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Fu Y, Bian X, Zou R, Jin R, Leng X, Fan F, Wei S, Cui X, Xiang J, Guan S. Hemodynamic alterations of flow diverters on aneurysms at the fetal posterior communicating artery: A simulation study using CFD to compare the surpass streamline, pipeline flex, and tubridge devices. J Neuroradiol 2024; 51:74-81. [PMID: 37442272 DOI: 10.1016/j.neurad.2023.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 07/03/2023] [Accepted: 07/10/2023] [Indexed: 07/15/2023]
Abstract
PURPOSE Traditional flow diverters (FDs) for treating aneurysms at the fetal posterior communicating artery are unsatisfactory. Surpass Streamline is a novel FD with different mesh characteristics; however, the outcomes for such aneurysms remain unclear. This study aimed to compare hemodynamic alterations induced by Surpass Streamline, Pipeline Flex, and Tubridge devices and explore possible strategies for aneurysms at the fetal posterior communicating artery. METHODS Two simulated aneurysms (Case 1, Case 2) were constructed from digital subtraction angiography (DSA). The three FDs were virtually deployed, and hemodynamic analysis based on computational fluid dynamics was performed. Hemodynamic parameters, including the sac-averaged velocity magnitude (Velocity), high-flow volume (HFV), and wall shear stress (WSS), were compared between each FD and the untreated model (control). Surpass Streamline was performed in real life for two aneurysms and the clinical outcomes were collected for analysis. RESULTS Compared to the control, the Surpass resulted in the most significant reduction in flow. In Case 1, the Velocity, HFV, and WSS were reduced by 51.6%, 78.1%, and 64.3%, respectively. In Case 2, the Velocity, HFV, and WSS were reduced by 48.0%, 81.1%, and 65.3%, respectively. Tubridge showed slightly larger changes in hemodynamic parameters than Pipeline. In addition, our analysis suggested that metal coverage was correlated with the WSS, Velocity, and HFV. The postoperative DSA showed that the aneurysm was nearly occluded in Case 1 and decreased in Case 2. CONCLUSION Compared to that with the Pipeline and Tubridge, the Surpass resulted in the greatest reduction in hemodynamic parameters and might be effective for aneurysms at the fetal posterior communicating artery. Virtual FD deployment and computational fluid dynamics analysis may be used to predict the treatment outcomes.
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Affiliation(s)
- Yu Fu
- Department of Neurointervention Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xin Bian
- ArteryFlow Technology Co., Ltd., Hangzhou, China
| | - Rong Zou
- ArteryFlow Technology Co., Ltd., Hangzhou, China
| | - Rongbo Jin
- ArteryFlow Technology Co., Ltd., Hangzhou, China
| | | | - Feng Fan
- Department of Neurointervention Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Sen Wei
- Department of Neurointervention Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xuan Cui
- Department of Neurointervention Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | | | - Sheng Guan
- Department of Neurointervention Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
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Hachem E, Meliga P, Goetz A, Rico PJ, Viquerat J, Larcher A, Valette R, Sanches AF, Lannelongue V, Ghraieb H, Nemer R, Ozpeynirci Y, Liebig T. Reinforcement learning for patient-specific optimal stenting of intracranial aneurysms. Sci Rep 2023; 13:7147. [PMID: 37130900 PMCID: PMC10154322 DOI: 10.1038/s41598-023-34007-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 04/22/2023] [Indexed: 05/04/2023] Open
Abstract
Developing new capabilities to predict the risk of intracranial aneurysm rupture and to improve treatment outcomes in the follow-up of endovascular repair is of tremendous medical and societal interest, both to support decision-making and assessment of treatment options by medical doctors, and to improve the life quality and expectancy of patients. This study aims at identifying and characterizing novel flow-deviator stent devices through a high-fidelity computational framework that combines state-of-the-art numerical methods to accurately describe the mechanical exchanges between the blood flow, the aneurysm, and the flow-deviator and deep reinforcement learning algorithms to identify a new stent concepts enabling patient-specific treatment via accurate adjustment of the functional parameters in the implanted state.
