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Wang M, Ching-Johnson JA, Yin H, O’Neil C, Li AX, Chu MWA, Bartha R, Pickering JG. Mapping microarchitectural degeneration in the dilated ascending aorta with ex vivo diffusion tensor imaging. EUROPEAN HEART JOURNAL OPEN 2024; 4:oead128. [PMID: 38162403 PMCID: PMC10755346 DOI: 10.1093/ehjopen/oead128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 10/26/2023] [Accepted: 11/30/2023] [Indexed: 01/03/2024]
Abstract
Aims Thoracic aortic aneurysms (TAAs) carry a risk of catastrophic dissection. Current strategies to evaluate this risk entail measuring aortic diameter but do not image medial degeneration, the cause of TAAs. We sought to determine if the advanced magnetic resonance imaging (MRI) acquisition strategy, diffusion tensor imaging (DTI), could delineate medial degeneration in the ascending thoracic aorta. Methods and results Porcine ascending aortas were subjected to enzyme microinjection, which yielded local aortic medial degeneration. These lesions were detected by DTI, using a 9.4 T MRI scanner, based on tensor disorientation, disrupted diffusion tracts, and altered DTI metrics. High-resolution spatial analysis revealed that fractional anisotropy positively correlated, and mean and radial diffusivity inversely correlated, with smooth muscle cell (SMC) and elastin content (P < 0.001 for all). Ten operatively harvested human ascending aorta samples (mean subject age 61.6 ± 13.3 years, diameter range 29-64 mm) showed medial pathology that was more diffuse and more complex. Nonetheless, DTI metrics within an aorta spatially correlated with SMC, elastin, and, especially, glycosaminoglycan (GAG) content. Moreover, there were inter-individual differences in slice-averaged DTI metrics. Glycosaminoglycan accumulation and elastin degradation were captured by reduced fractional anisotropy (R2 = 0.47, P = 0.043; R2 = 0.76, P = 0.002), with GAG accumulation also captured by increased mean diffusivity (R2 = 0.46, P = 0.045) and increased radial diffusivity (R2 = 0.60, P = 0.015). Conclusion Ex vivo high-field DTI can detect ascending aorta medial degeneration and can differentiate TAAs in accordance with their histopathology, especially elastin and GAG changes. This non-destructive window into aortic medial microstructure raises prospects for probing the risks of TAAs beyond lumen dimensions.
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Affiliation(s)
- Mofei Wang
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St. N. London, Canada, N6A 5B7
- Department of Biochemistry, Western University, 1151 Richmond St. N. London, Canada, N6A 3K7
| | - Justin A Ching-Johnson
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St. N. London, Canada, N6A 5B7
- Department of Medical Biophysics, Western University, 1151 Richmond St. N. London, Canada, N6A 3K7
| | - Hao Yin
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St. N. London, Canada, N6A 5B7
| | - Caroline O’Neil
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St. N. London, Canada, N6A 5B7
| | - Alex X Li
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St. N. London, Canada, N6A 5B7
| | - Michael W A Chu
- Department of Surgery, Western University, 1151 Richmond St. N. London, Canada, N6A 3K7
- London Health Sciences Centre, 339 Windermere Rd, London, Ontario, Canada, N6A 5A5
| | - Robert Bartha
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St. N. London, Canada, N6A 5B7
- Department of Medical Biophysics, Western University, 1151 Richmond St. N. London, Canada, N6A 3K7
| | - J Geoffrey Pickering
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St. N. London, Canada, N6A 5B7
- Department of Biochemistry, Western University, 1151 Richmond St. N. London, Canada, N6A 3K7
- Department of Medical Biophysics, Western University, 1151 Richmond St. N. London, Canada, N6A 3K7
- London Health Sciences Centre, 339 Windermere Rd, London, Ontario, Canada, N6A 5A5
- Department of Medicine, Western University, 1151 Richmond St. N. London, Canada N6A 3K7
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2
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Uncertainty Quantification in the In Vivo Image-Based Estimation of Local Elastic Properties of Vascular Walls. J Cardiovasc Dev Dis 2023; 10:jcdd10030109. [PMID: 36975873 PMCID: PMC10058982 DOI: 10.3390/jcdd10030109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/15/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Introduction: Patient-specific computational models are a powerful tool for planning cardiovascular interventions. However, the in vivo patient-specific mechanical properties of vessels represent a major source of uncertainty. In this study, we investigated the effect of uncertainty in the elastic module (E) on a Fluid–Structure Interaction (FSI) model of a patient-specific aorta. Methods: The image-based χ-method was used to compute the initial E value of the vascular wall. The uncertainty quantification was carried out using the generalized Polynomial Chaos (gPC) expansion technique. The stochastic analysis was based on four deterministic simulations considering four quadrature points. A deviation of about ±20% on the estimation of the E value was assumed. Results: The influence of the uncertain E parameter was evaluated along the cardiac cycle on area and flow variations extracted from five cross-sections of the aortic FSI model. Results of stochastic analysis showed the impact of E in the ascending aorta while an insignificant effect was observed in the descending tract. Conclusions: This study demonstrated the importance of the image-based methodology for inferring E, highlighting the feasibility of retrieving useful additional data and enhancing the reliability of in silico models in clinical practice.
