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Mahutga RR, Badal RM, Barocas VH, Alford PW. A multiscale discrete fiber model of failure in heterogeneous tissues: Applications to remodeled cerebral aneurysms. J Biomech 2024:112343. [PMID: 39341733 DOI: 10.1016/j.jbiomech.2024.112343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 09/19/2024] [Accepted: 09/23/2024] [Indexed: 10/01/2024]
Abstract
Damage-accumulation failure models are broadly used to examine tissue property changes caused by mechanical loading. However, damage accumulation models are purely phenomenological. The underlying justification in using this type of model is often that damage occurs to the extracellular fibers and/or cells which changes the fundamental mechanical behavior of the system. In this work, we seek to align damage accumulation models with microstructural models to predict alterations in the mechanical behavior of biological materials that arise from structural heterogeneity associated with nonuniform remodeling of tissues. Further, we seek to extend this multiscale model toward assessing catastrophic failure events such as cerebral aneurysm rupture. First, we demonstrate that a model made up of linear elastin and actin and nonlinear collagen fibers can replicate bot the pre-failure and failure tissue-scale mechanics of uniaxially-stretched cerebral aneurysms. Next, we investigate how mechanical heterogeneities, like those observed in cerebral aneurysms, influence fiber and tissue failure. Notably, we find that failure occurs and the interface between regions of high and low material stiffness, suggesting that spatial mechanical heterogeneity influences aneurysm failure behavior. This model system is a step toward linking structural changes in growth and remodeling to failure properties.
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Affiliation(s)
- Ryan R Mahutga
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Ruturaj M Badal
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Victor H Barocas
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Patrick W Alford
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA.
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2
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Tobe Y, Robertson AM, Ramezanpour M, Cebral JR, Watkins SC, Charbel FT, Amin-Hanjani S, Yu AK, Cheng BC, Woo HH. Comapping Cellular Content and Extracellular Matrix with Hemodynamics in Intact Arterial Tissues Using Scanning Immunofluorescent Multiphoton Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2024; 30:342-358. [PMID: 38525887 PMCID: PMC11057816 DOI: 10.1093/mam/ozae025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 03/26/2024]
Abstract
Deviation of blood flow from an optimal range is known to be associated with the initiation and progression of vascular pathologies. Important open questions remain about how the abnormal flow drives specific wall changes in pathologies such as cerebral aneurysms where the flow is highly heterogeneous and complex. This knowledge gap precludes the clinical use of readily available flow data to predict outcomes and improve treatment of these diseases. As both flow and the pathological wall changes are spatially heterogeneous, a crucial requirement for progress in this area is a methodology for acquiring and comapping local vascular wall biology data with local hemodynamic data. Here, we developed an imaging pipeline to address this pressing need. A protocol that employs scanning multiphoton microscopy was developed to obtain three-dimensional (3D) datasets for smooth muscle actin, collagen, and elastin in intact vascular specimens. A cluster analysis was introduced to objectively categorize the smooth muscle cells (SMC) across the vascular specimen based on SMC actin density. Finally, direct quantitative comparison of local flow and wall biology in 3D intact specimens was achieved by comapping both heterogeneous SMC data and wall thickness to patient-specific hemodynamic results.
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Affiliation(s)
- Yasutaka Tobe
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Anne M Robertson
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Mehdi Ramezanpour
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Juan R Cebral
- Department of Bioengineering, George Mason University, Fairfax, VA 22030, USA
| | - Simon C Watkins
- Department of Cell Biology, University of Pittsburgh, PA 15261, USA
| | - Fady T Charbel
- Department of Neurosurgery, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Sepideh Amin-Hanjani
- Department of Neurological Surgery, University Hospital Cleveland Medical Center, Cleveland, OH 44106, USA
| | - Alexander K Yu
- Department of Neurological Surgery, Allegheny Health Network, Pittsburgh, PA 15212, USA
| | - Boyle C Cheng
- Neuroscience and Orthopedic Institutes, Allegheny Health Network, Pittsburgh, PA 15212, USA
| | - Henry H Woo
- Department of Neurosurgery, Donald and Barbara Zucker School of Medicine at Hofstra Northwell, Manhasset, NY 11549, USA
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Li S, Huang Z, Chen H, Chen F. Proximal Clipping and Distal High-Flow Bypass in the Treatment of Giant/Complex Intracranial Aneurysm: An Opportunity or a Risk from a Fluid-Structural Interaction Analysis. Cardiovasc Eng Technol 2024; 15:159-170. [PMID: 38093146 DOI: 10.1007/s13239-023-00704-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 11/21/2023] [Indexed: 05/25/2024]
Abstract
OBJECTIVES Conventional clipping and endovascular treatment are difficult to apply for some giant intracranial aneurysms (GIAs), and sometimes extracranial-to-intracranial (EC-IC) bypass becomes the optional choice. However, not all GIA patients can benefit from it. This study aims to recognize the underlying problems. METHODS We included eligible patients in our care. Then, we researched from three levels: a retrospective review of clinical data, fluid-structural analysis from two representative patient-specific models, and fluid-structural interaction analysis for idealized models to investigate the hemodynamic and biomechanical mechanisms. RESULTS In this article, we report nine patients with GIA who underwent EC-IC surgery. Of them, three experienced dangerous postoperative hemorrhage, and one patient died. Among these three patients, two lacked the A1 segment of the anterior cerebral artery (ACA). The numerical simulation showed that after surgery, for the patient with an unruptured aneurysm and existence of ACA, the wall deformation, wall stress, pressure, and area of the oscillatory shear index (OSI) > 0.2 were decreased by 43%, 39%, 33%, and 13%, while the patient without A1 segment having postoperative hemorrhage showed 36%, 45%, 13%, and 55% increased, respectively. Thus, we postulated a dangerous "stump phenomenon" in such conditions and further demonstrated it from idealized models with different sizes of ACA. Finally, we found a larger anastomosis angle and smaller diameter of the graft can alleviate this effect. CONCLUSIONS Neurosurgeon should cautiously evaluate the opportunity and risk for such patients who have aplasia of the A1 segment of ACA when making clinical decisions.
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Affiliation(s)
- Shifu Li
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Central South University, 87 Xiangya Street, Changsha, 410008, Hunan, China
- Research Center for Cerebrovascular Diseases, Central South University, 87 Xiangya Street, Changsha, 410008, Hunan, China
- Xiangya Hospital, Hypothalamic-Pituitary Research Center, Central South University, 87 Xiangya Road, Changsha, 410008, Hunan, China
- Research Center for Cerebrovascular Disease, Central South University, 87 Xiangya Road, 410008, changsha, China
| | - Zheng Huang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Central South University, 87 Xiangya Street, Changsha, 410008, Hunan, China
- Research Center for Cerebrovascular Diseases, Central South University, 87 Xiangya Street, Changsha, 410008, Hunan, China
- Xiangya Hospital, Hypothalamic-Pituitary Research Center, Central South University, 87 Xiangya Road, Changsha, 410008, Hunan, China
| | - Hua Chen
- Department of Neurosurgery, Changde Hospital, Xiangya School of Medicine, Central South University (The First People's Hospital of Changde City), Changde, China.
| | - Fenghua Chen
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.
- National Clinical Research Center for Geriatric Disorders, Central South University, 87 Xiangya Street, Changsha, 410008, Hunan, China.
- Research Center for Cerebrovascular Diseases, Central South University, 87 Xiangya Street, Changsha, 410008, Hunan, China.
- Xiangya Hospital, Hypothalamic-Pituitary Research Center, Central South University, 87 Xiangya Road, Changsha, 410008, Hunan, China.
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Liao J, Misaki K, Uno T, Futami K, Nakada M, Sakamoto J. Determination of Significant Three-Dimensional Hemodynamic Features for Postembolization Recanalization in Cerebral Aneurysms Through Explainable Artificial Intelligence. World Neurosurg 2024; 184:e166-e177. [PMID: 38246531 DOI: 10.1016/j.wneu.2024.01.076] [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: 10/10/2023] [Revised: 01/12/2024] [Accepted: 01/13/2024] [Indexed: 01/23/2024]
Abstract
BACKGROUND Recanalization poses challenges after coil embolization in cerebral aneurysms. Establishing predictive models for postembolization recanalization is important for clinical decision making. However, conventional statistical and machine learning (ML) models may overlook critical parameters during the initial selection process. METHODS In this study, we automated the identification of significant hemodynamic parameters using a PointNet-based deep neural network (DNN), leveraging their three-dimensional spatial features. Further feature analysis was conducted using saliency mapping, an explainable artificial intelligence (XAI) technique. The study encompassed the analysis of velocity, pressure, and wall shear stress in both precoiling and postcoiling models derived from computational fluid dynamics simulations for 58 aneurysms. RESULTS Velocity was identified as the most pivotal parameter, supported by the lowest P value from statistical analysis and the highest area under the receiver operating characteristic curves/precision-recall curves values from the DNN model. Moreover, visual XAI analysis showed that robust injection flow zones, with notable impingement points in precoiling models, as well as pronounced interplay between flow dynamics and the coiling plane, were important three-dimensional features in identifying the recanalized aneurysms. CONCLUSIONS The combination of DNN and XAI was found to be an accurate and explainable approach not only at predicting postembolization recanalization but also at discovering unknown features in the future.