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Affiliation(s)
- E Hachem
- MINES Paris, PSL Research University, Centre de mise en forme des matériaux (CEMEF), CNRS UMR 7635, 06904, Sophia Antipolis Cedex, France.
| | - P Meliga
- MINES Paris, PSL Research University, Centre de mise en forme des matériaux (CEMEF), CNRS UMR 7635, 06904, Sophia Antipolis Cedex, France
| | - A Goetz
- MINES Paris, PSL Research University, Centre de mise en forme des matériaux (CEMEF), CNRS UMR 7635, 06904, Sophia Antipolis Cedex, France
| | - P Jeken Rico
- MINES Paris, PSL Research University, Centre de mise en forme des matériaux (CEMEF), CNRS UMR 7635, 06904, Sophia Antipolis Cedex, France
| | - J Viquerat
- MINES Paris, PSL Research University, Centre de mise en forme des matériaux (CEMEF), CNRS UMR 7635, 06904, Sophia Antipolis Cedex, France
| | - A Larcher
- MINES Paris, PSL Research University, Centre de mise en forme des matériaux (CEMEF), CNRS UMR 7635, 06904, Sophia Antipolis Cedex, France
| | - R Valette
- MINES Paris, PSL Research University, Centre de mise en forme des matériaux (CEMEF), CNRS UMR 7635, 06904, Sophia Antipolis Cedex, France
| | - A F Sanches
- Department of Neuroradiology, University Hospital Munich (LMU), Munich, Germany
| | - V Lannelongue
- MINES Paris, PSL Research University, Centre de mise en forme des matériaux (CEMEF), CNRS UMR 7635, 06904, Sophia Antipolis Cedex, France
| | - H Ghraieb
- MINES Paris, PSL Research University, Centre de mise en forme des matériaux (CEMEF), CNRS UMR 7635, 06904, Sophia Antipolis Cedex, France
| | - R Nemer
- MINES Paris, PSL Research University, Centre de mise en forme des matériaux (CEMEF), CNRS UMR 7635, 06904, Sophia Antipolis Cedex, France
| | - Y Ozpeynirci
- Department of Neuroradiology, University Hospital Munich (LMU), Munich, Germany
| | - T Liebig
- Department of Neuroradiology, University Hospital Munich (LMU), Munich, Germany
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Wang Y, Zhao L, Zheng Z, Zhang Y. Flow Resistance Analysis of Clinically Significant Portal Hypertension in Patients with Liver Cirrhosis. Can J Gastroenterol Hepatol 2022; 2022:9396371. [PMID: 36199982 DOI: 10.1155/2022/9396371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 07/01/2022] [Accepted: 09/02/2022] [Indexed: 11/18/2022] Open
Abstract
Cirrhosis-induced clinically significant portal hypertension (CSPH) is a fatal disease. Early detection of CSPH is vitally important to reduce the patients' mortality rate. In this study, combined with three-dimensional image construction technology and computational fluid dynamics (CFD), an image-based flow resistance analysis was proposed. The flow resistance analysis was performed for nine cirrhosis patients with CSPH and ten participants without liver diseases, respectively. The results showed that the flow resistance coefficient of the portal vein system in CSPH patients was significantly lower than that in the control group (0.97 ± 0.11 Pa/(mL/s) for CSPH patients; 1.80 ± 0.40 Pa/(mL/s) for the control group; P = 0.028). In contrast, although main portal vein dilation was found in CSPH patients, the cross-sectional area enlargement was not statistically significant (186.01 ± 57.48 mm2 for CSPH patients; 166.26 ± 33.74 mm2 for the control group; P = 0.39). The research outcomes indicated that the flow resistance analysis was more sensitive than the commonly used vessel size measurement in the detection of CSPH. In summary, we suggest using flow resistance analysis as a supplementary noninvasive method to detect cirrhosis patients with CSPH.
