E. Saloux - Academia.edu (original) (raw)

Papers by E. Saloux

Abstract—This paper evaluates five 3D ultrasound tracking algorithms regarding their ability to q... more Abstract—This paper evaluates five 3D ultrasound tracking algorithms regarding their ability to quantify abnormal defor-mation in timing or amplitude. A synthetic database of B-mode image sequences modeling healthy, ischemic and dyssynchrony cases was generated for that purpose. This database is made pub-licly available to the community. It combines recent advances in electromechanical and ultrasound modeling. For modeling heart mechanics, the Bestel-Clement-Sorine electromechanical model was applied to a realistic geometry. For ultrasound modeling, we applied a fast simulation technique to produce realistic images on a set of scatterers moving according to the electromechanical simulation result. Tracking and strain accuracies were computed and compared for all evaluated algorithms. For tracking, all methods were estimating myocardial displacements with an error below one milimeter on the ischemic sequences. The introduction of a dilated geometry was found to have a significant imp...

2017 IEEE 14th International Symposium on Biomedical Imaging (ISBI 2017), 2017

In this paper, we address the problem of automated pose classification and segmentation of the le... more In this paper, we address the problem of automated pose classification and segmentation of the left ventricle (LV) in 2D echocardiographic images. For this purpose, we compare two complementary approaches. The first one is based on engineering ad-hoc features according to the traditional machine learning paradigm. Namely, we extract phase features to build an unsupervised LV pose estimator, as well as a global image descriptor for view type classification. We also apply the Supervised Descent Method (SDM) to iteratively refine the LV contour. The second approach follows the deep learning framework, where a Convolutional Network (ConvNet) learns the visual features automatically. Our experiments on a large database of apical sequences show that the two approaches yield comparable results on view classification, but SDM outperforms ConvNet on LV segmentation at a significantly lower training computational cost.

2006 International Conference on Image Processing, 2006

In this paper, we propose to combine formally noise and shape priors in region-based active conto... more In this paper, we propose to combine formally noise and shape priors in region-based active contours. On the one hand, we use the general framework of exponential family as a prior model for noise. On the other hand, translation and scale invariant Legendre moments are considered to incorporate the shape prior (e.g. fidelity to a reference shape). The combination of the two prior terms in the active contour functional yields the final evolution equation whose evolution speed is rigorously derived using shape derivative tools. Experimental results on both synthetic images and real life cardiac echography data clearly demonstrate the robustness to initialization and noise, flexibility and large potential applicability of our segmentation algorithm.

European heart journal cardiovascular Imaging, 2014

We sought to describe our experience with major coronary anomalies (MCAs) diagnosed in transthora... more We sought to describe our experience with major coronary anomalies (MCAs) diagnosed in transthoracic echocardiography (TTE) in a large adult and paediatric population. MCAs may have serious clinical consequences. No echocardiographic studies have prospectively screened MCA in a general adult and paediatric population. From June 2008 to January 2012, a systematic search for MCA was prospectively conducted in children and adult patients, coming for a TTE. Three thousand five hundred and two patients (84% adults and 16% children) underwent a TTE. Fourteen coronary anomalies (0.39%) were diagnosed: nine anomalous origins of coronary artery from the opposite sinus with inter-arterial course, one abnormal left coronary artery from the pulmonary artery, three single coronary ostia, and one coronary fistula. Cardiac symptoms initiated investigation in seven patients. Five patients underwent specific surgery: two coronary reimplantations and three coronary bypass grafting. Ten patients had a...

Proceedings - International Symposium on Biomedical Imaging, 2013

ABSTRACT This article presents a new method for motion and strain estimation in 3D echocardiograp... more ABSTRACT This article presents a new method for motion and strain estimation in 3D echocardiography, called Sparse Demons, along with quantitative and qualitative evaluations from a dataset of synthetic ultrasound sequences. Motion estimation is based on a fast demons-like algorithm focusing on myocardial tissue. Synthetic 3D ultrasound images were generated by combining a biomechanical model of the heart with a realistic ultrasound imaging model. Ischemic areas were defined in the mechanical model to investigate whether our algorithm can discriminate healthy from diseased segments.

