Publications
131 results found
Oktay O, Bai W, Guerrero R, et al., 2016, Stratified decision forests for accurate anatomical landmark localization, IEEE Transactions on Medical Imaging, Vol: 36, Pages: 332-342, ISSN: 0278-0062
Accurate localization of anatomical landmarks is an important step in medical imaging, as it provides useful prior information for subsequent image analysis and acquisition methods. It is particularly useful for initialization of automatic image analysis tools (e.g. segmentation and registration) and detection of scan planes for automated image acquisition. Landmark localization has been commonly performed using learning based approaches, such as classifier and/or regressor models. However, trained models may not generalize well in heterogeneous datasets when the images contain large differences due to size, pose and shape variations of organs. To learn more data-adaptive and patient specific models, we propose a novel stratification based training model, and demonstrate its use in a decision forest. The proposed approach does not require any additional training information compared to the standard model training procedure and can be easily integrated into any decision tree framework. The proposed method is evaluated on 1080 3D highresolution and 90 multi-stack 2D cardiac cine MR images. The experiments show that the proposed method achieves state-of-theart landmark localization accuracy and outperforms standard regression and classification based approaches. Additionally, the proposed method is used in a multi-atlas segmentation to create a fully automatic segmentation pipeline, and the results show that it achieves state-of-the-art segmentation accuracy.
Schafer S, De Marvao A, Adami E, et al., 2016, Titin truncations cause penetrant cardiac phenotypes in disease and the general population, Congress of the European-Society-of-Cardiology (ESC), Publisher: European Society of Cardiology, Pages: 1408-1408, ISSN: 0195-668X
Dawes TJW, Corden B, Cotter S, et al., 2016, Moderate Physical Activity in Healthy Adults is Associated with Cardiac Remodeling, Circulation-Cardiovascular Imaging, Vol: 9, ISSN: 1942-0080
Background—Cardiac mass and volumes are often elevated in athletes, but it is not known whether moderate physical activity is also associated with cardiac dilatation and hypertrophy in a healthy adult population.Methods and Results—In total, 1096 adults (54% female, median age 39 years) without cardiovascular disease or cardiomyopathy-associated genetic variants underwent cardiac magnetic resonance imaging to determine biventricular volumes and function. Physical activity was assessed using a validated activity questionnaire. The relationship between cardiac parameters and activity was assessed using multiple linear regression adjusting for age, sex, race, and systolic blood pressure. Logistic regression was performed to determine the effect of activity on the likelihood of subjects having cardiac dilatation or hypertrophy according to standard cardiac magnetic resonance normal ranges. Increasing physical activity was associated with greater left ventricular (LV) mass (β=0.23; P<0.0001) and elevated LV and right ventricular volumes (LV: β=0.26, P<0.0001; right ventricular: β=0.26, P<0.0001). Physical activity had a larger effect on cardiac parameters than systolic blood pressure (0.06≤β≤0.21) and a similar effect to age (−0.20≤β≤−0.31). Increasing physical activity was a risk factor for meeting imaging criteria for LV hypertrophy (adjusted odds ratio 2.1; P<0.0001), LV dilatation (adjusted odds ratio 2.2; P<0.0001), and right ventricular dilatation (adjusted odds ratio 2.2; P<0.0001).Conclusions—Exercise-related cardiac remodeling is not confined to athletes, and there is a risk of overdiagnosing cardiac dilatation or hypertrophy in a proportion of active, healthy adults.
