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A Brush-Spin-Coating Method for Fabricating In Vitro Patient-Specific Vascular Models by Coupling 3D-Printing. Cardiovasc Eng Technol 2020; 12:200-214. [PMID: 33263929 DOI: 10.1007/s13239-020-00504-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 11/18/2020] [Indexed: 12/31/2022]
Abstract
PURPOSE In vitro patient-specific flexible vascular models are helpful for understanding the haemodynamic changes before and after endovascular treatment and for effective training of neuroendovascular interventionalists. However, it is difficult to fabricate models of overall unified or controllable thickness using existing manufacturing methods. In this study, we developed an improved and easily implemented method by combining 3D printing and brush-spin-coating processes to produce a transparent silicone model of uniform or varied thickness. METHODS First, a water-soluble inner-skeleton model, based on clinical data, was printed on a 3D printer. The skeleton model was subsequently fixed in a single-axis-rotation machine to enable continuous coating of silicone, the thickness of which was manually controlled by adsorption and removal of excess silicone in a brush-spinning operation. After the silicone layer was solidified, the inner skeleton was further dissolved in a hot water bath, affording a transparent vascular model with real geometry. To verify the controllability of the coating thickness by using this method, a straight tube, an idealised aneurysm model, a patient-specific aortic arch model, and an abdominal aortic aneurysm model were manufactured. RESULTS The different thicknesses of the manufactured tubes could be well controlled, with the relative standard deviations being 5.6 and 8.1% for the straight and aneurysm tubes, respectively. Despite of the diameter changing from 33 to 20 mm in the patient-specific aorta, the thickness of the fabricated aortic model remains almost the same along the longitudinal direction with a lower standard deviation of 3.1%. In the more complex patient-specific abdominal aneurysm model, varied thicknesses were realized to mimic the measured data from the CT images, where the middle of the aneurysm was with 2 mm and abdominal aorta as well as the iliac arteries had the normal thickness of 2.3 mm. CONCLUSION Through the brush-spin-coating method, models of different sizes and complexity with prescribed thickness can be manufactured, which will be helpful for developing surgical treatment strategies or training neuroendovascular interventionalists.
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Wan H, Lu G, Huang L, Ge L, Jiang Y, Li G, Leng X, Xiang J, Zhang X. Hemodynamic Effect of the Last Finishing Coils in Packing the Aneurysm Neck. Front Neurol 2020; 11:598412. [PMID: 33329354 PMCID: PMC7714910 DOI: 10.3389/fneur.2020.598412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 10/15/2020] [Indexed: 11/13/2022] Open
Abstract
Background: Using the finishing coils to densely pack the aneurysm neck is necessary. However, the exact hemodynamic effect of finishing coils in packing the aneurysm neck is unknown. Objective: To evaluate the hemodynamic characteristics of finishing coils to densely pack the aneurysm neck, using finite element method simulation. Methods: A computational study was performed based on a 44-year-old female patient with an unruptured wide-necked carotid-ophthalmic artery aneurysm treated with low-profile visualized intraluminal support stent-assisted coil embolization. Four computational fluid dynamics models including pre-treatment, post-stenting, common stent-assisted coil embolization (SACE), and common SACE with finishing coils were evaluated qualitatively and quantitatively. Results: Compared with the baseline of pretreatment model (100%), sac-averaged velocity in post-stenting, common SACE, and common SACE with finishing coil models decreased to 95.68%, 24.38%, and 13.20%, respectively; high flow volume (>0.1 m/s) around the aneurysm neck decreased to 92.19%, 9.59%, and 5.57%, respectively; and mean wall shear stress increased or decreased to 107%, 25.94%, and 23.89%, respectively. Conclusion: Finishing coils to densely pack the aneurysm neck can generate favorable hemodynamic modifications, which may decrease the recurrence.
