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Buchvald P, Capek L. Pre-selection blade size choice for the microsurgical clipping of cerebral artery aneurysms: A numerical study. J Clin Neurosci 2024; 122:25-31. [PMID: 38447246 DOI: 10.1016/j.jocn.2024.02.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 02/19/2024] [Accepted: 02/21/2024] [Indexed: 03/08/2024]
Abstract
BACKGROUND Brain strokes comprise the third leading cause of death worldwide. Microsurgical clipping is recognized as being one of the most effective approaches to the treatment of brain aneurysms. The incomplete closure of the distal-side aneurysm neck is the most common cause of the persistent filling of the dome. Since the diameter of the neck increases when the neck of the aneurysm is squeezed closed by the blades of the clip, the blades should be correspondingly longer. This study provided an assessment of whether the presurgical selection of clips using a 3D planning system is feasible in terms of selecting the most suitable clip for aneurysm occlusion. METHODS The computational model was created based on computer tomography data obtained from nine brain aneurysms. The closing of the aneurysm was provided in two steps. The first the length of the blades used for closing corresponded to the length of the aneurysm neck as confirmed by the radiological measurements. The second the length of the blades was adjusted according to stage one, so as to determine the minimum required for the closure of all the gaps in the interior space of the aneurysm neck. RESULTS No differences were detected between the radiological measurement of the aneurysm neck size and the measurements obtained from the reconstructed stereolithographic 3D models. It was observed that the size of the aneurysm neck increased following clipping by 40% to 60% of its original size. The larger the aneurysm neck, the greater the deformation of the aneurysm. CONCLUSION Firstly, the 3D reconstruction of CT/MRI data did not result in any loss of accuracy and the measurement of the neck of the aneurysm was the same for both of the methods employed. The second, and more important, outcome was that the deformation of the neck of the cerebral aneurysm is at least 1.4x greater than its original size. This information is essential in terms of the pre-selection of the size of the clip.
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Affiliation(s)
- Pavel Buchvald
- Dep. of Neurosurgery, Regional Hospital in Liberec, Czech Republic
| | - Lukas Capek
- Dep. Of Clinical Biomechanics, Regional Hospital in Liberec, Czech Republic; Technical University of Liberec, Czech Republic.
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Avril S, Gee MW, Hemmler A, Rugonyi S. Patient-specific computational modeling of endovascular aneurysm repair: State of the art and future directions. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3529. [PMID: 34490740 DOI: 10.1002/cnm.3529] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 08/30/2021] [Indexed: 06/13/2023]
Abstract
Endovascular aortic repair (EVAR) has become the preferred intervention option for aortic aneurysms and dissections. This is because EVAR is much less invasive than the alternative open surgery repair. While in-hospital mortality rates are smaller for EVAR than open repair (1%-2% vs. 3%-5%), the early benefits of EVAR are lost after 3 years due to larger rates of complications in the EVAR group. Clinicians follow instructions for use (IFU) when possible, but are left with personal experience on how to best proceed and what choices to make with respect to stent-graft (SG) model choice, sizing, procedural options, and their implications on long-term outcomes. Computational modeling of SG deployment in EVAR and tissue remodeling after intervention offers an alternative way of testing SG designs in silico, in a personalized way before intervention, to ultimately select the strategies leading to better outcomes. Further, computational modeling can be used in the optimal design of SGs in cases of complex geometries. In this review, we address some of the difficulties and successes associated with computational modeling of EVAR procedures. There is still work to be done in all areas of EVAR in silico modeling, including model validation, before models can be applied in the clinic, but much progress has already been made. Critical to clinical implementation are current efforts focusing on developing fast algorithms that can achieve (near) real-time solutions, as well as ways of dealing with inherent uncertainties related to patient aortic wall degradation on an individualized basis. We are optimistic that EVAR modeling in the clinic will soon become a reality to help clinicians optimize EVAR interventions and ultimately reduce EVAR-associated complications.
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Affiliation(s)
- Stéphane Avril
- Mines Saint-Étienne, Univ Lyon, Univ Jean Monnet, INSERM, Saint-Étienne, France
| | - Michael W Gee
- Mechanics & High Performance Computing Group, Department of Mechanical Engineering, Technical University of Munich, Garching, Germany
| | - André Hemmler
- Mechanics & High Performance Computing Group, Department of Mechanical Engineering, Technical University of Munich, Garching, Germany
| | - Sandra Rugonyi
- Biomedical Engineering Department, Oregon Health & Science University, Portland, Oregon, USA
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Santos GB, Oliveira I, Gasche JL, Militzer J, Baccin CE. Stent-Induced Vascular Remodeling in Two-Step Stent-Assisted Coiling Treatment of Brain Aneurysms: A Closer Look Into the Hemodynamic Changes During the Stent Healing Period. J Biomech Eng 2020; 143:1087599. [PMID: 33006371 DOI: 10.1115/1.4048645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Indexed: 11/08/2022]
Abstract
Stenting has become an important adjunctive tool for assisting coil embolization in complex-shaped intracranial aneurysms. However, as a secondary effect, stent deployment has been related to both immediate and delayed remodeling of the local vasculature. Recent studies have demonstrated that this phenomenon may assume different roles depending on the treatment stage. However, the extent of such event on the intra-aneurysmal hemodynamics is still unclear; especially when performing two-step stent-assisted coiling (SAC). Therefore, we performed computational fluid dynamics (CFD) analysis of the blood flow in four bifurcation aneurysms focusing on the stent healing period found in SAC as a two-step maneuver. Our results show that by changing the local vasculature, the intra-aneurysmal hemodynamics changes considerably. However, even though changes do occur, they were not consistent among the cases. Furthermore, by changing the local vasculature not only the shear levels change but also the shear distribution on the aneurysm surface. Additionally, a geometric analysis alone can mislead the estimation of the novel hemodynamic environment after vascular remodeling, especially in the presence of mixing streams. Therefore, although the novel local vasculature might induce an improved hemodynamic environment, it is also plausible to expect that adverse hemodynamic conditions might occur. This could pose a particularly delicate condition since the aneurysm surface remains completely exposed to the novel hemodynamic environment during the stent healing period. Finally, our study emphasizes that vascular remodeling should be considered when assessing the hemodynamics in aneurysms treated with stents, especially when evaluating the earlier stages of the treatment process.
