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Segherlou ZH, Shakeri-Darzekonani M, Khavandegar A, Stephenson S, Ciccone K, Masheghati F, Hosseini Siyanaki MR, Lyerly M, Lucke-Wold B. Hormonal influences on cerebral aneurysms: unraveling the complex connections. Expert Rev Endocrinol Metab 2024; 19:207-215. [PMID: 38712738 DOI: 10.1080/17446651.2024.2347275] [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: 12/17/2023] [Accepted: 04/22/2024] [Indexed: 05/08/2024]
Abstract
INTRODUCTION Intracranial aneurysms (IAs) occur in 3-5% of the general population and are characterized by localized structural deterioration of the arterial wall with loss of internal elastic lamina and disruption of the media. The risk of incidence and rupture of aneurysms depends on age, sex, ethnicity, and other different factors, indicating the influence of genetic and environmental factors. When an aneurysm ruptures, there is an estimated 20% mortality rate, along with an added 30-40% morbidity in survivors. The alterations in hormonal levels can influence IAs, while the rupture of an aneurysm can have various impacts on endocrine pathways and affect their outcome. AREA COVERED This review explores the reciprocal relationship between endocrinological changes (estrogen, growth hormone, and thyroid hormones) and IAs, as well as the effects of aneurysm ruptures on endocrine fluctuations. EXPERT OPINION Based on the data presented in this paper, we recommend further exploration into the influence of hormones on aneurysm formation and rupture. Additionally, we propose conducting endocrine assessments for patients who have experienced a rupture of IAs. Monitoring hormonal changes in patients with IAs could serve as a potential risk factor for rupture, leading to interventions in the approach to managing IAs.
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Affiliation(s)
| | | | - Armin Khavandegar
- College of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Sara Stephenson
- Biotechnology Department, Krieger School of Arts and Sciences, John Hopkins University, Baltimore, MD, USA
| | - Kimberly Ciccone
- Department of Behavioral Neuroscience, College of Arts and Sciences, University of North Florida, Jacksonville, FL, USA
| | - Forough Masheghati
- College of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Mac Lyerly
- School of Medicine, Wake Forest University, Winston-Salem, NC, USA
| | - Brandon Lucke-Wold
- Department of Neurosurgery, College of Medicine, University of Florida, Gainesville, FL, USA
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Hariri S, Mirzaei Poueinak M, Hassanvand A, Barzegar Gerdroodbary M, Faraji M. Effects of blood hematocrit on performance of endovascular coiling for treatment of middle cerebral artery (MCA) aneurysms: Computational study. INTERDISCIPLINARY NEUROSURGERY 2023. [DOI: 10.1016/j.inat.2023.101729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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Hadad S, Mut F, Chung BJ, Roa JA, Robertson AM, Hasan DM, Samaniego EA, Cebral JR. Regional Aneurysm Wall Enhancement is Affected by Local Hemodynamics: A 7T MRI Study. AJNR Am J Neuroradiol 2020; 42:464-470. [PMID: 33361379 DOI: 10.3174/ajnr.a6927] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 09/30/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND AND PURPOSE Aneurysm wall enhancement has been proposed as a biomarker for inflammation and instability. However, the mechanisms of aneurysm wall enhancement remain unclear. We used 7T MR imaging to determine the effect of flow in different regions of the wall. MATERIALS AND METHODS Twenty-three intracranial aneurysms imaged with 7T MR imaging and 3D angiography were studied with computational fluid dynamics. Local flow conditions were compared between aneurysm wall enhancement and nonenhanced regions. Aneurysm wall enhancement regions were subdivided according to their location on the aneurysm and relative to the inflow and were further compared. RESULTS On average, wall shear stress was lower in enhanced than in nonenhanced regions (P = .05). Aneurysm wall enhancement regions at the neck had higher wall shear stress gradients (P = .05) with lower oscillations (P = .05) than nonenhanced regions. In contrast, aneurysm wall enhancement regions at the aneurysm body had lower wall shear stress (P = .01) and wall shear stress gradients (P = .008) than nonenhanced regions. Aneurysm wall enhancement regions far from the inflow had lower wall shear stress (P = .006) than nonenhanced regions, while aneurysm wall enhancement regions close to the inflow tended to have higher wall shear stress than the nonenhanced regions, but this association was not significant. CONCLUSIONS Aneurysm wall enhancement regions tend to have lower wall shear stress than nonenhanced regions of the same aneurysm. Moreover, the association between flow conditions and aneurysm wall enhancement seems to depend on the location of the region on the aneurysm sac. Regions at the neck and close to the inflow tend to be exposed to higher wall shear stress and wall shear stress gradients. Regions at the body, dome, or far from the inflow tend to be exposed to uniformly low wall shear stress and have more aneurysm wall enhancement.
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Affiliation(s)
- S Hadad
- From the Departments of Bioengineering and Mechanical Engineering (S.H., F.M., J.R.C.), George Mason University, Fairfax, Virginia
| | - F Mut
- From the Departments of Bioengineering and Mechanical Engineering (S.H., F.M., J.R.C.), George Mason University, Fairfax, Virginia
| | - B J Chung
- Department of Applied Mathematics and Statistics (B.J.C.), Mountclair State University, Mountclair, New Jersey
| | - J A Roa
- Departments of Neurology, Neurosurgery, and Radiology (J.A.R., E.A.S.)
| | - A M Robertson
- Department of Mechanical Engineering and Material Science (A.M.R.), University of Pittsburgh, Pittsburgh, Pennsylvania
| | - D M Hasan
- Neurosurgery (D.M.H.), University of Iowa, Iowa City, Iowa
| | - E A Samaniego
- Departments of Neurology, Neurosurgery, and Radiology (J.A.R., E.A.S.)