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Affiliation(s)
- Hailin Wan
- Huashan Hospital, Fudan University, Shanghai, China
| | - Gang Lu
- Huashan Hospital, Fudan University, Shanghai, China
| | - Lei Huang
- Huashan Hospital, Fudan University, Shanghai, China
| | - Liang Ge
- Huashan Hospital, Fudan University, Shanghai, China
| | - Yeqing Jiang
- Huashan Hospital, Fudan University, Shanghai, China
| | - Gaohui Li
- ArteryFlow Technology Co., Ltd, Hangzhou, China
| | | | | | - Xiaolong Zhang
- Huashan Hospital, Fudan University, Shanghai, China
- *Correspondence: Xiaolong Zhang
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Mazzi V, Gallo D, Calò K, Najafi M, Khan MO, De Nisco G, Steinman DA, Morbiducci U. A Eulerian method to analyze wall shear stress fixed points and manifolds in cardiovascular flows. Biomech Model Mechanobiol 2019; 19:1403-1423. [PMID: 31865482 DOI: 10.1007/s10237-019-01278-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 12/08/2019] [Indexed: 12/12/2022]
Abstract
Based upon dynamical systems theory, a fixed point of a vector field such as the wall shear stress (WSS) at the luminal surface of a vessel is a point where the vector field vanishes. Unstable/stable manifolds identify contraction/expansion regions linking fixed points. The significance of such WSS topological features lies in their strong link with "disturbed" flow features like flow stagnation, separation and reversal, deemed responsible for vascular dysfunction initiation and progression. Here, we present a Eulerian method to analyze WSS topological skeleton through the identification and classification of WSS fixed points and manifolds in complex vascular geometries. The method rests on the volume contraction theory and analyzes the WSS topological skeleton through the WSS vector field divergence and Poincar[Formula: see text] index. The method is here applied to computational hemodynamics models of carotid bifurcation and intracranial aneurysm. An in-depth analysis of the time dependence of the WSS topological skeleton along the cardiac cycle is provided, enriching the information obtained from cycle-average WSS. Among the main findings, it emerges that on the carotid bifurcation, instantaneous WSS fixed points co-localize with cycle-average WSS fixed points for a fraction of the cardiac cycle ranging from 0 to [Formula: see text]; a persistent instantaneous WSS fixed point confined on the aneurysm dome does not co-localize with the cycle-average low-WSS region. In conclusion, the here presented approach shows the potential to speed up studies on the physiological significance of WSS topological skeleton in cardiovascular flows, ultimately increasing the chance of finding mechanistic explanations to clinical observations.
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Affiliation(s)
- Valentina Mazzi
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
- PolitoBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Diego Gallo
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
- PolitoBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Karol Calò
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
- PolitoBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Mehdi Najafi
- Biomedical Simulation Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | | | - Giuseppe De Nisco
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
- PolitoBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - David A Steinman
- Biomedical Simulation Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Umberto Morbiducci
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy.
- PolitoBIOMed Lab, Politecnico di Torino, Turin, Italy.
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Abstract
The region where the vascular lumen meets the surrounding endothelium cell layer, hence the interface region between haemodynamics and cell tissue, is of primary importance in the physiological functions of the cardiovascular system. The functions include mass transport to/from the blood and tissue, and signalling via mechanotransduction, which are primary functions of the cardiovascular system and abnormalities in these functions are known to affect disease formation and vascular remodelling. This region is denoted by the near-wall region in the present work, and we outline simple yet effective numerical recipes to analyse the near-wall flow field. Computational haemodynamics solutions are presented for six patient specific cerebral aneurysms, at three instances in the cardiac cycle: peak systole, end systole (taken as dicrotic notch) and end diastole. A sensitivity study, based on Newtonian and non-Newtonian rheological models, and different flow rate profiles, is effected for a selection of aneurysm cases. The near-wall flow field is described by the wall shear stress (WSS) and the divergence of wall shear stress (WSSdiv), as descriptors of tangential and normal velocity components, respectively, as well as the wall shear stress critical points. Relations between near-wall and free-stream flow fields are discussed.