Lecture Notes in Computer Science, 2010

Despite advances in both medical image analysis and intracardiac electrophysiological mapping tec... more Despite advances in both medical image analysis and intracardiac electrophysiological mapping technology, the understanding of cardiac mechano-electrical coupling is still incomplete. This knowledge is of high interest since it would help estimating the cardiac electrophysiology function from the analysis of widely available cardiac images, such as 3D echocardiography. This is important, for example, in the evaluation of the cardiac resynchronization therapy (CRT) where the placement and tuning of the pacemaker leads plays a crucial role in the outcome of the therapy. This paper proposes a method to estimate activation times of myocardium using a cardiac electromechanical model. We use Kernel Ridge Regression to find the relationship between the kinematic descriptors (strain and displacement) and the contraction force caused by the action potential propagation. This regression model is then applied to two 3D echocardiographic sequences from a patient, one in sinus rhythm and the other one with left ventricle pacing, for which strains and displacements have been estimated using incompressible diffeomorphic demons for non-rigid registration.

Lecture Notes in Computer Science, 2013

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Journal of Cardiovascular Magnetic Resonance, 2013

Background: Coronary artery disease (CAD) patients are at risk for life-threatening ventricular a... more Background: Coronary artery disease (CAD) patients are at risk for life-threatening ventricular arrhythmias (VA) related to scar tissue. Late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) can accurately identify myocardial scar extent. It has been shown that scar extent, particularly scar transmurality, percent scar and scar mass, are associated with the occurrence of appropriate implantable cardioverter-defibrillator (ICD) therapy. However, quantification of transmurality extent has never been studied. The purpose of our study was to evaluate whether different methods quantifying scar transmurality, percent scar and scar mass (assessed with LGE-CMR) can predict appropriate ICD therapy in CAD patients with a long term follow-up period. Methods and results: We enrolled retrospectively 66 patients with chronic CAD referred for primary or secondary preventive ICD implantation and LGE-CMR before ICD implantation. Using LGE-CMR, scar extent was assessed by measuring scar mass, percent scar and transmural scar extent using four different methods. The median follow-up duration was 41.5 months (interquartile range 22-52). The endpoint was the occurrence of appropriate device therapy and occurred in 14 patients. Pre-ICD revascularization and transmural scar extent were significantly associated with the study endpoint but the latter was especially highly dependent on the method used. Patients with appropriate device therapy had also larger scar mass (29.6 ± 14.5 g vs 17.1 ± 8.8 g, p = 0.004), and larger percent scar (15.1 ± 8.2% vs 9.9 ± 5.6%, p = 0.03) than patients without appropriate device therapy. In multivariate analysis, scar extent variables remained significantly associated with the study end-point. Conclusions: In this study of CAD patients implanted for primary or secondary preventive ICD, pre-ICD revascularization and scar extent studied by LGE-CMR were significantly associated with appropriate device therapy and can identify a subgroup of CAD patients with an increased risk of life-threatening VA. Depending of the method used, transmural scar extent may vary significantly and needs further studies to obtain a validated and consensual study method.

IEEE Transactions on Medical Imaging, 2013

This paper evaluates five 3D ultrasound tracking algorithms regarding their ability to quantify a... more This paper evaluates five 3D ultrasound tracking algorithms regarding their ability to quantify abnormal deformation in timing or amplitude. A synthetic database of B-mode image sequences modeling healthy, ischemic and dyssynchrony cases was generated for that purpose. This database is made publicly available to the community. It combines recent advances in electromechanical and ultrasound modeling. For modeling heart mechanics, the Bestel-Clement-Sorine electromechanical model was applied to a realistic geometry. For ultrasound modeling, we applied a fast simulation technique to produce realistic images on a set of scatterers moving according to the electromechanical simulation result. Tracking and strain accuracies were computed and compared for all evaluated algorithms. For tracking, all methods were estimating myocardial displacements with an error below one milimeter on the ischemic sequences. The introduction of a dilated geometry was found to have a significant impact on accuracy. Regarding strain, all methods were able to recover timing differences between segments, as well as low strain values. On all cases, radial strain was found to have a low accuracy in comparison to longitudinal and circumferential components.

This paper proposes a new simulation framework for generating realistic 3D ultrasound synthetic i... more This paper proposes a new simulation framework for generating realistic 3D ultrasound synthetic images that can serve for validating strain quantification algorithms. Our approach extends previous work and combines a real ultrasound sequence with synthetic biomechanical and ultrasound models. It provides images that fairly represent all typical ultrasound artifacts. Ground truth motion fields are unbiased to any tracking algorithm and model both healthy and pathological conditions.