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Affiliation(s)
- Jing Liao
- Division of Transdisciplinary Sciences, Graduate School of Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Kouichi Misaki
- Department of Neurosurgery, Kanazawa University, Kanazawa, Ishikawa, Japan.
| | - Tekehiro Uno
- Department of Neurosurgery, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Kazuya Futami
- Department of Neurosurgery, Hokuriku Central Hospital, Oyabe, Toyama, Japan
| | - Mitsutoshi Nakada
- Department of Neurosurgery, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Jiro Sakamoto
- Division of Mechanical Science and Engineering, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Ishikawa, Japan
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Hadad S, Mut F, Slawski M, Robertson AM, Cebral JR. Evaluation of predictive models of aneurysm focal growth and bleb development using machine learning techniques. J Neurointerv Surg 2024; 16:392-397. [PMID: 37230750 PMCID: PMC10674044 DOI: 10.1136/jnis-2023-020241] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 05/15/2023] [Indexed: 05/27/2023]
Abstract
BACKGROUND The presence of blebs increases the rupture risk of intracranial aneurysms (IAs). OBJECTIVE To evaluate whether cross-sectional bleb formation models can identify aneurysms with focalized enlargement in longitudinal series. METHODS Hemodynamic, geometric, and anatomical variables derived from computational fluid dynamics models of 2265 IAs from a cross-sectional dataset were used to train machine learning (ML) models for bleb development. ML algorithms, including logistic regression, random forest, bagging method, support vector machine, and K-nearest neighbors, were validated using an independent cross-sectional dataset of 266 IAs. The models' ability to identify aneurysms with focalized enlargement was evaluated using a separate longitudinal dataset of 174 IAs. Model performance was quantified by the area under the receiving operating characteristic curve (AUC), the sensitivity and specificity, positive predictive value, negative predictive value, F1 score, balanced accuracy, and misclassification error. RESULTS The final model, with three hemodynamic and four geometrical variables, along with aneurysm location and morphology, identified strong inflow jets, non-uniform wall shear stress with high peaks, larger sizes, and elongated shapes as indicators of a higher risk of focal growth over time. The logistic regression model demonstrated the best performance on the longitudinal series, achieving an AUC of 0.9, sensitivity of 85%, specificity of 75%, balanced accuracy of 80%, and a misclassification error of 21%. CONCLUSIONS Models trained with cross-sectional data can identify aneurysms prone to future focalized growth with good accuracy. These models could potentially be used as early indicators of future risk in clinical practice.
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Affiliation(s)
- Sara Hadad
- Department of Bioengineering, George Mason University, Fairfax, Virginia, USA
| | - Fernando Mut
- Department of Bioengineering, George Mason University, Fairfax, Virginia, USA
| | - Martin Slawski
- Statistics Department, George Mason University, Fairfax, Virginia, USA
| | - Anne M Robertson
- Departmnet of Mechanical enginering and Material Science, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Juan R Cebral
- Department of Bioengineering, George Mason University, Fairfax, Virginia, USA
- Department of Mechanical Engineering, George Mason University, Fairfax, Virginia, USA
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Shen J, Huang K, Zhu Y, Weng Y, Xiao F, Mungur R, Wu F, Pan J, Zhan R. Mean arterial pressure-aneurysm neck ratio predicts the rupture risk of intracranial aneurysm by reflecting pressure at the dome. Front Aging Neurosci 2023; 15:1082800. [PMID: 36819719 PMCID: PMC9928879 DOI: 10.3389/fnagi.2023.1082800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/16/2023] [Indexed: 02/04/2023] Open
Abstract
Background and purpose The unruptured intracranial aneurysm (UIA) has high disability and mortality rate after rupture, it is particularly important to assess the risk of UIA and to carry out individualized treatment. The objective of this research is to introduce a novel parameter to predict the rupture risk of UIA. Methods A total of 649 patients with 964 intracranial aneurysms in our center were enrolled. A novel parameter named mean arterial pressure-aneurysmal neck ratio (MAPN) was defined. Ten baseline clinical features and twelve aneurysm morphological characteristics were extracted to generate the MAPN model. The discriminatory performance of the MAPN model was compared with the PHASES score and the UCAS score. Results In hemodynamic analysis, MAPN was positively correlated with wall shear stress and aneurysm top pressure, with Pearson correlation coefficients of 0.887 and 0.791, respectively. The MAPN was larger in the ruptured group (36.62 ± 18.96 vs. 28.38 ± 14.58, P < 0.001). The area under the curve (AUC) of the MAPN was superior than the AUC of aspect ratio (AR) and the bottleneck factor (BN), they were 0.64 (P < 0.001; 95% CI, 0.588-0.692), 0.611 (P < 0.001; 95% CI, 0.559-0.663) and 0.607 (P < 0.001; 95% CI, 0.554-0.660), respectively. The MAPN model constructed by aneurysm size, aneurysm location, presence of secondary sacs and MAPN, demonstrated good discriminatory ability. The MAPN model exhibited superior performance compared with the UCAS score and the PHASES score (the AUC values were 0.799 [P < 0.001; 95% CI, 0.756-0.840], 0.763 [P < 0.001; 95% CI,0.719-0.807] and 0.741 [P < 0.001; 95% CI, 0.695-0.787], respectively; the sensitivities were 0.849, 0.758 and 0.753, respectively). Conclusions Research demonstrates the potential of MAPN to augment the clinical decision-making process for assessing the rupture risk of UIAs.
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Salimi Ashkezari SF, Mut F, Robertson AM, Cebral JR. Differences Between Ruptured Aneurysms With and Without Blebs: Mechanistic Implications. Cardiovasc Eng Technol 2023; 14:92-103. [PMID: 35819581 PMCID: PMC10029732 DOI: 10.1007/s13239-022-00640-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 07/01/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE Blebs are known risk factors for intracranial aneurysm (IA) rupture. We analyzed differences between IAs that ruptured with blebs and those that ruptured without developing blebs to identify distinguishing characteristics among them and suggest possible mechanistic implications. METHODS Using image-based models, 25 hemodynamic and geometric parameters were compared between ruptured IAs with and without blebs (n = 673), stratified by location. Hemodynamic and geometric differences between bifurcation and sidewall aneurysms and for aneurysms at five locations were also analyzed. RESULTS Ruptured aneurysms harboring blebs were exposed to higher flow conditions than aneurysms that ruptured without developing blebs, and this was consistent across locations. Bifurcation aneurysms were exposed to higher flow conditions than sidewall aneurysms. They had larger maximum wall shear stress (WSS), more concentrated WSS distribution, and larger numbers of critical points than sidewall aneurysms. Additionally, bifurcation aneurysms were larger, more elongated, and had more distorted shapes than sidewall aneurysms. Aneurysm morphology was associated with aneurysm location (p < 0.01). Flow conditions were different between aneurysm locations. CONCLUSION Aneurysms at different locations are likely to develop into varying morphologies and thus be exposed to diverse flow conditions that may predispose them to follow distinct pathways towards rupture with or without bleb development. This could explain the diverse rupture rates and bleb presence in aneurysms at different locations.
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Affiliation(s)
- Seyedeh Fatemeh Salimi Ashkezari
- Department of Bioengineering, Volgenau School of Engineering, George Mason University, 4400 University Drive, Fairfax, VA, 22030, USA.
| | - Fernando Mut
- Department of Bioengineering, Volgenau School of Engineering, George Mason University, 4400 University Drive, Fairfax, VA, 22030, USA
| | - Anne M Robertson
- Department of Mechanical Engineering and Material Science, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Juan R Cebral
- Department of Bioengineering, Volgenau School of Engineering, George Mason University, 4400 University Drive, Fairfax, VA, 22030, USA
- Department of Mechanical Engineering, George Mason University, Fairfax, VA, USA
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Morel S, Bijlenga P, Kwak BR. Intracranial aneurysm wall (in)stability-current state of knowledge and clinical perspectives. Neurosurg Rev 2022; 45:1233-1253. [PMID: 34743248 PMCID: PMC8976821 DOI: 10.1007/s10143-021-01672-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 09/15/2021] [Accepted: 10/05/2021] [Indexed: 12/19/2022]
Abstract
Intracranial aneurysm (IA), a local outpouching of cerebral arteries, is present in 3 to 5% of the population. Once formed, an IA can remain stable, grow, or rupture. Determining the evolution of IAs is almost impossible. Rupture of an IA leads to subarachnoid hemorrhage and affects mostly young people with heavy consequences in terms of death, disabilities, and socioeconomic burden. Even if the large majority of IAs will never rupture, it is critical to determine which IA might be at risk of rupture. IA (in)stability is dependent on the composition of its wall and on its ability to repair. The biology of the IA wall is complex and not completely understood. Nowadays, the risk of rupture of an IA is estimated in clinics by using scores based on the characteristics of the IA itself and on the anamnesis of the patient. Classification and prediction using these scores are not satisfying and decisions whether a patient should be observed or treated need to be better informed by more reliable biomarkers. In the present review, the effects of known risk factors for rupture, as well as the effects of biomechanical forces on the IA wall composition, will be summarized. Moreover, recent advances in high-resolution vessel wall magnetic resonance imaging, which are promising tools to discriminate between stable and unstable IAs, will be described. Common data elements recently defined to improve IA disease knowledge and disease management will be presented. Finally, recent findings in genetics will be introduced and future directions in the field of IA will be exposed.