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Arzani A, Shadden SC. Wall shear stress fixed points in cardiovascular fluid mechanics. J Biomech 2018; 73:145-152. [DOI: 10.1016/j.jbiomech.2018.03.034] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/09/2018] [Accepted: 03/21/2018] [Indexed: 12/13/2022]
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Kawakami T, Takao H, Ichikawa C, Kamiya K, Murayama Y, Motosuke M. The impact of deformation of an aneurysm model under pulsatile flow on hemodynamic analysis. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2016:2668-2671. [PMID: 28268870 DOI: 10.1109/embc.2016.7591279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Hemodynamic analysis of cerebral aneurysms has been widely carried out to clarify the mechanisms of their growth and rupture. In several cases, patient-specific aneurysm models made of transparent polymers have been used. Even though periodic changes in aneurysms due to the pulsation of blood flow could be important, the deformation of the model geometry and its effect on hemodynamic evaluation has not been fully investigated. In addition, the fabrication accuracy of aneurysm models has not been evaluated even though it may affect the hemodynamic parameters to be analyzed. In this study, the fabrication accuracy of a silicone aneurysm model was investigated. Additionally, the deformation of the model under pulsatile flow as well as its correlation with flow behavior was evaluated. Consequently, a fabrication method for an aneurysm model with high accuracy was established and the importance of the wall thickness of the model was also specified.
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Lawonn K, Glaßer S, Vilanova A, Preim B, Isenberg T. Occlusion-free Blood Flow Animation with Wall Thickness Visualization. IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2016; 22:728-737. [PMID: 26529724 DOI: 10.1109/tvcg.2015.2467961] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present the first visualization tool that combines pathlines from blood flow and wall thickness information. Our method uses illustrative techniques to provide occlusion-free visualization of the flow. We thus offer medical researchers an effective visual analysis tool for aneurysm treatment risk assessment. Such aneurysms bear a high risk of rupture and significant treatment-related risks. Therefore, to get a fully informed decision it is essential to both investigate the vessel morphology and the hemodynamic data. Ongoing research emphasizes the importance of analyzing the wall thickness in risk assessment. Our combination of blood flow visualization and wall thickness representation is a significant improvement for the exploration and analysis of aneurysms. As all presented information is spatially intertwined, occlusion problems occur. We solve these occlusion problems by dynamic cutaway surfaces. We combine this approach with a glyph-based blood flow representation and a visual mapping of wall thickness onto the vessel surface. We developed a GPU-based implementation of our visualizations which facilitates wall thickness analysis through real-time rendering and flexible interactive data exploration mechanisms. We designed our techniques in collaboration with domain experts, and we provide details about the evaluation of the technique and tool.
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Kim BJ, Ha H, Huh HK, Kim GB, Kim JS, Kim N, Lee SJ, Kang DW, Kwon SU. Post-stenotic Recirculating Flow May Cause Hemodynamic Perforator Infarction. J Stroke 2015; 18:66-72. [PMID: 26687122 PMCID: PMC4747075 DOI: 10.5853/jos.2015.01445] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Revised: 10/05/2015] [Accepted: 10/17/2015] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND AND PURPOSE The primary mechanism underlying paramedian pontine infarction (PPI) is atheroma obliterating the perforators. Here, we encountered a patient with PPI in the post-stenotic area of basilar artery (BA) without a plaque, shown by high-resolution magnetic resonance imaging (HR-MRI). We performed an experiment using a 3D-printed BA model and a particle image velocimetry (PIV) to explore the hemodynamic property of the post-stenotic area and the mechanism of PPI. METHODS 3D-model of a BA stenosis was reconstructed with silicone compound using a 3D-printer based on the source image of HR-MRI. Working fluid seeded with fluorescence particles was used and the velocity of those particles was measured horizontally and vertically. Furthermore, microtubules were inserted into the posterior aspect of the model to measure the flow rates of perforators (pre-and post-stenotic areas). The flow rates were compared between the microtubules. RESULTS A recirculating flow was observed from the post-stenotic area in both directions forming a spiral shape. The velocity of the flow in these regions of recirculation was about one-tenth that of the flow in other regions. The location of recirculating flow well corresponded with the area with low-signal intensity at the time-of-flight magnetic resonance angiography and the location of PPI. Finally, the flow rate through the microtubule inserted into the post-stenotic area was significantly decreased comparing to others (P<0.001). CONCLUSIONS Perforator infarction may be caused by a hemodynamic mechanism altered by stenosis that induces a recirculation flow. 3D-printed modeling and PIV are helpful understanding the hemodynamics of intracranial stenosis.