IEEE Transactions on Medical Imaging, 2015

Quantification of cardiac deformation and strain with 3D ultrasound takes considerable research e... more Quantification of cardiac deformation and strain with 3D ultrasound takes considerable research efforts. Nevertheless, a widespread use of these techniques in clinical practice is still held back due to the lack of a solid verification process to quantify and compare performance. In this context, the use of fully synthetic sequences has become an established tool for initial in silico evaluation. Nevertheless, the realism of existing simulation techniques is still too limited to represent reliable benchmarking data. Moreover, the fact that different centers typically make use of in-house developed simulation pipelines makes a fair comparison difficult. In this context, this paper introduces a novel pipeline for the generation of synthetic 3D cardiac ultrasound image sequences. State-of-the art solutions in the fields of electromechanical modeling and ultrasound simulation are combined within an original framework that exploits a real ultrasound recording to learn and simulate realistic speckle textures. The simulated images show typical artifacts that make motion tracking in ultrasound challenging. The ground-truth displacement field is available voxelwise and is fully controlled by the electromechanical model. By progressively modifying mechanical and ultrasound parameters, the sensitivity of 3D strain algorithms to pathology and image properties can be evaluated. The proposed pipeline is used to generate an initial library of 8 sequences including healthy and pathological cases, which is made freely accessible to the research community via our project web-page.

European Heart Journal

Background/Introduction Left ventricular remodeling following ST-elevation myocardial infarction ... more Background/Introduction Left ventricular remodeling following ST-elevation myocardial infarction (STEMI) is associated with poor outcome. Neprilysin inhibition leads to improved outcome in patients with altered left ventricular ejection fraction (LVEF). Purpose We aimed to assess the association between serum levels of neprilysin and left ventricular (LV) volumes, function and remodeling in STEMI patients with successful myocardial reperfusion. Methods Sixty-eight patients were admitted for STEMI and had both plasma neprilysin measurement at baseline and 3D transthoracic echocardiogram at baseline and at follow-up (7 months). We compared 3 groups: a group with a low-level of plasma neprilysin (<125 pg/mL, i.e. the lower limit of detection of the assay, 38 patients) and the two other groups were defined as being below or above the median value of the remaining samples (15 patients each). Results Median age was 58.5±12.8 years and 56 (82.4%) were men. Median LVEF was 45.0±8.5%. Bas...

European Heart Journal - Cardiovascular Imaging

Funding Acknowledgements Philips BACKGROUND Developing new training tools for TransThoracic Echoc... more Funding Acknowledgements Philips BACKGROUND Developing new training tools for TransThoracic Echocardiography (TTE) is more important than ever, as the use of ultrasound expands with the advent of mobile devices, both reducing costs and increasing the number of sites and operators. Two major challenges are the lack of experts to meet the growing demand for training and the risk of unnecessary examinations and misdiagnosis by users who lack proper training. PURPOSE To evaluate Artificial Intelligence (AI)-assisted TTE for assessing and improving novices" echocardiography skills. METHODS AI-assisted TTE relies on real-time analysis of the ultrasound stream by AI algorithms (e.g. for automated view recognition) to provide adaptive feedback to the user. It was compared to standard TTE in a prospective study including 40 medical students with no prior ultrasound experience ("novices") and 40 healthy volunteers of varying echogenicity. Novices received a standardized 10-minu...

European Heart Journal - Cardiovascular Imaging

Funding Acknowledgements Philips BACKGROUND Accurate and reproducible echocardiographic measureme... more Funding Acknowledgements Philips BACKGROUND Accurate and reproducible echocardiographic measurements are paramount for objective assessment and follow-up of the cardiac function. However, manual contouring – e.g., for determining left ventricular (LV) volumes and ejection fraction (EF) – is limited by image quality and operator experience. Meanwhile, despite the wider availability of (semi-)automated tools, strong multimodal validation is still lacking for their widespread and safe use in the clinical routine. PURPOSE To evaluate the accuracy and reproducibility of an Artificial Intelligence (AI)-based semi-automated tool to compute LV volumes and EF, in comparison with manual contouring, using cardiac magnetic resonance (cMR) as reference. METHODS Manual and AI measurements from echocardiography were compared to measurements from cMR in a retrospective two-centre study. One hundred fourteen patients in sinus rhythm were included; among those, 85 had abnormal LV function (56 dilated...