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Affiliation(s)
- Sandrine Morel
- Department of Pathology and Immunology, Faculty of Medicine, Centre Medical Universitaire, University of Geneva, Rue Michel-Servet 1, 1211, Geneva, Switzerland.
- Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
| | - Philippe Bijlenga
- Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Brenda R Kwak
- Department of Pathology and Immunology, Faculty of Medicine, Centre Medical Universitaire, University of Geneva, Rue Michel-Servet 1, 1211, Geneva, Switzerland
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Sunderland K, Jiang J, Zhao F. Disturbed flow's impact on cellular changes indicative of vascular aneurysm initiation, expansion, and rupture: A pathological and methodological review. J Cell Physiol 2022; 237:278-300. [PMID: 34486114 PMCID: PMC8810685 DOI: 10.1002/jcp.30569] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/06/2021] [Accepted: 08/16/2021] [Indexed: 01/03/2023]
Abstract
Aneurysms are malformations within the arterial vasculature brought on by the structural breakdown of the microarchitecture of the vessel wall, with aneurysms posing serious health risks in the event of their rupture. Blood flow within vessels is generally laminar with high, unidirectional wall shear stressors that modulate vascular endothelial cell functionality and regulate vascular smooth muscle cells. However, altered vascular geometry induced by bifurcations, significant curvature, stenosis, or clinical interventions can alter the flow, generating low stressor disturbed flow patterns. Disturbed flow is associated with altered cellular morphology, upregulated expression of proteins modulating inflammation, decreased regulation of vascular permeability, degraded extracellular matrix, and heightened cellular apoptosis. The understanding of the effects disturbed flow has on the cellular cascades which initiate aneurysms and promote their subsequent growth can further elucidate the nature of this complex pathology. This review summarizes the current knowledge about the disturbed flow and its relation to aneurysm pathology, the methods used to investigate these relations, as well as how such knowledge has impacted clinical treatment methodologies. This information can contribute to the understanding of the development, growth, and rupture of aneurysms and help develop novel research and aneurysmal treatment techniques.
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Affiliation(s)
- Kevin Sunderland
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI 49931
| | - Jingfeng Jiang
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI 49931,Corresponding Authors: Feng Zhao, 101 Bizzell Street, College Station, TX 77843-312, Tel : 979-458-1239, , Jingfeng Jiang, 1400 Townsend Dr., Houghton, MI 49931, Tel: 906-487-1943
| | - Feng Zhao
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843,Corresponding Authors: Feng Zhao, 101 Bizzell Street, College Station, TX 77843-312, Tel : 979-458-1239, , Jingfeng Jiang, 1400 Townsend Dr., Houghton, MI 49931, Tel: 906-487-1943
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Kulkarni R, Andraska E, McEnaney R. Structural Remodeling of the Extracellular Matrix in Arteriogenesis: A Review. Front Cardiovasc Med 2021; 8:761007. [PMID: 34805316 PMCID: PMC8602576 DOI: 10.3389/fcvm.2021.761007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 10/11/2021] [Indexed: 01/10/2023] Open
Abstract
Lower extremity arterial occlusive disease (AOD) results in significant morbidity and mortality for the population, with up to 10% of patients ultimately requiring amputation. An alternative method for non-surgical revascularization which is yet to be fully understood is the optimization of the body's own natural collateral arterial network in a process known as arteriogenesis. Under conditions of conductance vessel stenosis or occlusion resulting in increased flow, shear forces, and pressure gradients within collaterals, positive remodeling occurs to increase the diameter and capacity of these vessels. The creation of a distal arteriovenous fistula (AVF) will drive increased arteriogenesis as compared to collateral formation with the occlusion of a conductance vessel alone by further increasing flow through these arterioles, demonstrating the capacity for arteriogenesis to form larger, more efficient collaterals beyond what is spontaneously achieved after arterial occlusion. Arteries rely on an extracellular matrix (ECM) composed of elastic fibers and collagens that provide stability under hemodynamic stress, and ECM remodeling is necessary to allow for increased diameter and flow conductance in mature arterial structures. When positive remodeling occurs, digestion of lamella and the internal elastic lamina (IEL) by matrix metalloproteinases (MMPs) and other elastases results in the rearrangement and thinning of elastic structures and may be replaced with disordered elastin synthesis without recovery of elastic function. This results in transmission of wall strain to collagen and potential for aneurysmal degeneration along collateral networks, as is seen in the pancreaticoduodenal artery (PDA) after celiac occlusion and inferior mesenteric artery (IMA) with concurrent celiac and superior mesenteric artery (SMA) occlusions. Further understanding into the development of collaterals is required to both better understand aneurysmal degeneration and optimize collateral formation in AOD.
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Affiliation(s)
- Rohan Kulkarni
- Division of Vascular Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, United States
| | - Elizabeth Andraska
- Division of Vascular Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, United States
| | - Ryan McEnaney
- Division of Vascular Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, United States
- Veterans Affairs Hospitals Pittsburgh Healthcare System, Pittsburgh, PA, United States
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The association between hemodynamics and wall characteristics in human intracranial aneurysms: a review. Neurosurg Rev 2021; 45:49-61. [PMID: 33913050 DOI: 10.1007/s10143-021-01554-w] [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: 02/17/2021] [Revised: 04/02/2021] [Accepted: 04/20/2021] [Indexed: 12/28/2022]
Abstract
Hemodynamics plays a key role in the natural history of intracranial aneurysms (IAs). However, studies exploring the association between aneurysmal hemodynamics and the biological and mechanical characteristics of the IA wall in humans are sparse. In this review, we survey the current body of literature, summarize the studies' methodologies and findings, and assess the degree of consensus among them. We used PubMed to perform a systematic review of studies that explored the association between hemodynamics and human IA wall features using different sources. We identified 28 publications characterizing aneurysmal flow and the IA wall: 4 using resected tissues, 17 using intraoperative images, and 7 using vessel wall magnetic resonance imaging (MRI). Based on correlation to IA tissue, higher flow conditions, such as high wall shear stress (WSS) with complex pattern and elevated pressure, were associated with degenerated walls and collagens with unphysiological orientation and faster synthesis. MRI studies strongly supported that low flow, characterized by low WSS and high blood residence time, was associated with thicker walls and post-contrast enhancement. While significant discrepancies were found among those utilized intraoperative images, they generally supported that thicker walls coexist at regions with prolonged residence time and that thinner regions are mainly exposed to higher pressure with complex WSS patterns. The current body of literature supports a theory of two general hemodynamic-biologic mechanisms for IA development. One, where low flow conditions are associated with thickening and atherosclerotic-like remodeling, and the other where high and impinging flow conditions are related to wall degeneration, thinning, and collagen remodeling.
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Salimi Ashkezari SF, Mut F, Chung BJ, Robertson AM, Frösen J, Cebral JR. Analysis of hemodynamic changes from aneurysm inception to large sizes. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3415. [PMID: 33205887 PMCID: PMC8991439 DOI: 10.1002/cnm.3415] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 10/30/2020] [Accepted: 11/15/2020] [Indexed: 06/11/2023]
Abstract
While previous studies have identified many risk factors for the progression and rupture of cerebral aneurysms, the changes in aneurysm flow characteristics during its evolution are not fully understood. This work analyzes the changes in the aneurysm hemodynamic environment from its initial development to later stages when the aneurysm has substantially enlarged. A total of 88 aneurysms at four locations were studied with image based computational fluid dynamics (CFD). Two synthetic sequences representing the aneurysm geometry at three earlier stages were generated by shrinking the aneurysm sac while keeping the neck fixed or shrinking the neck simultaneously. The flow conditions were then quantitatively compared between these two modes of evolution. As aneurysms enlarged, the inflow rate increased in growing neck sequences, but decreased in fixed neck sequences. The inflow jet became more concentrated in both sequences. The mean aneurysm flow velocity and wall shear stress decreased in both sequences, but they decreased faster in enlarging aneurysms if the neck was fixed. Additionally, the intra-aneurysmal flows became more complex and more unstable, wall shear stress distribution became more oscillatory, and the area under low wall shear stress increased for both sequences. The evolution of flow characteristics of aneurysms with fixed and growing necks are different. The observed trends suggest that fixed neck aneurysms may evolve towards a flow environment characteristic of stable aneurysms faster than aneurysms with growing necks, which could also evolve towards a more disfavorable environment.