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Affiliation(s)
- Gabriel B Santos
- Department of Mechanical Engineering, School of Engineering, São Paulo State University (UNESP), Ilha Solteira, São Paulo 15385-000, Brazil
| | - Iago Oliveira
- Department of Mechanical Engineering, School of Engineering, São Paulo State University (UNESP), Ilha Solteira, São Paulo 15385-000, Brazil
| | - José L Gasche
- Department of Mechanical Engineering, School of Engineering, São Paulo State University (UNESP), Ilha Solteira, São Paulo 15385-000, Brazil
| | - Julio Militzer
- Department of Mechanical Engineering, Faculty of Engineering, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Carlos E Baccin
- Interventional Neuroradiology, Hospital Israelita Albert Einstein, São Paulo, São Paulo 05652-900, Brazil
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Závodszky G, Csippa B, Paál G, Szikora I. A novel virtual flow diverter implantation method with realistic deployment mechanics and validated force response. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3340. [PMID: 32279440 PMCID: PMC7317397 DOI: 10.1002/cnm.3340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 04/01/2020] [Accepted: 04/02/2020] [Indexed: 06/11/2023]
Abstract
Virtual flow diverter deployment techniques underwent significant development during the last couple of years. Each existing technique displays advantageous features, as well as significant limitations. One common drawback is the lack of quantitative validation of the mechanics of the device. In the following work, we present a new spring-mass-based method with validated mechanical responses that combines many of the useful capabilities of previous techniques. The structure of the virtual braids naturally incorporates the axial length changes as a function of the local expansion diameter. The force response of the model was calibrated using the measured response of real FDs. The mechanics of the model allows to replicate the expansion process during deployment, including additional effects such as the push-pull technique that is required for the deployment of braided FDs to achieve full opening and proper wall apposition. Furthermore, it is a computationally highly efficient solution that requires little pre-processing and has a run-time of a few seconds on a general laptop and thus allows for exploratory analyses. The model was applied in a patient-specific geometry, where corresponding accurate control measurements in a 3D-printed model were also available. The analysis shows the effects of FD oversizing and push-pull application on the radial expansion, surface density, and on the wall contact pressure.
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Affiliation(s)
- Gábor Závodszky
- Computational Science Lab, Faculty of Science, Institute for InformaticsUniversity of AmsterdamAmsterdamNetherlands
- Department of Hydrodynamic SystemsBudapest University of Technology and EconomicsBudapestHungary
| | - Benjámin Csippa
- Department of Hydrodynamic SystemsBudapest University of Technology and EconomicsBudapestHungary
| | - György Paál
- Department of Hydrodynamic SystemsBudapest University of Technology and EconomicsBudapestHungary
| | - István Szikora
- Department of NeurointerventionsNational Institute of Clinical NeurosciencesBudapestHungary
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Hydrodynamic Resistance of Intracranial Flow-Diverter Stents: Measurement Description and Data Evaluation. Cardiovasc Eng Technol 2019; 11:1-13. [PMID: 31797262 PMCID: PMC7002337 DOI: 10.1007/s13239-019-00445-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 11/20/2019] [Indexed: 01/11/2023]
Abstract
Purpose Intracranial aneurysms are malformations forming bulges on the walls of brain arteries. A flow diverter device is a fine braided wire structure used for the endovascular treatment of brain aneurysms. This work presents a rig and a protocol for the measurement of the hydrodynamic resistance of flow diverter stents. Hydrodynamic resistance is interpreted here as the pressure loss versus volumetric flow rate function through the mesh structure. The difficulty of the measurement is the very low flow rate range and the extreme sensitivity to contamination and disturbances. Methods Rigorous attention was paid to reproducibility, hence a strict protocol was designed to ensure controlled circumstances and accuracy. Somewhat unusually, the history of the development of the rig, including the pitfalls was included in the paper. In addition to the hydrodynamic resistance measurements, the geometrical properties—metallic surface area, pore density, deployed and unconstrained length and diameter—of the stent deployment were measured. Results Based on our evaluation method a confidence band can be determined for a given deployment scenario. Collectively analysing the hydrodynamic resistance and the geometric indices, a deeper understanding of an implantation can be obtained. Our results suggest that to correctly interpret the hydrodynamic resistance of a scenario, the deployment length has to be considered. To demonstrate the applicability of the measurement, as a pilot study the results of four intracranial flow diverter stents of two types and sizes have been reported in this work. The results of these measurements even on this small sample size provide valuable information on differences between stent types and deployment scenarios.
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CFD-Based Comparison Study of a New Flow Diverting Stent and Commercially-Available Ones for the Treatment of Cerebral Aneurysms. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9071341] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Flow-diverting stents (FDSs) show considerable promise for the treatment of cerebral aneurysms by diverting blood flow away from the aneurysmal sacs, however, post-treatment complications such as failure of occlusion and subarachnoid haemorrhaging remain and vary with the FDS used. Based on computational fluid dynamics (CFD), this study aimed to investigate the performance of a new biodegradable stent as compared to two metallic commercially available FDSs. CFD models were developed for an idealized cerebral artery with a sidewall aneurysmal sac treated by deploying the aforementioned stents of different porosities (90, 80, and 70 % ) respectively. By using these models, the simulation and analysis were performed, with a focus on comparing the local hemodynamics or the blood flow in the stented arteries as compared to the one without the stent deployment. For the comparison, we computed and compared the flow velocity, wall shear stress (WSS) and pressure distributions, as well as the WSS related indices, all of which are of important parameters for studying the occlusion and potential rupture of the aneurysm. Our results illustrate that the WSS decreases within the aneurysmal sac on the treated arteries, which is more significant for the stents with lower porosity or finer mesh. Our results also show that the maximum WSS near the aneurysmal neck increases regardless of the stents used. In addition, the WSS related indices including the time-average WSS, oscillatory shear index and relative residence time show different distributions, depending on the FDSs. Together, we found that the finer mesh stents provide more flow reduction and smaller region characterized by high oscillatory shear index, while the new stent has a higher relative residence time.
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Joshi KC, Larrabide I, Saied A, Elsaid N, Fernandez H, Lopes DK. Software-based simulation for preprocedural assessment of braided stent sizing: a validation study. J Neurosurg 2018; 131:1423-1429. [PMID: 30497172 DOI: 10.3171/2018.5.jns18976] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 05/29/2018] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The authors sought to validate the use of a software-based simulation for preassessment of braided self-expanding stents in the treatment of wide-necked intracranial aneurysms. METHODS This was a retrospective, observational, single-center study of 13 unruptured and ruptured intracranial aneurysms treated with braided self-expanding stents. Pre- and postprocedural angiographic studies were analyzed. ANKYRAS software was used to compare the following 3 variables: the manufacturer-given nominal length (NL), software-calculated simulated length (SL), and the actual measured length (ML) of the stent. Appropriate statistical methods were used to draw correlations among the 3 lengths. RESULTS In this study, data obtained in 13 patients treated with braided self-expanding stents were analyzed. Data for the 3 lengths were collected for all patients. Error discrepancy was calculated by mean squared error (NL to ML -22.2; SL to ML -6.14, p < 0.05), mean absolute error (NL to ML 3.88; SL to ML -1.84, p < 0.05), and mean error (NL to ML -3.81; SL to ML -1.22, p < 0.05). CONCLUSIONS The ML was usually less than the NL given by the manufacturer, indicating significant change in length in most cases. Computational software-based simulation for preassessment of the braided self-expanding stents is a safe and effective way for accurately calculating the change in length to aid in choosing the right-sized stent for optimal placement in complex intracranial vasculature.
