The Experts below are selected from a list of 9522 Experts worldwide ranked by ideXlab platform
Hugues Talbot - One of the best experts on this subject based on the ideXlab platform.
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Myocardial Perfusion Simulation for Coronary Artery Disease: A Coupled Patient-Specific Multiscale Model
Annals of Biomedical Engineering, 2020Co-Authors: L Papamanolis, Hyunjin Kim, C Jaquet, Matthew Sinclair, Michiel Schaap, Ibrahim Danad, Paul Knaapen, Laurent Najman, Pepijn Diemen, Hugues TalbotAbstract:Patient-specific models of Blood Flow are being used clinically to diagnose and plan treatment for coronary artery disease. A remaining challenge is bridging scales from Flow in arteries to the micro-circulation supplying the myocardium. Previously proposed models are descriptive rather than predictive and have not been applied to human data. The goal here is to develop a multiscale patient-specific model enabling Blood Flow Simulation from large coronary arteries to myocardial tissue. Patient vasculatures are segmented from coronary computed tomography angiography data and extended from the image-based model down to the arteriole level using a space-filling forest of synthetic trees. Blood Flow is modeled by coupling a 1D model of the coronary arteries to a single-compartment Darcy myocardium model. Simulated results on five patients with non-obstructive coronary artery disease compare overall well to [ $$^{15}$$ 15 O] $$\text {H}_{{2}}$$ H 2 O PET exam data for both resting and hyperemic conditions. Results on a patient with severe obstructive disease link coronary artery narrowing with impaired myocardial Blood Flow, demonstrating the model’s ability to predict myocardial regions with perfusion deficit. This is the first report of a computational model for simulating Blood Flow from the epicardial coronary arteries to the left ventricle myocardium applied to and validated on human data.
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Myocardial Perfusion Simulation for Coronary Artery Disease: A Coupled Patient-Specific Multiscale Model
Annals of Biomedical Engineering, 2020Co-Authors: L Papamanolis, C Jaquet, Matthew Sinclair, Michiel Schaap, Ibrahim Danad, P A Van Diemen, Paul Knaapen, Laurent Najman, Hyun Kim, Hugues TalbotAbstract:Patient-specific models of Blood Flow are being used clinically to diagnose and plan treatment for coronary artery disease. A remaining challenge is bridging scales from Flow in arteries to the micro-circulation supplying the myocardium. Previously proposed models are descriptive rather than predictive and have not been applied to human data. The goal here is to develop a multiscale patient-specific model enabling Blood Flow Simulation from large coronary arteries to myocardial tissue. Patient vasculatures are segmented from coronary computed tomography angiography data and extended from the image-based model down to the arteriole level using a space-filling forest of synthetic trees. Blood Flow is modeled by coupling a 1D model of the coronary arteries to a single-compartment Darcy myocardium model. Simulated results on five patients with non-obstructive coronary artery disease compare overall well to [15O] H2O PET exam data for both resting and hyperemic conditions. Results on a patient with severe obstructive disease link coronary artery narrowing with impaired myocardial Blood Flow, demonstrating the model’s ability to predict myocardial regions with perfusion deficit. This is the first report of a computational model for simulating Blood Flow from the epicardial coronary arteries to the left ventricle myocardium applied to and validated on human data.
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patient specific multiscale myocardial Blood Flow Simulation for coronary artery disease
Computer Methods in Biomechanics and Biomedical Engineering, 2020Co-Authors: L Papamanolis, Hyunjin Kim, C Jaquet, Matthew Sinclair, Michiel Schaap, Ibrahim Danad, P A Van Diemen, Paul Knaapen, Laurent Najman, Hugues TalbotAbstract:Patient-specific models of Blood Flow are used for diagnosing Coronary Artery Disease (CAD). A remaining challenge is bridging scales from Flow in arteries to the micro-circulation supplying the my...