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Affiliation(s)
| | - Fernando Mut
- Bioengineering Department, George Mason University, Fairfax, Virginia, USA
| | - Bong Jae Chung
- Department of Mathematical Sciences, Montclair State University, Montclair, New Jersey, USA
| | - Anne M Robertson
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Juhana Frösen
- Hemorrhagic Brain Pathology Research Group, Department of Neurosurgery, Kuopio University Hospital, Kuopio, Finland
| | - Juan R Cebral
- Bioengineering Department, George Mason University, Fairfax, Virginia, USA
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13
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A review of hemodynamic parameters in cerebral aneurysm. INTERDISCIPLINARY NEUROSURGERY-ADVANCED TECHNIQUES AND CASE MANAGEMENT 2020. [DOI: 10.1016/j.inat.2020.100716] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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14
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Teixeira FS, Neufeld E, Kuster N, Watton PN. Modeling intracranial aneurysm stability and growth: an integrative mechanobiological framework for clinical cases. Biomech Model Mechanobiol 2020; 19:2413-2431. [PMID: 32533497 PMCID: PMC7603456 DOI: 10.1007/s10237-020-01351-2] [Citation(s) in RCA: 3] [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: 08/13/2019] [Accepted: 05/12/2020] [Indexed: 11/03/2022]
Abstract
We present a novel patient-specific fluid-solid-growth framework to model the mechanobiological state of clinically detected intracranial aneurysms (IAs) and their evolution. The artery and IA sac are modeled as thick-walled, non-linear elastic fiber-reinforced composites. We represent the undulation distribution of collagen fibers: the adventitia of the healthy artery is modeled as a protective sheath whereas the aneurysm sac is modeled to bear load within physiological range of pressures. Initially, we assume the detected IA is stable and then consider two flow-related mechanisms to drive enlargement: (1) low wall shear stress; (2) dysfunctional endothelium which is associated with regions of high oscillatory flow. Localized collagen degradation and remodelling gives rise to formation of secondary blebs on the aneurysm dome. Restabilization of blebs is achieved by remodelling of the homeostatic collagen fiber stretch distribution. This integrative mechanobiological modelling workflow provides a step towards a personalized risk-assessment and treatment of clinically detected IAs.
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Affiliation(s)
| | - Esra Neufeld
- IT’IS Foundation & ETH Zürich, Zürich, Switzerland
| | - Niels Kuster
- IT’IS Foundation & ETH Zürich, Zürich, Switzerland
| | - Paul N. Watton
- Department of Computer Science, Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, UK
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, USA
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15
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Frösen J, Cebral J, Robertson AM, Aoki T. Flow-induced, inflammation-mediated arterial wall remodeling in the formation and progression of intracranial aneurysms. Neurosurg Focus 2020; 47:E21. [PMID: 31261126 DOI: 10.3171/2019.5.focus19234] [Citation(s) in RCA: 155] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Accepted: 05/01/2019] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Unruptured intracranial aneurysms (UIAs) are relatively common lesions that may cause devastating intracranial hemorrhage, thus producing considerable suffering and anxiety in those affected by the disease or an increased likelihood of developing it. Advances in the knowledge of the pathobiology behind intracranial aneurysm (IA) formation, progression, and rupture have led to preclinical testing of drug therapies that would prevent IA formation or progression. In parallel, novel biologically based diagnostic tools to estimate rupture risk are approaching clinical use. Arterial wall remodeling, triggered by flow and intramural stresses and mediated by inflammation, is relevant to both. METHODS This review discusses the basis of flow-driven vessel remodeling and translates that knowledge to the observations made on the mechanisms of IA initiation and progression on studies using animal models of induced IA formation, study of human IA tissue samples, and study of patient-derived computational fluid dynamics models. RESULTS Blood flow conditions leading to high wall shear stress (WSS) activate proinflammatory signaling in endothelial cells that recruits macrophages to the site exposed to high WSS, especially through macrophage chemoattractant protein 1 (MCP1). This macrophage infiltration leads to protease expression, which disrupts the internal elastic lamina and collagen matrix, leading to focal outward bulging of the wall and IA initiation. For the IA to grow, collagen remodeling and smooth muscle cell (SMC) proliferation are essential, because the fact that collagen does not distend much prevents the passive dilation of a focal weakness to a sizable IA. Chronic macrophage infiltration of the IA wall promotes this SMC-mediated growth and is a potential target for drug therapy. Once the IA wall grows, it is subjected to changes in wall tension and flow conditions as a result of the change in geometry and has to remodel accordingly to avoid rupture. Flow affects this remodeling process. CONCLUSIONS Flow triggers an inflammatory reaction that predisposes the arterial wall to IA initiation and growth and affects the associated remodeling of the UIA wall. This chronic inflammation is a putative target for drug therapy that would stabilize UIAs or prevent UIA formation. Moreover, once this coupling between IA wall remodeling and flow is understood, data from patient-specific flow models can be gathered as part of the diagnostic workup and utilized to improve risk assessment for UIA initiation, progression, and eventual rupture.
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Affiliation(s)
- Juhana Frösen
- 1Department of Neurosurgery, and.,2Hemorrhagic Brain Pathology Research Group, Kuopio University Hospital, Kuopio, Finland
| | - Juan Cebral
- 3Bioengineering Department, Volgenau School of Engineering, George Mason University, Fairfax, Virginia
| | - Anne M Robertson
- 4Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Tomohiro Aoki
- 5Department of Molecular Pharmacology, Research Institute, and.,6Core Research for Evolutional Science and Technology (CREST) from Japan Agency for Medical Research and Development (AMED), National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
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16
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Gholampour S, Mehrjoo S. Effect of bifurcation in the hemodynamic changes and rupture risk of small intracranial aneurysm. Neurosurg Rev 2020; 44:1703-1712. [PMID: 32803404 DOI: 10.1007/s10143-020-01367-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/01/2020] [Accepted: 08/10/2020] [Indexed: 11/29/2022]
Abstract
The role of bifurcations is prominent in the intracranial aneurysm (IA) evaluation, and there are many contradictions and complexities in the rupture risk of small IA. Therefore, in the present study, the effect of bifurcation on the manner of hemodynamic changes and the rupture risk of the small middle cerebral artery (MCA) aneurysm is investigated. 3D anatomical models of the MCAs of 21 healthy subjects, 19 patients/IA/bifurcation, and 19 patients/IA were generated, and the models were analyzed by the computational fluid dynamic (CFD) analysis. The presence of bifurcation in the pathway of the blood flow in the parent artery of healthy subjects has reduced the maximum velocity, flow rate, and wall shear stress (WSS) by 25.8%, 38.6%, and 11.1%, respectively. The bifurcation decreased the maximum velocity and flow rate in the neck and sac of the aneurysm by 1.65~2.1 times, respectively. It increased the maximum WSS, and phase lag between the WSS graph of healthy subjects and patients by 12.8%~13.9% and 10.2%~40.4%, respectively. The effect of bifurcation on the Womersley number change in the aneurysm was insignificant, and the blood flow was in the laminar flow condition in all samples. The results also showed bifurcation increased the phase lag between the flow rate and pressure gradient graphs up to approximately 1.5 times. The rupture prediction index for patients/IA/bifurcation and patients/IA was 62.1%(CV = 4.1) and 51.8%(CV = 4.4), respectively. Thus, in equal conditions, the presence of bifurcation increased the probability of the rupture of the aneurysm by 19.9%.
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Affiliation(s)
- Seifollah Gholampour
- Department of Biomedical Engineering, North Tehran Branch, Islamic Azad University, Tehran, Iran.
| | - Saeed Mehrjoo
- Department of Biomedical Engineering, North Tehran Branch, Islamic Azad University, Tehran, Iran
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17
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Rayz VL, Cohen-Gadol AA. Hemodynamics of Cerebral Aneurysms: Connecting Medical Imaging and Biomechanical Analysis. Annu Rev Biomed Eng 2020; 22:231-256. [PMID: 32212833 DOI: 10.1146/annurev-bioeng-092419-061429] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the last two decades, numerous studies have conducted patient-specific computations of blood flow dynamics in cerebral aneurysms and reported correlations between various hemodynamic metrics and aneurysmal disease progression or treatment outcomes. Nevertheless, intra-aneurysmal flow analysis has not been adopted in current clinical practice, and hemodynamic factors usually are not considered in clinical decision making. This review presents the state of the art in cerebral aneurysm imaging and image-based modeling, discussing the advantages and limitations of each approach and focusing on the translational value of hemodynamic analysis. Combining imaging and modeling data obtained from different flow modalities can improve the accuracy and fidelity of resulting velocity fields and flow-derived factors that are thought to affect aneurysmal disease progression. It is expected that predictive models utilizing hemodynamic factors in combination with patient medical history and morphological data will outperform current risk scores and treatment guidelines. Possible future directions include novel approaches enabling data assimilation and multimodality analysis of cerebral aneurysm hemodynamics.