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Affiliation(s)
| | | | - Ahmed Saied
- 3Department of Neurology, Mansoura University, Mansoura, Egypt; and
| | - Nada Elsaid
- 1Department of Neurosurgery, Rush Medical Center, Chicago, Illinois
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8
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Casciaro ME, Dottori J, El-Batti S, Alsac JM, Mousseaux E, Larrabide I, Craiem D. Effects on Aortoiliac Fluid Dynamics After Endovascular Sealing of Abdominal Aneurysms. Vasc Endovascular Surg 2018; 52:621-628. [PMID: 30058480 DOI: 10.1177/1538574418791059] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES: To evaluate the effects on aortoiliac fluid dynamics after the implantation of an endograft based on endovascular aneurysm sealing (EVAS) versus endovascular aneurysm repair (EVAR) strategy. METHODS: An adaptive geometrical deformable model was used for aortic lumen segmentation in 8 patients before and after the surgery. Abdominal aneurysms were treated with an endograft based on the EVAS system (Nellix, n = 4) and with a device based on an anatomical fixation technology (n = 4). Pressure, blood velocity, and wall shear stress (WSS) were estimated at different aortic regions using computational fluid dynamics methods. Physiologic inlet/outlet flow values at the abdominal aorta, the celiac trunk, and the mesenteric and the renal arteries were set. Pressure references were set at iliac arteries outlet. RESULTS: Maximum aneurysm sizes were similar for both groups in the preoperative scans. The lumen area was lower after EVAR ( P < .05) and EVAS ( P < .01) compared to preoperative aortic lumen sizes. Pressure increase was higher in the proximal abdominal aorta after EVAS compared to EVAR (2.3 ± 0.3 mm Hg vs 0.9 ± 0.3 mm Hg, P < .001). Peak blood velocities inside the endografts were 3-fold higher for EVAS compared to EVAR (54 ± 5 cm/s vs 17 ± 4 cm/s, P < .01). Velocities at the iliac arteries also remained higher for EVAS (38 ± 4 cm/s vs 24 ± 4 cm/s, P < .05). Peak WSS at the iliac arteries remained higher for EVAS compared to EVAR group ( P < .05). CONCLUSION: The significant modification of the aortic bifurcation anatomy after EVAS alters aortoiliac fluid dynamics, showing a pressure impact at the renal arteries level and an acceleration of the blood velocity at the iliac region with a concomitant increase in peak WSS.
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Affiliation(s)
- Mariano E Casciaro
- 1 Instituto de Medicina Traslacional, Trasplante y Bioingeniería (IMeTTyB), Universidad Favaloro-CONICET, Buenos Aires, Argentina
| | | | - Salma El-Batti
- 3 APHP, Hôpital Européen Georges Pompidou, Paris, France
| | | | - Elie Mousseaux
- 3 APHP, Hôpital Européen Georges Pompidou, Paris, France
| | | | - Damian Craiem
- 1 Instituto de Medicina Traslacional, Trasplante y Bioingeniería (IMeTTyB), Universidad Favaloro-CONICET, Buenos Aires, Argentina.,3 APHP, Hôpital Européen Georges Pompidou, Paris, France
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9
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Zhang Q, Liu J, Zhang Y, Zhang Y, Tian Z, Li W, Chen J, Mo X, Cai Y, Paliwal N, Meng H, Wang Y, Wang S, Yang X. Efficient simulation of a low-profile visualized intraluminal support device: a novel fast virtual stenting technique. Chin Neurosurg J 2018; 4:6. [PMID: 32922867 PMCID: PMC7398371 DOI: 10.1186/s41016-018-0112-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 02/28/2018] [Indexed: 11/17/2022] Open
Abstract
Background The low-profile visualized intraluminal support (LVIS) stent has become a promising endovascular option for treating intracranial aneurysms. To achieve better treatment of aneurysms using LVIS, we developed a fast virtual stenting technique for use with LVIS (F-LVIS) to evaluate hemodynamic changes in the aneurysm and validate its reliability. Methods A patient-specific aneurysm was selected for making comparisons between the real LVIS (R-LVIS) and the F-LVIS. To perform R-LVIS stenting, a hollow phantom based on a patient-specific aneurysm was fabricated using a three-dimensional printer. An R-LVIS was released in the phantom according to standard procedure. F-LVIS was then applied successfully in this aneurysm model. The computational fluid dynamics (CFD) values were calculated for both the F-LVIS and R-LVIS models. Qualitative and quantitative comparisons of the two models focused on hemodynamic parameters. Results The hemodynamic characteristics for R-LVIS and F-LVIS were well matched. Representative contours of velocities and wall shear stress (WSS) were consistently similar in both distribution and magnitude. The velocity vectors also showed high similarity, although the R-LVIS model showed faster and more fluid streams entering the aneurysm. Variation tendencies of the velocity in the aneurysm and the WSS on the aneurysm wall were also similar in the two models, with no statistically significant differences in either velocity or WSS. Conclusions The results of the computational hemodynamics indicate that F-LVIS is suitable for evaluating hemodynamic factors. This novel F-LVIS is considered efficient, practical, and effective.