| | - J R Cebral
- From the Departments of Bioengineering and Mechanical Engineering (S.H., F.M., J.R.C.), George Mason University, Fairfax, Virginia
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Evaluating the Effectiveness of 2 Different Flow Diverter Stents Based on the Stagnation Region Formation in an Aneurysm Sac Using Lagrangian Coherent Structure. World Neurosurg 2019; 127:e727-e737. [DOI: 10.1016/j.wneu.2019.03.255] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 03/23/2019] [Accepted: 03/25/2019] [Indexed: 12/16/2022]
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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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Four-Dimensional Phase Contrast Magnetic Resonance Imaging Protocol Optimization Using Patient-Specific 3-Dimensional Printed Replicas for In Vivo Imaging Before and After Flow Diverter Placement. World Neurosurg 2017. [DOI: 10.1016/j.wneu.2017.06.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Sarrami-Foroushani A, Lassila T, Frangi AF. Virtual endovascular treatment of intracranial aneurysms: models and uncertainty. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2017; 9. [PMID: 28488754 DOI: 10.1002/wsbm.1385] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 01/09/2017] [Accepted: 02/07/2017] [Indexed: 01/11/2023]
Abstract
Virtual endovascular treatment models (VETMs) have been developed with the view to aid interventional neuroradiologists and neurosurgeons to pre-operatively analyze the comparative efficacy and safety of endovascular treatments for intracranial aneurysms. Based on the current state of VETMs in aneurysm rupture risk stratification and in patient-specific prediction of treatment outcomes, we argue there is a need to go beyond personalized biomechanical flow modeling assuming deterministic parameters and error-free measurements. The mechanobiological effects associated with blood clot formation are important factors in therapeutic decision making and models of post-treatment intra-aneurysmal biology and biochemistry should be linked to the purely hemodynamic models to improve the predictive power of current VETMs. The influence of model and parameter uncertainties associated to each component of a VETM is, where feasible, quantified via a random-effects meta-analysis of the literature. This allows estimating the pooled effect size of these uncertainties on aneurysmal wall shear stress. From such meta-analyses, two main sources of uncertainty emerge where research efforts have so far been limited: (1) vascular wall distensibility, and (2) intra/intersubject systemic flow variations. In the future, we suggest that current deterministic computational simulations need to be extended with strategies for uncertainty mitigation, uncertainty exploration, and sensitivity reduction techniques. WIREs Syst Biol Med 2017, 9:e1385. doi: 10.1002/wsbm.1385 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Ali Sarrami-Foroushani
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
| | - Toni Lassila
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
| | - Alejandro F Frangi
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
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Vali A, Abla AA, Lawton MT, Saloner D, Rayz VL. Computational Fluid Dynamics modeling of contrast transport in basilar aneurysms following flow-altering surgeries. J Biomech 2016; 50:195-201. [PMID: 27890537 DOI: 10.1016/j.jbiomech.2016.11.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 11/05/2016] [Indexed: 10/20/2022]
Abstract
In vivo measurement of blood velocity fields and flow descriptors remains challenging due to image artifacts and limited resolution of current imaging methods; however, in vivo imaging data can be used to inform and validate patient-specific computational fluid dynamics (CFD) models. Image-based CFD can be particularly useful for planning surgical interventions in complicated cases such as fusiform aneurysms of the basilar artery, where it is crucial to alter pathological hemodynamics while preserving flow to the distal vasculature. In this study, patient-specific CFD modeling was conducted for two basilar aneurysm patients considered for surgical treatment. In addition to velocity fields, transport of contrast agent was simulated for the preoperative and postoperative conditions using two approaches. The transport of a virtual contrast passively following the flow streamlines was simulated to predict post-surgical flow regions prone to thrombus deposition. In addition, the transport of a mixture of blood with an iodine-based contrast agent was modeled to compare and verify the CFD results with X-ray angiograms. The CFD-predicted patterns of contrast flow were qualitatively compared to in vivo X-ray angiograms acquired before and after the intervention. The results suggest that the mixture modeling approach, accounting for the flow rates and properties of the contrast injection, is in better agreement with the X-ray angiography data. The virtual contrast modeling assessed the residence time based on flow patterns unaffected by the injection procedure, which makes the virtual contrast modeling approach better suited for prediction of thrombus deposition, which is not limited to the peri-procedural state.
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Affiliation(s)
- Alireza Vali
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Adib A Abla
- Department of Neurosurgery, University of Arkansas for Medical Science, AR, USA
| | - Michael T Lawton
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
| | - David Saloner
- Department of Radiology and Biomedical Imaging University of California, San Francisco, CA, USA
| | - Vitaliy L Rayz
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Mechanical Engineering, University of Wisconsin, Milwaukee, WI, USA.
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Basic Principles of Hemodynamics and Cerebral Aneurysms. World Neurosurg 2016; 88:311-319. [DOI: 10.1016/j.wneu.2016.01.031] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 01/03/2016] [Accepted: 01/05/2016] [Indexed: 11/18/2022]
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Khodaee F, Vahidi B, Fatouraee N. Analysis of mechanical parameters on the thromboembolism using a patient-specific computational model. Biomech Model Mechanobiol 2016; 15:1295-305. [DOI: 10.1007/s10237-016-0762-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 01/11/2016] [Indexed: 12/16/2022]
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Chung B, Cebral JR. CFD for Evaluation and Treatment Planning of Aneurysms: Review of Proposed Clinical Uses and Their Challenges. Ann Biomed Eng 2014; 43:122-38. [DOI: 10.1007/s10439-014-1093-6] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 08/08/2014] [Indexed: 11/29/2022]
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Castro MA. Understanding the role of hemodynamics in the initiation, progression, rupture, and treatment outcome of cerebral aneurysm from medical image-based computational studies. ISRN RADIOLOGY 2013; 2013:602707. [PMID: 24967285 PMCID: PMC4045510 DOI: 10.5402/2013/602707] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 06/19/2013] [Indexed: 12/31/2022]
Abstract
About a decade ago, the first image-based computational hemodynamic studies of cerebral aneurysms were presented. Their potential for clinical applications was the result of a right combination of medical image processing, vascular reconstruction, and grid generation techniques used to reconstruct personalized domains for computational fluid and solid dynamics solvers and data analysis and visualization techniques. A considerable number of studies have captivated the attention of clinicians, neurosurgeons, and neuroradiologists, who realized the ability of those tools to help in understanding the role played by hemodynamics in the natural history and management of intracranial aneurysms. This paper intends to summarize the most relevant results in the field reported during the last years.