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3
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Roy T, Guddati MN. Full waveform inversion for arterial viscoelasticity. Phys Med Biol 2023; 68. [PMID: 36753775 PMCID: PMC10124368 DOI: 10.1088/1361-6560/acba7a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 02/08/2023] [Indexed: 02/10/2023]
Abstract
Objective. Arterial viscosity is emerging as an important biomarker, in addition to the widely used arterial elasticity. This paper presents an approach to estimate arterial viscoelasticity using shear wave elastography (SWE).Approach. While dispersion characteristics are often used to estimate elasticity from SWE data, they are not sufficiently sensitive to viscosity. Driven by this, we develop a full waveform inversion (FWI) methodology, based on directly matching predicted and measured wall velocity in space and time, to simultaneously estimate both elasticity and viscosity. Specifically, we propose to minimize an objective function capturing the correlation between measured and predicted responses of the anterior wall of the artery.Results. The objective function is shown to be well-behaving (generally convex), leading us to effectively use gradient optimization to invert for both elasticity and viscosity. The resulting methodology is verified with synthetic data polluted with noise, leading to the conclusion that the proposed FWI is effective in estimating arterial viscoelasticity.Significance. Accurate estimation of arterial viscoelasticity, not just elasticity, provides a more precise characterization of arterial mechanical properties, potentially leading to a better indicator of arterial health.
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Affiliation(s)
- Tuhin Roy
- North Carolina State University, Raleigh, NC, United States of America
| | - Murthy N Guddati
- North Carolina State University, Raleigh, NC, United States of America
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4
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Introduction of a Novel Image-Based and Non-Invasive Method for the Estimation of Local Elastic Properties of Great Vessels. ELECTRONICS 2022. [DOI: 10.3390/electronics11132055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background: In the context of a growing demand for the use of in silico models to meet clinical requests, image-based methods play a crucial role. In this study, we present a parametric equation able to estimate the elasticity of vessel walls, non-invasively and indirectly, from information uniquely retrievable from imaging. Methods: A custom equation was iteratively refined and tuned from the simulations of a wide range of different vessel models, leading to the definition of an indirect method able to estimate the elastic modulus E of a vessel wall. To test the effectiveness of the predictive capability to infer the E value, two models with increasing complexity were used: a U-shaped vessel and a patient-specific aorta. Results: The original formulation was demonstrated to deviate from the ground truth, with a difference of 89.6%. However, the adoption of our proposed equation was found to significantly increase the reliability of the estimated E value for a vessel wall, with a mean percentage error of 9.3% with respect to the reference values. Conclusion: This study provides a strong basis for the definition of a method able to estimate local mechanical information of vessels from data easily retrievable from imaging, thus potentially increasing the reliability of in silico cardiovascular models.