European Heart Journal - Cardiovascular Imaging

Funding Acknowledgements Fondation de Recherche Scientifique Belge FRSM PDR 19488731 BACKGROUND 2... more Funding Acknowledgements Fondation de Recherche Scientifique Belge FRSM PDR 19488731 BACKGROUND 2D-speckle-tracking (ST) echocardiography is currently widely used for estimation of global (G) and regional myocardial deformation. In previous works, we showed good correlation between global longitudinal (LS) and circumferential strain (CS) from one 2DST vendor with cMR-Tagging, however with significant bias between both methods. Also, we found poorer agreement between 2DST and cMR-Tagging on regional basis. However it is unknown how 2DST from other vendors would comparte to cMR tagging. PURPOSE To asssess vendor differences in global and regional strain assessment and compare 1) the agreement of 2 different 2DST softwares for global and regional LS and CS among each other and against cMR-Tagging as reference; and 2) the accuracy of both softwares to detect infarcted segments. METHODS 100 subjects with different cardiac disease (among which 31 with chronic infarct) underwent 2DST and t...

Echocardiography, 2017

Cardiac manifestations in Fabry disease are mainly characterized by left ventricular hypertrophy ... more Cardiac manifestations in Fabry disease are mainly characterized by left ventricular hypertrophy (LVH). The aims of this study were (1) to describe the pattern of regional strain in patients with Fabry disease and (2) to assess whether this pattern may help differentiate patients with Fabry disease from patients with sarcomeric hypertrophic cardiomyopathy (HCM). Seventy-seven subjects were investigated: patients with Fabry disease (n=37; 57% with LVH), patients with HCM (n=21), and healthy controls (n=19). Global and segmental longitudinal and circumferential strain (CS) analyses were performed by two-dimensional speckle strain imaging. Base-to-apex longitudinal and CS gradient, defined as the peak gradient difference between averaged basal and apical strain, was calculated. Longitudinal strain gradient did not differ between controls and Fabry patients without hypertrophy (respectively: -10±3.2 vs -8±4.3, P=.41) or between the HCM group and Fabry patients with hypertrophy (respectively: -7.5±4.5 vs -9±4.5, P=.37). The CS gradient was lower in Fabry patients without hypertrophy compared to the controls (respectively: 1±8 vs 14.2±9.5, P&lt;.01), and lower in Fabry patients with hypertrophy compared to the HCM group (respectively: 0.5±8 vs 6±9, P&lt;.01). Base-to-apex CS gradient was lost in both Fabry groups. Loss of base-to-apex CS gradient may be a specific left ventricular deformation pattern of Fabry cardiomyopathy in patients with and without LVH.

European Heart Journal – Cardiovascular Imaging, 2015

Introduction: The relationship between the appropriateness of the transthoracic echocardiography ... more Introduction: The relationship between the appropriateness of the transthoracic echocardiography (TTE) and its clinical impact is still a matter of debate. Objective: The aim of this study was to assess the degree of adherence to the appropriate use criteria for echocardiography, in a tertiary public hospital in the United Kingdom, as well as the clinical impact of the exam on patient management. Methods: 859 TTE's performed consecutively during January 2014 were reviewed to assess its appropriateness, and were classified as appropriate, uncertain or inappropriate using the 2011 guidelines. Subsequently, patient's files were examined to determine the clinical impact of the TTE which was assigned to one of the following three categories: (1) active change in care, (2) continuation of current care, or (3) no change in care. Patients which files were not available were excluded (259). All classifications were evaluated by two independent cardiologists, with no direct relation to the study. Results: Our sample had a mean age of 63 + 17 years with a gender balance. The majority of the exams were requested at the outpatient (81.4%) clinic, by cardiologists (50.3%) and general practitioners (13.4%). Regarding the main findings, in 7.6% of the studies there were moderate to severe systolic dysfunction; 4.0% showed severe valvular heart disease and 5.1% had significant pulmonary hypertension. Relatively to the appropriateness of the TTE requests, 76.5% were considered appropriate, 7.1% inappropriate and 12.6% uncertain. With respect to the clinical impact of the TTE's, 42.7% of the exams led to an active change in care, 15.6% to a continuation of the care and 11.5% revealed no change in care. Age (b0.90, P=0.05) and outpatient setting (b4.4, P,0.01) were the most important predictors of an active change of care exam. On the contrary, the appropriateness of the TTE's requests (b1.1, P=0.56) and the specialist ordering the exams (b0.81, P=0.26) were not independently associated. Conclusion: Our data showed that almost 8 out of 10 TTE were considered appropriate, and 4 out of 10 exams had an active clinical impact.