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Affiliation(s)
- Marcelo A. Castro
- Grupo de Investigación y Desarrollo en Bioingeniería, Facultad Regional Buenos Aires, Universidad Tecnológica Nacional, CONICET, Medrano 951, CP 1179, Buenos Aires, Argentina
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Sadasivan C, Fiorella DJ, Woo HH, Lieber BB. Physical factors effecting cerebral aneurysm pathophysiology. Ann Biomed Eng 2013; 41:1347-65. [PMID: 23549899 DOI: 10.1007/s10439-013-0800-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Accepted: 03/21/2013] [Indexed: 12/21/2022]
Abstract
Many factors that are either blood-, wall-, or hemodynamics-borne have been associated with the initiation, growth, and rupture of intracranial aneurysms. The distribution of cerebral aneurysms around the bifurcations of the circle of Willis has provided the impetus for numerous studies trying to link hemodynamic factors (flow impingement, pressure, and/or wall shear stress) to aneurysm pathophysiology. The focus of this review is to provide a broad overview of such hemodynamic associations as well as the subsumed aspects of vascular anatomy and wall structure. Hemodynamic factors seem to be correlated to the distribution of aneurysms on the intracranial arterial tree and complex, slow flow patterns seem to be associated with aneurysm growth and rupture. However, both the prevalence of aneurysms in the general population and the incidence of ruptures in the aneurysm population are extremely low. This suggests that hemodynamic factors and purely mechanical explanations by themselves may serve as necessary, but never as necessary and sufficient conditions of this disease's causation. The ultimate cause is not yet known, but it is likely an additive or multiplicative effect of a handful of biochemical and biomechanical factors.
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Affiliation(s)
- Chander Sadasivan
- Department of Neurological Surgery, Stony Brook University Medical Center, 100 Nicolls Road, HSC T12, Room 080, Stony Brook, NY 11794-8122, USA
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Cebral JR, Raschi M. Suggested connections between risk factors of intracranial aneurysms: a review. Ann Biomed Eng 2012; 41:1366-83. [PMID: 23242844 DOI: 10.1007/s10439-012-0723-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 12/07/2012] [Indexed: 12/01/2022]
Abstract
The purpose of this article is to review studies of aneurysm risk factors and the suggested hypotheses that connect the different risk factors and the underlying mechanisms governing the aneurysm natural history. The result of this work suggests that at the center of aneurysm evolution there is a cycle of wall degeneration and weakening in response to changing hemodynamic loading and biomechanic stress. This progressive wall degradation drives the geometrical evolution of the aneurysm until it stabilizes or ruptures. Risk factors such as location, genetics, smoking, co-morbidities, and hypertension seem to affect different components of this cycle. However, details of these interactions or their relative importance are still not clearly understood.
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Affiliation(s)
- Juan R Cebral
- Center for Computational Fluid Dynamics, George Mason University, Fairfax, VA, USA.
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Magnetic resonance fluid dynamics for intracranial aneurysms--comparison with computed fluid dynamics. Acta Neurochir (Wien) 2012; 154:993-1001. [PMID: 22392013 DOI: 10.1007/s00701-012-1305-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 02/06/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND Hemodynamics in intracranial aneurysms is thought to play an important role in their growth and rupture. Usual computed fluid dynamics (CFD) based on three-dimensional (3D) computed tomographic (CT) angiography requires a time-consuming process for analysis. Magnetic resonance fluid dynamics (MRFD) based on MR images is a new tool for analyzing flow dynamics and a promising method for obtaining such information more easily. We compared the data from MRFD and CFD and studied the clinical feasibility of MRFD. METHODS A total of 15 aneurysms, including two ruptured ones, in 15 patients were investigated with MR imaging and 3D-CT angiography. The flow data of MRFD and CFD, 3D stream lines, flow velocity profile and wall shear stress (WSS) were extracted from the image reconstruction and were compared each other. RESULTS Both flow dynamics images showed quite similar 3D flow pattern and WSS map. However, the calculated value of maximum WSS was quite different and there was no significant correlation. Further, in one ruptured case, CFD showed less visualization to evaluate the intra-aneurysmal flow. Interestingly, one delayed rupture case showed a particular flow pattern with abnormal secondary flow in the bottom of the aneurysm before rupture, which might suggest the specific finding of rupture risk. CONCLUSION MRFD is a valuable and less invasive tool to evaluate aneurysmal fluid dynamics. It can be obtained from the usual MRI examination without contrast medium and exposure to radiation. Although there is a problem of consistency of the absolute value of WSS between MRFD and conventional CFD, it may be useful to predict the risk of enlargement or rupture of aneurysms based on the information of the similar distribution of WSS and flow patterns. The quantifiable analysis and establishment of a meaningful threshold for high risk should be further studied.
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Ramalho S, Moura A, Gambaruto AM, Sequeira A. Sensitivity to outflow boundary conditions and level of geometry description for a cerebral aneurysm. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2012; 28:697-713. [PMID: 25364846 DOI: 10.1002/cnm.2461] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 10/14/2011] [Accepted: 12/06/2011] [Indexed: 06/04/2023]
Abstract
Mathematical models, namely the flow boundary conditions, as well as the detail of the bounding geometry, can highly influence the computed flow field. In this work, an anatomically realistic portion of cerebral vasculature with a saccular aneurysm, and its geometric idealisation, are considered. The importance of the geometric description, namely including the side branches or modelling them as holes in the main vessel, is studied. Several approaches to prescribe the outflow boundary conditions at the side branches are analysed, including the traction-free condition, zero velocity (hence neglecting the side-branch), and the coupling with simple zero-dimensional and one-dimensional models. Results of the effects of outflow boundary modelling choice on computed haemodynamic parameters are used to identify appropriateness of the models based on the physical interpretation. Estimated range of error-bars associated to outflow boundary model choice and the level of geometric details are presented for patient-specific computational haemodynamics, and can serve as invitation for future studies. The zero-dimensional and one-dimensional models are shown to provide good representations of the side branches in the case of the clipped geometry.