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From real MRA to virtual MRA: Towards an open-source framework
2016Co-Authors: Nicolas Passat, Stéphanie Salmon, Jean-paul Armspach, Benoît Naegel, Christophe Prud'homme, Hugues Talbot, Alexandre Fortin, Simon Garnotel, Odyssée Merveille, Olivia MiraucourtAbstract:Angiographic imaging is a crucial domain of medical imaging. In particular , Magnetic Resonance Angiography (MRA) is used for both clinical and research purposes. This article presents the first framework geared toward the design of virtual MRA images from real MRA images. It relies on a pipeline that involves image processing, vascular modeling, computational fluid dynamics and MR image Simulation, with several purposes. It aims to provide to the whole scientific community (1) software tools for MRA analysis and Blood Flow Simulation ; and (2) data (computational meshes, virtual MRAs with associated ground truth), in an open-source / open-data paradigm. Beyond these purposes, it constitutes a versatile tool for progressing in the understanding of vascular networks, especially in the brain, and the associated imaging technologies.
Peter V. Coveney - One of the best experts on this subject based on the ideXlab platform.
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validation of patient specific cerebral Blood Flow Simulation using transcranial doppler measurements
Frontiers in Physiology, 2018Co-Authors: Derek Groen, Robin A. Richardson, Rachel Coy, Ulf D Schiller, Hoskote Chandrashekar, Fergus Robertson, Peter V. CoveneyAbstract:We present a validation study comparing results from a patient-specific lattice-Boltzmann Simulation to transcranial Doppler (TCD) velocity measurements in four different planes of the middle cerebral artery (MCA). As part of the study, we compared Simulations using a Newtonian and a Carreau-Yasuda rheology model. We also investigated the viability of using downscaled velocities to reduce the required resolution. Simulations with unscaled velocities predict the maximum Flow velocity with an error of less than 9%, independent of the rheology model chosen. The accuracy of the Simulation predictions worsens considerably when Simulations are run at reduced velocity, as is for example the case when inFlow velocities from healthy individuals are used on a vascular model of a stroke patient. Our results demonstrate the importance of using directly measured and patient-specific inFlow velocities when simulating Blood Flow in MCAs. We conclude that localized TCD measurements together with predictive Simulations can be used to obtain Flow estimates with high fidelity over a larger region, and reduce the need for more invasive Flow measurement procedures.
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In situ ray tracing and computational steering for interactive Blood Flow Simulation
Computer Physics Communications, 2010Co-Authors: Marco D. Mazzeo, Steven Manos, Peter V. CoveneyAbstract:Recent algorithm and hardware developments have significantly improved our capability to interactively visualise time-varying Flow fields. However, when visualising very large dynamically varying datasets interactively there are still limitations in the scalability and efficiency of these methods. Here we present a rendering pipeline which employs an efficient in situ ray tracing technique to visualise Flow fields as they are simulated. The ray casting approach is particularly well suited for the visualisation of large and sparse time-varying datasets, where it is capable of rendering fluid Flow fields at high image resolutions and at interactive frame rates on a single multi-core processor using OpenMP. The parallel implementation of our in situ visualisation method relies on MPI, requires no specialised hardware support, and employs the same underlying spatial decomposition as the fluid simulator. The visualisation pipeline allows the user to operate on a commodity computer and explore the Simulation output interactively. Our Simulation environment incorporates numerous features that can be utilised in a wide variety of research contexts.
Yoshinobu Onuma - One of the best experts on this subject based on the ideXlab platform.