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Affiliation(s)
- Vitaliy L Rayz
- Weldon School of Biomedical Engineering and School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, USA;
| | - Aaron A Cohen-Gadol
- Department of Neurosurgery, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.,Goodman Campbell Brain and Spine, Carmel, Indiana 46032, USA
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18
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Hackenberg KAM, Rajabzadeh-Oghaz H, Dreier R, Buchholz BA, Navid A, Rocke DM, Abdulazim A, Hänggi D, Siddiqui A, Macdonald RL, Meng H, Etminan N. Collagen Turnover in Relation to Risk Factors and Hemodynamics in Human Intracranial Aneurysms. Stroke 2020; 51:1624-1628. [PMID: 32192404 DOI: 10.1161/strokeaha.120.029335] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose- Determinants for molecular and structural instability, that is, impending growth or rupture, of intracranial aneurysms (IAs) remain uncertain. To elucidate this, we endeavored to estimate the actual turnover rates of the main molecular constituent in human IA (collagen) on the basis of radiocarbon (14C) birth dating in relation to IA hemodynamics. Methods- Collagen turnover rates in excised human IA samples were calculated using mathematical modeling of 14C birth dating data of collagen in relation to risk factors and histological markers for collagen maturity/turnover in selected IA. Hemodynamics were simulated using image-based computational fluid dynamics. Correlation, logistic regression, and receiver operating characteristic analyses were performed. Results- Collagen turnover rates were estimated in 46 IA (43 patients); computational fluid dynamics could be performed in 20 IA (20 patients). The mean collagen turnover rate (γ) constituted 126% (±1% error) per year. For patients with arterial hypertension, γ was greater than 2600% annually, whereas γ was distinctly lower with 32% (±1% error) per year for patients without risk factors, such as smoking and hypertension. There was a distinct association between histological presence of rather immature collagen in human IA and the presence of modifiable risk factors. Spatial-temporal averaged wall shear stress predicted rapid collagen turnover (odds ratio, 1.6 [95% CI, 1.0-2.7]). Receiver operating characteristic analysis demonstrated a good test accuracy (area under the curve, 0.798 [95% CI, 0.598-0.998]) for average wall shear stress with a threshold ≥4.9 Pa for rapid collagen turnover. Conclusions- Our data indicate that turnover rates and stability of collagen in human IA are strongly associated with the presence of modifiable risk factors and aneurysmal hemodynamics. These findings underline the importance of strict risk factor modification in patients with unruptured IA. Future should include more detailed risk factor data to establish a more causal understanding of hemodynamics and the rupture risk of individual IA.
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Affiliation(s)
- Katharina A M Hackenberg
- From the Department of Neurosurgery, University Hospital Mannheim, Medical Faculty Mannheim, University of Heidelberg, Germany (K.A.M.H., A.A., D.H., N.E.)
| | - Hamidreza Rajabzadeh-Oghaz
- Department of Mechanical and Aerospace Engineering, Canon Stroke and Vascular Research Center (H.R.-O.), University at Buffalo, New York
| | - Rita Dreier
- Institute for Physiological Chemistry and Pathobiochemistry, Westfalian Wilhelms-University, Münster, Germany (R.D.)
| | - Bruce A Buchholz
- Center for Accelerator Mass Spectrometry (B.A.B.), Lawrence Livermore National Laboratory, Livermore, CA
| | - Ali Navid
- Biosciences and Biotechnology Division (A.N.), Lawrence Livermore National Laboratory, Livermore, CA
| | - David M Rocke
- Biosciences and Biotechnology Division (A.N.), Lawrence Livermore National Laboratory, Livermore, CA
| | - Amr Abdulazim
- From the Department of Neurosurgery, University Hospital Mannheim, Medical Faculty Mannheim, University of Heidelberg, Germany (K.A.M.H., A.A., D.H., N.E.)
| | - Daniel Hänggi
- From the Department of Neurosurgery, University Hospital Mannheim, Medical Faculty Mannheim, University of Heidelberg, Germany (K.A.M.H., A.A., D.H., N.E.)
| | - Adnan Siddiqui
- Department of Neurosurgery, Canon Stroke and Vascular Research Center, Jacobs School of Medicine and Biomedical Sciences (A.S.), University at Buffalo, New York.,Department of Radiology, Jacobs School of Medicine and Biomedical Sciences (A.S.), University at Buffalo, New York.,Department of Neurosurgery, Gates Vascular Institute, Kaleida Health, Jacobs Institute (A.S.), University at Buffalo, New York
| | - R Loch Macdonald
- Department of Neurological Surgery, UCSF Fresno, CA (R.L.M.).,Department of Surgery, University of Toronto, Ontario, Canada (R.L.M.)
| | - Hui Meng
- Department of Mechanical and Aerospace Engineering, Canon Stroke and Vascular Research Center, Jacobs School of Medicine and Biomedical Sciences (H.M.), University at Buffalo, New York.,Department of Biomedical Engineering, Jacobs School of Medicine and Biomedical Sciences (H.M.), University at Buffalo, New York.,Department of Neurosurgery, Jacobs School of Medicine and Biomedical Sciences (H.M.), University at Buffalo, New York
| | - Nima Etminan
- From the Department of Neurosurgery, University Hospital Mannheim, Medical Faculty Mannheim, University of Heidelberg, Germany (K.A.M.H., A.A., D.H., N.E.)
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19
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Gade PS, Tulamo R, Lee KW, Mut F, Ollikainen E, Chuang CY, Jae Chung B, Niemelä M, Rezai Jahromi B, Aziz K, Yu A, Charbel FT, Amin-Hanjani S, Frösen J, Cebral JR, Robertson AM. Calcification in Human Intracranial Aneurysms Is Highly Prevalent and Displays Both Atherosclerotic and Nonatherosclerotic Types. Arterioscler Thromb Vasc Biol 2019; 39:2157-2167. [PMID: 31462093 PMCID: PMC6911659 DOI: 10.1161/atvbaha.119.312922] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Although the clinical and biological importance of calcification is well recognized for the extracerebral vasculature, its role in cerebral vascular disease, particularly, intracranial aneurysms (IAs), remains poorly understood. Extracerebrally, 2 distinct mechanisms drive calcification, a nonatherosclerotic, rapid mineralization in the media and a slower, inflammation driven, atherosclerotic mechanism in the intima. This study aims to determine the prevalence, distribution, and type (atherosclerotic, nonatherosclerotic) of calcification in IAs and assess differences in occurrence between ruptured and unruptured IAs. Approach and Results: Sixty-five 65 IA specimens (48 unruptured, 17 ruptured) were resected perioperatively. Calcification and lipid pools were analyzed nondestructively in intact samples using high resolution (0.35 μm) microcomputed tomography. Calcification is highly prevalent (78%) appearing as micro (<500 µm), meso (500 µm-1 mm), and macro (>1 mm) calcifications. Calcification manifests in IAs as both nonatherosclerotic (calcification distinct from lipid pools) and atherosclerotic (calcification in the presence of lipid pools) with 3 wall types: Type I-only calcification, no lipid pools (20/51, 39%), Type II-calcification and lipid pools, not colocalized (19/51, 37%), Type III-calcification colocalized with lipid pools (12/51, 24%). Ruptured IAs either had no calcifications or had nonatherosclerotic micro- or meso-calcifications (Type I or II), without macro-calcifications. CONCLUSIONS Calcification in IAs is substantially more prevalent than previously reported and presents as both nonatherosclerotic and atherosclerotic types. Notably, ruptured aneurysms had only nonatherosclerotic calcification, had significantly lower calcification fraction, and did not contain macrocalcifications. Improved understanding of the role of calcification in IA pathology should lead to new therapeutic targets.
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Affiliation(s)
- Piyusha S Gade
- From the Department of Bioengineering (P.S.G., K.L., A.M.R.), University of Pittsburgh, PA
| | - Riikka Tulamo
- Department of Vascular Surgery (R.T.), Helsinki University Hospital, University of Helsinki, Finland
| | - Kee-Won Lee
- From the Department of Bioengineering (P.S.G., K.L., A.M.R.), University of Pittsburgh, PA
| | - Fernando Mut
- Department of Bioengineering, George Mason University, Fairfax, VA (F.M., J.R.C.)
| | - Eliisa Ollikainen
- Department of Mechanical Engineering and Materials Science (E.O., C.-Y.C., A.M.R.), University of Pittsburgh, PA.,Department of Neurosurgery (E.O., M.N., B.R.J.), Helsinki University Hospital, University of Helsinki, Finland
| | - Chih-Yuan Chuang
- Department of Mechanical Engineering and Materials Science (E.O., C.-Y.C., A.M.R.), University of Pittsburgh, PA
| | - Bong Jae Chung
- Department of Mathematical Sciences, Montclair State University, NJ (B.J.C.)
| | - Mika Niemelä
- Department of Neurosurgery (E.O., M.N., B.R.J.), Helsinki University Hospital, University of Helsinki, Finland
| | - Behnam Rezai Jahromi
- Department of Neurosurgery (E.O., M.N., B.R.J.), Helsinki University Hospital, University of Helsinki, Finland
| | - Khaled Aziz
- Department of Neurosurgery, Allegheny General Hospital, Pittsburgh, PA (K.A., A.Y.)
