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Peng C, He W, Luan J, Yuan T, Fu W, Shi Y, Wang S. Preliminary establishment and validation of the inversion method for growth and remodeling parameters of patient-specific abdominal aortic aneurysm. Biomech Model Mechanobiol 2024; 23:1137-1148. [PMID: 38548952 DOI: 10.1007/s10237-024-01828-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 02/09/2024] [Indexed: 08/24/2024]
Abstract
Traditional medical imaging and biomechanical studies have challenges in analyzing the long-term evolution process of abdominal aortic aneurysm (AAA). The homogenized constrained mixture theory (HCMT) allows for quantitative analysis of the changes in the multidimensional morphology and composition of AAA. However, the accuracy of HCMT still requires further clinical verification. This study aims to establish a patient-specific AAA growth model based on HCMT, simulate the long-term growth and remodeling (G&R) process of AAA, and validate the feasibility and accuracy of the method using two additional AAA cases with five follow-up datasets. The media and adventitia layers of AAA were modeled as mixtures composed of elastin, collagen fibers, and smooth muscle cells (SMCs). The strain energy function was used to describe the continuous deposition and degradation effect of the mixture during the AAA evolution. Multiple sets of growth parameters were applied to finite element simulations, and the simulation results were compared with the follow-up data for gradually selecting the optimal growth parameters. Two additional AAA patients with different growth rates were used for validating this method, the optimal growth parameters were obtained using the first two follow-up imaging data, and the growth model was applied to simulate the subsequent four time points. The differences between the simulated diameters and the follow-up diameters of AAA were compared to validate the accuracy of the mechanistic model. The growth parameters, especially the stress-mediated substance deposition gain factor, are highly related to the AAA G&R process. When setting the optimal growth parameters to simulate AAA growth, the proportion of simulation results within the distance of less than 0.5 mm from the baseline models is above 80%. For the validating cases, the mean difference rates between the simulated diameter and the real-world diameter are within 2.5%, which basically meets the clinical demand for quantitatively predicting the AAA growth in maximum diameters. This study simulated the growth process of AAA, and validated the accuracy of this mechanistic model. This method was proved to be used to predict the G&R process of AAA caused by dynamic changes in the mixtures of the AAA vessel wall during long-term, assisting accurately and quantitatively predicting the multidimensional morphological development and mixtures evolution process of AAA in the clinic.
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Affiliation(s)
- Chen Peng
- Artificial Intelligence Research Institute, Zhejiang Lab, Hangzhou, Zhejiang, China
- Department of Aeronautics and Astronautics, Institute of Biomechanics, Fudan University, Shanghai, China
| | - Wei He
- Department of Vascular Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jingyang Luan
- Department of Vascular Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Tong Yuan
- Department of Vascular Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Weiguo Fu
- Department of Vascular Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
- Institute of Vascular Surgery, Fudan University, Shanghai, China
- National Clinical Research Center for Interventional Medicine, Fudan University, Shanghai, China
| | - Yun Shi
- Department of Vascular Surgery, Zhongshan Hospital, Fudan University, Shanghai, China.
- Institute of Vascular Surgery, Fudan University, Shanghai, China.
- National Clinical Research Center for Interventional Medicine, Fudan University, Shanghai, China.
| | - Shengzhang Wang
- Department of Aeronautics and Astronautics, Institute of Biomechanics, Fudan University, Shanghai, China.
- Institute of Biomedical Engineering Technology, Academy for Engineering and Technology, Fudan University, Shanghai, China.
- Yiwu Research Institute, Fudan University, Yiwu, Zhejiang, China.