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Xu J, Karmonik C, Yu Y, Lv N, Shi Z, Liu JM, Huang Q. Modeling Flow Diverters using a Porous Medium Approach: A Fast Alternative to Virtual Flow Diverter Deployment. World Neurosurg 2022; 164:e501-e508. [PMID: 35552028 DOI: 10.1016/j.wneu.2022.04.132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND The Tubridge flow diverter (FD) is a novel device aimed at reconstructing the parent artery and eliminating the aneurysm. Numerical simulations based on virtual FD deployment allow the assessment of the complex nature of aneurismal flow changes before the actual intervention but are demanding on computational resources. Here, we evaluate an alternative strategy of modeling FD effects for the Tubridge system using a porous medium. The goal of this study is to reduce demands on time and complexity of the simulation procedure for applications in clinical research. METHODS Ten patient-specific aneurysm models were reconstructed from retrospectively collected diagnostic 3D-DSA images. Virtual FDs were deployed (SolidWorks, Meshmixer) and corresponding porous medium patches were constructed at the ostium with a research CFD prototype (Siemens Healthineers, Forchheim, Germany). Hemodynamic conditions were simulated in two approaches. RESULTS Hemodynamics inside the aneurysm based on these two approaches were compared. Both approaches yielded similar results. Mean wall shear stress (WSS) and mean pressure of the aneurysmal wall correlated significantly (r=0.8, r=1.0, p-value<0.05) as did mean velocity, mean pressure at a region inside the aneurysm, at the ostium and at a cross section containing the main vertex (for velocities r=0.9; for pressures r=1.0, p-value<0.05). The use of porous medium patches reduced the preparation and simulation time together by approximately 50%. CONCLUSION Using a porous medium approach yields comparable mean values for hemodynamic alterations compared to direct virtual FD simulations. Additionally, the porous medium approach greatly reduced the modeling complexity and computation time.
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Affiliation(s)
- Jinyu Xu
- From the Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Christof Karmonik
- Translational Imaging Center, MRI core, Houston Methodist Research Institute, Houston TX, USA
| | - Ying Yu
- From the Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Nan Lv
- From the Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Zhaoyue Shi
- Translational Imaging Center, MRI core, Houston Methodist Research Institute, Houston TX, USA
| | - Jian-Min Liu
- From the Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China.
| | - Qinghai Huang
- From the Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China.
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Uchiyama Y, Fujimura S, Takao H, Suzuki T, Ishibashi T, Otani K, Karagiozov K, Fukudome K, Yamamoto H, Yamamoto M, Murayama Y. Role of patient-specific blood properties in computational fluid dynamics simulation of flow diverter deployed cerebral aneurysms. Technol Health Care 2022; 30:839-850. [PMID: 35068427 PMCID: PMC9398066 DOI: 10.3233/thc-213216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND: Hemodynamics and their clinical outcome of cerebral aneurysms treated with flow diverter (FD) stents have thus far been investigated using computational fluid dynamics (CFD) simulations. Although human blood is characterized as a non-Newtonian patientspecific fluid, non-patient-specific blood properties (PSBP) were applied in most extant studies. OBJECTIVE: To investigate the hemodynamic effects caused by PSBPs in aneurysms treated with FD stents. METHODS: We measured blood properties (density and viscosity) for 12 patients who underwent FD stent deployment. We conducted CFD simulations with the measured PSBPs and non-PSBPs quoted from previous studies. The average blood flow velocity and wall shear stress within the aneurysms were calculated and two simulation patterns were compared. RESULTS: The velocity and wall shear stress changed by 2.93% and 3.16% on average, respectively, without an FD stent deployed. Conversely, with the FD stents deployed, the change rates increased to 11.1% and 9.06% on average, respectively. CONCLUSIONS: The change in hemodynamic parameters if PSBPs are considered, may not be negligible when conducting CFD simulations of FD stent deployed aneurysms To obtain an adequate hemodynamic environment for cerebral aneurysms with FD stents deployed, it is recommended to use PSBPs for CFD simulations.