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5
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Roy T, Urban M, Xu Y, Greenleaf J, Guddati MN. Multimodal guided wave inversion for arterial stiffness: methodology and validation in phantoms. Phys Med Biol 2021; 66. [PMID: 34061042 DOI: 10.1088/1361-6560/ac01b7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 05/14/2021] [Indexed: 11/12/2022]
Abstract
Arterial stiffness is an important biomarker for many cardiovascular diseases. Shear wave elastography is a recent technique aimed at estimating local arterial stiffness using guided wave inversion (GWI), i.e. matching the computed and measured wave dispersion. This paper develops and validates a new GWI approach by synthesizing various recent observations and algorithms: (a) refinements to signal processing to obtain more accurate experimental dispersion curves; (b) an efficient forward model to compute theoretical dispersion curves for immersed, incompressible cylindrical waveguides; (c) an optimization framework based on the recent observation that the measured dispersion curve is multimodal, i.e. it matches for not one but two different wave modes in two different frequency ranges. The resulting inversion approach is validated using extensive experimental data from rubber tube phantoms, not only for modulus estimation but also to simultaneously estimate modulus and wall thickness. The observations indicate that the modulus estimates are best performed with the information on wall thickness. The approach, which takes less than half a minute to run, is shown to be accurate, with the modulus estimated with less than 4% error for 70% of the experiments.
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Affiliation(s)
- Tuhin Roy
- Department of Civil Engineering, North Carolina State University, Raleigh, NC, United States of America
| | - Matthew Urban
- Department of Radiology, Mayo Clinic, Rochester, MN, United States of America.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States of America
| | - Yingzheng Xu
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, United States of America
| | - James Greenleaf
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States of America
| | - Murthy N Guddati
- Department of Civil Engineering, North Carolina State University, Raleigh, NC, United States of America
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6
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Vignali E, di Bartolo F, Gasparotti E, Malacarne A, Concistré G, Chiaramonti F, Murzi M, Positano V, Landini L, Celi S. Correlation between micro and macrostructural biaxial behavior of ascending thoracic aneurysm: a novel experimental technique. Med Eng Phys 2020; 86:78-85. [PMID: 33261737 DOI: 10.1016/j.medengphy.2020.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 10/01/2020] [Accepted: 10/21/2020] [Indexed: 02/08/2023]
Abstract
Mechanical properties and microstructural modifications of vessel tissues are strongly linked, as established in the state of the art of cardiovascular diseases. Techniques to obtain both mechanical and structural information are reported, but the possibility to obtain real-time microstructural and macrostructural data correlated is still lacking. An experimental approach to characterize the aortic tissue is presented. A setup integrating biaxial traction and Small Angle Light Scattering (SALS) analysis is described. The system was adopted to test ex-vivo aorta specimens from healthy and aneusymatic (aTAA) cases. A significant variation of the fiber dispersion with respect to the unloaded state was encountered during the material traction. The corresponding microstructural and mechanical data were successfully used to fit a given anisotropic constitutive model, with satisfactory R2 values (0.97±0.11 and 0.96±0.17, for aTAA and healthy population, respectively) and fiber dispersion parameters variations between the aTAA and healthy populations (0.39±0.23 and 0.15±0.10). The method integrating the biaxial/SALS technique was validated, allowing for real-time synchronization between mechanical and microstructural analysis of anisotropic biological tissues.
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Affiliation(s)
- Emanuele Vignali
- BioCardioLab, Ospedale del Cuore, Fondazione Toscana G. Monasterio, Massa, Italy; Department of Information Engineering, University of Pisa, Pisa, Italy
| | - Francesco di Bartolo
- BioCardioLab, Ospedale del Cuore, Fondazione Toscana G. Monasterio, Massa, Italy; Department of Information Engineering, University of Pisa, Pisa, Italy
| | - Emanuele Gasparotti
- BioCardioLab, Ospedale del Cuore, Fondazione Toscana G. Monasterio, Massa, Italy; Department of Information Engineering, University of Pisa, Pisa, Italy
| | | | - Giovanni Concistré
- Adult Cardiosurgery Unit, Ospedale del Cuore, Fondazione Toscana Gabriele Monasterio, Massa, Italy
| | - Francesca Chiaramonti
- Adult Cardiosurgery Unit, Ospedale del Cuore, Fondazione Toscana Gabriele Monasterio, Massa, Italy
| | - Michele Murzi
- Adult Cardiosurgery Unit, Ospedale del Cuore, Fondazione Toscana Gabriele Monasterio, Massa, Italy
| | - Vincenzo Positano
- BioCardioLab, Ospedale del Cuore, Fondazione Toscana G. Monasterio, Massa, Italy
| | - Luigi Landini
- Department of Information Engineering, University of Pisa, Pisa, Italy
| | - Simona Celi
- BioCardioLab, Ospedale del Cuore, Fondazione Toscana G. Monasterio, Massa, Italy.