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Affiliation(s)
- Qianqian Zhang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jian Liu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yisen Zhang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Ying Zhang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Zhongbin Tian
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Wenqiang Li
- Department of Neurosurgery, The First Affiliated Hospital, Nanchang University, Nanchang, China
| | - Junfan Chen
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xiao Mo
- Capital Medical University School of Biomedical Engineering, Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Beijing, China
| | - Yunhan Cai
- Institute of Biomechanics, Department of Aeronautics and Astronautics, Fudan University, Shanghai, China
| | - Nikhil Paliwal
- Toshiba Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, New York USA.,Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, New York USA
| | - Hui Meng
- Toshiba Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, New York USA.,Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, New York USA.,Department of Neurosurgery, University at Buffalo, The State University of New York, Buffalo, New York USA
| | - Yang Wang
- Department of Neurosurgery, The First Affiliated Hospital, Nanchang University, Nanchang, China
| | - Shengzhang Wang
- Institute of Biomechanics, Department of Aeronautics and Astronautics, Fudan University, Shanghai, China
| | - Xinjian Yang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
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Narata AP, de Moura FS, Larrabide I, Perrault CM, Patat F, Bibi R, Velasco S, Januel AC, Cognard C, Chapot R, Bouakaz A, Sennoga CA, Marzo A. The Role of Hemodynamics in Intracranial Bifurcation Arteries after Aneurysm Treatment with Flow-Diverter Stents. AJNR Am J Neuroradiol 2018; 39:323-330. [PMID: 29170270 DOI: 10.3174/ajnr.a5471] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 10/02/2017] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Treatment of intracranial bifurcation aneurysms with flow-diverter stents can lead to caliber changes of the distal vessels in a subacute phase. This study aims to evaluate whether local anatomy and flow disruption induced by flow-diverter stents are associated with vessel caliber changes in intracranial bifurcations. MATERIALS AND METHODS Radiologic images and demographic data were acquired for 25 patients with bifurcation aneurysms treated with flow-diverter stents. Whisker plots and Mann-Whitney rank sum tests were used to evaluate if anatomic data and caliber changes could be linked. Symmetry/asymmetry were defined as diameter ratio 1 = symmetric and diameter ratio <1 = asymmetric. Computational fluid dynamics was performed on idealized and patient-specific anatomies to evaluate flow changes induced by flow-diverter stents in the jailed vessel. RESULTS Statistical analysis identified a marked correspondence between asymmetric bifurcation and caliber change. Symmetry ratios were lower for cases showing narrowing or subacute occlusion (medium daughter vessel diameter ratio = 0.59) compared with cases with posttreatment caliber conservation (medium daughter vessel diameter ratio = 0.95). Computational fluid dynamics analysis in idealized and patient-specific anatomies showed that wall shear stress in the jailed vessel was more affected when flow-diverter stents were deployed in asymmetric bifurcations (diameter ratio <0.65) and less affected when deployed in symmetric anatomies (diameter ratio ∼1.00). CONCLUSIONS Anatomic data analysis showed statistically significant correspondence between caliber changes and bifurcation asymmetry characterized by diameter ratio <0.7 (P < .001). Similarly, computational fluid dynamics results showed the highest impact on hemodynamics when flow-diverter stents are deployed in asymmetric bifurcations (diameter ratio <0.65) with noticeable changes on wall sheer stress fields. Further research and clinical validation are necessary to identify all elements involved in vessel caliber changes after flow-diverter stent procedures.
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Affiliation(s)
- A P Narata
- From the University Hospital of Tours (A.P.N., R.B.), Tours, France
| | - F S de Moura
- Engineering, Modeling, and Applied Social Sciences Center (F.S.d.M.), Federal University of ABC, Santo André, Brazil
| | - I Larrabide
- PLADEMA-CONICET (I.L.), Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina
| | - C M Perrault
- Mechanical Engineering Department, INSIGNEO Institute for in Silico Medicine (C.M.P., A.M.), University of Sheffield, Sheffield, United Kingdom
| | - F Patat
- UMR "Imagerie et Cerveau," Inserm U930 (F.P., A.B., C.A.S.), Université Francois Rabelais, Tours, France
| | - R Bibi
- From the University Hospital of Tours (A.P.N., R.B.), Tours, France
| | - S Velasco
- University Hospital of Poitiers (S.V.), Poitiers, France
| | - A-C Januel
- University Hospital of Toulouse (A.-C.J., C.C.), Toulouse, France
| | - C Cognard
- University Hospital of Toulouse (A.-C.J., C.C.), Toulouse, France
| | - R Chapot
- Alfried Krupp Krankenhaus (R.C.), Essen, Germany
| | - A Bouakaz
- UMR "Imagerie et Cerveau," Inserm U930 (F.P., A.B., C.A.S.), Université Francois Rabelais, Tours, France
| | - C A Sennoga
- UMR "Imagerie et Cerveau," Inserm U930 (F.P., A.B., C.A.S.), Université Francois Rabelais, Tours, France
| | - A Marzo
- Mechanical Engineering Department, INSIGNEO Institute for in Silico Medicine (C.M.P., A.M.), University of Sheffield, Sheffield, United Kingdom
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11
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Zhang Q, Meng Z, Zhang Y, Yao K, Liu J, Zhang Y, Jing L, Yang X, Paliwal N, Meng H, Wang S. Phantom-based experimental validation of fast virtual deployment of self-expandable stents for cerebral aneurysms. Biomed Eng Online 2016; 15:125. [PMID: 28155680 PMCID: PMC5260011 DOI: 10.1186/s12938-016-0250-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Endovascular intervention using a stent is a mainstream treatment for cerebral aneurysms. To assess the effect of intervention strategies on aneurysm hemodynamics, we have developed a fast virtual stenting (FVS) technique to simulate stent deployment in patient-specific aneurysms. However, quantitative validation of the FVS against experimental data has not been fully addressed. In this study, we performed in vitro analysis of a patient-specific model to illustrate the realism and usability of this novel FVS technique. METHODS We selected a patient-specific aneurysm and reproduced it in a manufactured realistic aneurismal phantom. Three numerical simulation models of the aneurysm with an Enterprise stent were constructed. Three models were constructed to obtain the stented aneurysms: a physical phantom scanned by micro-CT, fast virtual stenting technique and finite element method. The flow in the three models was simulated using a computational fluid dynamics software package, and the hemodynamics parameters for the three models were calculated and analyzed. RESULTS The computational hemodynamics in the patient-specific aneurysm of the three models resembled the very well. A qualitative comparison revealed high similarity in the wall shear stress, streamline, and velocity plane among the three different methods. Quantitative comparisons revealed that the difference ratios of the hemodynamic parameters were less than 10%, with the difference ratios for area average of wall shear stress in the aneurysm being very low. CONCLUSIONS In conclusion, the results of the computational hemodynamics indicate that FVS is suitable for evaluation of the hemodynamic factors that affect treatment outcomes.
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Affiliation(s)
- Qianqian Zhang
- Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Zhuangyuan Meng
- Department of Mechanics and Engineering Science, Fudan University, 220 Handan Rd., Yangpu District, Shanghai, 200433, China
| | - Ying Zhang
- Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Kai Yao
- Department of Mechanics and Engineering Science, Fudan University, 220 Handan Rd., Yangpu District, Shanghai, 200433, China
| | - Jian Liu
- Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yisen Zhang
- Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Linkai Jing
- Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xinjian Yang
- Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
| | - Nikhil Paliwal
- Toshiba Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Hui Meng
- Toshiba Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Shengzhang Wang
- Department of Mechanics and Engineering Science, Fudan University, 220 Handan Rd., Yangpu District, Shanghai, 200433, China.