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Affiliation(s)
- Yuya Uchiyama
- Graduate School of Mechanical Engineering, Tokyo University of Science, Katsushika-ku, Tokyo, Japan
- Department of Innovation for Medical Information Technology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Soichiro Fujimura
- Department of Innovation for Medical Information Technology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
- Department of Mechanical Engineering, Tokyo University of Science, Katsushika-ku, Tokyo, Japan
| | - Hiroyuki Takao
- Graduate School of Mechanical Engineering, Tokyo University of Science, Katsushika-ku, Tokyo, Japan
- Department of Innovation for Medical Information Technology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
- Department of Neurosurgery, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Takashi Suzuki
- Department of Innovation for Medical Information Technology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Toshihiro Ishibashi
- Department of Neurosurgery, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Katharina Otani
- Department of Neurosurgery, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
- Siemens Healthcare Japan K.K., Shinagawa-ku, Tokyo, Japan
| | - Kostadin Karagiozov
- Department of Neurosurgery, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Koji Fukudome
- Department of Mechanical Engineering, Tokyo University of Science, Katsushika-ku, Tokyo, Japan
| | - Hideki Yamamoto
- Faculty of Environmental and Urban Engineering, Kansai University Fukita-shi, Osaka, Japan
| | - Makoto Yamamoto
- Department of Mechanical Engineering, Tokyo University of Science, Katsushika-ku, Tokyo, Japan
| | - Yuichi Murayama
- Department of Neurosurgery, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
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GÜZELDAĞ H, ONAN B, PİŞKİN FC, SÖZÜTOK S. Geniş boyunlu paraoftalmik anevrizmaların akım çevirici stent implantasyonu ile endovasküler tedavisi. Cukurova Medical Journal 2021. [DOI: 10.17826/cumj.977944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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7
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Ou C, Hou X, Duan CZ, Zhang X, Chong W, Qian Y. Flow diverter modeled as heterogeneous and anisotropic porous medium: Simulation, experimental validation and case analysis. J Biomech 2021; 123:110525. [PMID: 34023757 DOI: 10.1016/j.jbiomech.2021.110525] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 04/23/2021] [Accepted: 05/09/2021] [Indexed: 11/22/2022]
Abstract
Simulation of flow diverter (FD) treated aneurysm can evaluate treatment efficacy and aid treatment planning. However, explicit modeling of thin wires of FD impose extremely high demand of computational resources and time, which limit its use in time-sensitive presurgical planning. One alternative approach is to model FD as homogenous porous medium, which saves time but with compromise in accuracy. We proposed a new method to model FD as heterogeneous and anisotropic porous medium whose properties were determined from local porosity. The new method was validated by comparing with PIV measurement from an in-vitro phantom. Simulation result was in good agreement with experimental measurement. Four patient cases were further analyzed to compare the new method with the homogenous porous media method. Results showed that in patient cases with curved artery, new method was preferred over the homogenous method, as the assumption of homogenous porosity led to overpredicted flow reduction effect by as much as 87.9%, which may lead to overoptimistic decision making and poor prognosis. Our new method can provide timely and accurate simulation to aid in the treatment planning of aneurysms.
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Chivukula VK, Marsh L, Chassagne F, Barbour MC, Kelly CM, Levy S, Geindreau C, Roscoat SRD, Kim LJ, Levitt MR, Aliseda A. Lagrangian Trajectory Simulation of Platelets and Synchrotron Microtomography Augment Hemodynamic Analysis of Intracranial Aneurysms Treated With Embolic Coils. J Biomech Eng 2021; 143:1102198. [PMID: 33665669 DOI: 10.1115/1.4050375] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Indexed: 11/08/2022]
Abstract
As frequency of endovascular treatments for intracranial aneurysms increases, there is a growing need to understand the mechanisms for coil embolization failure. Computational fluid dynamics (CFD) modeling often simplifies modeling the endovascular coils as a homogeneous porous medium (PM), and focuses on the vascular wall endothelium, not considering the biomechanical environment of platelets. These assumptions limit the accuracy of computations for treatment predictions. We present a rigorous analysis using X-ray microtomographic imaging of the coils and a combination of Lagrangian (platelet) and Eulerian (endothelium) metrics. Four patient-specific, anatomically accurate in vitro flow phantoms of aneurysms are treated with the same patient-specific endovascular coils. Synchrotron tomography scans of the coil mass morphology are obtained. Aneurysmal hemodynamics are computationally simulated before and after coiling, using patient-specific velocity/pressure measurements. For each patient, we analyze the trajectories of thousands of platelets during several cardiac cycles, and calculate residence times (RTs) and shear exposure, relevant to thrombus formation. We quantify the inconsistencies of the PM approach, comparing them with coil-resolved (CR) simulations, showing the under- or overestimation of key hemodynamic metrics used to predict treatment outcomes. We fully characterize aneurysmal hemodynamics with converged statistics of platelet RT and shear stress history (SH), to augment the traditional wall shear stress (WSS) on the vascular endothelium. Incorporating microtomographic scans of coil morphology into hemodynamic analysis of coiled intracranial aneurysms, and augmenting traditional analysis with Lagrangian platelet metrics improves CFD predictions, and raises the potential for understanding and clinical translation of computational hemodynamics for intracranial aneurysm treatment outcomes.