Abstract—This paper evaluates five 3D ultrasound tracking algorithms regarding their ability to q... more Abstract—This paper evaluates five 3D ultrasound tracking algorithms regarding their ability to quantify abnormal defor-mation in timing or amplitude. A synthetic database of B-mode image sequences modeling healthy, ischemic and dyssynchrony cases was generated for that purpose. This database is made pub-licly available to the community. It combines recent advances in electromechanical and ultrasound modeling. For modeling heart mechanics, the Bestel-Clement-Sorine electromechanical model was applied to a realistic geometry. For ultrasound modeling, we applied a fast simulation technique to produce realistic images on a set of scatterers moving according to the electromechanical simulation result. Tracking and strain accuracies were computed and compared for all evaluated algorithms. For tracking, all methods were estimating myocardial displacements with an error below one milimeter on the ischemic sequences. The introduction of a dilated geometry was found to have a significant imp...

2017 IEEE 14th International Symposium on Biomedical Imaging (ISBI 2017), 2017

In this paper, we address the problem of automated pose classification and segmentation of the le... more In this paper, we address the problem of automated pose classification and segmentation of the left ventricle (LV) in 2D echocardiographic images. For this purpose, we compare two complementary approaches. The first one is based on engineering ad-hoc features according to the traditional machine learning paradigm. Namely, we extract phase features to build an unsupervised LV pose estimator, as well as a global image descriptor for view type classification. We also apply the Supervised Descent Method (SDM) to iteratively refine the LV contour. The second approach follows the deep learning framework, where a Convolutional Network (ConvNet) learns the visual features automatically. Our experiments on a large database of apical sequences show that the two approaches yield comparable results on view classification, but SDM outperforms ConvNet on LV segmentation at a significantly lower training computational cost.

2006 International Conference on Image Processing, 2006

In this paper, we propose to combine formally noise and shape priors in region-based active conto... more In this paper, we propose to combine formally noise and shape priors in region-based active contours. On the one hand, we use the general framework of exponential family as a prior model for noise. On the other hand, translation and scale invariant Legendre moments are considered to incorporate the shape prior (e.g. fidelity to a reference shape). The combination of the two prior terms in the active contour functional yields the final evolution equation whose evolution speed is rigorously derived using shape derivative tools. Experimental results on both synthetic images and real life cardiac echography data clearly demonstrate the robustness to initialization and noise, flexibility and large potential applicability of our segmentation algorithm.

European heart journal cardiovascular Imaging, 2014

We sought to describe our experience with major coronary anomalies (MCAs) diagnosed in transthora... more We sought to describe our experience with major coronary anomalies (MCAs) diagnosed in transthoracic echocardiography (TTE) in a large adult and paediatric population. MCAs may have serious clinical consequences. No echocardiographic studies have prospectively screened MCA in a general adult and paediatric population. From June 2008 to January 2012, a systematic search for MCA was prospectively conducted in children and adult patients, coming for a TTE. Three thousand five hundred and two patients (84% adults and 16% children) underwent a TTE. Fourteen coronary anomalies (0.39%) were diagnosed: nine anomalous origins of coronary artery from the opposite sinus with inter-arterial course, one abnormal left coronary artery from the pulmonary artery, three single coronary ostia, and one coronary fistula. Cardiac symptoms initiated investigation in seven patients. Five patients underwent specific surgery: two coronary reimplantations and three coronary bypass grafting. Ten patients had a...

Proceedings - International Symposium on Biomedical Imaging, 2013

ABSTRACT This article presents a new method for motion and strain estimation in 3D echocardiograp... more ABSTRACT This article presents a new method for motion and strain estimation in 3D echocardiography, called Sparse Demons, along with quantitative and qualitative evaluations from a dataset of synthetic ultrasound sequences. Motion estimation is based on a fast demons-like algorithm focusing on myocardial tissue. Synthetic 3D ultrasound images were generated by combining a biomechanical model of the heart with a realistic ultrasound imaging model. Ischemic areas were defined in the mechanical model to investigate whether our algorithm can discriminate healthy from diseased segments.