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7
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Fanni BM, Sauvage E, Celi S, Norman W, Vignali E, Landini L, Schievano S, Positano V, Capelli C. A Proof of Concept of a Non-Invasive Image-Based Material Characterization Method for Enhanced Patient-Specific Computational Modeling. Cardiovasc Eng Technol 2020; 11:532-543. [PMID: 32748364 DOI: 10.1007/s13239-020-00479-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 07/22/2020] [Indexed: 11/30/2022]
Abstract
PURPOSE Computational models of cardiovascular structures rely on their accurate mechanical characterization. A validated method able to infer the material properties of patient-specific large vessels is currently lacking. The aim of the present study is to present a technique starting from the flow-area (QA) method to retrieve basic material properties from magnetic resonance (MR) imaging. METHODS The proposed method was developed and tested, first, in silico and then in vitro. In silico, fluid-structure interaction (FSI) simulations of flow within a deformable pipe were run with varying elastic modules (E) between 0.5 and 32 MPa. The proposed QA-based formulation was assessed and modified based on the FSI results to retrieve E values. In vitro, a compliant phantom connected to a mock circulatory system was tested within MR scanning. Images of the phantom were acquired and post-processed according to the modified formulation to infer E of the phantom. Results of in vitro imaging assessment were verified against standard tensile test. RESULTS In silico results from FSI simulations were used to derive the correction factor to the original formulation based on the geometrical and material characteristics. In vitro, the modified QA-based equation estimated an average E = 0.51 MPa, 2% different from the E derived from tensile tests (i.e. E = 0.50 MPa). CONCLUSION This study presented promising results of an indirect and non-invasive method to establish elastic properties from solely MR images data, suggesting a potential image-based mechanical characterization of large blood vessels.
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Affiliation(s)
- B M Fanni
- BioCardioLab, Bioengineering Unit, Fondazione Toscana Gabriele Monasterio, Via Aurelia Sud, 54100, Massa, Italy.,Department of Information Engineering, University of Pisa, Via Girolamo Caruso 16, 56122, Pisa, Italy
| | - E Sauvage
- UCL Institute of Cardiovascular Science, 20c Guilford Street, London, WC1N 1DZ, UK.,Great Ormond Street Hospital for Children, NHS Foundation Trust, 30 Great Ormond Street, London, WC1N 3JH, UK
| | - S Celi
- BioCardioLab, Bioengineering Unit, Fondazione Toscana Gabriele Monasterio, Via Aurelia Sud, 54100, Massa, Italy.
| | - W Norman
- UCL Institute of Cardiovascular Science, 20c Guilford Street, London, WC1N 1DZ, UK.,Great Ormond Street Hospital for Children, NHS Foundation Trust, 30 Great Ormond Street, London, WC1N 3JH, UK
| | - E Vignali
- BioCardioLab, Bioengineering Unit, Fondazione Toscana Gabriele Monasterio, Via Aurelia Sud, 54100, Massa, Italy.,Department of Information Engineering, University of Pisa, Via Girolamo Caruso 16, 56122, Pisa, Italy
| | - L Landini
- BioCardioLab, Bioengineering Unit, Fondazione Toscana Gabriele Monasterio, Via Aurelia Sud, 54100, Massa, Italy.,Department of Information Engineering, University of Pisa, Via Girolamo Caruso 16, 56122, Pisa, Italy
| | - S Schievano
- UCL Institute of Cardiovascular Science, 20c Guilford Street, London, WC1N 1DZ, UK.,Great Ormond Street Hospital for Children, NHS Foundation Trust, 30 Great Ormond Street, London, WC1N 3JH, UK
| | - V Positano
- BioCardioLab, Bioengineering Unit, Fondazione Toscana Gabriele Monasterio, Via Aurelia Sud, 54100, Massa, Italy
| | - C Capelli
- UCL Institute of Cardiovascular Science, 20c Guilford Street, London, WC1N 1DZ, UK.,Great Ormond Street Hospital for Children, NHS Foundation Trust, 30 Great Ormond Street, London, WC1N 3JH, UK
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8
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Black RA, Houston G. 40th Anniversary Issue: Reflections on papers from the archive on "Cardiovascular devices and modelling". Med Eng Phys 2020; 72:74-75. [PMID: 31554581 DOI: 10.1016/j.medengphy.2019.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Richard A Black
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, Scotland, UK.