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Affiliation(s)
| | - Laurel Marsh
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195
| | - Fanette Chassagne
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195
| | - Michael C Barbour
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195
| | - Cory M Kelly
- Department of Neurological Surgery, University of Washington, Seattle, WA 98195; Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA 98195
| | - Samuel Levy
- Department of Neurological Surgery, University of Washington, Seattle, WA 98195; Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA 98195
| | - Christian Geindreau
- Laboratoire 3SR, Université Grenoble Alpes, 1270 Rue de la Piscine, Gières 38610, France
| | | | - Louis J Kim
- Department of Neurological Surgery, University of Washington, Seattle, WA 98195; Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA 98195; Department of Radiology, University of Washington, Seattle, WA 98195
| | - Michael R Levitt
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195; Department of Neurological Surgery, University of Washington, Seattle, WA 98195; Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA 98195; Department of Radiology, University of Washington, Seattle, WA 98195
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195; Department of Neurological Surgery, University of Washington, Seattle, WA 98195; Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA 98195
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Sunohara T, Imamura H, Goto M, Fukumitsu R, Matsumoto S, Fukui N, Oomura Y, Akiyama T, Fukuda T, Go K, Kajiura S, Shigeyasu M, Asakura K, Horii R, Sakai C, Sakai N. Neck Location on the Outer Convexity is a Predictor of Incomplete Occlusion in Treatment with the Pipeline Embolization Device: Clinical and Angiographic Outcomes. AJNR Am J Neuroradiol 2021; 42:119-125. [PMID: 33184073 DOI: 10.3174/ajnr.a6859] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 08/11/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND AND PURPOSE With the increasing use of the Pipeline Embolization Device for the treatment of aneurysms, predictors of clinical and angiographic outcomes are needed. This study aimed to identify predictors of incomplete occlusion at last angiographic follow-up. MATERIALS AND METHODS In our retrospective, single-center cohort study, 105 ICA aneurysms in 89 subjects were treated with Pipeline Embolization Devices. Patients were followed per standardized protocol. Clinical and angiographic outcomes were analyzed. We introduced a new morphologic classification based on the included angle of the parent artery against the neck location: outer convexity type (included angle, <160°), inner convexity type (included angle, >200°), and lateral wall type (160° ≤ included angle ≤200°). This classification reflects the metal coverage rate and flow dynamics. RESULTS Imaging data were acquired in 95.3% of aneurysms persistent at 6 months. Complete occlusion was achieved in 70.5%, and incomplete occlusion, in 29.5% at last follow-up. Multivariable regression analysis revealed that 60 years of age or older (OR, 5.70; P = .001), aneurysms with the branching artery from the dome (OR, 10.56; P = .002), fusiform aneurysms (OR, 10.2; P = .009), and outer convexity-type saccular aneurysms (versus inner convexity type: OR, 30.3; P < .001; versus lateral wall type: OR, 9.71; P = .001) were independently associated with a higher rate of incomplete occlusion at the last follow-up. No permanent neurologic deficits or rupture were observed in the follow-up period. CONCLUSIONS The aneurysm neck located on the outer convexity is a new, incomplete occlusion predictor, joining older age, fusiform aneurysms, and aneurysms with the branching artery from the dome. No permanent neurologic deficits or rupture was observed in the follow-up, even with incomplete occlusion.