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Affiliation(s)
- S Ramalho
- Dept. of Mathematics and CEMAT/IST, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais 1, 1049-001, Lisboa, Portugal
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Cebral J, Mut F, Sforza D, Löhner R, Scrivano E, Lylyk P, Putman C. Clinical Application of Image-Based CFD for Cerebral Aneurysms. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2011; 27:977-992. [PMID: 21822465 PMCID: PMC3150562 DOI: 10.1002/cnm.1373] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
During the last decade, the convergence of medical imaging and computational modeling technologies has enabled tremendous progress in the development and application of image-based computational fluid dynamics modeling of patient-specific blood flows. These techniques have been used for studying the basic mechanisms involved in the initiation and progression of vascular diseases, for studying possible ways to improve the diagnosis and evaluation of patients by incorporating hemodynamics information to the anatomical data typically available, and for the development of computational tools that can be used to improve surgical and endovascular treatment planning. However, before these technologies can have a significant impact on the routine clinical practice, it is still necessary to demonstrate the connection between the extra information provided by the models and the natural progression of vascular diseases and the outcome of interventions. This paper summarizes some of our contributions in this direction, focusing in particular on cerebral aneurysms.
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Bogunović H, Pozo JM, Villa-Uriol MC, Majoie CBLM, van den Berg R, Gratama van Andel HAF, Macho JM, Blasco J, Román LS, Frangi AF. Automated segmentation of cerebral vasculature with aneurysms in 3DRA and TOF-MRA using geodesic active regions: an evaluation study. Med Phys 2011; 38:210-22. [PMID: 21361189 DOI: 10.1118/1.3515749] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To evaluate the suitability of an improved version of an automatic segmentation method based on geodesic active regions (GAR) for segmenting cerebral vasculature with aneurysms from 3D x-ray reconstruction angiography (3DRA) and time of flight magnetic resonance angiography (TOF-MRA) images available in the clinical routine. METHODS Three aspects of the GAR method have been improved: execution time, robustness to variability in imaging protocols, and robustness to variability in image spatial resolutions. The improved GAR was retrospectively evaluated on images from patients containing intracranial aneurysms in the area of the Circle of Willis and imaged with two modalities: 3DRA and TOF-MRA. Images were obtained from two clinical centers, each using different imaging equipment. Evaluation included qualitative and quantitative analyses of the segmentation results on 20 images from 10 patients. The gold standard was built from 660 cross-sections (33 per image) of vessels and aneurysms, manually measured by interventional neuroradiologists. GAR has also been compared to an interactive segmentation method: isointensity surface extraction (ISE). In addition, since patients had been imaged with the two modalities, we performed an intermodality agreement analysis with respect to both the manual measurements and each of the two segmentation methods. RESULTS Both GAR and ISE differed from the gold standard within acceptable limits compared to the imaging resolution. GAR (ISE) had an average accuracy of 0.20 (0.24) mm for 3DRA and 0.27 (0.30) mm for TOF-MRA, and had a repeatability of 0.05 (0.20) mm. Compared to ISE, GAR had a lower qualitative error in the vessel region and a lower quantitative error in the aneurysm region. The repeatability of GAR was superior to manual measurements and ISE. The intermodality agreement was similar between GAR and the manual measurements. CONCLUSIONS The improved GAR method outperformed ISE qualitatively as well as quantitatively and is suitable for segmenting 3DRA and TOF-MRA images from clinical routine.
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Affiliation(s)
- Hrvoje Bogunović
- Center for Computational Imaging and Simulation Technologies in Biomedicine, Universitat Pompeu Fabra and Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine, Barcelona 08018, Spain.
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Wurm G, Lehner M, Tomancok B, Kleiser R, Nussbaumer K. Cerebrovascular biomodeling for aneurysm surgery: simulation-based training by means of rapid prototyping technologies. Surg Innov 2011; 18:294-306. [PMID: 21307017 DOI: 10.1177/1553350610395031] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVE Opportunities for developing procedural skills are progressively rare. Therefore, sophisticated educational tools are highly warranted. METHODS This study compared stereolithography and 3-dimensional printing for simulating cerebral aneurysm surgery. The latter jets multiple materials simultaneously and thus has the ability to print assemblies of multiple materials with different features. The authors created the solid skull and the cerebral vessels in different materials to simulate the real aneurysm when clipped. RESULTS Precise plastic replicas of complex anatomical data provide intuitive tactile views that can be scrutinized from any perspective. Hollowed out vessel sections allow serial clipping efforts, evaluation of different clips, and clip positions. The models can be used for accurate prediction of vascular anatomy, for optimization of teaching surgical skills, for advanced procedural competency training, and for patient counseling. CONCLUSION Simultaneous 3-dimensional printing is the most promising rapid prototyping technique to produce biomodels that meet the high demands of neurovascular surgery.
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Affiliation(s)
- Gabriele Wurm
- Department of Neurosurgery, Landes-Nervenklinik Wagner Jauregg, Linz, Austria.
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Pennati G, Migliavacca F, Dubini G, Bove EL. Modeling of systemic-to-pulmonary shunts in newborns with a univentricular circulation: State of the art and future directions. PROGRESS IN PEDIATRIC CARDIOLOGY 2010. [DOI: 10.1016/j.ppedcard.2010.09.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/01/2022]
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Cebral JR, Mut F, Weir J, Putman CM. Association of hemodynamic characteristics and cerebral aneurysm rupture. AJNR Am J Neuroradiol 2010; 32:264-70. [PMID: 21051508 DOI: 10.3174/ajnr.a2274] [Citation(s) in RCA: 268] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. This report describes a study of the associations between qualitative intra-aneurysmal hemodynamics and the rupture of cerebral aneurysms. MATERIALS AND METHODS Two hundred ten consecutive aneurysms were analyzed by using patient-specific CFD simulations under pulsatile flow conditions. The aneurysms were classified into categories by 2 blinded observers, depending on the complexity and stability of the flow pattern, size of the impingement region, and inflow concentration. A statistical analysis was then performed with respect to the history of previous rupture. Interobserver variability analysis was performed. RESULTS Ruptured aneurysms were more likely to have complex flow patterns (83%, P < .001), stable flow patterns (75%, P = .0018), concentrated inflow (66%, P = <.0001), and small impingement regions (76%, P = .0006) compared with unruptured aneurysms. Interobserver variability analyses indicated that all the classifications performed were in very good agreement-that is, well within the 95% CI. CONCLUSIONS A qualitative hemodynamic analysis of cerebral aneurysms by using image-based patient-specific geometries has shown that concentrated inflow jets, small impingement regions, complex flow patterns, and unstable flow patterns are correlated with a clinical history of prior aneurysm rupture. These qualitative measures provide a starting point for more sophisticated quantitative analysis aimed at assigning aneurysm risk of future rupture. These analyses highlight the potential for CFD to play an important role in the clinical determination of aneurysm risks.