de Marvao A, Cook SA, O'Regan DP, 2016, Precursors of Hypertensive Heart Phenotype Develop in Healthy Adults: An Alternative Explanation Reply, JACC-Cardiovascular Imaging, Vol: 9, Pages: 763-764, ISSN: 1936-878X
Corden B, de Marvao A, Dawes T, et al., 2016, Relationship between body composition and left ventricular geometry using three dimensional cardiovascular magnetic resonance, Journal of Cardiovascular Magnetic Resonance, Vol: 18, ISSN: 1532-429X
BackgroundAlthough obesity is associated with alterations in left ventricular (LV) mass and volume which are of prognostic significance, widely differing patterns of remodelling have been attributed to adiposity. Our aim was to define the relationship between body composition and LV geometry using three-dimensional cardiovascular magnetic resonance.MethodsIn an observational study 1530 volunteers (55 % female, mean age 41.3 years) without known cardiovascular disease underwent investigation including breath-hold high spatial resolution 3D cines. Atlas-based segmentation and co-registration was used to create a statistical model of wall thickness (WT) and relative wall thickness (RWT) throughout the LV. The relationship between bio-impedence body composition and LV geometry was assessed using 3D regression models adjusted for age, systolic blood pressure (BP), gender, race and height, with correction to control the false discovery rate.ResultsLV mass was positively associated with fat mass in women but not in men (LV mass: women β = 0.11, p < 0.0001; men β = −0.01, p = 0.82). The 3D models revealed that in males fat mass was strongly associated with a concentric increase in relative wall thickness (RWT) throughout most of the LV (β = 0.37, significant area = 96 %) and a reduced mid-ventricular cavity (β = −0.22, significant area = 91 %). In women the regional concentric hypertrophic association was weaker, and the basal lateral wall showed an inverse relationship between RWT and fat mass (β = −0.11, significant area = 4.8 %).ConclusionsIn an adult population without known cardiovascular disease increasing body fat is predominately associated with asymmetric concentric hypertrophy independent of systolic BP, with women demonstrating greater cavity dilatation than men. Conventional mass
Dawes T, de Marvao A, Shi W, et 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
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- Citations: 1
de Marvao A, Meyer H, Dawes T, et al., 2016, Development of integrated high-resolution three-dimensional MRI and computational modelling techniques to identify novel genetic and anthropometric determinants of cardiac form and function, Spring Meeting on Clinician Scientists in Training, Publisher: ELSEVIER SCIENCE INC, Pages: 36-36, ISSN: 0140-6736
Dawes TJW, Gandhi A, de Marvao A, et al., 2016, Pulmonary artery stiffness is independently associated with right ventricular mass and function: a cardiac magnetic resonance study., Radiology, Vol: 280, ISSN: 1527-1315
PurposeTo determine the relationship between pulmonary artery (PA) stiffness and both right ventricular (RV) mass and function with cardiac magnetic resonance (MR) imaging.Materials and MethodsThe study was approved by the local research ethics committee, and all participants gave written informed consent. Cardiac MR imaging was performed at 1.5 T in 156 healthy volunteers (63% women; age range, 19–61 years; mean age, 36.1 years). High-temporal-resolution phase-contrast imaging was performed in the main and right PAs. Pulmonary pulse wave velocity (PWV) was determined by the interval between arterial systolic upslopes. RV function was assessed with feature tracking to derive peak systolic strain and strain rate, as well as peak early-diastolic strain rate. RV volumes, ejection fraction (RVEF), and mass were measured from the cine images. The association of pulmonary PWV with RV function and mass was quantified with univariate linear regression. Interstudy repeatability was assessed with intraclass correlation.ResultsThe repeatability coefficient for pulmonary PWV was 0.96. Increases in pulmonary PWV and RVEF were associated with increases in age (r = 0.32, P < .001 and r = 0.18, P = .025, respectively). After adjusting for age (P = .090), body surface area (P = .073), and sex (P = .005), pulmonary PWV demonstrated an independent positive association with RVEF (r = 0.34, P = .026). Significant associations were also seen with RV mass (r = 0.41, P = .004), RV radial strain (r = 0.38, P = .022), and strain rate (r = 0.35, P = .002), and independent negative associations were seen with radial (r = 0.27, P = .003), longitudinal (r = 0.40, P = .007), and circumferential (r = 0.31, P = .005) peak early-diastolic strain rate with the same covariates.ConclusionPulmonary PWV is reliably assessed with cardiac MR imaging. In subjects with no known cardiovascular disease, increasing PA stiffness is associated with increasing age and is also moderately associated with bo
Marvao AD, Meyer HV, Dawes TJ, et 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
Quinlan M, Jaijee S, de Marvao A, et al., 2016, Exercise CMR: Real-time assessment of cardiac performance with phase contrast imaging, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 1-2, ISSN: 1097-6647
Oktay O, Tarroni G, Bai W, et 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
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- Citations: 2
Dawes T, Gandhi A, de Marvao AS, et al., 2015, Pulmonary Artery Stiffness is an Independent Predictor of Right Ventricular Mass and Function, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
Dawes T, de Marvao A, Shi W, et al., 2015, Systolic Motion of the Basal Right Ventricular Freewall is the Strongest Predictor of Global Function: A High Resolution 3D Cardiac Magnetic Resonance Study, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
de Marvao A, Dawes TJW, Shi W, et 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
Bai W, Shi W, de Marvao A, et 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.