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Margaretha Nievergeld AH, Maas EJ, de Ruijter J, Cornelia Fonken JH, Henricus Maria van Sambeek MR, Paulus Lopata RG. Automatic Segmentation and Mechanical Characterisation of the Intraluminal Thrombus and Arterial Wall of Abdominal Aortic Aneurysms Using Time Resolved 3D Ultrasound Images. Eur J Vasc Endovasc Surg 2023; 66:418-427. [PMID: 36963747 DOI: 10.1016/j.ejvs.2023.03.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 01/19/2023] [Accepted: 03/17/2023] [Indexed: 03/26/2023]
Abstract
OBJECTIVE This study proposed a method for semi-automatic segmentation of abdominal aortic aneurysms (AAAs) and their intraluminal thrombus (ILT), based on time resolved 3D ultrasound (US), and validated results with computed tomography (CT). Mechanical properties of both wall and ILT were determined, and possible correlations with ILT size and blood pressure were investigated. METHODS A semi-automatic segmentation algorithm was developed combining a star-Kalman approach with a 3D snake algorithm. The segmented geometries of both lumen and inner vessel wall were validated with both manual US based segmentations and CT based segmentations. Finally, the lumen and vessel wall distensibility and ILT compressibility were estimated and correlated with ILT size and blood pressure. RESULTS For the vessel wall and lumen, the median Similarity Index (SI) was 92% (IQR 90, 94%) and 83% (IQR 75, 87%), respectively. The distensibility of the vessel wall could be determined in 37 of 40 cases and had a median value of 0.28 10-5 Pa-1 (IQR 0.18, 0.51 ×10-5). The median systolic to diastolic volume change of the ILT was determined successfully in 21 of 40 patients, and was -0.57% (IQR -1.1, 1.2%). The vessel and lumen distensibility showed a strong correlation with the systolic pressure (p < .010), rather than with the diastolic pressure. Lumen distensibility was strongly correlated with ILT thickness (p = .023). The performance of the semi-automatic segmentation algorithm was shown to be as good as the manual segmentations and highly dependent on the visibility of the ILT (limited contrast in seven patients and clutter in nine patients). CONCLUSION This study has shown promising results for mechanical characterisation of the vessel, and ILT, including a correlation between distensibility, ILT size, and blood pressure. For future work, the inclusion rate needs to be increased by improving the image contrast with novel US techniques.
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Affiliation(s)
- Arjet Helena Margaretha Nievergeld
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Department of Vascular Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands.
| | - Esther Jorien Maas
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Department of Vascular Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands
| | - Joerik de Ruijter
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Judith Helena Cornelia Fonken
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Department of Vascular Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands
| | - Marcus Rodolph Henricus Maria van Sambeek
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Department of Vascular Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands
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Mutlu O, Salman HE, Al-Thani H, El-Menyar A, Qidwai UA, Yalcin HC. How does hemodynamics affect rupture tissue mechanics in abdominal aortic aneurysm: Focus on wall shear stress derived parameters, time-averaged wall shear stress, oscillatory shear index, endothelial cell activation potential, and relative residence time. Comput Biol Med 2023; 154:106609. [PMID: 36724610 DOI: 10.1016/j.compbiomed.2023.106609] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 01/19/2023] [Accepted: 01/22/2023] [Indexed: 01/24/2023]
Abstract
An abdominal aortic aneurysm (AAA) is a critical health condition with a risk of rupture, where the diameter of the aorta enlarges more than 50% of its normal diameter. The incidence rate of AAA has increased worldwide. Currently, about three out of every 100,000 people have aortic diseases. The diameter and geometry of AAAs influence the hemodynamic forces exerted on the arterial wall. Therefore, a reliable assessment of hemodynamics is crucial for predicting the rupture risk. Wall shear stress (WSS) is an important metric to define the level of the frictional force on the AAA wall. Excessive levels of WSS deteriorate the remodeling mechanism of the arteries and lead to abnormal conditions. At this point, WSS-related hemodynamic parameters, such as time-averaged WSS (TAWSS), oscillatory shear index (OSI), endothelial cell activation potential (ECAP), and relative residence time (RRT) provide important information to evaluate the shear environment on the AAA wall in detail. Calculation of these parameters is not straightforward and requires a physical understanding of what they represent. In addition, computational fluid dynamics (CFD) solvers do not readily calculate these parameters when hemodynamics is simulated. This review aims to explain the WSS-derived parameters focusing on how these represent different characteristics of disturbed hemodynamics. A representative case is presented for spatial and temporal formulation that would be useful for interested researchers for practical calculations. Finally, recent hemodynamics investigations relating WSS-related parameters with AAA rupture risk assessment are presented. This review will be useful to understand the physical representation of WSS-related parameters in cardiovascular flows and how they can be calculated practically for AAA investigations.