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Affiliation(s)
- J R Cebral
- Department of Computational and Data Sciences, Center for Computational Fluid Dynamics, George Mason University, Fairfax, Virginia 22030, USA.
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Computational Hemodynamics in Cerebral Aneurysms: The Effects of Modeled Versus Measured Boundary Conditions. Ann Biomed Eng 2010; 39:884-96. [DOI: 10.1007/s10439-010-0187-z] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Accepted: 10/09/2010] [Indexed: 10/18/2022]
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24
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Cross-flow at the anterior communicating artery and its implication in cerebral aneurysm formation. J Biomech 2010; 43:2189-95. [DOI: 10.1016/j.jbiomech.2010.03.039] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 03/23/2010] [Accepted: 03/23/2010] [Indexed: 11/22/2022]
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Temporal variations of wall shear stress parameters in intracranial aneurysms--importance of patient-specific inflow waveforms for CFD calculations. Acta Neurochir (Wien) 2010; 152:1391-8; discussion 1398. [PMID: 20390310 DOI: 10.1007/s00701-010-0647-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 03/18/2010] [Indexed: 10/19/2022]
Abstract
PURPOSE To assess reliability of wall shear stress (WSS)calculations using computational fluid dynamics (CFD) dependent on inflow in internal carotid artery aneurysms (ICA). MATERIALS AND METHODS Six unruptured ICA aneurysms were studied. 3D computational meshes were created from 3D digital subtraction angiographic images (Axiom Artis dBA, Siemens Medical Solutions). Transient CFD simulations(Fluent, ANSYS Inc.) were performed for two inflow conditions: (1) idealized averaged waveform from normal subjects (ID) and (2) patient-specific waveform (PS)measured with 2D phase contrast magnetic resonance imaging. Stability of calculation was assessed by comparing mean WSS (<WSS>), temporal wall shear stress magnitude variation (Delta WSS), and oscillatory shear index(OSI, a measure of variation in the WSS direction) on the aneurysmal wall for both conditions. RESULTS For all cases, mean relative difference (PS-ID) of WSS (<WSS>) was -15% (range -32% to 11%). Mean Delta WSS difference was -29.3% ( -100% to 67%). Mean OSI difference was 7.5% (-12% to 40%). Large variations in histograms of these parameters were noted. CONCLUSION For accurate calculations of WSS parameters,patient-specific information on physiological flow may be necessary. Results obtained with averaged or idealized flow waveforms may have to be interpreted with caution.
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Villa-Uriol MC, Larrabide I, Pozo JM, Kim M, Camara O, De Craene M, Zhang C, Geers AJ, Morales H, Bogunović H, Cardenes R, Frangi AF. Toward integrated management of cerebral aneurysms. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2010; 368:2961-82. [PMID: 20478916 DOI: 10.1098/rsta.2010.0095] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In the last few years, some of the visionary concepts behind the virtual physiological human began to be demonstrated on various clinical domains, showing great promise for improving healthcare management. In the current work, we provide an overview of image- and biomechanics-based techniques that, when put together, provide a patient-specific pipeline for the management of intracranial aneurysms. The derivation and subsequent integration of morphological, morphodynamic, haemodynamic and structural analyses allow us to extract patient-specific models and information from which diagnostic and prognostic descriptors can be obtained. Linking such new indices with relevant clinical events should bring new insights into the processes behind aneurysm genesis, growth and rupture. The development of techniques for modelling endovascular devices such as stents and coils allows the evaluation of alternative treatment scenarios before the intervention takes place and could also contribute to the understanding and improved design of more effective devices. A key element to facilitate the clinical take-up of all these developments is their comprehensive validation. Although a number of previously published results have shown the accuracy and robustness of individual components, further efforts should be directed to demonstrate the diagnostic and prognostic efficacy of these advanced tools through large-scale clinical trials.
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Affiliation(s)
- M C Villa-Uriol
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Information and Communication Technologies Department, Universitat Pompeu Fabra, c/Tanger 122-140, 08018 Barcelona, Spain.
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Chang HH, Duckwiler GR, Valentine DJ, Chu WC. Computer-assisted extraction of intracranial aneurysms on 3D rotational angiograms for computational fluid dynamics modeling. Med Phys 2010; 36:5612-21. [PMID: 20095274 DOI: 10.1118/1.3260841] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Three-dimensional rotational angiography (3DRA) is an evolving imaging procedure from traditional digital subtraction angiography and is gaining much interest for detecting intracranial aneurysms. Computational fluid dynamics (CFD) modeling plays an important role in understanding the biomechanical properties and in facilitating the prediction of aneurysm rupture. A successful computational study relies on an accurate description of the vascular geometry that is obtained from volumetric images. METHODS The authors propose a new aneurysm segmentation algorithm to facilitate the study of CFD. This software combines a region-growing segmentation method with the 3D extension of a deformable contour based on a charged fluid model. A charged fluid model essentially consists of a set of charged elements that are governed by the nature of electrostatics. The approach requires no prior knowledge of anatomic structures and automatically segments the vasculature after the end-user selects a vessel section in a plane image. RESULTS Experimental results on 15 cases indicate that aneurysm structures were effectively segmented and in good agreement with manual delineation outcomes. In comparison with the existing methods, the algorithm provided a much higher overlap index with respect to the ground truth. Furthermore, the outcomes of the proposed approach achieved a clean representation of vascular structures that is advantageous for hemodynamics analyses. CONCLUSIONS A new aneurysm segmentation framework in an attempt to automatically segment vascular structures in 3DRA image volumes has been developed. The proposed algorithm demonstrated promising performance and unique characteristics to adequately segment aneurysms in 3DRA image volumes for further study in computational fluid dynamics.