| | - Gregor Houston
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, Scotland, UK
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9
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Aiello M, Cavaliere C, D'Albore A, Salvatore M. The Challenges of Diagnostic Imaging in the Era of Big Data. J Clin Med 2019; 8:E316. [PMID: 30845692 PMCID: PMC6463157 DOI: 10.3390/jcm8030316] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 02/27/2019] [Accepted: 02/28/2019] [Indexed: 01/08/2023] Open
Abstract
The diagnostic imaging field has undergone considerable growth both in terms of technological development and market expansion; with the following increasing production of a considerable amount of data that potentially fully poses diagnostic imaging in the Big data in the context of healthcare. Nevertheless, the mere production of a large amount of data does not automatically permit the real exploitation of their intrinsic value. Therefore, it is necessary to develop digital platforms and applications that favor the correct and advantageous management of diagnostic images such as Big data. This work aims to frame the role of diagnostic imaging in this new scenario, emphasizing the open challenges in exploiting such intense data generation for decision making with Big data analytics.
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Affiliation(s)
- Marco Aiello
- IRCCS SDN, Via Gianturco 113, Napoli 80143, Italy.
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10
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Bosi GM, Capelli C, Cheang MH, Delahunty N, Mullen M, Taylor AM, Schievano S. Population-specific material properties of the implantation site for transcatheter aortic valve replacement finite element simulations. J Biomech 2018; 71:236-244. [PMID: 29482928 PMCID: PMC5889787 DOI: 10.1016/j.jbiomech.2018.02.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 02/07/2018] [Accepted: 02/09/2018] [Indexed: 10/31/2022]
Abstract
Patient-specific computational models are an established tool to support device development and test under clinically relevant boundary conditions. Potentially, such models could be used to aid the clinical decision-making process for percutaneous valve selection; however, their adoption in clinical practice is still limited to individual cases. To be fully informative, they should include patient-specific data on both anatomy and mechanics of the implantation site. In this work, fourteen patient-specific computational models for transcatheter aortic valve replacement (TAVR) with balloon-expandable Sapien XT devices were retrospectively developed to tune the material parameters of the implantation site mechanical model for the average TAVR population. Pre-procedural computed tomography (CT) images were post-processed to create the 3D patient-specific anatomy of the implantation site. Balloon valvuloplasty and device deployment were simulated with finite element (FE) analysis. Valve leaflets and aortic root were modelled as linear elastic materials, while calcification as elastoplastic. Material properties were initially selected from literature; then, a statistical analysis was designed to investigate the effect of each implantation site material parameter on the implanted stent diameter and thus identify the combination of material parameters for TAVR patients. These numerical models were validated against clinical data. The comparison between stent diameters measured from post-procedural fluoroscopy images and final computational results showed a mean difference of 2.5 ± 3.9%. Moreover, the numerical model detected the presence of paravalvular leakage (PVL) in 79% of cases, as assessed by post-TAVR echocardiographic examination. The final aim was to increase accuracy and reliability of such computational tools for prospective clinical applications.