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Affiliation(s)
- Onur Mutlu
- Biomedical Research Center, Qatar University, Doha, Qatar
| | - Huseyin Enes Salman
- Department of Mechanical Engineering, TOBB University of Economics and Technology, Ankara, Turkey
| | - Hassan Al-Thani
- Department of Surgery, Trauma and Vascular Surgery, Hamad General Hospital, Hamad Medical Corporation, P.O. Box 3050, Doha, Qatar
| | - Ayman El-Menyar
- Department of Surgery, Trauma and Vascular Surgery, Hamad General Hospital, Hamad Medical Corporation, P.O. Box 3050, Doha, Qatar; Clinical Medicine, Weill Cornell Medical College, Doha, Qatar
| | - Uvais Ahmed Qidwai
- Department of Computer Science Engineering, Qatar University, Doha, Qatar
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Arbănași EM, Mureșan AV, Coșarcă CM, Arbănași EM, Niculescu R, Voidăzan ST, Ivănescu AD, Hălmaciu I, Filep RC, Mărginean L, Suzuki S, Chirilă TV, Kaller R, Russu E. Computed Tomography Angiography Markers and Intraluminal Thrombus Morphology as Predictors of Abdominal Aortic Aneurysm Rupture. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:15961. [PMID: 36498041 PMCID: PMC9741090 DOI: 10.3390/ijerph192315961] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 11/26/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Background: Abdominal aortic aneurysm (AAA) is a complex vascular disease characterized by progressive and irreversible local dilatation of the aortic wall. Currently, the indication for repair is linked to the transverse diameter of the abdominal aorta, using computed tomography angiography imagery, which is one of the most used markers for aneurysmal growth. This study aims to verify the predictive role of imaging markers and underlying risk factors in AAA rupture. Methods: The present study was designed as an observational, analytical, retrospective cohort study and included 220 patients over 18 years of age with a diagnosis of AAA, confirmed by computed tomography angiography (CTA), admitted to Vascular Surgery Clinic of Mures County Emergency Hospital in Targu Mures, Romania, between January 2018 and September 2022. Results: Patients with a ruptured AAA had higher incidences of AH (p = 0.006), IHD (p = 0.001), AF (p < 0.0001), and MI (p < 0.0001), and higher incidences of all risk factors (tobacco (p = 0.001), obesity (p = 0.02), and dyslipidemia (p < 0.0001)). Multivariate analysis showed that a high baseline value of all imaging ratios markers was a strong independent predictor of AAA rupture (for all p < 0.0001). Moreover, a higher baseline value of DAmax (OR:3.91; p = 0.001), SAmax (OR:7.21; p < 0.001), and SLumenmax (OR:34.61; p < 0.001), as well as lower baseline values of DArenal (OR:7.09; p < 0.001), DACT (OR:12.71; p < 0.001), DAfemoral (OR:2.56; p = 0.005), SArenal (OR:4.56; p < 0.001), SACT (OR:3.81; p < 0.001), and SThrombusmax (OR:5.27; p < 0.001) were independent predictors of AAA rupture. In addition, AH (OR:3.33; p = 0.02), MI (OR:3.06; p = 0.002), and PAD (OR:2.71; p = 0.004) were all independent predictors of AAA rupture. In contrast, higher baseline values of SAmax/Lumenmax (OR:0.13; p < 0.001) and ezetimibe (OR:0.45; p = 0.03) were protective factors against AAA rupture. Conclusions: According to our findings, a higher baseline value of all imaging markers ratios at CTA strongly predicts AAA rupture and AH, MI, and PAD highly predicted the risk of rupture in AAA patients. Furthermore, the diameter of the abdominal aorta at different levels has better accuracy and a higher predictive role of rupture than the maximal diameter of AAA.