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12
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Tian Z, Zhang Y, Jing L, Liu J, Zhang Y, Yang X. Rupture Risk Assessment for Mirror Aneurysms with Different Outcomes in the Same Patient. Front Neurol 2016; 7:219. [PMID: 27994571 PMCID: PMC5136536 DOI: 10.3389/fneur.2016.00219] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/21/2016] [Indexed: 11/17/2022] Open
Abstract
Background The purpose of this research was to analyze the effect of morphologic and hemodynamic characteristics on mirror aneurysms in which one ruptured and the other did not, within the same patient, and to identify reliable predictors of rupture. Methods We performed three-dimensional angiographic imaging in 56 patients with intracranial mirror aneurysms for computational fluid dynamic studies from January 2009 to December 2015. The ruptured aneurysm simulations were conducted with geometry obtained after rupture. The significance of morphologic and hemodynamic parameters with respect to rupture was analyzed. Multivariate logistic regression analysis was applied to significant parameters to identify independent discriminators. Results Three morphologic factors (aneurysm size, aspect ratio, and size ratio) and two hemodynamic factors [time-averaged mean wall shear stress (WSS) and low WSS area] were statistically associated with aneurysm rupture (p < 0.05). On multivariate logistic regression, a larger size (OR 2.572, p = 0.001) and lower WSS (OR 0.609, p = 0.045) were independent significant factors for rupture. Conclusion Larger aneurysm size and lower WSS were independently associated with the rupture status of aneurysms. These findings need to be confirmed by large multicenter and multi-population studies.
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Affiliation(s)
- Zhongbin Tian
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Beijing Tian Tan Hospital, Capital Medical University , Beijing , China
| | - Yisen Zhang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Beijing Tian Tan Hospital, Capital Medical University , Beijing , China
| | - Linkai Jing
- Medical Center, Tsinghua University, Beijing, China; Department of Neurosurgery, Medical Center, Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing, China
| | - Jian Liu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Beijing Tian Tan Hospital, Capital Medical University , Beijing , China
| | - Ying Zhang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Beijing Tian Tan Hospital, Capital Medical University , Beijing , China
| | - Xinjian Yang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Beijing Tian Tan Hospital, Capital Medical University , Beijing , China
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13
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Wang C, Tian Z, Liu J, Jing L, Paliwal N, Wang S, Zhang Y, Xiang J, Siddiqui AH, Meng H, Yang X. Flow diverter effect of LVIS stent on cerebral aneurysm hemodynamics: a comparison with Enterprise stents and the Pipeline device. J Transl Med 2016; 14:199. [PMID: 27370946 PMCID: PMC4930570 DOI: 10.1186/s12967-016-0959-9] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 06/23/2016] [Indexed: 11/14/2022] Open
Abstract
Background The aim of this study was to quantify the effect of the new Low-profile Visualized Intraluminal Support (LVIS®D) device and the difference of fluid diverting effect compared with the Pipeline device and the Enterprise stent using computational fluid dynamics (CFD). Methods In this research, we simulated three aneurysms constructed from 3D digital subtraction angiography (DSA). The Enterprise, LVIS and the Pipeline device were virtually conformed to fit into the vessel lumen and placed across the aneurysm orifice. Computational fluid dynamics analysis was performed to compare the hemodynamic differences such as WSS, Velocity and Pressure among these stents. Results Control referred to the unstented model, the percentage of hemodynamic changes were all compared to Control. A single LVIS stent caused more wall shear stress reduction than double Enterprise stents (39.96 vs. 30.51 %) and velocity (23.13 vs. 18.64 %). Significant reduction in wall shear stress (63.88 %) and velocity (46.05 %) was observed in the double-LVIS stents. A single Pipeline showed less reduction in WSS (51.08 %) and velocity (37.87 %) compared with double-LVIS stent. The double-Pipeline stents resulted in the most reduction in WSS (72.37 %) and velocity (54.26 %). Moreover, the pressure increased with minuscule extent after stenting, compared with the unstented model. Conclusions This is the first study analyzing flow modifications associated with LVIS stents. We found that the LVIS stent has certain hemodynamic effects on cerebral aneurysms: a single LVIS stent caused more flow reductions than the double-Enterprise stent but less than a Pipeline device. Nevertheless, the double-LVIS stent resulted in a better flow diverting effect than a Pipeline device.
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Affiliation(s)
- Chao Wang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tian Tan Hospital, Capital Medical University, TiantanXili 6, Dongcheng District, Beijing, China.,Department of Neurosurgery, The Affiliated Hospital, Binzhou Medical University, Binzhou, Shandong, China
| | - Zhongbin Tian
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tian Tan Hospital, Capital Medical University, TiantanXili 6, Dongcheng District, Beijing, China
| | - Jian Liu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tian Tan Hospital, Capital Medical University, TiantanXili 6, Dongcheng District, Beijing, China
| | - Linkai Jing
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tian Tan Hospital, Capital Medical University, TiantanXili 6, Dongcheng District, Beijing, China
| | - Nikhil Paliwal
- Toshiba Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, NY, USA.,Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Shengzhang Wang
- Department of Mechanics and Engineering Science, Fudan University, Shanghai, China
| | - Ying Zhang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tian Tan Hospital, Capital Medical University, TiantanXili 6, Dongcheng District, Beijing, China
| | - Jianping Xiang
- Toshiba Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, NY, USA.,Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Adnan H Siddiqui
- Toshiba Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, NY, USA.,Department of Neurosurgery, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Hui Meng
- Toshiba Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, NY, USA.,Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Xinjian Yang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tian Tan Hospital, Capital Medical University, TiantanXili 6, Dongcheng District, Beijing, China.