Dawes T, De Marvao A, Shi W, et 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
De Marvao A, Dawes T, Shi W, et 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
Corden B, De Marvao ASM, Dawes TJW, et al., 2015, Left ventricular remodelling with increasing body fat: a 3D cardiac phenotyping study, Congress of the European-Society-of-Cardiology (ESC), Publisher: Oxford University Press (OUP), Pages: 118-118, ISSN: 1522-9645
Francis C, de Marvao A, O'Regan DP, et 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
De Marvao A, Dawes TJ, Shi W, et al., 2015, Adverse changes in left ventricular structure begin at normotensive systolic blood pressures: A high resolution MRI study, Journal of Cardiovascular Magnetic Resonance, Pages: 1-2, ISSN: 1097-6647
Alenaini W, O'Regan DP, de Marvao A, et 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, Pages: O44-O44, ISSN: 1097-6647
Kelner KL, 2015, What happens when titins are trimmed?, Science, Vol: 347, Pages: 244-244, ISSN: 0036-8075
Roberts AM, Ware JS, Herman DS, et al., 2015, What Happens When Titins Are Trimmed?, SCIENCE TRANSLATIONAL MEDICINE, Vol: 7, ISSN: 1946-6234
Roberts AM, Ware JS, Herman DS, et al., 2015, Integrated allelic, transcriptional, and phenomic dissection of the cardiac effects of titin truncations in health and disease, Science Translational Medicine, Vol: 7, Pages: 270ra6-270ra6, ISSN: 1946-6234
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.
de Marvao A, Dawes TJ, Shi W, et 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
Wang H, Shi W, Bai W, et 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
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- Citations: 5
de Marvao A, Dawes TJW, Shi W, et 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
Shi W, Lombaert H, Bai W, et 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.
Shi W, Lombaert H, Bai W, et 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
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- Citations: 11
Wang Z, Bhatia K, Glocker B, et al., 2014, Geodesic Patch-based Segmentation, Medical Image Computing and Computer-Assisted Intervention – MICCAI 2014, Publisher: Springer, Pages: 666-673, ISSN: 0302-9743
Label propagation has been shown to be effective in many automatic segmentation applications. However, its reliance on accurate image alignment means that segmentation results can be affected by any registration errors which occur. Patch-based methods relax this dependence by avoiding explicit one-to-one correspondence assumptions between images but are still limited by the search window size. Too small, and it does not account for enough registration error; too big, and it becomes more likely to select incorrect patches of similar appearance for label fusion. This paper presents a novel patch-based label propagation approach which uses relative geodesic distances to define patient-specific coordinate systems as spatial context to overcome this problem. The approach is evaluated on multi-organ segmentation of 20 cardiac MR images and 100 abdominal CT images, demonstrating competitive results.
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