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Affiliation(s)
- Emil Marian Arbănași
- Doctoral School of Medicine and Pharmacy, George Emil Palade University of Medicine, Pharmacy, Sciences and Technology of Targu Mures, 540142 Targu Mures, Romania
- Clinic of Vascular Surgery, Mures County Emergency Hospital, 540136 Targu Mures, Romania
| | - Adrian Vasile Mureșan
- Clinic of Vascular Surgery, Mures County Emergency Hospital, 540136 Targu Mures, Romania
- Department of Surgery, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 540139 Targu Mures, Romania
| | - Cătălin Mircea Coșarcă
- Clinic of Vascular Surgery, Mures County Emergency Hospital, 540136 Targu Mures, Romania
| | - Eliza Mihaela Arbănași
- Faculty of Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 540139 Targu Mures, Romania
| | - Raluca Niculescu
- Department of Pathophysiology, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 540139 Targu Mures, Romania
| | - Septimiu Toader Voidăzan
- Department of Epidemiology, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 540139 Targu Mures, Romania
| | - Adrian Dumitru Ivănescu
- Department of Anatomy, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 540139 Targu Mures, Romania
| | - Ioana Hălmaciu
- Department of Anatomy, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 540139 Targu Mures, Romania
| | - Rareș Cristian Filep
- Department of Radiology, Mures County Emergency Hospital, 540136 Targu Mures, Romania
| | - Lucian Mărginean
- Department of Radiology, Mures County Emergency Hospital, 540136 Targu Mures, Romania
| | - Shuko Suzuki
- Queensland Eye Institute, South Brisbane, QLD 4101, Australia
| | - Traian V. Chirilă
- Queensland Eye Institute, South Brisbane, QLD 4101, Australia
- School of Chemistry & Physics, Queensland University of Technology, Brisbane, QLD 4001, Australia
- Australian Institute of Bioengineering & Nanotechnology (AIBN), University of Queensland, St. Lucia, QLD 4072, Australia
- Faculty of Medicine, University of Queensland, Herston, QLD 4006, Australia
- School of Molecular Sciences, University of Western Australia, Crawley, WA 6009, Australia
- Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 540139 Targu Mures, Romania
| | - Réka Kaller
- Doctoral School of Medicine and Pharmacy, George Emil Palade University of Medicine, Pharmacy, Sciences and Technology of Targu Mures, 540142 Targu Mures, Romania
- Clinic of Vascular Surgery, Mures County Emergency Hospital, 540136 Targu Mures, Romania
| | - Eliza Russu
- Clinic of Vascular Surgery, Mures County Emergency Hospital, 540136 Targu Mures, Romania
- Department of Surgery, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 540139 Targu Mures, Romania
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Manenti A, Farinetti A, Manco G, Mattioli AV. Intraluminal thrombus and abdominal aortic aneurysm complications. Ann Vasc Surg 2022; 83:e11-e12. [DOI: 10.1016/j.avsg.2022.03.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 03/16/2022] [Indexed: 11/30/2022]
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Lorandon F, Rinckenbach S, Settembre N, Steinmetz E, Mont LSD, Avril S. Stress Analysis in AAA does not Predict Rupture Location Correctly in Patients with Intraluminal Thrombus. Ann Vasc Surg 2021; 79:279-289. [PMID: 34648863 DOI: 10.1016/j.avsg.2021.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 08/21/2021] [Accepted: 08/31/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND A biomechanical approach to the rupture risk of an abdominal aortic aneurysm could be a solution to ensure a personalized estimate of this risk. It is still difficult to know in what conditions, the assumptions made by biomechanics, are valid. The objective of this work was to determine the individual biomechanical rupture threshold and to assess the correlation between their rupture sites and the locations of their maximum stress comparing two computed tomography scan (CT) before and at time of rupture. METHODS We included 5 patients who had undergone two CT; one within the last 6 months period before rupture and a second CT scan just before the surgical procedure for the rupture. All DICOM data, both pre- and rupture, were processed following the same following steps: generation of a 3D geometry of the abdominal aortic aneurysm, meshing and computational stress analysis using the finite element method. We used two different modelling scenarios to study the distribution of the stresses, a "wall" model without intraluminal thrombus (ILT) and a "thrombus" model with ILT. RESULTS The average time between the pre-rupture and rupture CT scans was 44 days (22-97). The median of the maximum stresses applied to the wall between the pre-rupture and rupture states were 0.817 MPa (0.555-1.295) and 1.160 MPa (0.633-1.625) for the "wall" model; and 0.365 MPa (0.291-0.753) and 0.390 MPa (0.343-0.819) for the "thrombus" model. There was an agreement between the site of rupture and the location of maximum stress for only 1 patient, who was the only patient without ILT. CONCLUSIONS We observed a large variability of stress values at rupture sites between patients. The rupture threshold strongly varied between individuals depending on the intraluminal thrombus. The site of rupture did not correlate with the maximum stress except for 1 patient.