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14
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Hemodynamic Alterations for Various Stent Configurations in Idealized Wide-neck Basilar Tip Aneurysm. J Med Biol Eng 2016. [DOI: 10.1007/s40846-016-0139-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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15
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Larrabide I, Geers AJ, Morales HG, Bijlenga P, Rüfenacht DA. Change in aneurysmal flow pulsatility after flow diverter treatment. Comput Med Imaging Graph 2016; 50:2-8. [DOI: 10.1016/j.compmedimag.2015.01.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Revised: 12/16/2014] [Accepted: 01/19/2015] [Indexed: 11/30/2022]
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16
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Hemodynamic alterations after stent implantation in 15 cases of intracranial aneurysm. Acta Neurochir (Wien) 2016; 158:811-819. [PMID: 26746828 DOI: 10.1007/s00701-015-2696-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 12/24/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND Stent-assisted coiling technology has been widely used in the treatment of intracranial aneurysms. In the current study, we investigated the intra-aneurysmal hemodynamic alterations after stent implantation and their association with the aneurysm location. METHODS We first retrospectively studied 15 aneurysm cases [8 internal carotid artery-ophthalmic artery (ICA-OphA) aneurysms and 7 posterior communicating artery (PcoA) aneurysms] treated with Enterprise stents and coils. Then, based on the patient-specific geometries before and after stenting, we built virtual stenting computational fluid dynamics (CFD) simulation models. RESULTS Before and after the stent deployment, the average wall shear stress (WSS) on the aneurysmal sac at systolic peak changed from 7.04 Pa (4.14 Pa, 15.77 Pa) to 6.04 Pa (3.86 Pa, 11.13 Pa), P = 0.001; the spatially averaged flow velocity in the perpendicular plane of the aneurysm dropped from 0.5 m/s (0.28 m/s, 0.7 m/s) to 0.33 m/s (0.25 m/s, 0.49 m/s), P = 0.001, respectively. Post stent implantation, the WSS in ICA-OphA aneurysms and PcoA aneurysms decreased by 14.4 % (P = 0.012) and 16.6 % (P = 0.018), respectively, and the flow velocity also reduced by 10.3 % (P = 0.029) and 10.5 % (P = 0.013), respectively. Changes in the WSS, flow velocity, and pressure were not significantly different between ICA-OphA and PcoA aneurysms (P > 0.05). Stent implantation did not significantly change the peak systolic pressure in either aneurysm type. CONCLUSION After the stent implantation, both the intra-aneurysmal flow velocity and WSS decreased independently of aneurysm type (ICA-OphA and PcoA). Little change was observed in peak systolic pressure.
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17
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Paliwal N, Yu H, Xu J, Xiang J, Siddiqui A, Yang X, Li H, Meng H. Virtual stenting workflow with vessel-specific initialization and adaptive expansion for neurovascular stents and flow diverters. Comput Methods Biomech Biomed Engin 2016; 19:1423-1431. [PMID: 26899135 DOI: 10.1080/10255842.2016.1149573] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Endovascular intervention using traditional neurovascular stents and densely braided flow diverters (FDs) have become the preferred treatment strategies for traditionally challenging intracranial aneurysms. Modeling stent and FD deployment in patient-specific aneurysms and its flow modification results prior to the actual intervention can potentially predict the patient outcome and treatment optimization. We present a clinically focused, streamlined virtual stenting workflow that efficiently simulates stent and FD treatment in patient-specific aneurysms based on expanding a simplex mesh structure. The simplex mesh is generated using an innovative vessel-specific initialization technique, which uses the patient's parent artery diameter to identify the initial position of the simplex mesh inside the artery. A novel adaptive expansion algorithm enables the acceleration of deployment process by adjusting the expansion forces based on the distance of the simplex mesh from the parent vessel. The virtual stenting workflow was tested by modeling the treatment of two patient-specific aneurysms using the Enterprise stent and the Pipeline Embolization Device (commercial FD). Both devices were deployed in the aneurysm models in a few seconds. Computational fluid dynamics analyses of pre- and post-treatment aneurysmal hemodynamics show flow reduction in the aneurysmal sac in treated aneurysms, with the FD diverting more flow than the Enterprise stent. The test results show that this workflow can rapidly simulate clinical deployment of stents and FDs, hence paving the way for its future clinical implementation.
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Affiliation(s)
- Nikhil Paliwal
- Department of Mechanical & Aerospace Engineering, University at Buffalo, State University of New York, Buffalo, NY.,Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, NY
| | - Hongyu Yu
- School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Jinhui Xu
- Department of Computer Science & Engineering, University at Buffalo, State University of New York, Buffalo, NY
| | - Jianping Xiang
- Department of Neurosurgery, University at Buffalo, State University of New York, Buffalo, NY.,Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, NY
| | - Adnan Siddiqui
- Department of Neurosurgery, University at Buffalo, State University of New York, Buffalo, NY.,Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, NY
| | - Xinjian Yang
- Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Beijing, China
| | - Haiyun Li
- School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Hui Meng
- Department of Mechanical & Aerospace Engineering, University at Buffalo, State University of New York, Buffalo, NY.,Department of Neurosurgery, University at Buffalo, State University of New York, Buffalo, NY.,Department of Biomedical Engineering, University at Buffalo, State University of New York, Buffalo, NY.,Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, NY
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18
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Poelma C, Watton PN, Ventikos Y. Transitional flow in aneurysms and the computation of haemodynamic parameters. J R Soc Interface 2015; 12:rsif.2014.1394. [PMID: 25694540 DOI: 10.1098/rsif.2014.1394] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Haemodynamic forces appear to play an influential role in the evolution of aneurysms. This has led to numerous studies, usually based on computational fluid dynamics. Their focus is predominantly on the wall shear stress (WSS) and associated derived parameters, attempting to find correlations between particular patterns of haemodynamic indices and regions subjected to disease formation and progression. The indices are generally determined by integration of flow properties over a single cardiac cycle. In this study, we illustrate that in some cases the transitional flow in aneurysms can lead to significantly different WSS distributions in consecutive cardiac cycles. Accurate determination of time-averaged haemodynamic indices may thus require simulation of a large number of cycles, which contrasts with the common approach to determine parameters using data from a single cycle. To demonstrate the role of transitional flow, two exemplary cases are considered: flow in an abdominal aortic aneurysm and in an intracranial aneurysm. The key differences that are observed between these cases are explained in terms of the integral timescale of the transitional flows in comparison with the cardiac cycle duration: for relatively small geometries, transients will decay before the next cardiac cycle. In larger geometries, transients are still present when the systolic phase produces new instabilities. These residual fluctuations serve as random initial conditions and thus seed different flow patterns in each cycle. To judge whether statistics are converged, the derived indices from at least two successive cardiac cycles should be compared.
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Affiliation(s)
- Christian Poelma
- Laboratory for Aero and Hydrodynamics, Delft University of Technology, Delft, The Netherlands
| | - Paul N Watton
- Department of Computer Science and INSIGNEO Institute of In Silico Medicine, University of Sheffield, Sheffield, UK
| | - Yiannis Ventikos
- Department of Mechanical Engineering, University College London, London, UK
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19
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Peach TW, Spranger K, Ventikos Y. Towards Predicting Patient-Specific Flow-Diverter Treatment Outcomes for Bifurcation Aneurysms: From Implantation Rehearsal to Virtual Angiograms. Ann Biomed Eng 2015; 44:99-111. [PMID: 26240061 PMCID: PMC4690836 DOI: 10.1007/s10439-015-1395-3] [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: 03/31/2015] [Accepted: 07/15/2015] [Indexed: 12/14/2022]
Abstract
Despite accounting for the majority of all cerebral aneurysm cases, bifurcation aneurysms present many challenges to standard endovascular treatment techniques. This study examines the treatment of bifurcation aneurysms endovascularly with flow-diverting stents and presents an integrative computational modeling suite allowing for rehearsing all aspects of the treatment. Six bifurcation aneurysms are virtually treated with 70% porosity flow-diverters. Substantial reduction (>50%) in aneurysm inflow due to device deployment is predicted in addition to reductions in peak and average aneurysm wall shear stress to values considered physiologically normal. The subsequent impact of flow-diverter deployment on daughter vessels that are jailed by the device is investigated further, with a number of simulations conducted with increased outlet pressure conditions at jailed vessels. Increased outlet pressures at jailed daughter vessels are found to have little effect on device-induced aneurysm inflow reduction, but large variation (13–86%) is seen in the resulting reduction in daughter vessel flow rate. Finally, we propose a potentially powerful approach for validation of such models, by introducing an angiographic contrast model, with contrast transport modeled both before and after virtual treatment. Virtual angiograms and contrast residence curves are created, which offer unique clinical relevance and the potential for future in vivo verification of simulated results.