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Strut protrusion and shape impact on endothelial shear stress: insights from pre-clinical study comparing Mirage and Absorb bioresorbable scaffolds
The International Journal of Cardiovascular Imaging, 2017Co-Authors: Erhan Tenekecioglu, Christos Bourantas, Solomon Su, Tom Crake, Carlos Collet, Yoshinobu Onuma, Yosuke Miyazaki, Yohei Sotomi, Ryo Torii, Patrick W.j.c. SerruysAbstract:Protrusion of scaffold struts is related with local coronary Flow dynamics that can promote scaffold restenosis and thrombosis. That fact has prompted us to investigate in vivo the protrusion status of different types of scaffolds and their relationship with endothelial shear stress (ESS) distributions. Six Absorb everolimus-eluting Bioresorbable Vascular Scaffolds (Absorb, Abbott Vascular) and 11 Mirage sirolimus-eluting Bioresorbable Microfiber Scaffolds (Mirage, Manli Cardiology) were implanted in coronaries of eight mini pigs. Optical coherence tomography (OCT) was performed post-scaffold implantation and obtained images were fused with angiographic data to reconstruct the three dimensional coronary anatomy. Blood Flow Simulation was performed and ESS distribution was estimated for each scaffold. Protrusion distance was estimated using a dedicated software. Correlation between OCT-derived protrusion and ESS distribution was assessed for both scaffold groups. A significant difference was observed in the protrusion distances (156 ± 137 µm for Absorb, 139 ± 153 µm for Mirage; p = 0.035), whereas difference remained after adjusting the protrusion distances according to the luminal areas. Strut protrusion of Absorb is inversely correlated with ESS (r = −0.369, p
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strut protrusion and shape impact on endothelial shear stress insights from pre clinical study comparing mirage and absorb bioresorbable scaffolds
International Journal of Cardiovascular Imaging, 2017Co-Authors: Erhan Tenekecioglu, Christos Bourantas, Tom Crake, Carlos Collet, Yoshinobu Onuma, Yosuke Miyazaki, Yohei Sotomi, Ryo Torii, Patrick W.j.c. SerruysAbstract:Protrusion of scaffold struts is related with local coronary Flow dynamics that can promote scaffold restenosis and thrombosis. That fact has prompted us to investigate in vivo the protrusion status of different types of scaffolds and their relationship with endothelial shear stress (ESS) distributions. Six Absorb everolimus-eluting Bioresorbable Vascular Scaffolds (Absorb, Abbott Vascular) and 11 Mirage sirolimus-eluting Bioresorbable Microfiber Scaffolds (Mirage, Manli Cardiology) were implanted in coronaries of eight mini pigs. Optical coherence tomography (OCT) was performed post-scaffold implantation and obtained images were fused with angiographic data to reconstruct the three dimensional coronary anatomy. Blood Flow Simulation was performed and ESS distribution was estimated for each scaffold. Protrusion distance was estimated using a dedicated software. Correlation between OCT-derived protrusion and ESS distribution was assessed for both scaffold groups. A significant difference was observed in the protrusion distances (156 ± 137 µm for Absorb, 139 ± 153 µm for Mirage; p = 0.035), whereas difference remained after adjusting the protrusion distances according to the luminal areas. Strut protrusion of Absorb is inversely correlated with ESS (r = −0.369, p < 0.0001), whereas in Mirage protrusion was positively correlated with EES (r = 0.192, p < 0.0001). Protrusion distance was higher in Absorb than in Mirage. The protrusion of the thick quadratic struts of Absorb has a tendency to lower shear stress in the close vicinity of struts. However, circular shape of the less thick struts of Mirage didn’t show this trend in creating zone of recirculation around the struts. Strut geometry has different effect on the relationship between protrusion and shear stress in Absorb and Mirage scaffolds.
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fast virtual functional assessment of intermediate coronary lesions using routine angiographic data and Blood Flow Simulation in humans comparison with pressure wire fractional Flow reserve
Eurointervention, 2014Co-Authors: Michail I. Papafaklis, Christos Bourantas, Yoshinobu Onuma, Lampros Lakkas, Takashi Muramatsu, Yuki Ishibashi, Shimpei Nakatani, Jurgen Ligthart, Mauro Echavarriapinto, Georgia TsirkaAbstract:Aims: To develop a simplified approach of virtual functional assessment of coronary stenosis from routine angiographic data and test it against fractional Flow reserve using a pressure wire (wire-FFR). Methods and results: Three-dimensional quantitative coronary angiography (3D-QCA) was performed in 139 vessels (120 patients) with intermediate lesions assessed by wire-FFR (reference standard: .0.80). The 3D-QCA models were processed with computational fluid dynamics (CFD) to calculate the lesion-specific pressure gradient (?¢P) and construct the ?¢P.Flow curve, from which the virtual functional assessment index (vFAI) was derived. The discriminatory power of vFAI for ischaemia-producing lesions was high (area under the receiver operator characteristic curve [AUC]: 92% [95% CI: 86-96%]). Diagnostic accuracy, sensitivity and specificity for the optimal vFAI cut-point (.0.82) were 88%, 90% and 86%, respectively. Virtual-FAI demonstrated superior discrimination against 3D-QCA.derived % area stenosis (AUC: 78% [95% CI: 70-84%]; p<0.0001 compared to vFAI). There was a close correlation (r=0.78, p<0.0001) and agreement of vFAI compared to wire-FFR (mean difference: .0.0039?}0.085, p=0.59). Conclusions: We developed a fast and simple CFD-powered virtual haemodynamic assessment model using only routine angiography and without requiring any invasive physiology measurements/hyperaemia induction. Virtual-FAI showed a high diagnostic performance and incremental value to QCA for predicting wire-FFR; this ?gless invasive?h approach could have important implications for patient management and cost.