| | - Alexander Yu
- Department of Neurosurgery, Allegheny General Hospital, Pittsburgh, PA (K.A., A.Y.)
| | - Fady T Charbel
- Department of Neurosurgery, University of Illinois at Chicago (F.T.C., S.A.-H.)
| | | | - Juhana Frösen
- Department of Neurosurgery, Kuopio University Hospital, Finland (J.F.)
| | - Juan R Cebral
- Department of Bioengineering, George Mason University, Fairfax, VA (F.M., J.R.C.)
| | - Anne M Robertson
- From the Department of Bioengineering (P.S.G., K.L., A.M.R.), University of Pittsburgh, PA.,Department of Mechanical Engineering and Materials Science (E.O., C.-Y.C., A.M.R.), University of Pittsburgh, PA
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20
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Morel S, Diagbouga MR, Dupuy N, Sutter E, Braunersreuther V, Pelli G, Corniola M, Gondar R, Jägersberg M, Isidor N, Schaller K, Bochaton-Piallat ML, Bijlenga P, Kwak BR. Correlating Clinical Risk Factors and Histological Features in Ruptured and Unruptured Human Intracranial Aneurysms: The Swiss AneuX Study. J Neuropathol Exp Neurol 2019; 77:555-566. [PMID: 29688417 PMCID: PMC6005054 DOI: 10.1093/jnen/nly031] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Pathogenesis of intracranial aneurysm is complex and the precise biomechanical processes leading to their rupture are uncertain. The goal of our study was to characterize the aneurysmal wall histologically and to correlate histological characteristics with clinical and radiological factors used to estimate the risk of rupture. A new biobank of aneurysm domes resected at the Geneva University Hospitals (Switzerland) was used. Histological analysis revealed that unruptured aneurysms have a higher smooth muscle cell (SMC) content and a lower macrophage content than ruptured domes. These differences were associated with more collagen in unruptured samples, whereas the elastin content was not affected. Collagen content and type distribution were different between thick and thin walls of unruptured aneurysms. Classification of aneurysm domes based on histological characteristics showed that unruptured samples present organized wall rich in endothelial and SMCs compared with ruptured samples. Finally, aneurysm wall composition was altered in unruptured domes of patients presenting specific clinical factors used to predict rupture such as large dome diameter, dome irregularities, and smoking. Our study shows that the wall of aneurysm suspected to be at risk for rupture undergoes structural alterations relatively well associated with clinical and radiological factors currently used to predict this risk.
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Affiliation(s)
- Sandrine Morel
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Mannekomba R Diagbouga
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Nicolas Dupuy
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Esther Sutter
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Vincent Braunersreuther
- Department of Clinical Pathology, Faculty of Medicine, University of Geneva and Geneva University Hospitals, Geneva, Switzerland
| | - Graziano Pelli
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Marco Corniola
- Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Renato Gondar
- Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Max Jägersberg
- Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Nathalie Isidor
- Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Hospitals, Geneva, Switzerland.,Clinical Trial Unit, Faculty of Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Karl Schaller
- Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Hospitals, Geneva, Switzerland
| | | | - Philippe Bijlenga
- Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Brenda R Kwak
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Department of Medical Specializations - Cardiology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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21
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Mut F, Chung BJ, Chudyk J, Lylyk P, Kadirvel R, Kallmes DF, Cebral JR. Image-based modeling of blood flow in cerebral aneurysms treated with intrasaccular flow diverting devices. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3202. [PMID: 30891958 PMCID: PMC6687514 DOI: 10.1002/cnm.3202] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 01/18/2019] [Accepted: 03/17/2019] [Indexed: 05/20/2023]
Abstract
Modeling the flow dynamics in cerebral aneurysms after the implantation of intrasaccular devices is important for understanding the relationship between flow conditions created immediately posttreatment and the subsequent outcomes. This information, ideally available a priori based on computational modeling prior to implantation, is valuable to identify which aneurysms will occlude immediately and which aneurysms will likely remain patent and would benefit from a different procedure or device. In this report, a methodology for modeling the hemodynamics in intracranial aneurysms treated with intrasaccular flow diverting devices is described. This approach combines an image-guided, virtual device deployment within patient-specific vascular models with an immersed boundary method on adaptive unstructured grids. A partial mesh refinement strategy that reduces the number of mesh elements near the aneurysm dome where the flow conditions are largely stagnant was compared with the full refinement strategy that refines the mesh everywhere around the device wires. The results indicate that using the partial mesh refinement approach is adequate for analyzing the posttreatment hemodynamics, at a reduced computational cost. The results obtained on a series of four cerebral aneurysms treated with different intrasaccular devices were in good qualitative agreement with angiographic observations. Promising results were obtained relating posttreatment flow conditions and outcomes of treatments with intrasaccular devices, which need to be confirmed on larger series.
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Affiliation(s)
- Fernando Mut
- Bioengineering Department, Volgenau School of Engineering, George Mason University, Fairfax, Virginia, USA
| | - Bong Jae Chung
- Department of Mathematical Sciences, Montclair State University, Montclair, New Jersey, USA
| | - Jorge Chudyk
- Interventional Neuroradiology, Clinica ENERI, Buenos Aires, Argentina
| | - Pedro Lylyk
- Interventional Neuroradiology, Clinica ENERI, Buenos Aires, Argentina
| | | | - David F Kallmes
- Interventional Neuroradiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Juan R Cebral
- Bioengineering Department, Volgenau School of Engineering, George Mason University, Fairfax, Virginia, USA
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22
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Levitt MR, Mandrycky C, Abel A, Kelly CM, Levy S, Chivukula VK, Zheng Y, Aliseda A, Kim LJ. Genetic correlates of wall shear stress in a patient-specific 3D-printed cerebral aneurysm model. J Neurointerv Surg 2019; 11:999-1003. [PMID: 30979845 DOI: 10.1136/neurintsurg-2018-014669] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 12/29/2022]
Abstract
OBJECTIVES To study the correlation between wall shear stress and endothelial cell expression in a patient-specific, three-dimensional (3D)-printed model of a cerebral aneurysm. MATERIALS AND METHODS A 3D-printed model of a cerebral aneurysm was created from a patient's angiogram. After populating the model with human endothelial cells, it was exposed to media under flow for 24 hours. Endothelial cell morphology was characterized in five regions of the 3D-printed model using confocal microscopy. Endothelial cells were then harvested from distinct regions of the 3D-printed model for mRNA collection and gene analysis via quantitative polymerase chain reaction (qPCR.) Cell morphology and mRNA measurement were correlated with computational fluid dynamics simulations. RESULTS The model was successfully populated with endothelial cells, which survived under flow for 24 hours. Endothelial morphology showed alignment with flow in the proximal and distal parent vessel and aneurysm neck, but disorganization in the aneurysm dome. Genetic analysis of endothelial mRNA expression in the aneurysm dome and distal parent vessel was compared with the proximal parent vessels. ADAMTS-1 and NOS3 were downregulated in the aneurysm dome, while GJA4 was upregulated in the distal parent vessel. Disorganized morphology and decreased ADAMTS-1 and NOS3 expression correlated with areas of substantially lower wall shear stress and wall shear stress gradient in computational fluid dynamics simulations. CONCLUSIONS Creating 3D-printed models of patient-specific cerebral aneurysms populated with human endothelial cells is feasible. Analysis of these cells after exposure to flow demonstrates differences in both cell morphology and genetic expression, which correlate with areas of differential hemodynamic stress.