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Affiliation(s)
- Herng-Hua Chang
- Institute of Biomedical Engineering, National Yang-Ming University, 155 Linong Street, Section 2, Beitou, Taipei 112, Taiwan
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Cebral JR, Sheridan M, Putman CM. Hemodynamics and bleb formation in intracranial aneurysms. AJNR Am J Neuroradiol 2009; 31:304-10. [PMID: 19797790 DOI: 10.3174/ajnr.a1819] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Intracranial aneurysms with irregular shapes and blebs or secondary outpouchings have been correlated with increased rupture risk. The purpose of this study was to investigate possible associations between the local hemodynamics and the formation of blebs in cerebral aneurysms. MATERIALS AND METHODS Computational models of 20 cerebral aneurysms harboring 30 well-defined blebs were constructed from 3D rotational angiographies. Models representing the aneurysm before bleb formation were constructed by virtually removing the blebs from the anatomic models. Computational fluid dynamics simulations of the aneurysm before and after bleb formation were performed under pulsatile flows. Flow and WSS visualizations were used to analyze the local hemodynamics in the region of the aneurysm that developed the bleb. RESULTS Most blebs (80%) occurred at or adjacent to the aneurysm region with the highest WSS before bleb formation, and near the flow impaction zone. Most blebs (83%) were found in regions of the aneurysm previously subjected to high or moderate WSS and progressed to low WSS states after the blebs were formed. Most blebs (77%) were aligned or adjacent to the inflow jet, whereas 17% were aligned with the outflow jet, and only 6% were not aligned with the flow direction. In addition, 90% of the aneurysms had maximal WSS higher than or similar to the WSS in the parent artery. CONCLUSIONS Blebs form at or adjacent to regions of high WSS and are aligned with major intra-aneurysmal flow structures. Formation of blebs results in a lower WSS state with formation of a counter current vortex. These findings imply that locally elevated WSS could contribute to the focalized wall damage that formed these structures.
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Affiliation(s)
- J R Cebral
- Center for Computational Fluid Dynamics, Department of Computational and Data Sciences, College of Sciences, George Mason University, Fairfax, Virginia 22030, USA.
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Reichold J, Stampanoni M, Lena Keller A, Buck A, Jenny P, Weber B. Vascular graph model to simulate the cerebral blood flow in realistic vascular networks. J Cereb Blood Flow Metab 2009; 29:1429-43. [PMID: 19436317 DOI: 10.1038/jcbfm.2009.58] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
At its most fundamental level, cerebral blood flow (CBF) may be modeled as fluid flow driven through a network of resistors by pressure gradients. The composition of the blood as well as the cross-sectional area and length of a vessel are the major determinants of its resistance to flow. Here, we introduce a vascular graph modeling framework based on these principles that can compute blood pressure, flow and scalar transport in realistic vascular networks. By embedding the network in a computational grid representative of brain tissue, the interaction between the two compartments can be captured in a truly three-dimensional manner and may be applied, among others, to simulate oxygen extraction from the vessels. Moreover, we have devised an upscaling algorithm that significantly reduces the computational expense and eliminates the need for detailed knowledge on the topology of the capillary bed. The vascular graph framework has been applied to investigate the effect of local vascular dilation and occlusion on the flow in the surrounding network.
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Transient stenotic-like occlusions as a possible mechanism for renovascular hypertension due to aneurysm. ACTA ACUST UNITED AC 2009; 3:192-200. [DOI: 10.1016/j.jash.2009.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 02/12/2009] [Accepted: 02/13/2009] [Indexed: 11/22/2022]
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Chien A, Castro MA, Tateshima S, Sayre J, Cebral J, Viñuela F. Quantitative hemodynamic analysis of brain aneurysms at different locations. AJNR Am J Neuroradiol 2009; 30:1507-12. [PMID: 19406766 DOI: 10.3174/ajnr.a1600] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Studies have shown that the occurrence of brain aneurysms and risk of rupture vary between locations. However, the reason that aneurysms at different branches of the cerebral arteries have different clinical presentations is not clear. Because research has indicated that aneurysm hemodynamics may be one of the important factors related to aneurysm growth and rupture, our aim was to analyze and compare the flow parameters in aneurysms at different locations. MATERIALS AND METHODS A total of 24 patient-specific aneurysm models were constructed by using 3D rotational angiographic data for the hemodynamic simulation. Previously developed computational fluid dynamics software was applied to each aneurysm to simulate the blood-flow properties. Hemodynamic data at peak pulsatile flow were recorded, and wall shear stress (WSS) and flow rate in the aneurysms and parent arteries were quantitatively compared. To validate our method, a comparison with a previously reported technique was also performed. RESULTS WSS and flow rate in the aneurysms at the peak of the cardiac cycle were found to differ in magnitude between different locations. Multiple comparisons among locations showed higher WSS and flow rate in middle cerebral artery aneurysms and lower WSS and flow rate in basilar artery and anterior communicating artery aneurysms. CONCLUSIONS We observed changes in hemodynamic values that may be related to aneurysm location. Further study of aneurysm locations with a large number of cases is needed to test this hypothesis.
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Affiliation(s)
- A Chien
- Division of Interventional Neuroradiology, David Geffen School of Medicine, University of California-Los Angeles, 10833 LeConte Avenue, Los Angeles, CA 90095, USA.