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Affiliation(s)
- Fanny Lorandon
- Department of Vascular and Endovascular Surgery, University Hospital of Besançon, Besançon, Saint Etienne, France..
| | - Simon Rinckenbach
- Department of Vascular and Endovascular Surgery, University Hospital of Besançon, Besançon, Saint Etienne, France.; EA3920, University Hospital of Besançon, Besançon, France
| | - Nicla Settembre
- Department of Vascular Surgery, University Hospital of Nancy, Nancy, France
| | - Eric Steinmetz
- Department of Vascular Surgery, University Hospital of Dijon, Dijon, France
| | - Lucie Salomon Du Mont
- Department of Vascular and Endovascular Surgery, University Hospital of Besançon, Besançon, Saint Etienne, France.; EA3920, University Hospital of Besançon, Besançon, France
| | - Stephane Avril
- Mines Saint-Etienne, Univ Lyon, INSERM, U 1059 Sainbiose, Centre CIS, F - 42023 Saint-Etienne, France..
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He Z, Mongrain R, Lessard S, Chayer B, Cloutier G, Soulez G. Anthropomorphic and biomechanical mockup for abdominal aortic aneurysm. Med Eng Phys 2020; 77:60-68. [PMID: 31954613 DOI: 10.1016/j.medengphy.2019.12.005] [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: 03/27/2019] [Revised: 09/08/2019] [Accepted: 12/15/2019] [Indexed: 11/16/2022]
Abstract
Abdominal aortic aneurysm (AAA) is an asymptomatic condition due to the dilation of abdominal aorta along with progressive wall degeneration, where rupture of AAA is life-threatening. Failures of AAA endovascular repair (EVAR) reflect our inadequate knowledge about the complex interaction between the aortic wall and medical devices. In this regard, we are presenting a hydrogel-based anthropomorphic mockup (AMM) to better understand the biomechanical constraints during EVAR. By adjusting the cryogenic treatments, we tailored the hydrogel to mimic the mechanical behavior of human AAA wall, thrombus and abdominal fat. A specific molding sequence and a pressurizing system were designed to reproduce the geometrical and diseased characteristics of AAA. A mechanically, anatomically and pathologically realistic AMM for AAA was developed for the first time, EVAR experiments were then performed with and without the surrounding fat. Substantial displacements of the aortic centerlines and vessel expansion were observed in the case without surrounding fat, revealing an essential framework created by the surrounding fat to account for the interactions with medical devices. In conclusion, the importance to consider surrounding tissue for the global deformation of AAA during EVAR was highlighted. Furthermore, potential use of this AMM for medical training was also suggested.
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Affiliation(s)
- Zinan He
- McGill University, 845 Sherbrooke Street West, Montréal, Québec H3A 0G4, Canada; Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), 900 Rue Saint-Denis, Montréal, Québec H2X 0A9, Canada
| | - Rosaire Mongrain
- McGill University, 845 Sherbrooke Street West, Montréal, Québec H3A 0G4, Canada
| | - Simon Lessard
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), 900 Rue Saint-Denis, Montréal, Québec H2X 0A9, Canada
| | - Boris Chayer
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), 900 Rue Saint-Denis, Montréal, Québec H2X 0A9, Canada
| | - Guy Cloutier
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), 900 Rue Saint-Denis, Montréal, Québec H2X 0A9, Canada; Université de Montréal, 2900 Boulevard Edouard-Montpetit, Montréal, Québec H3T 1J4, Canada
| | - Gilles Soulez
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), 900 Rue Saint-Denis, Montréal, Québec H2X 0A9, Canada; Université de Montréal, 2900 Boulevard Edouard-Montpetit, Montréal, Québec H3T 1J4, Canada.