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Affiliation(s)
- Michael R Levitt
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Radiology, University of Washington, Seattle, WA, USA.,Mechanical Engineering, University of Washington, Seattle, WA, USA.,Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA
| | | | - Ashley Abel
- Neurological Surgery, University of Washington, Seattle, WA, USA
| | - Cory M Kelly
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA
| | - Samuel Levy
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA
| | | | - Ying Zheng
- Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA.,Bioengineering, University of Washington, Seattle, WA, USA
| | - Alberto Aliseda
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Mechanical Engineering, University of Washington, Seattle, WA, USA.,Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA
| | - Louis J Kim
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Radiology, University of Washington, Seattle, WA, USA.,Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA
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23
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Gade PS, Robertson AM, Chuang CY. Multiphoton Imaging of Collagen, Elastin, and Calcification in Intact Soft-Tissue Samples. CURRENT PROTOCOLS IN CYTOMETRY 2019; 87:e51. [PMID: 30379412 PMCID: PMC6314890 DOI: 10.1002/cpcy.51] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Multiphoton-induced second-harmonic generation and two-photon excitation enable imaging of collagen and elastin fibers at micron-level resolution to depths of hundreds of microns, without the use of exogenous stains. These attributes can be leveraged for quantitative analysis of the 3D architecture of collagen and elastin fibers within intact, soft tissue specimens such as the artery and bladder wall. This architecture influences the function of intramural cells and also plays a primary role in determining tissue passive mechanical properties. Calcification deposition in soft tissues is a highly prevalent pathology in both older and diseased populations that can alter tissue properties. In this unit, we provide a protocol for simultaneous multiphoton microscopy (MPM) imaging and analysis of 3D collagen and elastin structures with calcification, which is effective for fixed and fresh intact samples. We also provide an associated micro-CT protocol to identify regions of interest in the samples as a means to target the MPM imaging. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Piyusha S. Gade
- Department of Bioengineerin, University of Pittsburgh Pittsburgh, PA
| | - Anne M. Robertson
- Department of Bioengineerin, University of Pittsburgh Pittsburgh, PA
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh Pittsburgh, PA
| | - Chih-Yuan Chuang
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh Pittsburgh, PA
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24
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Cebral JR, Mut F, Gade P, Cheng F, Tobe Y, Frosen J, Robertson AM. Combining data from multiple sources to study mechanisms of aneurysm disease: Tools and techniques. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e3133. [PMID: 30055087 PMCID: PMC6231954 DOI: 10.1002/cnm.3133] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 06/14/2018] [Accepted: 07/15/2018] [Indexed: 05/31/2023]
Abstract
INTRODUCTION Connecting local hemodynamics, biomechanics, and tissue properties in cerebral aneurysms is important for understanding the processes of wall degeneration and subsequent aneurysm progression and rupture. This challenging problem requires integration of data from multiple sources. METHODS This paper describes the tools and techniques developed to integrate data from multiple sources, including clinical information, 3D imaging, intraoperative videos, ex vivo micro-computed tomography (CT), and multiphoton microscopy. Central to this approach is a 3D tissue model constructed from micro-CT images of aneurysm samples resected during neurosurgery. This model is aligned to vascular models constructed from 3D clinical images and is used to map and compare flow, biomechanics, and tissue data. RESULTS The approach is illustrated with data of three human intracranial aneurysms. These case studies demonstrated the ability of this approach to study relationships between different factors affecting the aneurysm wall and produced provocative observations that will be further studied with larger series. For instance, "atherosclerotic" and "hyperplastic" looking parts of the aneurysm corresponded to thicker walls and occurred in regions of recirculating flow and low wall shear stress (WSS); thin regions were associated with inflow jets, flow impingement, and high WSS; blebs had walls of varying structures, including calcified, thin, or hyperplastic walls. CONCLUSIONS The current approach enables the study of interactions of multiple factors thought to be responsible for the progressive degradation and weakening of the aneurysm wall during its evolution.
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Affiliation(s)
- Juan R Cebral
- Bioengineering Department, Volgenau School of Engineering, George Mason University, Fairfax, Virginia, USA
| | - Fernando Mut
- Bioengineering Department, Volgenau School of Engineering, George Mason University, Fairfax, Virginia, USA
| | - Piyusha Gade
- Mechanical Engineering and Materials Science and Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Fangzhou Cheng
- Mechanical Engineering and Materials Science and Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Yasutaka Tobe
- Mechanical Engineering and Materials Science and Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Juhana Frosen
- Hemorrhagic Brain Pathology Research Group, Neurocenter, Kuopio University Hospital, Kuopio, Finland
| | - Anne M Robertson
- Mechanical Engineering and Materials Science and Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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25
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Sang C, Maiti S, Fortunato RN, Kofler J, Robertson AM. A Uniaxial Testing Approach for Consistent Failure in Vascular Tissues. J Biomech Eng 2018; 140:2675125. [PMID: 29560496 PMCID: PMC5938069 DOI: 10.1115/1.4039577] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although uniaxial tensile testing is commonly used to evaluate failure properties of vascular tissue, there is no established protocol for specimen shape or gripping method. Large percentages of specimens are reported to fail near the clamp and can potentially confound the studies, or, if discarded will result in sample waste. The objective of this study is to identify sample geometry and clamping conditions that can achieve consistent failure in the midregion of small arterial specimens, even for vessels from older individuals. Failure location was assessed in 17 dogbone specimens from human cerebral and sheep carotid arteries using soft inserts. For comparison with commonly used protocols, an additional 22 rectangular samples were tested using either sandpaper or foam tape inserts. Midsample failure was achieved in 94% of the dogbone specimens, while only 14% of the rectangular samples failed in the midregion, the other 86% failing close to the clamps. Additionally, we found midregion failure was more likely to be abrupt, caused by cracking or necking. In contrast, clamp failure was more likely to be gradual and included a delamination mode not seen in midregion failure. Hence, this work provides an approach that can be used to obtain consistent midspecimen failure, avoiding confounding clamp-related artifacts. Furthermore, with consistent midregion failure, studies can be designed to image the failure process in small vascular samples providing valuable quantitative information about changes to collagen and elastin structure during the failure process.
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Affiliation(s)
- Chao Sang
- Department of Mechanical Engineering and
Materials Science,
University of Pittsburgh,
636 Benedum Hall 3700 O'Hara Street,
Pittsburgh, PA 15261
e-mail:
| | - Spandan Maiti
- Department of Bioengineering,
University of Pittsburgh,
302 Benedum Hall 3700 O'Hara Street,
Pittsburgh, PA 15261
e-mail:
| | - Ronald N. Fortunato
- Department of Mechanical Engineering and
Materials Science,
University of Pittsburgh,
636 Benedum Hall 3700 O'Hara Street,
Pittsburgh, PA 15261
e-mail:
| | - Julia Kofler
- Department of Pathology,
University of Pittsburgh,
S701.3 Scaife Hall,
Pittsburgh, PA 15261
e-mail:
| | - Anne M. Robertson
- Department of Mechanical Engineering and
Materials Science,
University of Pittsburgh,
440 Benedum Hall 3700 O'Hara Street,
Pittsburgh, PA 15261
e-mail:
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26
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Doddasomayajula R, Chung BJ, Mut F, Jimenez CM, Hamzei-Sichani F, Putman CM, Cebral JR. Hemodynamic Characteristics of Ruptured and Unruptured Multiple Aneurysms at Mirror and Ipsilateral Locations. AJNR Am J Neuroradiol 2017; 38:2301-2307. [PMID: 28982787 DOI: 10.3174/ajnr.a5397] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 08/01/2017] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Different hemodynamic patterns have been associated with aneurysm rupture. The objective was to test whether hemodynamic characteristics of the ruptured aneurysm in patients with multiple aneurysms were different from those in unruptured aneurysms in the same patient. MATERIALS AND METHODS Twenty-four mirror and 58 ipsilateral multiple aneurysms with 1 ruptured and the others unruptured were studied. Computational fluid dynamics models were created from 3D angiographies. Case-control studies of mirror and ipsilateral aneurysms were performed with paired Wilcoxon tests. RESULTS In mirror pairs, the ruptured aneurysm had more oscillatory wall shear stress (P = .007) than the unruptured one and tended to be more elongated (higher aspect ratio), though this trend achieved only marginal significance (P = .03, 1-sided test). In ipsilateral aneurysms, ruptured aneurysms had larger maximum wall shear (P = .05), more concentrated (P < .001) and oscillatory wall shear stress (P < .001), stronger (P < .001) and more concentrated inflow jets (P < .001), larger maximum velocity (P < .001), and more complex flow patterns (P < .001) compared with unruptured aneurysms. Additionally, ruptured aneurysms were larger (P < .001) and more elongated (P < .001) and had wider necks (P < .001) and lower minimum wall shear stress (P < .001) than unruptured aneurysms. CONCLUSIONS High wall shear stress oscillations and larger aspect ratios are associated with rupture in mirror aneurysms. Adverse flow conditions characterized by high and concentrated inflow jets; high, concentrated, and oscillatory wall shear stress; and strong, complex and unstable flow patterns are associated with rupture in ipsilateral multiple aneurysms. In multiple ipsilateral aneurysms, these unfavorable flow conditions are more likely to develop in larger, more elongated, more wide-necked, and more distal aneurysms.