Lecture Notes in Computer Science, 2010

Despite advances in both medical image analysis and intracardiac electrophysiological mapping tec... more Despite advances in both medical image analysis and intracardiac electrophysiological mapping technology, the understanding of cardiac mechano-electrical coupling is still incomplete. This knowledge is of high interest since it would help estimating the cardiac electrophysiology function from the analysis of widely available cardiac images, such as 3D echocardiography. This is important, for example, in the evaluation of the cardiac resynchronization therapy (CRT) where the placement and tuning of the pacemaker leads plays a crucial role in the outcome of the therapy. This paper proposes a method to estimate activation times of myocardium using a cardiac electromechanical model. We use Kernel Ridge Regression to find the relationship between the kinematic descriptors (strain and displacement) and the contraction force caused by the action potential propagation. This regression model is then applied to two 3D echocardiographic sequences from a patient, one in sinus rhythm and the other one with left ventricle pacing, for which strains and displacements have been estimated using incompressible diffeomorphic demons for non-rigid registration.

Lecture Notes in Computer Science, 2013

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Journal of Cardiovascular Magnetic Resonance, 2013

Background: Coronary artery disease (CAD) patients are at risk for life-threatening ventricular a... more Background: Coronary artery disease (CAD) patients are at risk for life-threatening ventricular arrhythmias (VA) related to scar tissue. Late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) can accurately identify myocardial scar extent. It has been shown that scar extent, particularly scar transmurality, percent scar and scar mass, are associated with the occurrence of appropriate implantable cardioverter-defibrillator (ICD) therapy. However, quantification of transmurality extent has never been studied. The purpose of our study was to evaluate whether different methods quantifying scar transmurality, percent scar and scar mass (assessed with LGE-CMR) can predict appropriate ICD therapy in CAD patients with a long term follow-up period. Methods and results: We enrolled retrospectively 66 patients with chronic CAD referred for primary or secondary preventive ICD implantation and LGE-CMR before ICD implantation. Using LGE-CMR, scar extent was assessed by measuring scar mass, percent scar and transmural scar extent using four different methods. The median follow-up duration was 41.5 months (interquartile range 22-52). The endpoint was the occurrence of appropriate device therapy and occurred in 14 patients. Pre-ICD revascularization and transmural scar extent were significantly associated with the study endpoint but the latter was especially highly dependent on the method used. Patients with appropriate device therapy had also larger scar mass (29.6 ± 14.5 g vs 17.1 ± 8.8 g, p = 0.004), and larger percent scar (15.1 ± 8.2% vs 9.9 ± 5.6%, p = 0.03) than patients without appropriate device therapy. In multivariate analysis, scar extent variables remained significantly associated with the study end-point. Conclusions: In this study of CAD patients implanted for primary or secondary preventive ICD, pre-ICD revascularization and scar extent studied by LGE-CMR were significantly associated with appropriate device therapy and can identify a subgroup of CAD patients with an increased risk of life-threatening VA. Depending of the method used, transmural scar extent may vary significantly and needs further studies to obtain a validated and consensual study method.

IEEE Transactions on Medical Imaging, 2013

This paper evaluates five 3D ultrasound tracking algorithms regarding their ability to quantify a... more This paper evaluates five 3D ultrasound tracking algorithms regarding their ability to quantify abnormal deformation in timing or amplitude. A synthetic database of B-mode image sequences modeling healthy, ischemic and dyssynchrony cases was generated for that purpose. This database is made publicly available to the community. It combines recent advances in electromechanical and ultrasound modeling. For modeling heart mechanics, the Bestel-Clement-Sorine electromechanical model was applied to a realistic geometry. For ultrasound modeling, we applied a fast simulation technique to produce realistic images on a set of scatterers moving according to the electromechanical simulation result. Tracking and strain accuracies were computed and compared for all evaluated algorithms. For tracking, all methods were estimating myocardial displacements with an error below one milimeter on the ischemic sequences. The introduction of a dilated geometry was found to have a significant impact on accuracy. Regarding strain, all methods were able to recover timing differences between segments, as well as low strain values. On all cases, radial strain was found to have a low accuracy in comparison to longitudinal and circumferential components.

This paper proposes a new simulation framework for generating realistic 3D ultrasound synthetic i... more This paper proposes a new simulation framework for generating realistic 3D ultrasound synthetic images that can serve for validating strain quantification algorithms. Our approach extends previous work and combines a real ultrasound sequence with synthetic biomechanical and ultrasound models. It provides images that fairly represent all typical ultrasound artifacts. Ground truth motion fields are unbiased to any tracking algorithm and model both healthy and pathological conditions.