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Affiliation(s)
- T W Peach
- Department of Mechanical Engineering, University College London, London, UK.,Department of Engineering Science, University of Oxford, Oxford, UK
| | - K Spranger
- Department of Mechanical Engineering, University College London, London, UK
| | - Y Ventikos
- Department of Mechanical Engineering, University College London, London, UK.
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20
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Karunanithi K, Lee CJ, Chong W, Qian Y. The influence of flow diverter’s angle of curvature across the aneurysm neck on its haemodynamics. Proc Inst Mech Eng H 2015; 229:560-9. [DOI: 10.1177/0954411915593303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Flow diverter stents have provided a new method of endovascular reconstruction for large and complex aneurysms. Understanding the impact of the flow diverter’s angle of curvature across the neck and its metal coverage rate on the haemodynamics of aneurysm is crucial to maximize the mass flow reduction inside the aneurysm, post-deployment. The aim of this study is to understand the correlation between the angle of curvature of flow diverter across the aneurysm neck and the metal coverage rate, and the aneurysm’s haemodynamics, using computational fluid dynamics. Varying the flow diverter angle resulted in varying metal coverage rate across the aneurysm neck for two patient vessel geometries, A (straight artery) and B (curved artery) with aspect ratios of 3.1 and 2.9, respectively. The results indicate that there exists a relationship between the aneurysm’s haemodynamics and the flow diverter’s angle of curvature across its neck. Moreover, the calculations indicated that cases with a moderately curved flow diverter, with an associated metal coverage rate of 50%–60%, achieve maximum flow reduction inside the aneurysm due to a stable flow resistance in the direction normal to the blood flow.
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Affiliation(s)
- Kaavya Karunanithi
- Australian School of Advanced Medicine, Macquarie University, Macquarie Park, NSW, Australia
| | - Chang Joon Lee
- Australian School of Advanced Medicine, Macquarie University, Macquarie Park, NSW, Australia
| | | | - Yi Qian
- Australian School of Advanced Medicine, Macquarie University, Macquarie Park, NSW, Australia
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21
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Fernandez H, Macho JM, Blasco J, Roman LS, Mailaender W, Serra L, Larrabide I. Computation of the change in length of a braided device when deployed in realistic vessel models. Int J Comput Assist Radiol Surg 2015; 10:1659-65. [PMID: 26062795 DOI: 10.1007/s11548-015-1230-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 05/28/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE An important issue in the deployment of braided stents, such as flow diverters, is the change in length, also known as foreshortening, underwent by the device when is released from the catheter into a blood vessel. The position of the distal end is controlled by the interventionist, but knowing a priori the position of the proximal end of the device is not trivial. In this work, we assess and validate a novel computer method to predict the length that a braided stent will adopt inside a silicon model of an anatomically accurate vessel. METHODS Three-dimensional rotational angiography images of aneurysmatic patients were used to generate surface models of the vessels (3D meshes) and then create accurate silicon models from them. A braided stent was deployed into each silicon model to measure its length. The same stents deployed on the silicon models were virtually deployed on the 3D meshes using the method being evaluated. RESULTS The method was applied to five stent placements on three different silicon models. The length adopted by the real braided device in the silicon models varies between 15 and 30% from the stent length specified by the manufacturer. The final length predicted by the method was within the estimated error of the measured real stent length. CONCLUSIONS The method provides, in a few seconds, the length of a braided stent deployed inside a vessel, showing an accurate estimation of the final length for the cases studied. This technique could provide useful information for planning the intervention and improve endovascular treatment of intracranial aneurysms in the future.
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Affiliation(s)
| | - Juan M Macho
- Hospital Clinic Provincial de Barcelona, Barcelona, Spain
| | - Jordi Blasco
- Hospital Clinic Provincial de Barcelona, Barcelona, Spain
| | - Luis San Roman
- Hospital Clinic Provincial de Barcelona, Barcelona, Spain
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22
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Bouillot P, Brina O, Ouared R, Lovblad KO, Farhat M, Mendes Pereira V. Hemodynamic transition driven by stent porosity in sidewall aneurysms. J Biomech 2015; 48:1300-9. [DOI: 10.1016/j.jbiomech.2015.02.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 02/04/2015] [Accepted: 02/15/2015] [Indexed: 10/23/2022]
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23
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Bouillot P, Brina O, Ouared R, Yilmaz H, Lovblad KO, Farhat M, Mendes Pereira V. Computational fluid dynamics with stents: quantitative comparison with particle image velocimetry for three commercial off the shelf intracranial stents. J Neurointerv Surg 2015; 8:309-15. [DOI: 10.1136/neurintsurg-2014-011468] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 12/19/2014] [Indexed: 01/06/2023]
Abstract
Background and purposeValidation of computational fluid dynamics (CFD) in stented intracranial aneurysms (IAs) is still lacking, to reliably predict prone to occlusion hemodynamics, probing, in particular, velocity reduction, and flow pattern changes. This study compares CFD outcome with particle imaging velocimetry (PIV) for three commercial off the shelf (COTS) stents of different material densities.Material and methodsThe recently developed uniform and high precision multi-time lag PIV method was applied to a sidewall aneurysm before and after implantation of three COTS stents with high, intermediate, and low material densities. The measured laser sheet flow patterns and velocity reductions were compared with CFD results and correlated with stent material density.ResultsVelocity reduction was in good agreement for unstented high and low porosity stented IA, while flow pattern change was fully matched for unstented and high porosity stented IA. Poor CFD–PIV matching in IA was found for intermediate porosity stents.ConclusionsCFD reproduced fully PIV measurements in unstented and high porosity stented IAs. With low porosity stents, CFD reproduced velocity reduction and high velocities close to the neck, while a marked mismatch on sluggish flow was found at the dome. CFD was unable to match PIV with intermediate porosity stents for which hemodynamic transition occurred.