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Affiliation(s)
- Bum Joon Kim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Hojin Ha
- Center for Biofluid and Biomimic Research, Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Korea
| | - Hyung Kyu Huh
- Center for Biofluid and Biomimic Research, Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Korea
| | - Guk Bae Kim
- Asan Institute of Life Science, Asan Medical Center, Seoul, Korea
| | - Jong S Kim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Namkug Kim
- Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.,Department of Convergence Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Sang-Joon Lee
- Center for Biofluid and Biomimic Research, Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Korea
| | - Dong-Wha Kang
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Sun U Kwon
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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Anderson JR, Thompson WL, Alkattan AK, Diaz O, Klucznik R, Zhang YJ, Britz GW, Grossman RG, Karmonik C. Three-dimensional printing of anatomically accurate, patient specific intracranial aneurysm models. J Neurointerv Surg 2015; 8:517-20. [PMID: 25862767 DOI: 10.1136/neurintsurg-2015-011686] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 03/23/2015] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To develop and validate a method for creating realistic, patient specific replicas of cerebral aneurysms by means of fused deposition modeling. METHODS The luminal boundaries of 10 cerebral aneurysms, together with adjacent proximal and distal sections of the parent artery, were segmented based on DSA images, and corresponding virtual three-dimensional (3D) surface reconstructions were created. From these, polylactic acid and MakerBot Flexible Filament replicas of each aneurysm were created by means of fused deposition modeling. The accuracy of the replicas was assessed by quantifying statistical significance in the variations of their inner dimensions relative to 3D DSA images. Feasibility for using these replicas as flow phantoms in combination with phase contrast MRI was demonstrated. RESULTS 3D printed aneurysm models were created for all 10 subjects. Good agreement was seen between the models and the source anatomy. Aneurysm diameter measurements of the printed models and source images correlated well (r=0.999; p<0.001), with no statistically significant group difference (p=0.4) or observed bias. The SDs of the measurements were 0.5 mm and 0.2 mm for source images and 3D models, respectively. 3D printed models could be imaged with flow via MRI. CONCLUSIONS The 3D printed aneurysm models presented were accurate and were able to be produced inhouse. These models can be used for previously cited applications, but their anatomical accuracy also enables their use as MRI flow phantoms for comparison with ongoing studies of computational fluid dynamics. Proof of principle imaging experiments confirm MRI flow phantom utility.
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Affiliation(s)
- Jeff R Anderson
- MRI Core, Houston Methodist Research Institute, Houston, Texas, USA
| | | | | | - Orlando Diaz
- Cerebrovascular Center, Houston Methodist Hospital, Houston, Texas, USA Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas, USA
| | - Richard Klucznik
- Cerebrovascular Center, Houston Methodist Hospital, Houston, Texas, USA Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas, USA
| | - Yi J Zhang
- Cerebrovascular Center, Houston Methodist Hospital, Houston, Texas, USA Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas, USA
| | - Gavin W Britz
- Cerebrovascular Center, Houston Methodist Hospital, Houston, Texas, USA Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas, USA
| | - Robert G Grossman
- Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas, USA
| | - Christof Karmonik
- MRI Core, Houston Methodist Research Institute, Houston, Texas, USA Cerebrovascular Center, Houston Methodist Hospital, Houston, Texas, USA Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas, USA
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Jeong W, Han M, Rhee K. The hemodynamic alterations induced by the vascular angular deformation in stent-assisted coiling of bifurcation aneurysms. Comput Biol Med 2014; 53:1-8. [DOI: 10.1016/j.compbiomed.2014.07.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 07/07/2014] [Accepted: 07/15/2014] [Indexed: 10/25/2022]
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Goubergrits L, Schaller J, Kertzscher U, Woelken T, Ringelstein M, Spuler A. Hemodynamic impact of cerebral aneurysm endovascular treatment devices: coils and flow diverters. Expert Rev Med Devices 2014; 11:361-73. [PMID: 24918904 DOI: 10.1586/17434440.2014.925395] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Coils and flow diverters or stents are devices successfully used to treat cerebral aneurysms. Treatment aims to reduce intra-aneurysmal flow, thereby separating the aneurysmal sac from the blood circulation. The focus and this manuscript combining literature review and our original research is an analysis of changes in aneurysmal hemodynamics caused by endovascular treatment devices. Knowledge of post-treatment hemodynamics is a path to successful long-term treatment. Summarizing findings on hemodynamic impact of treatment devices, we conclude: coiling and stenting do not affect post-treatment intra-aneurysmal pressure, but significantly alter aneurysmal hemodynamics through flow reduction and a change in flow structure. The impact of treatment devices on aneurysmal flow depends, however, on a set of parameters including device geometry, course of placement, parent vessel and aneurysm geometry.