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Grinberg L, Anor T, Madsen JR, Yakhot A, Karniadakis GE. LARGE-SCALE SIMULATION OF THE HUMAN ARTERIAL TREE. Clin Exp Pharmacol Physiol 2009; 36:194-205. [DOI: 10.1111/j.1440-1681.2008.05010.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Castro MA, Putman CM, Sheridan MJ, Cebral JR. Hemodynamic patterns of anterior communicating artery aneurysms: a possible association with rupture. AJNR Am J Neuroradiol 2009; 30:297-302. [PMID: 19131411 DOI: 10.3174/ajnr.a1323] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The anterior communicating artery (AcomA) is a predilect location of aneurysms which typically carry higher rupture risks than other locations in the anterior circulation. The purpose of this study was to characterize the different flow types present in AcomA aneurysms and to investigate possible associations with rupture. MATERIALS AND METHODS Patient-specific computational models of 26 AcomA aneurysms were constructed from 3D rotational angiography images. Bilateral images were acquired in 15 patients who had both A1 segments of the anterior cerebral arteries, and models of the whole anterior circulation were created by fusing the reconstructed left and right arterial trees. Computational fluid dynamics simulations were performed under pulsatile flow conditions measured on a healthy subject. Visualizations of flow velocity, instantaneous streamlines, and wall shear stress (WSS) were performed. These were analyzed for flow patterns, size of the impaction zone, and peak WSS and then correlations were made with prior history of rupture. RESULTS Aneurysms with small impaction zones were more likely to have ruptured than those with large impaction zones (83% versus 63%). Maximum intra-aneurysmal WSS (MWSS) for the unruptured aneurysms ranged from 10 to 230 dyne/cm(2) (mean, 114 dyne/cm(2)) compared with ruptured aneurysms, which ranged from 35 to 1500 dyne/cm(2) (mean, 271 dyne/cm(2)). This difference in MWSS was statistically significant at 90% confidence levels (P = .10). CONCLUSIONS Aneurysms with small impaction zones, higher flow rates entering the aneurysm, and elevated MWSS are associated with a clinical history of previous rupture.
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Affiliation(s)
- M A Castro
- Department of Computational and Data Sciences, College of Sciences, George Mason University, Fairfax, Va., USA
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Abstract
Advances in numerical methods and three-dimensional imaging techniques have enabled the quantification of cardiovascular mechanics in subject-specific anatomic and physiologic models. Patient-specific models are being used to guide cell culture and animal experiments and test hypotheses related to the role of biomechanical factors in vascular diseases. Furthermore, biomechanical models based on noninvasive medical imaging could provide invaluable data on the in vivo service environment where cardiovascular devices are employed and on the effect of the devices on physiologic function. Finally, patient-specific modeling has enabled an entirely new application of cardiovascular mechanics, namely predicting outcomes of alternate therapeutic interventions for individual patients. We review methods to create anatomic and physiologic models, obtain properties, assign boundary conditions, and solve the equations governing blood flow and vessel wall dynamics. Applications of patient-specific models of cardiovascular mechanics are presented, followed by a discussion of the challenges and opportunities that lie ahead.
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Affiliation(s)
- C.A. Taylor
- Department of Bioengineering, Stanford University, Stanford, California;
| | - C.A. Figueroa
- Department of Bioengineering, Stanford University, Stanford, California;
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Hemodynamics and cerebrovascular disease. ACTA ACUST UNITED AC 2008; 70:447-53. [DOI: 10.1016/j.surneu.2008.07.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Accepted: 07/16/2008] [Indexed: 11/20/2022]
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Chien A, Tateshima S, Castro M, Sayre J, Cebral J, Viñuela F. Patient-specific flow analysis of brain aneurysms at a single location: comparison of hemodynamic characteristics in small aneurysms. Med Biol Eng Comput 2008; 46:1113-20. [DOI: 10.1007/s11517-008-0400-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 09/17/2008] [Indexed: 10/21/2022]
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Sato K, Imai Y, Ishikawa T, Matsuki N, Yamaguchi T. The importance of parent artery geometry in intra-aneurysmal hemodynamics. Med Eng Phys 2008; 30:774-82. [DOI: 10.1016/j.medengphy.2007.09.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Kakalis NMP, Mitsos AP, Byrne JV, Ventikos Y. The haemodynamics of endovascular aneurysm treatment: a computational modelling approach for estimating the influence of multiple coil deployment. IEEE TRANSACTIONS ON MEDICAL IMAGING 2008; 27:814-824. [PMID: 18541488 DOI: 10.1109/tmi.2008.915549] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This paper proposes a novel computational methodology for modelling the haemodynamic effects of endovascular coil embolization for cerebral aneurysms. We employ high-resolution 3-D angiographic data to reconstruct the intracranial geometry and we model the coiled part of the aneurysm as a porous medium, with porosity decreasing as coils are inserted. The actual dimensions of the coils employed are used to determine the characteristics of the porous medium. Simulation results for saccular aneurysms from the anterior communicating and middle cerebral arteries show that insertion of coils rapidly changes intraaneurysmal blood flow and causes reduction in mural pressure and blood velocity up to stagnation, providing favorable conditions for thrombus formation and obliteration of the aneurysm.
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Affiliation(s)
- Nikolaos M P Kakalis
- Department of Engineering Science and the Institute of Biomedical Engineering, University of Oxford, Oxford OX1 3PJ, UK
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3-Dimensional rotational angiography for the treatment of spinal cord vascular malformations. ACTA ACUST UNITED AC 2008; 69:369-73; discussion 373-4. [DOI: 10.1016/j.surneu.2007.03.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Accepted: 03/01/2007] [Indexed: 11/19/2022]
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Mynard JP, Nithiarasu P. A 1D arterial blood flow model incorporating ventricular pressure, aortic valve and regional coronary flow using the locally conservative Galerkin (LCG) method. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/cnm.1117] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Haemodynamic simulation of aneurysm coiling in an anatomically accurate computational fluid dynamics model: technical note. Neuroradiology 2007; 50:341-7. [DOI: 10.1007/s00234-007-0334-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Accepted: 10/17/2007] [Indexed: 11/26/2022]
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Hoh BL, Sistrom CL, Firment CS, Fautheree GL, Velat GJ, Whiting JH, Reavey-Cantwell JF, Lewis SB. BOTTLENECK FACTOR AND HEIGHT-WIDTH RATIO. Neurosurgery 2007; 61:716-22; discussion 722-3. [DOI: 10.1227/01.neu.0000298899.77097.bf] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
OBJECTIVE
Determining factors predictive of the natural risk of rupture of cerebral aneurysms is difficult because of the need to control for confounding variables. We studied factors associated with rupture in a study model of patients with multiple cerebral aneurysms, one aneurysm that had ruptured and one or more that had not, in which each patient served as their own internal control.