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Affiliation(s)
- Giorgia M Bosi
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK; Cardiovascular Engineering Laboratory, UCL Mechanical Engineering, London, UK.
| | - Claudio Capelli
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Mun Hong Cheang
- Barts Health NHS Trust, University College London Hospital, London, UK
| | - Nicola Delahunty
- Barts Health NHS Trust, University College London Hospital, London, UK
| | - Michael Mullen
- Barts Health NHS Trust, University College London Hospital, London, UK
| | - Andrew M Taylor
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Silvia Schievano
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
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11
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Collagen fibre characterisation in arterial tissue under load using SALS. J Mech Behav Biomed Mater 2017; 75:359-368. [DOI: 10.1016/j.jmbbm.2017.07.036] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 07/13/2017] [Accepted: 07/25/2017] [Indexed: 01/06/2023]
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12
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Akyildiz AC, Chai CK, Oomens CWJ, van der Lugt A, Baaijens FPT, Strijkers GJ, Gijsen FJH. 3D Fiber Orientation in Atherosclerotic Carotid Plaques. J Struct Biol 2017; 200:28-35. [PMID: 28838817 DOI: 10.1016/j.jsb.2017.08.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 07/18/2017] [Accepted: 08/20/2017] [Indexed: 11/26/2022]
Abstract
Atherosclerotic plaque rupture is the primary trigger of fatal cardiovascular events. Fibrillar collagen in atherosclerotic plaques and their directionality are anticipated to play a crucial role in plaque rupture. This study aimed assessing 3D fiber orientations and architecture in atherosclerotic plaques for the first time. Seven carotid plaques were imaged ex-vivo with a state-of-the-art Diffusion Tensor Imaging (DTI) technique, using a high magnetic field (9.4Tesla) MRI scanner. A 3D spin-echo sequence with uni-polar diffusion sensitizing pulsed field gradients was utilized for DTI and fiber directions were assessed from diffusion tensor measurements. The distribution of the 3D fiber orientations in atherosclerotic plaques were quantified and the principal fiber orientations (circumferential, longitudinal or radial) were determined. Overall, 52% of the fiber orientations in the carotid plaque specimens were closest to the circumferential direction, 34% to the longitudinal direction, and 14% to the radial direction. Statistically no significant difference was measured in the amount of the fiber orientations between the concentric and eccentric plaque sites. However, concentric plaque sites showed a distinct structural organization, where the principally longitudinally oriented fibers were closer to the luminal side and the principally circumferentially oriented fibers were located more abluminally. The acquired unique information on 3D plaque fiber direction will help understanding pathobiological mechanisms of atherosclerotic plaque progression and pave the road to more realistic biomechanical plaque modeling for rupture assessment.
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Affiliation(s)
- Ali C Akyildiz
- Department of Biomedical Engineering, Erasmus Medical Center, Rotterdam, The Netherlands.
| | - Chen-Ket Chai
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Cees W J Oomens
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Aad van der Lugt
- Department of Radiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Frank P T Baaijens
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Gustav J Strijkers
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Frank J H Gijsen
- Department of Biomedical Engineering, Erasmus Medical Center, Rotterdam, The Netherlands
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13
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Astaneh AV, Urban MW, Aquino W, Greenleaf JF, Guddati MN. Arterial waveguide model for shear wave elastography: implementation andin vitrovalidation. Phys Med Biol 2017; 62:5473-5494. [DOI: 10.1088/1361-6560/aa6ee3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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14
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Cuomo F, Roccabianca S, Dillon-Murphy D, Xiao N, Humphrey JD, Figueroa CA. Effects of age-associated regional changes in aortic stiffness on human hemodynamics revealed by computational modeling. PLoS One 2017; 12:e0173177. [PMID: 28253335 PMCID: PMC5333881 DOI: 10.1371/journal.pone.0173177] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 02/16/2017] [Indexed: 02/04/2023] Open
Abstract
Although considered by many as the gold standard clinical measure of arterial stiffness, carotid-to-femoral pulse wave velocity (cf-PWV) averages material and geometric properties over a large portion of the central arterial tree. Given that such properties may evolve differentially as a function of region in cases of hypertension and aging, among other conditions, there is a need to evaluate the potential utility of cf-PWV as an early diagnostic of progressive vascular stiffening. In this paper, we introduce a data-driven fluid-solid-interaction computational model of the human aorta to simulate effects of aging-related changes in regional wall properties (e.g., biaxial material stiffness and wall thickness) and conduit geometry (e.g., vessel caliber, length, and tortuosity) on several metrics of arterial stiffness, including distensibility, augmented pulse pressure, and cyclic changes in stored elastic energy. Using the best available biomechanical data, our results for PWV compare well to findings reported for large population studies while rendering a higher resolution description of evolving local and global metrics of aortic stiffening. Our results reveal similar spatio-temporal trends between stiffness and its surrogate metrics, except PWV, thus indicating a complex dependency of the latter on geometry. Lastly, our analysis highlights the importance of the tethering exerted by external tissues, which was iteratively estimated until hemodynamic simulations recovered typical values of tissue properties, pulse pressure, and PWV for each age group.
