Ware JS, Cook SA, O'Regan DPet al., 2016, Moderate Physical Activity in Healthy Adults Is Associated With Cardiac Remodeling, CIRCULATION-CARDIOVASCULAR IMAGING, Vol: 9, ISSN: 1941-9651

JOURNAL ARTICLE

Dawes TJW, Gandhi A, de Marvao A, Buzaco R, Tokarczuk P, Quinlan M, Durighel G, Diamond T, Garcia LM, de Cesare A, Cook SA, O'Regan DPet al., 2016, Pulmonary Artery Stiffness Is Independently Associated with Right Ventricular Mass and Function: A Cardiac MR Imaging Study, RADIOLOGY, Vol: 280, Pages: 398-404, ISSN: 0033-8419

JOURNAL ARTICLE

Durighel G, Tokarczuk PF, Karsa A, Gordon F, Cook SA, O'Regan DPet al., 2016, Acute myocardial infarction: susceptibility-weighted cardiac MRI for the detection of reperfusion haemorrhage at 1.5 T, CLINICAL RADIOLOGY, Vol: 71, Pages: E150-E156, ISSN: 0009-9260

JOURNAL ARTICLE

Harden SP, Bull RK, Bury RW, Castellano EA, Clayton B, Hamilton MCK, Morgan-Hughes GJ, O'Regan D, Padley SPG, Roditi GH, Roobottom CA, Stirrup J, Nicol EDet al., 2016, The safe practice of CT coronary angiography in adult patients in UK imaging departments, CLINICAL RADIOLOGY, Vol: 71, Pages: 722-728, ISSN: 0009-9260

JOURNAL ARTICLE

Jaijee S, Quinlan M, Tokarczuk P, Statton B, Berry A, Diamond T, Howard L, Gibbs S, O'Regan Det al., 2016, DETERIORATION OF RIGHT VENTRICULAR FUNCTION ON EXERCISE DETECTED BY EXERCISE CARDIAC MAGNETIC RESONANCE IMAGING IN PATIENTS WITH PULMONARY ARTERIAL HYPERTENSION, Annual Conference of the British-Cardiovascular-Society (BCS) on Prediction and Prevention, Publisher: BMJ PUBLISHING GROUP, Pages: A88-A89, ISSN: 1355-6037

CONFERENCE PAPER

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

Jaijee S, Statton B, Quinlan M, Berry A, Tokarczuk P, Murphy K, Tighe H, Lawlee E, Diamond T, Garcia LM, Howard L, O'Regan DP, Gibbs JSRet al., 2016, Right ventricular function in acute and chronic pulmonary hypertension using exercise cardiac magnetic resonance imaging, Congress of the European-Society-of-Cardiology (ESC), Publisher: OXFORD UNIV PRESS, Pages: 1186-1186, ISSN: 0195-668X

CONFERENCE PAPER

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