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fusion of optical coherence tomographic and angiographic data for more accurate evaluation of the endothelial shear stress patterns and neointimal distribution after bioresorbable scaffold implantation comparison with intravascular ultrasound derived
International Journal of Cardiovascular Imaging, 2014Co-Authors: Christos Bourantas, Yoshinobu Onuma, Michail I. Papafaklis, Lampros Lakkas, Takashi Muramatsu, Antonis I Sakellarios, Yaojun Zhang, Roberto Diletti, Paschalis Bizopoulos, Fanis G KalatzisAbstract:Intravascular ultrasound (IVUS)-based reconstructions have been traditionally used to examine the effect of endothelial shear stress (ESS) on neointimal formation. The aim of this analysis is to compare the association between ESS and neointimal thickness (NT) in models obtained by the fusion of optical coherence tomography (OCT) and coronary angiography and in the reconstructions derived by the integration of IVUS and coronary angiography. We analyzed data from six patients implanted with an Absorb bioresorbable vascular scaffold that had biplane angiography, IVUS and OCT investigation at baseline and 6 or 12 months follow-up. The IVUS and OCT follow-up data were fused separately with the angiographic data to reconstruct the luminal morphology at baseline and follow-up. Blood Flow Simulation was performed on the baseline reconstructions and the ESS was related to NT. In the OCT-based reconstructions the ESS were lower compared to the IVUS-based models (1.29 ± 0.66 vs. 1.87 ± 0.66 Pa, P = 0.030). An inverse correlation was noted between the logarithmic transformed ESS and the measured NT in all the OCT-based models which was higher than the correlation reported in five of the six IVUS-derived models (-0.52 ± 0.19 Pa vs. -0.10 ± 0.04, P = 0.028). Fusion of OCT and coronary angiography appears superior to IVUS-based reconstructions; therefore it should be the method of choice for the study of the effect of the ESS on neointimal proliferation.
Alfons G Hoekstra - One of the best experts on this subject based on the ideXlab platform.
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optimizing parallel performance of the cell based Blood Flow Simulation software hemocell
International Conference on Computational Science, 2019Co-Authors: Victor Azizi W Tarksalooyeh, Gabor Zavodszky, Alfons G HoekstraAbstract:Large scale cell based Blood Flow Simulations are expensive, both in time and resource requirements. HemoCell can perform such Simulations on high performance computing resources by dividing the Simulation domain into multiple blocks. This division has a performance impact caused by the necessary communication between the blocks. In this paper we implement an efficient algorithm for computing the mechanical model for HemoCell together with an improved communication structure. The result is an up to 4 times performance increase for Blood Flow Simulations performed with HemoCell.
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ICCS (3) - Optimizing Parallel Performance of the Cell Based Blood Flow Simulation Software HemoCell
Lecture Notes in Computer Science, 2019Co-Authors: Victor Azizi W Tarksalooyeh, Gabor Zavodszky, Alfons G HoekstraAbstract:Large scale cell based Blood Flow Simulations are expensive, both in time and resource requirements. HemoCell can perform such Simulations on high performance computing resources by dividing the Simulation domain into multiple blocks. This division has a performance impact caused by the necessary communication between the blocks. In this paper we implement an efficient algorithm for computing the mechanical model for HemoCell together with an improved communication structure. The result is an up to 4 times performance increase for Blood Flow Simulations performed with HemoCell.