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Affiliation(s)
- Federica Cuomo
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, United States of America
| | | | - Nan Xiao
- Department of Biomedical Engineering, King’s College London, London, United Kingdom
| | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, United States of America
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, Connecticut, United States of America
| | - C. Alberto Figueroa
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Biomedical Engineering, King’s College London, London, United Kingdom
- Department of Surgery, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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15
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Bosi GM, Biffi B, Biglino G, Lintas V, Jones R, Tzamtzis S, Burriesci G, Migliavacca F, Khambadkone S, Taylor AM, Schievano S. Can finite element models of ballooning procedures yield mechanical response of the cardiovascular site to overexpansion? J Biomech 2016; 49:2778-2784. [PMID: 27395759 PMCID: PMC5522534 DOI: 10.1016/j.jbiomech.2016.06.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 06/09/2016] [Accepted: 06/13/2016] [Indexed: 11/23/2022]
Abstract
Patient-specific numerical models could aid the decision-making process for percutaneous valve selection; in order to be fully informative, they should include patient-specific data of both anatomy and mechanics of the implantation site. This information can be derived from routine clinical imaging during the cardiac cycle, but data on the implantation site mechanical response to device expansion are not routinely available. We aim to derive the implantation site response to overexpansion by monitoring pressure/dimensional changes during balloon sizing procedures and by applying a reverse engineering approach using a validated computational balloon model. This study presents the proof of concept for such computational framework tested in-vitro. A finite element (FE) model of a PTS-X405 sizing balloon (NuMed, Inc., USA) was created and validated against bench tests carried out on an ad hoc experimental apparatus: first on the balloon alone to replicate free expansion; second on the inflation of the balloon in a rapid prototyped cylinder with material deemed suitable for replicating pulmonary arteries in order to validate balloon/implantation site interaction algorithm. Finally, the balloon was inflated inside a compliant rapid prototyped patient-specific right ventricular outflow tract to test the validity of the approach. The corresponding FE simulation was set up to iteratively infer the mechanical response of the anatomical model. The test in this simplified condition confirmed the feasibility of the proposed approach and the potential for this methodology to provide patient-specific information on mechanical response of the implantation site when overexpanded, ultimately for more realistic computational simulations in patient-specific settings.
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Affiliation(s)
- Giorgia M Bosi
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK.
| | - Benedetta Biffi
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK; Department of Medical Physics & Biomedical Engineering, UCL, London, UK
| | - Giovanni Biglino
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Valentina Lintas
- Laboratory of Biological Structure Mechanics (LaBS), Chemistry, Materials and Chemical Engineering Department "Giulio Natta", Politecnico di Milano, Italy
| | - Rod Jones
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Spyros Tzamtzis
- UCL Mechanical Engineering, Cardiovascular Engineering Laboratory, University College London, UK
| | - Gaetano Burriesci
- UCL Mechanical Engineering, Cardiovascular Engineering Laboratory, University College London, UK
| | - Francesco Migliavacca
- Laboratory of Biological Structure Mechanics (LaBS), Chemistry, Materials and Chemical Engineering Department "Giulio Natta", Politecnico di Milano, Italy
| | - Sachin Khambadkone
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Andrew M Taylor
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
| | - Silvia Schievano
- Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK
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