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Affiliation(s)
- Leonid Goubergrits
- Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
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In vitro study of hemodynamic treatment improvement: Hunterian ligation of a fenestrated basilar artery aneurysm after coiling. Int J Artif Organs 2014; 37:325-35. [PMID: 24811187 DOI: 10.5301/ijao.5000314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2014] [Indexed: 11/20/2022]
Abstract
Hunterian ligation affecting hemodynamics in vessels was proposed to avoid rebleeding in a case of a fenestrated basilar artery aneurysm after incomplete coil occlusion. We studied the hemodynamics in vitro to predict the hemodynamic changes near the aneurysm remnant caused by Hunterian ligation. A transparent model was fabricated based on three-dimensional rotational angiography imaging. Arteries were segmented and reconstructed. Pulsatile flow in the artery segments near the partially occluded (coiled) aneurysm was investigated by means of particle image velocimetry. The hemodynamic situation was investigated before and after Hunterian ligation of either the left or the right vertebral artery (LVA/RVA). Since post-ligation flow rate in the basilar artery was unknown, reduced and retained flow rates were simulated for both ligation options. Flow in the RVA and in the corresponding fenestra vessel is characterized by a vortex at the vertebrobasilar junction, whereas the LVA exhibits undisturbed laminar flow. Both options (RVA or LVA ligation) cause a significant flow reduction near the aneurysm remnant with a retained flow rate. The impact of RVA ligation is, however, significantly higher. This in vitro case study shows that flow reduction near the aneurysm remnant can be achieved by Hunterian ligation and that this effect depends largely on the selection of the ligated vessel. Thus the ability of the proposed in vitro pipe-line to improve hemodynamic impact of the proposed therapy was successfully proved.
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Mine B, Pierot L, Lubicz B. Intrasaccular flow-diversion for treatment of intracranial aneurysms: the Woven EndoBridge. Expert Rev Med Devices 2014; 11:315-25. [PMID: 24694000 DOI: 10.1586/17434440.2014.907741] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Endovascular approach is now the first option for the treatment of most intracranial aneurysms (IA). However, remaining limitations are the suboptimal stability of aneurysm occlusion and the treatment of complex IA. The use of conventional and flow diverter stents has partially addressed these limitations. Nevertheless, as intraluminal devices, stents require aggressive antiplatelet therapy and are associated with higher thromboembolic (TE) complication rates. Intrasaccular flow disrupters (IFD) are newly developed braided-wire devices designed to achieve flow disruption at the neck without placing material in the parent vessel and without the need of antiplatelet therapy. First clinical series have shown promising anatomical and clinical results. Our purpose is to describe the available IFD and to review the literature about their efficacy, safety, limitations, and developments.