IEEE Transactions on Medical Imaging, 2015

Quantification of cardiac deformation and strain with 3D ultrasound takes considerable research e... more Quantification of cardiac deformation and strain with 3D ultrasound takes considerable research efforts. Nevertheless, a widespread use of these techniques in clinical practice is still held back due to the lack of a solid verification process to quantify and compare performance. In this context, the use of fully synthetic sequences has become an established tool for initial in silico evaluation. Nevertheless, the realism of existing simulation techniques is still too limited to represent reliable benchmarking data. Moreover, the fact that different centers typically make use of in-house developed simulation pipelines makes a fair comparison difficult. In this context, this paper introduces a novel pipeline for the generation of synthetic 3D cardiac ultrasound image sequences. State-of-the art solutions in the fields of electromechanical modeling and ultrasound simulation are combined within an original framework that exploits a real ultrasound recording to learn and simulate realistic speckle textures. The simulated images show typical artifacts that make motion tracking in ultrasound challenging. The ground-truth displacement field is available voxelwise and is fully controlled by the electromechanical model. By progressively modifying mechanical and ultrasound parameters, the sensitivity of 3D strain algorithms to pathology and image properties can be evaluated. The proposed pipeline is used to generate an initial library of 8 sequences including healthy and pathological cases, which is made freely accessible to the research community via our project web-page.

European Heart Journal

Background/Introduction Left ventricular remodeling following ST-elevation myocardial infarction ... more Background/Introduction Left ventricular remodeling following ST-elevation myocardial infarction (STEMI) is associated with poor outcome. Neprilysin inhibition leads to improved outcome in patients with altered left ventricular ejection fraction (LVEF). Purpose We aimed to assess the association between serum levels of neprilysin and left ventricular (LV) volumes, function and remodeling in STEMI patients with successful myocardial reperfusion. Methods Sixty-eight patients were admitted for STEMI and had both plasma neprilysin measurement at baseline and 3D transthoracic echocardiogram at baseline and at follow-up (7 months). We compared 3 groups: a group with a low-level of plasma neprilysin (<125 pg/mL, i.e. the lower limit of detection of the assay, 38 patients) and the two other groups were defined as being below or above the median value of the remaining samples (15 patients each). Results Median age was 58.5±12.8 years and 56 (82.4%) were men. Median LVEF was 45.0±8.5%. Bas...

European Heart Journal - Cardiovascular Imaging

Funding Acknowledgements Philips BACKGROUND Developing new training tools for TransThoracic Echoc... more Funding Acknowledgements Philips BACKGROUND Developing new training tools for TransThoracic Echocardiography (TTE) is more important than ever, as the use of ultrasound expands with the advent of mobile devices, both reducing costs and increasing the number of sites and operators. Two major challenges are the lack of experts to meet the growing demand for training and the risk of unnecessary examinations and misdiagnosis by users who lack proper training. PURPOSE To evaluate Artificial Intelligence (AI)-assisted TTE for assessing and improving novices" echocardiography skills. METHODS AI-assisted TTE relies on real-time analysis of the ultrasound stream by AI algorithms (e.g. for automated view recognition) to provide adaptive feedback to the user. It was compared to standard TTE in a prospective study including 40 medical students with no prior ultrasound experience ("novices") and 40 healthy volunteers of varying echogenicity. Novices received a standardized 10-minu...

European Heart Journal - Cardiovascular Imaging

Funding Acknowledgements Philips BACKGROUND Accurate and reproducible echocardiographic measureme... more Funding Acknowledgements Philips BACKGROUND Accurate and reproducible echocardiographic measurements are paramount for objective assessment and follow-up of the cardiac function. However, manual contouring – e.g., for determining left ventricular (LV) volumes and ejection fraction (EF) – is limited by image quality and operator experience. Meanwhile, despite the wider availability of (semi-)automated tools, strong multimodal validation is still lacking for their widespread and safe use in the clinical routine. PURPOSE To evaluate the accuracy and reproducibility of an Artificial Intelligence (AI)-based semi-automated tool to compute LV volumes and EF, in comparison with manual contouring, using cardiac magnetic resonance (cMR) as reference. METHODS Manual and AI measurements from echocardiography were compared to measurements from cMR in a retrospective two-centre study. One hundred fourteen patients in sinus rhythm were included; among those, 85 had abnormal LV function (56 dilated...