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24
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Accuracy and Reproducibility of Patient-Specific Hemodynamic Models of Stented Intracranial Aneurysms: Report on the Virtual Intracranial Stenting Challenge 2011. Ann Biomed Eng 2014; 43:154-67. [DOI: 10.1007/s10439-014-1082-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 07/31/2014] [Indexed: 10/24/2022]
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25
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Ma D, Dumont TM, Kosukegawa H, Ohta M, Yang X, Siddiqui AH, Meng H. High fidelity virtual stenting (HiFiVS) for intracranial aneurysm flow diversion: in vitro and in silico. Ann Biomed Eng 2013; 41:2143-56. [PMID: 23604850 DOI: 10.1007/s10439-013-0808-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Accepted: 04/05/2013] [Indexed: 11/30/2022]
Abstract
A flow diverter (FD) is a flexible, densely braided stent-mesh device placed endoluminally across an intracranial aneurysm to induce its thrombotic occlusion. FD treatment planning using computational virtual stenting and flow simulation requires accurate representation of the expanded FD geometry. We have recently developed a high fidelity virtual stenting (HiFiVS) technique based on finite element analysis to simulate detailed FD deployment processes in patient-specific aneurysms (Ma et al. J. Biomech. 45:2256-2263,(2012)). This study tests if HiFiVS simulation can recapitulate real-life FD implantation. We deployed two identical FDs (Pipeline Embolization Device) into phantoms of a wide-necked segmental aneurysm using a clinical push-pull technique with different delivery wire advancements. We then simulated these deployment processes using HiFiVS and compared results against experimental recording. Stepwise comparison shows that the simulations precisely reproduced the FD deployment processes recorded in vitro. The local metal coverage rate and pore density quantifications demonstrated that simulations reproduced detailed FD mesh geometry. These results provide validation of the HiFiVS technique, highlighting its unique capability of accurately representing stent intervention in silico.
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Affiliation(s)
- Ding Ma
- Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, 875 Ellicott Street, Buffalo, NY 14203, USA
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26
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Janiga G, Rössl C, Skalej M, Thévenin D. Realistic virtual intracranial stenting and computational fluid dynamics for treatment analysis. J Biomech 2013; 46:7-12. [DOI: 10.1016/j.jbiomech.2012.08.047] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 07/13/2012] [Accepted: 08/31/2012] [Indexed: 11/27/2022]
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27
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Tang AYS, Chan HN, Tsang ACO, Leung GKK, Leung KM, Yu ACH, Chow KW. The effects of stent porosity on the endovascular treatment of intracranial aneurysms located near a bifurcation. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/jbise.2013.68099] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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28
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Larrabide I, Villa-Uriol MC, Cárdenes R, Barbarito V, Carotenuto L, Geers AJ, Morales HG, Pozo JM, Mazzeo MD, Bogunović H, Omedas P, Riccobene C, Macho JM, Frangi AF. AngioLab--a software tool for morphological analysis and endovascular treatment planning of intracranial aneurysms. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2012; 108:806-819. [PMID: 22749086 DOI: 10.1016/j.cmpb.2012.05.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 04/18/2012] [Accepted: 05/04/2012] [Indexed: 06/01/2023]
Abstract
Determining whether and how an intracranial aneurysm should be treated is a tough decision that clinicians face everyday. Emerging computational tools could help clinicians analyze clinical data and make these decisions. AngioLab is a single graphical user interface, developed on top of the open source framework GIMIAS, that integrates some of the latest image analysis and computational modeling tools for intracranial aneurysms. Two workflows are available: Advanced Morphological Analysis (AMA) and Endovascular Treatment Planning (ETP). AngioLab has been evaluated by a total of 62 clinicians, who considered the information provided by AngioLab relevant and meaningful. They acknowledged the emerging need of these type of tools and the potential impact they might have on the clinical decision-making process.
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Affiliation(s)
- Ignacio Larrabide
- Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine, Barcelona, Spain.
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Larrabide I, Aguilar ML, Morales HG, Geers AJ, Kulcsár Z, Rüfenacht D, Frangi AF. Intra-aneurysmal pressure and flow changes induced by flow diverters: relation to aneurysm size and shape. AJNR Am J Neuroradiol 2012; 34:816-22. [PMID: 23019173 DOI: 10.3174/ajnr.a3288] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Effects of blood flow modification by flow diverters are observed to lead often to aneurysm thrombosis and reverse remodeling. For this process, to further understand the potential roles of intra-aneurysmal blood pressure changes and aneurysm morphologies, 23 patients were studied by numeric simulation. MATERIALS AND METHODS 3D imaging of aneurysms of different sizes and shapes, all located at the supraclinoid segment of the ICA (n=23), was prepared for CFD simulations. Hemodynamic variables were calculated for conditions before and after virtual FD implantation, reconstituting a vessel wall scaffold across the aneurysm neck. WSS, velocity, residence time, turnover time, and intra-aneurysmal pressure were assessed statistically. RESULTS After placement of FDs, significant reductions inside the aneurysm were observed for most hemodynamic variables (P<.01) except mean intra-aneurysmal pressures. For minimum/maximum intra-aneurysmal pressure values, small but significant changes were found; however, they were considered too small to be of relevance. CONCLUSIONS Calculations in 23 cases did not reveal significant intra-aneurysmal mean or peak pressure changes, indicating a minor role of pressure changes in the rare event of secondary ruptures after FD use. Other hemodynamic variables (WSS and velocity) exhibited more significant changes, indicating their role in intra-aneurysmal thrombus formation. Size-dependent, significantly higher reduction in WSS (P=.069) and velocity (P=.013) was observed in small aneurysms compared with larger ones. When it came to shape, there were significantly higher reductions in WSS (P=.055) and velocity (P=.065) and a significantly higher increase in turnover time in fusiform aneurysms compared with saccular aneurysms.
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Affiliation(s)
- I Larrabide
- Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine, Barcelona, Spain.
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Abstract
The Virtual Physiological Human is synonymous with a programme in computational biomedicine that aims to develop a framework of methods and technologies to investigate the human body as a whole. It is predicated on the transformational character of information technology, brought to bear on that most crucial of human concerns, our own health and well-being.
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Affiliation(s)
- Peter V. Coveney
- Centre for Computational Science, University College London, 20 Gordon Street, London WC1H 0AJ, UK
| | - Vanessa Diaz
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
| | - Peter Hunter
- Auckland Bioengineering Institute, The University of Auckland, Auckland 1142, New Zealand
| | - Peter Kohl
- Heart Science Centre, Imperial College, Harefield Hospital, Hill End Road, Harefield UB9 6JH, UK
| | - Marco Viceconti
- Medical Technology Laboratory, Instituto Orthopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna, Italy
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