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Affiliation(s)
- Benjamin Mine
- Department of Diagnostic and Interventional Neuroradiology, Erasme University Hospital, Route de Lennik 808, 1070 Brussels, Belgium
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Park ST, Yoon K, Ko YB, Suh DC. Computational Fluid Dynamics of Intracranial and Extracranal Arteries using 3-Dimensional Angiography: Technical Considerations with Physician's Point of View. Neurointervention 2013; 8:92-100. [PMID: 24024073 PMCID: PMC3766807 DOI: 10.5469/neuroint.2013.8.2.92] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/23/2013] [Indexed: 11/24/2022] Open
Abstract
We investigate the potentials and limitations of computational fluid dynamics (CFD) analysis of patient specific models from 3D angiographies. There are many technical problems in acquisition of proper vascular models, in pre-processing for making 2D surface and 3D volume meshes and also in post-processing steps for display the CFD analysis. We hope that our study could serves as a technical reference to validating other tools and CFD results.
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Affiliation(s)
- Sung-Tae Park
- Department of Radiology, Soonchunhyang University Hospital, Seoul, Korea
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15
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Jeong W, Han MH, Rhee K. Effects of framing coil shape, orientation, and thickness on intra-aneurysmal flow. Med Biol Eng Comput 2013; 51:981-90. [DOI: 10.1007/s11517-013-1073-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 03/29/2013] [Indexed: 11/30/2022]
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16
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Morales HG, Larrabide I, Geers AJ, Dai D, Kallmes DF, Frangi AF. Analysis and quantification of endovascular coil distribution inside saccular aneurysms using histological images. J Neurointerv Surg 2012; 5 Suppl 3:iii33-7. [PMID: 22914746 DOI: 10.1136/neurintsurg-2012-010456] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE Endovascular coiling is often performed by first placing coils along the aneurysm wall to create a frame and then by filling up the aneurysm core. However, little attention has been paid to quantifying this filling strategy and to see how it changes for different packing densities. The purpose of this work is to analyze and quantify endovascular coil distribution inside aneurysms based on serial histological images of experimental aneurysms. METHOD Seventeen histological images from 10 elastase-induced saccular aneurysms in rabbits treated with coils were studied. In-slice coil density, defined as the area taken up by coil winds, was calculated on each histological image. Images were analyzed by partitioning the aneurysm along its longitudinal and radial axes. Coil distribution was quantified by measuring and comparing the in-slice coil density of each partition. RESULTS Mean total in-slice coil density was 22.0 ± 6.2% (range 10.1-30.2%). The density was non-significantly different (p = 0.465) along the longitudinal axis. A significant difference (p < 0.001) between peripheral and core densities was found. Additionally, the peripheral-core density ratio was observed to be inversely proportional to the total in-slice coil density (R(2)=0.57, p <0.001). This ratio was near unity for high in-slice coil density (around 30%). CONCLUSIONS These findings demonstrate and confirm that coils tend to be located near the aneurysm periphery when few are inserted. However, when more coils are added, the radial distribution becomes more homogeneous. Coils are homogeneously distributed along the longitudinal axis.
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Affiliation(s)
- Hernán G Morales
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Information and Communication Technologies Department, Universitat Pompeu Fabra, Barcelona, Spain
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Ugron Á, Szikora I, Paál G. Haemodynamic changes induced by intrasaccular packing on intracranial aneurysms: A computational fluid dynamic study. Interv Med Appl Sci 2012. [DOI: 10.1556/imas.4.2012.2.4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
Endovascular treatment of intracranial aneurysms is a routine medical practice. The most widely used technique is the packing the aneurysm sac with an embolic material. To gain deeper understanding in the effects of specific treatment methods, the intra-aneurysmal haemodynamics are studied with the help of patient-specific computational models. Numerical simulations demonstrated that embolisation with liquid polymer results in an overall decrease of the wall shear stress and pressure in the aneurysm region. Within the range of clinically relevant packing density, simulation of coil embolisation showed homogenisation and decrease of the wall loads on the aneurysm sac. Increasing the packing density above 20% produces little or no further reduction of intra-aneurysmal flow. Sufficient packing of the aneurysm sac results in significant intra-aneurysmal flow decrease associated with reduced wall loads but locally increased pressure or wall shear stress zones may appear depending on the specific vessel geometry.