European Heart Journal - Cardiovascular Imaging

Funding Acknowledgements Fondation de Recherche Scientifique Belge FRSM PDR 19488731 BACKGROUND 2... more Funding Acknowledgements Fondation de Recherche Scientifique Belge FRSM PDR 19488731 BACKGROUND 2D-speckle-tracking (ST) echocardiography is currently widely used for estimation of global (G) and regional myocardial deformation. In previous works, we showed good correlation between global longitudinal (LS) and circumferential strain (CS) from one 2DST vendor with cMR-Tagging, however with significant bias between both methods. Also, we found poorer agreement between 2DST and cMR-Tagging on regional basis. However it is unknown how 2DST from other vendors would comparte to cMR tagging. PURPOSE To asssess vendor differences in global and regional strain assessment and compare 1) the agreement of 2 different 2DST softwares for global and regional LS and CS among each other and against cMR-Tagging as reference; and 2) the accuracy of both softwares to detect infarcted segments. METHODS 100 subjects with different cardiac disease (among which 31 with chronic infarct) underwent 2DST and t...

Echocardiography, 2017

Cardiac manifestations in Fabry disease are mainly characterized by left ventricular hypertrophy ... more Cardiac manifestations in Fabry disease are mainly characterized by left ventricular hypertrophy (LVH). The aims of this study were (1) to describe the pattern of regional strain in patients with Fabry disease and (2) to assess whether this pattern may help differentiate patients with Fabry disease from patients with sarcomeric hypertrophic cardiomyopathy (HCM). Seventy-seven subjects were investigated: patients with Fabry disease (n=37; 57% with LVH), patients with HCM (n=21), and healthy controls (n=19). Global and segmental longitudinal and circumferential strain (CS) analyses were performed by two-dimensional speckle strain imaging. Base-to-apex longitudinal and CS gradient, defined as the peak gradient difference between averaged basal and apical strain, was calculated. Longitudinal strain gradient did not differ between controls and Fabry patients without hypertrophy (respectively: -10±3.2 vs -8±4.3, P=.41) or between the HCM group and Fabry patients with hypertrophy (respectively: -7.5±4.5 vs -9±4.5, P=.37). The CS gradient was lower in Fabry patients without hypertrophy compared to the controls (respectively: 1±8 vs 14.2±9.5, P&lt;.01), and lower in Fabry patients with hypertrophy compared to the HCM group (respectively: 0.5±8 vs 6±9, P&lt;.01). Base-to-apex CS gradient was lost in both Fabry groups. Loss of base-to-apex CS gradient may be a specific left ventricular deformation pattern of Fabry cardiomyopathy in patients with and without LVH.

European Heart Journal – Cardiovascular Imaging, 2015

Introduction: The relationship between the appropriateness of the transthoracic echocardiography ... more Introduction: The relationship between the appropriateness of the transthoracic echocardiography (TTE) and its clinical impact is still a matter of debate. Objective: The aim of this study was to assess the degree of adherence to the appropriate use criteria for echocardiography, in a tertiary public hospital in the United Kingdom, as well as the clinical impact of the exam on patient management. Methods: 859 TTE's performed consecutively during January 2014 were reviewed to assess its appropriateness, and were classified as appropriate, uncertain or inappropriate using the 2011 guidelines. Subsequently, patient's files were examined to determine the clinical impact of the TTE which was assigned to one of the following three categories: (1) active change in care, (2) continuation of current care, or (3) no change in care. Patients which files were not available were excluded (259). All classifications were evaluated by two independent cardiologists, with no direct relation to the study. Results: Our sample had a mean age of 63 + 17 years with a gender balance. The majority of the exams were requested at the outpatient (81.4%) clinic, by cardiologists (50.3%) and general practitioners (13.4%). Regarding the main findings, in 7.6% of the studies there were moderate to severe systolic dysfunction; 4.0% showed severe valvular heart disease and 5.1% had significant pulmonary hypertension. Relatively to the appropriateness of the TTE requests, 76.5% were considered appropriate, 7.1% inappropriate and 12.6% uncertain. With respect to the clinical impact of the TTE's, 42.7% of the exams led to an active change in care, 15.6% to a continuation of the care and 11.5% revealed no change in care. Age (b0.90, P=0.05) and outpatient setting (b4.4, P,0.01) were the most important predictors of an active change of care exam. On the contrary, the appropriateness of the TTE's requests (b1.1, P=0.56) and the specialist ordering the exams (b0.81, P=0.26) were not independently associated. Conclusion: Our data showed that almost 8 out of 10 TTE were considered appropriate, and 4 out of 10 exams had an active clinical impact.