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Analysis of morphological and hemodynamical indexes in abdominal aortic aneurysms as preliminary indicators of intraluminal thrombus deposition. Biomech Model Mechanobiol 2019; 19:1035-1053. [PMID: 31820279 DOI: 10.1007/s10237-019-01269-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 11/22/2019] [Indexed: 10/25/2022]
Abstract
In this paper, we study the correlation between the wall shear stress, a hemodynamical index derived from numerical simulations, and an new index MFA-ILT for the characterization of intraluminal thrombus (ILT) in the presence of abdominal aortic aneurysms. Based on the processing of medical images, we define our index MFA-ILT by projecting onto lumen surface a measure of the ILT thickness. From the physical point of view, hemodynamical indexes describe the mechanical stimuli at which the luminal surface of the vessel wall is subject to, due to blood flow. Specifically, we consider the time-averaged wall shear stress and the oscillatory shear index. The first index provides a measurement of the averaged magnitude of the shear stress; the second index measures the rate of change of shear stress. To reconstruct the hemodynamical indexes, we build in silico three-dimensional models. We use the same physical parameters and boundary conditions for all the aneurysms in the sample. The computer simulations do not require any additional invasive patient examination. We consider eleven cases of abdominal aortic aneurysms spanning a wide range of different morphological features. All the cases are characterized by a thin intraluminal thrombus. We can, therefore, assume that the lumen we currently observe does not significantly differ from the one before the thrombus deposition. Our results suggest that the value of wall shear stresses and intraluminal thrombus deposition are correlated. Moreover, we conclude that in six cases time-averaged wall shear stress provides a preliminary indication of the area at risk of thrombus deposition.
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Kontopodis N, Koncar I, Tzirakis K, Tavlas E, Davidovic L, Ioannou CV. Intraluminal Thrombus Deposition Is Reduced in Ruptured Compared to Diameter-matched Intact Abdominal Aortic Aneurysms. Ann Vasc Surg 2018; 55:189-195. [PMID: 30287289 DOI: 10.1016/j.avsg.2018.07.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/23/2018] [Accepted: 07/07/2018] [Indexed: 11/20/2022]
Abstract
BACKGROUND The aim of this study is to compare the pattern of intraluminal thrombus (ILT) deposition in diameter-matched ruptured and nonruptured abdominal aortic aneurysms (AAAs). METHODS We performed a single-center, retrospective study. Ruptured AAAs were collected during 24 months. Diameter-matched intact lesions were randomly selected in a 2:1 ratio and served as controls. ILT cross-sectional area, relative area, maximum thickness, and asymmetric distribution were recorded at the site of maximum aneurysm size and compared between groups. Moreover, additional comparisons were performed inside the group of ruptured AAAs, between the site of maximum size and the site of rupture. RESULTS Fifteen ruptured cases were compared with 30 nonruptured cases. ILT relative area (37.5% vs. 73.5%, P = 0.004) and maximum thickness (14.5 vs. 28 mm, P= 0.0017) were significantly reduced among ruptured compared to intact AAAs. The latter group presented mostly an anterior eccentric ILT deposition, while the former presented a more symmetrical pattern. The site of rupture was located at the site of maximum size in only 2 cases. In general, ILT was reduced at the site of rupture compared to the site of maximum aneurysm size in ruptured cases but differences did not reach statistical significance. CONCLUSIONS In similar sized AAAs, ILT is reduced in ruptured compared to nonruptured cases.
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Affiliation(s)
- Nikolaos Kontopodis
- Vascular Surgery Unit, Department of Cardiothoracic and Vascular Surgery, Medical School, University of Crete, Heraklion, Greece.
| | - Igor Koncar
- Department of Vascular and Endovascular Surgery, Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Department of Vascular and Endovascular Surgery, Clinic Center of Serbia, Belgrade, Serbia
| | - Konstantinos Tzirakis
- Institute of Applied Mathematics, Foundation of Research and Technology Hellas, Heraklion, Greece
| | - Emmanouil Tavlas
- Vascular Surgery Unit, Department of Cardiothoracic and Vascular Surgery, Medical School, University of Crete, Heraklion, Greece
| | - Lazar Davidovic
- Department of Vascular and Endovascular Surgery, Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Department of Vascular and Endovascular Surgery, Clinic Center of Serbia, Belgrade, Serbia
| | - Christos V Ioannou
- Vascular Surgery Unit, Department of Cardiothoracic and Vascular Surgery, Medical School, University of Crete, Heraklion, Greece
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