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Affiliation(s)
- Ádám Ugron
- 1 Department of Hydrodynamic Systems, Budapest University of Technology and Economics, Budapest, Hungary
- 3 Budapest University of Technology and Economics, P.O. Box 91, H-1521, Budapest, Hungary
| | - István Szikora
- 2 National Institute of Neurosciences, Budapest, Hungary
| | - György Paál
- 1 Department of Hydrodynamic Systems, Budapest University of Technology and Economics, Budapest, Hungary
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18
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Morales HG, Kim M, Vivas EE, Villa-Uriol MC, Larrabide I, Sola T, Guimaraens L, Frangi AF. How do coil configuration and packing density influence intra-aneurysmal hemodynamics? AJNR Am J Neuroradiol 2011; 32:1935-41. [PMID: 21885712 DOI: 10.3174/ajnr.a2635] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Endovascular coiling is a well-established therapy for treating intracranial aneurysms. Nonetheless, postoperative hemodynamic changes induced by this therapy remain not fully understood. The purpose of this work is to assess the influence of coil configuration and packing density on intra-aneurysmal hemodynamics. MATERIALS AND METHODS Three 3D rotational angiography images of 3 intracranial aneurysms before and after endovascular coiling were used. For each aneurysm, a 3D representation of the vasculature was obtained after the segmentation of the images. Afterward, a virtual coiling technique was used to treat the aneurysm geometries with coil models. The aneurysms were coiled with 5 packing densities, and each was generated by using 3 coil configurations. Computational fluid dynamics analyses were carried out in both untreated and treated aneurysm geometries. Statistical tests were performed to evaluate the relative effect of coil configuration on local hemodynamics. RESULTS The intra-aneurysmal blood flow velocity and wall shear stress were diminished as packing density increased. Aneurysmal flow velocity was reduced >50% due to the first inserted coils (packing density <12%) but with a high dependency on coil configuration. Nonsignificant differences (P > .01) were found in the hemodynamics due to coil configuration for high packing densities (near 30%). A damping effect was observed on the intra-aneurysmal blood flow waveform after coiling. CONCLUSIONS Intra-aneurysmal hemodynamics are altered by coils. Coil configuration might reduce its influence on intra-aneurysmal hemodynamics as the packing density increases until an insignificant influence could be achieved for high packing densities.
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Affiliation(s)
- H G Morales
- Center for Computational Imaging & Simulation Technologies in Biomedicine, Information & Communication Technologies Department, Universitat Pompeu Fabra, Barcelona, Spain.
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Goubergrits L, Schaller J, Kertzscher U, van den Bruck N, Poethkow K, Petz C, Hege HC, Spuler A. Statistical wall shear stress maps of ruptured and unruptured middle cerebral artery aneurysms. J R Soc Interface 2011; 9:677-88. [PMID: 21957117 DOI: 10.1098/rsif.2011.0490] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Haemodynamics and morphology play an important role in the genesis, growth and rupture of cerebral aneurysms. The goal of this study was to generate and analyse statistical wall shear stress (WSS) distributions and shapes in middle cerebral artery (MCA) saccular aneurysms. Unsteady flow was simulated in seven ruptured and 15 unruptured MCA aneurysms. In order to compare these results, all geometries must be brought in a uniform coordinate system. For this, aneurysms with corresponding WSS data were transformed into a uniform spherical shape; then, all geometries were uniformly aligned in three-dimensional space. Subsequently, we compared statistical WSS maps and surfaces of ruptured and unruptured aneurysms. No significant (p > 0.05) differences exist between ruptured and unruptured aneurysms regarding radius and mean WSS. In unruptured aneurysms, statistical WSS map relates regions with high (greater than 3 Pa) WSS to the neck region. In ruptured aneurysms, additional areas with high WSS contiguous to regions of low (less than 1 Pa) WSS are found in the dome region. In ruptured aneurysms, we found significantly lower WSS. The averaged aneurysm surface of unruptured aneurysms is round shaped, whereas the averaged surface of ruptured cases is multi-lobular. Our results confirm the hypothesis of low WSS and irregular shape as the essential rupture risk parameters.
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Affiliation(s)
- L Goubergrits
- Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin, Berlin, Germany.
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