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Affiliation(s)
- R Doddasomayajula
- From the Bioengineering Department (R.D., B.J.C., F.M., J.R.C.), George Mason University, Fairfax, Virginia
| | - B J Chung
- From the Bioengineering Department (R.D., B.J.C., F.M., J.R.C.), George Mason University, Fairfax, Virginia
| | - F Mut
- From the Bioengineering Department (R.D., B.J.C., F.M., J.R.C.), George Mason University, Fairfax, Virginia
| | - C M Jimenez
- Neurosurgery Department (C.M.J.), University of Antioquia, Medellin, Colombia
| | - F Hamzei-Sichani
- Department of Neurosurgery (F.H.-S.), Mt. Sinai Medical Center, New York, New York
| | - C M Putman
- Interventional Neuroradiology (C.M.P.), Inova Fairfax Hospital, Falls Church, Virginia
| | - J R Cebral
- From the Bioengineering Department (R.D., B.J.C., F.M., J.R.C.), George Mason University, Fairfax, Virginia
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27
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Longo M, Granata F, Racchiusa S, Mormina E, Grasso G, Longo GM, Garufi G, Salpietro FM, Alafaci C. Role of Hemodynamic Forces in Unruptured Intracranial Aneurysms: An Overview of a Complex Scenario. World Neurosurg 2017; 105:632-642. [DOI: 10.1016/j.wneu.2017.06.035] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 06/04/2017] [Accepted: 06/05/2017] [Indexed: 12/16/2022]
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28
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Petridis AK, Kaschner M, Cornelius JF, Kamp MA, Tortora A, Steiger HJ, Turowski B. A New Imaging Tool for Realtime Measurement of Flow Velocity in Intracranial Aneurysms. Clin Pract 2017; 7:975. [PMID: 28839527 PMCID: PMC5543827 DOI: 10.4081/cp.2017.975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/19/2017] [Indexed: 12/03/2022] Open
Abstract
With modern imaging modalities of the brain a significant number of unruptured aneurysms are detected. However, not every aneurysm is prone to rupture. Because treatment morbidity is about 10% it is crucial to identify unstable aneurysms for which treatment should be discussed. Recently, new imaging tools allow analysis of flow dynamics and wall stability have become available. It seems that they might provide additional data for better risk profiling. In this study we present a new imaging tool for analysis of flow dynamics, which calculates fluid velocity in an aneurysm (Phillips Electronics, N.V.). It may identify regions with high flow and calculate flow reduction after stenting of aneurysms. Contrast is injected with a stable injection speed of 2 mL/sec for 3 sec. Two clinical cases are illustrated. Velocity in aneurysms and areas of instability can be identified and calculated during angiography in real-time. After stenting and flow diverter deployment flow reduction in the internal carotid aneurysm was reduced by 60% and there was a reduction of about 65% in the posterior cerebral artery in the second case we are reporting. The dynamic flow software calculates the flow profile in the aneurysm immediately after contrast injection. It is a real-time, patient specific tool taking into account systole, diastole and flexibility of the vasculature. These factors are an improvement as compared to current models of computational flow dynamics. We think it is a highly efficient, user friendly tool. Further clinical studies are on their way.
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Affiliation(s)
- Athanasios K Petridis
- Department of Neurosurgery Institute of Neuroradiology, Heinrich Heine University Duesseldorf, Germany
| | - Marius Kaschner
- Institute of Neuroradiology, Heinrich Heine University Duesseldorf, Germany
| | - Jan F Cornelius
- Department of Neurosurgery Institute of Neuroradiology, Heinrich Heine University Duesseldorf, Germany
| | - Marcel A Kamp
- Department of Neurosurgery Institute of Neuroradiology, Heinrich Heine University Duesseldorf, Germany
| | - Angelo Tortora
- Department of Neurosurgery Institute of Neuroradiology, Heinrich Heine University Duesseldorf, Germany
| | - Hans-Jakob Steiger
- Department of Neurosurgery Institute of Neuroradiology, Heinrich Heine University Duesseldorf, Germany
| | - Bernd Turowski
- Institute of Neuroradiology, Heinrich Heine University Duesseldorf, Germany
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29
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Cebral JR, Mut F, Chung BJ, Spelle L, Moret J, van Nijnatten F, Ruijters D. Understanding Angiography-Based Aneurysm Flow Fields through Comparison with Computational Fluid Dynamics. AJNR Am J Neuroradiol 2017; 38:1180-1186. [PMID: 28385882 DOI: 10.3174/ajnr.a5158] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 01/25/2017] [Indexed: 12/17/2022]
Abstract
BACKGROUND AND PURPOSE Hemodynamics is thought to be an important factor for aneurysm progression and rupture. Our aim was to evaluate whether flow fields reconstructed from dynamic angiography data can be used to realistically represent the main flow structures in intracranial aneurysms. MATERIALS AND METHODS DSA-based flow reconstructions, obtained during interventional treatment, were compared qualitatively with flow fields obtained from patient-specific computational fluid dynamics models and quantitatively with projections of the computational fluid dynamics fields (by computing a directional similarity of the vector fields) in 15 cerebral aneurysms. RESULTS The average similarity between the DSA and the projected computational fluid dynamics flow fields was 78% in the parent artery, while it was only 30% in the aneurysm region. Qualitatively, both the DSA and projected computational fluid dynamics flow fields captured the location of the inflow jet, the main vortex structure, the intrasaccular flow split, and the main rotation direction in approximately 60% of the cases. CONCLUSIONS Several factors affect the reconstruction of 2D flow fields from dynamic angiography sequences. The most important factors are the 3-dimensionality of the intrasaccular flow patterns and inflow jets, the alignment of the main vortex structure with the line of sight, the overlapping of surrounding vessels, and possibly frame rate undersampling. Flow visualization with DSA from >1 projection is required for understanding of the 3D intrasaccular flow patterns. Although these DSA-based flow quantification techniques do not capture swirling or secondary flows in the parent artery, they still provide a good representation of the mean axial flow and the corresponding flow rate.
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Affiliation(s)
- J R Cebral
- From the Bioengineering Department (J.R.C., F.M., B.J.C.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia
| | - F Mut
- From the Bioengineering Department (J.R.C., F.M., B.J.C.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia
| | - B J Chung
- From the Bioengineering Department (J.R.C., F.M., B.J.C.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia
| | - L Spelle
- Faculté de Médecine Paris-Sud (L.S.), Le Kremlin-Bicetre, France
| | - J Moret
- Interventional Neuroradiology (J.M.), Beaujon University Hospital, Clichy, France
| | - F van Nijnatten
- Image Guided Therapy Innovation (F.v.N., D.R.), Philips Healthcare, Best, the Netherlands
| | - D Ruijters
- Image Guided Therapy Innovation (F.v.N., D.R.), Philips Healthcare, Best, the Netherlands
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30
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Cebral J, Ollikainen E, Chung BJ, Mut F, Sippola V, Jahromi BR, Tulamo R, Hernesniemi J, Niemelä M, Robertson A, Frösen J. Flow Conditions in the Intracranial Aneurysm Lumen Are Associated with Inflammation and Degenerative Changes of the Aneurysm Wall. AJNR Am J Neuroradiol 2017; 38:119-126. [PMID: 27686488 PMCID: PMC5233582 DOI: 10.3174/ajnr.a4951] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/22/2016] [Indexed: 12/31/2022]
Abstract
BACKGROUND AND PURPOSE Saccular intracranial aneurysm is a common disease that may cause devastating intracranial hemorrhage. Hemodynamics, wall remodeling, and wall inflammation have been associated with saccular intracranial aneurysm rupture. We investigated how saccular intracranial aneurysm hemodynamics is associated with wall remodeling and inflammation of the saccular intracranial aneurysm wall. MATERIALS AND METHODS Tissue samples resected during a saccular intracranial aneurysm operation (11 unruptured, 9 ruptured) were studied with histology and immunohistochemistry. Patient-specific computational models of hemodynamics were created from preoperative CT angiographies. RESULTS More stable and less complex flows were associated with thick, hyperplastic saccular intracranial aneurysm walls, while slower flows with more diffuse inflow were associated with degenerated and decellularized saccular intracranial aneurysm walls. Wall degeneration (P = .041) and rupture were associated with increased inflammation (CD45+, P = .031). High wall shear stress (P = .018), higher vorticity (P = .046), higher viscous dissipation (P = .046), and high shear rate (P = .046) were associated with increased inflammation. Inflammation was also associated with lack of an intact endothelium (P = .034) and the presence of organized luminal thrombosis (P = .018), though overall organized thrombosis was associated with low minimum wall shear stress (P = .034) and not with the flow conditions associated with inflammation. CONCLUSIONS Flow conditions in the saccular intracranial aneurysm are associated with wall remodeling. Inflammation, which is associated with degenerative wall remodeling and rupture, is related to high flow activity, including elevated wall shear stress. Endothelial injury may be a mechanism by which flow induces inflammation in the saccular intracranial aneurysm wall. Hemodynamic simulations might prove useful in identifying saccular intracranial aneurysms at risk of developing inflammation, a potential biomarker for rupture.
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Affiliation(s)
- J Cebral
- From the Bioengineering Department (J.C., B.J.C., F.M.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia
| | - E Ollikainen
- Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland
| | - B J Chung
- From the Bioengineering Department (J.C., B.J.C., F.M.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia
| | - F Mut
- From the Bioengineering Department (J.C., B.J.C., F.M.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia
| | - V Sippola
- Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland
| | - B R Jahromi
- Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland
| | - R Tulamo
- Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland
- Department of Vascular Surgery (R.T.), Helsinki University Central Hospital, Helsinki, Finland
| | - J Hernesniemi
- Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland
| | - M Niemelä
- Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland
| | - A Robertson
- Mechanical Engineering and Materials Science and Department of Bioengineering (A.R.), Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - J Frösen
- Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland
- Department of Neurosurgery and Hemorrhagic Brain Pathology Research Group (J.F.), Neurocenter, Kuopio University Hospital, Kuopio, Finland
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