Christos Bourantas - One of the best experts on this subject based on the ideXlab platform.
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Strut protrusion and shape impact on endothelial shear stress: insights from pre-clinical study comparing Mirage and Absorb bioresorbable scaffolds
The International Journal of Cardiovascular Imaging, 2017Co-Authors: Erhan Tenekecioglu, Christos Bourantas, Solomon Su, Tom Crake, Carlos Collet, Yoshinobu Onuma, Yosuke Miyazaki, Yohei Sotomi, Ryo Torii, Patrick W.j.c. SerruysAbstract:Protrusion of scaffold struts is related with local coronary Flow dynamics that can promote scaffold restenosis and thrombosis. That fact has prompted us to investigate in vivo the protrusion status of different types of scaffolds and their relationship with endothelial shear stress (ESS) distributions. Six Absorb everolimus-eluting Bioresorbable Vascular Scaffolds (Absorb, Abbott Vascular) and 11 Mirage sirolimus-eluting Bioresorbable Microfiber Scaffolds (Mirage, Manli Cardiology) were implanted in coronaries of eight mini pigs. Optical coherence tomography (OCT) was performed post-scaffold implantation and obtained images were fused with angiographic data to reconstruct the three dimensional coronary anatomy. Blood Flow Simulation was performed and ESS distribution was estimated for each scaffold. Protrusion distance was estimated using a dedicated software. Correlation between OCT-derived protrusion and ESS distribution was assessed for both scaffold groups. A significant difference was observed in the protrusion distances (156 ± 137 µm for Absorb, 139 ± 153 µm for Mirage; p = 0.035), whereas difference remained after adjusting the protrusion distances according to the luminal areas. Strut protrusion of Absorb is inversely correlated with ESS (r = −0.369, p
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strut protrusion and shape impact on endothelial shear stress insights from pre clinical study comparing mirage and absorb bioresorbable scaffolds
International Journal of Cardiovascular Imaging, 2017Co-Authors: Erhan Tenekecioglu, Christos Bourantas, Tom Crake, Carlos Collet, Yoshinobu Onuma, Yosuke Miyazaki, Yohei Sotomi, Ryo Torii, Patrick W.j.c. SerruysAbstract:Protrusion of scaffold struts is related with local coronary Flow dynamics that can promote scaffold restenosis and thrombosis. That fact has prompted us to investigate in vivo the protrusion status of different types of scaffolds and their relationship with endothelial shear stress (ESS) distributions. Six Absorb everolimus-eluting Bioresorbable Vascular Scaffolds (Absorb, Abbott Vascular) and 11 Mirage sirolimus-eluting Bioresorbable Microfiber Scaffolds (Mirage, Manli Cardiology) were implanted in coronaries of eight mini pigs. Optical coherence tomography (OCT) was performed post-scaffold implantation and obtained images were fused with angiographic data to reconstruct the three dimensional coronary anatomy. Blood Flow Simulation was performed and ESS distribution was estimated for each scaffold. Protrusion distance was estimated using a dedicated software. Correlation between OCT-derived protrusion and ESS distribution was assessed for both scaffold groups. A significant difference was observed in the protrusion distances (156 ± 137 µm for Absorb, 139 ± 153 µm for Mirage; p = 0.035), whereas difference remained after adjusting the protrusion distances according to the luminal areas. Strut protrusion of Absorb is inversely correlated with ESS (r = −0.369, p < 0.0001), whereas in Mirage protrusion was positively correlated with EES (r = 0.192, p < 0.0001). Protrusion distance was higher in Absorb than in Mirage. The protrusion of the thick quadratic struts of Absorb has a tendency to lower shear stress in the close vicinity of struts. However, circular shape of the less thick struts of Mirage didn’t show this trend in creating zone of recirculation around the struts. Strut geometry has different effect on the relationship between protrusion and shear stress in Absorb and Mirage scaffolds.