METHODS
We collected aneurysm location, one-dimensional measurements, and two-dimensional indices from the computed tomographic angiograms of patients in the proposed study model and compared ruptured versus unruptured aneurysms. Bivariate statistics were supplemented with multivariable logistic regression analysis to model ruptured status. A total of 40 candidate models were evaluated for predictive power and fit with Wald scoring, Cox and Snell R2, Hosmer and Lemeshow tests, case classification counting, and residual analysis to determine which of the computed tomographic angiographic measurements or indices were jointly associated with and predictive of aneurysm rupture.
RESULTS
Thirty patients with 67 aneurysms (30 ruptured, 37 unruptured) were studied. Maximum diameter, height, maximum width, bulge height, parent artery diameter, aspect ratio, bottleneck factor, and aneurysm/parent artery ratio were significantly (P < 0.05) associated with ruptured aneurysms on bivariate analysis. When best subsets and stepwise multivariable logistic regression was performed, bottleneck factor (odds ratio = 1.25, confidence interval = 1.11–1.41 for every 0.1 increase) and height-width ratio (odds ratio = 1.23, confidence interval = 1.03–1.47 for every 0.1 increase) were the only measures that were significantly predictive of rupture.
CONCLUSION
In a case-control study of patients with multiple cerebral aneurysms, increased bottleneck factor and height-width ratio were consistently associated with rupture.
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Affiliation(s)
- Brian L. Hoh
- Department of Neurological Surgery, University of Florida College of Medicine, Gainesville, Florida
| | - Christopher L. Sistrom
- Department of Radiology, University of Florida College of Medicine, Gainesville, Florida
| | - Christopher S. Firment
- Department of Radiology, University of Florida College of Medicine, Gainesville, Florida
| | - Gregory L. Fautheree
- Department of Neurological Surgery, University of Florida College of Medicine, Gainesville, Florida
| | - Gregory J. Velat
- Department of Neurological Surgery, University of Florida College of Medicine, Gainesville, Florida
| | - Jobyna H. Whiting
- Department of Neurological Surgery, University of Florida College of Medicine, Gainesville, Florida
| | - John F. Reavey-Cantwell
- Department of Neurological Surgery, University of Florida College of Medicine, Gainesville, Florida
| | - Stephen B. Lewis
- Department of Neurological Surgery, University of Florida College of Medicine, Gainesville, Florida
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Moftakhar R, Aagaard-Kienitz B, Johnson K, Turski PA, Turk AS, Niemann DB, Consigny D, Grinde J, Wieben O, Mistretta CA. Noninvasive measurement of intra-aneurysmal pressure and flow pattern using phase contrast with vastly undersampled isotropic projection imaging. AJNR Am J Neuroradiol 2007; 28:1710-4. [PMID: 17885239 PMCID: PMC8134201 DOI: 10.3174/ajnr.a0648] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Currently, more reliable parameters to predict the risk of aneurysmal rupture are needed. Intra-aneurysmal pressure gradients and flow maps could provide additional information regarding the risk of rupture. Our hypothesis was that phase contrast with vastly undersampled isotropic projection reconstruction (PC-VIPR), a novel 3D MR imaging sequence, could accurately assess intra-aneurysmal pressure gradients in a canine aneurysmal model when compared with invasive measurements. MATERIALS AND METHODS A total of 13 surgically created aneurysms in 8 canines were included in this study. Pressure measurements were performed in the parent vessel, aneurysm neck, and 5 regions within the aneurysmal sac with a microcatheter. PC-VIPR sequence was used to obtain cardiac-gated velocity measurements in a region covering the entire aneurysm. The velocity and pressure gradient maps derived from the PC-VIPR data were then coregistered with the anatomic DSA images and compared with catheter measurements. RESULTS In 7 of the bifurcation aneurysms, the velocity flow maps demonstrated a recirculation flow pattern with a small neck-to-dome pressure gradient (mean, +0.5 mm Hg). In 1 bifurcation aneurysm, a flow jet extending from the neck to the dome with significantly greater pressure gradient (+50.2 mm Hg) was observed. All sidewall aneurysms had low flow in the sac with intermediate pressure gradients (mean, +8.3 mm Hg). High statistical correlation existed between PC-VIPR aneurysmal pressures and microcatheter pressure measurements (R = 0.82, P < .01). CONCLUSION PC-VIPR can provide anatomic as well as noninvasive quantitative and qualitative hemodynamic information in the canine aneurysm model. The PC-VIPR intra-aneurysmal pressure measurements correlated well with catheter measurements.
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Affiliation(s)
- R Moftakhar
- Department of Neurosurgery, University of Wisconsin Hospital and Clinics, Madison, WI 53792, USA
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Cebral JR, Pergolizzi RS, Putman CM. Computational fluid dynamics modeling of intracranial aneurysms: qualitative comparison with cerebral angiography. Acad Radiol 2007; 14:804-13. [PMID: 17574131 DOI: 10.1016/j.acra.2007.03.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 03/08/2007] [Accepted: 03/09/2007] [Indexed: 11/23/2022]
Abstract
RATIONALE AND OBJECTIVE The purpose of this study is to determine whether computational fluid dynamics modeling can correctly predict the location of the major intra-aneurysmal flow structures that can be identified by conventional angiography. MATERIALS AND METHODS Patient-specific models of three cerebral aneurysms were constructed from three-dimensional rotational angiography images and computational fluid dynamic simulations performed. Using these velocity fields, contrast transport was simulated and visualizations constructed to provide a "virtual" angiogram. These models were then compared to images from high frame rate conventional angiography to compare flow structures. RESULTS Computational fluid dynamics simulations showed three distinct flow types ranging from simple to complex. Virtual angiographic images showed good agreement with images from conventional angiography for all three aneurysms with analogous size and orientation of the inflow jet, regions of impaction, and flow type. Large intra-aneurysmal vortices and regions of outflow also corresponded between the images. CONCLUSIONS Patient-specific image-based computational models of cerebral aneurysms can realistically reproduce the major intra-aneurysmal flow structures observed with conventional angiography. The agreement between computational models and angiographic structures is less for slower zones of recirculation later in the cardiac cycle.
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Affiliation(s)
- Juan R Cebral
- School of Computational Sciences, George Mason University, Fairfax, VA 22030, USA
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