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fast virtual functional assessment of intermediate coronary lesions using routine angiographic data and Blood Flow Simulation in humans comparison with pressure wire fractional Flow reserve
Eurointervention, 2014Co-Authors: Michail I. Papafaklis, Christos Bourantas, Yoshinobu Onuma, Lampros Lakkas, Takashi Muramatsu, Yuki Ishibashi, Shimpei Nakatani, Jurgen Ligthart, Mauro Echavarriapinto, Georgia TsirkaAbstract:Aims: To develop a simplified approach of virtual functional assessment of coronary stenosis from routine angiographic data and test it against fractional Flow reserve using a pressure wire (wire-FFR). Methods and results: Three-dimensional quantitative coronary angiography (3D-QCA) was performed in 139 vessels (120 patients) with intermediate lesions assessed by wire-FFR (reference standard: .0.80). The 3D-QCA models were processed with computational fluid dynamics (CFD) to calculate the lesion-specific pressure gradient (?¢P) and construct the ?¢P.Flow curve, from which the virtual functional assessment index (vFAI) was derived. The discriminatory power of vFAI for ischaemia-producing lesions was high (area under the receiver operator characteristic curve [AUC]: 92% [95% CI: 86-96%]). Diagnostic accuracy, sensitivity and specificity for the optimal vFAI cut-point (.0.82) were 88%, 90% and 86%, respectively. Virtual-FAI demonstrated superior discrimination against 3D-QCA.derived % area stenosis (AUC: 78% [95% CI: 70-84%]; p<0.0001 compared to vFAI). There was a close correlation (r=0.78, p<0.0001) and agreement of vFAI compared to wire-FFR (mean difference: .0.0039?}0.085, p=0.59). Conclusions: We developed a fast and simple CFD-powered virtual haemodynamic assessment model using only routine angiography and without requiring any invasive physiology measurements/hyperaemia induction. Virtual-FAI showed a high diagnostic performance and incremental value to QCA for predicting wire-FFR; this ?gless invasive?h approach could have important implications for patient management and cost.
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fusion of optical coherence tomographic and angiographic data for more accurate evaluation of the endothelial shear stress patterns and neointimal distribution after bioresorbable scaffold implantation comparison with intravascular ultrasound derived
International Journal of Cardiovascular Imaging, 2014Co-Authors: Christos Bourantas, Yoshinobu Onuma, Michail I. Papafaklis, Lampros Lakkas, Takashi Muramatsu, Antonis I Sakellarios, Yaojun Zhang, Roberto Diletti, Paschalis Bizopoulos, Fanis G KalatzisAbstract:Intravascular ultrasound (IVUS)-based reconstructions have been traditionally used to examine the effect of endothelial shear stress (ESS) on neointimal formation. The aim of this analysis is to compare the association between ESS and neointimal thickness (NT) in models obtained by the fusion of optical coherence tomography (OCT) and coronary angiography and in the reconstructions derived by the integration of IVUS and coronary angiography. We analyzed data from six patients implanted with an Absorb bioresorbable vascular scaffold that had biplane angiography, IVUS and OCT investigation at baseline and 6 or 12 months follow-up. The IVUS and OCT follow-up data were fused separately with the angiographic data to reconstruct the luminal morphology at baseline and follow-up. Blood Flow Simulation was performed on the baseline reconstructions and the ESS was related to NT. In the OCT-based reconstructions the ESS were lower compared to the IVUS-based models (1.29 ± 0.66 vs. 1.87 ± 0.66 Pa, P = 0.030). An inverse correlation was noted between the logarithmic transformed ESS and the measured NT in all the OCT-based models which was higher than the correlation reported in five of the six IVUS-derived models (-0.52 ± 0.19 Pa vs. -0.10 ± 0.04, P = 0.028). Fusion of OCT and coronary angiography appears superior to IVUS-based reconstructions; therefore it should be the method of choice for the study of the effect of the ESS on neointimal proliferation.