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Affiliation(s)
- T Sunohara
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan.
| | - H Imamura
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - M Goto
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - R Fukumitsu
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - S Matsumoto
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - N Fukui
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Y Oomura
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - T Akiyama
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - T Fukuda
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - K Go
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - S Kajiura
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - M Shigeyasu
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - K Asakura
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - R Horii
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - C Sakai
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
| | - N Sakai
- From the Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan
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Fathi MF, Perez-Raya I, Baghaie A, Berg P, Janiga G, Arzani A, D'Souza RM. Super-resolution and denoising of 4D-Flow MRI using physics-Informed deep neural nets. Comput Methods Programs Biomed 2020; 197:105729. [PMID: 33007592 DOI: 10.1016/j.cmpb.2020.105729] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 08/23/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND AND OBJECTIVE Time resolved three-dimensional phase contrast magnetic resonance imaging (4D-Flow MRI) has been used to non-invasively measure blood velocities in the human vascular system. However, issues such as low spatio-temporal resolution, acquisition noise, velocity aliasing, and phase-offset artifacts have hampered its clinical application. In this research, we developed a purely data-driven method for super-resolution and denoising of 4D-Flow MRI. METHODS The flow velocities, pressure, and the MRI image magnitude are modeled as a patient-specific deep neural net (DNN). For training, 4D-Flow MRI images in the complex Cartesian space are used to impose data-fidelity. Physics of fluid flow is imposed through regularization. Creative loss function terms have been introduced to handle noise and super-resolution. The trained patient-specific DNN can be sampled to generate noise-free high-resolution flow images. The proposed method has been implemented using the TensorFlow DNN library and tested on numerical phantoms and validated in-vitro using high-resolution particle image velocitmetry (PIV) and 4D-Flow MRI experiments on transparent models subjected to pulsatile flow conditions. RESULTS In case of numerical phantoms, we were able to increase spatial resolution by a factor of 100 and temporal resolution by a factor of 5 compared to the simulated 4D-Flow MRI. There is an order of magnitude reduction of velocity normalized root mean square error (vNRMSE). In case of the in-vitro validation tests with PIV as reference, there is similar improvement in spatio-temporal resolution. Although the vNRMSE is reduced by 50%, the method is unable to negate a systematic bias with respect to the reference PIV that is introduced by the 4D-Flow MRI measurement. CONCLUSIONS This work has demonstrated the feasibility of using the readily available machinery of deep learning to enhance 4D-Flow MRI using a purely data-driven method. Unlike current state-of-the-art methods, the proposed method is agnostic to geometry and boundary conditions and therefore eliminates the need for tedious tasks such as accurate image segmentation for geometry, image registration, and estimation of boundary flow conditions. Arbitrary regions of interest can be selected for processing. This work will lead to user-friendly analysis tools that will enable quantitative hemodynamic analysis of vascular diseases in a clinical setting.
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Affiliation(s)
- Mojtaba F Fathi
- Dept. of Mechanical Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Isaac Perez-Raya
- Dept. of Mechanical Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Ahmadreza Baghaie
- Dept. of Electrical and Computer Engineering, New York Institute of Technology, Long Island, NY, USA
| | - Philipp Berg
- Lab. of Fluid Dynamics and Technical Flows, University of Magdeburg, Germany; Research Campus STIMULATE, University of Magdeburg, Magdeburg, Germany
| | - Gabor Janiga
- Lab. of Fluid Dynamics and Technical Flows, University of Magdeburg, Germany; Research Campus STIMULATE, University of Magdeburg, Magdeburg, Germany
| | - Amirhossein Arzani
- Dept. of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, USA
| | - Roshan M D'Souza
- Dept. of Mechanical Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
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Chaparro-rico BDM, Sebastiano F, Cafolla D. A Smart Stent for Monitoring Eventual Restenosis: Computational Fluid Dynamic and Finite Element Analysis in Descending Thoracic Aorta. Machines 2020; 8:81. [DOI: 10.3390/machines8040081] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Even though scientific studies of smart stents are extensive, current smart stents focus on pressure sensors. This paper presents a novel implantable biocompatible smart stent for monitoring eventual restenosis. The device is comprised of a metal mesh structure, a biocompatible and adaptable envelope, and pair-operated ultrasonic sensors for restenosis monitoring through flow velocity. Aside from continuous monitoring of restenosis post-implantation, it is also important to evaluate whether the stent design itself causes complications such as restenosis or thrombosis. Therefore, computational fluid dynamic (CFD) analysis before and after stent implantation were carried out as well as finite element analysis (FEA). The proposed smart stent was put in the descending thoracic section of a virtually reconstructed aorta that comes from a computed tomography (CT) scan. Blood flow velocity showed that after stent implantation, there is not liquid retention or vortex generation. In addition, blood pressures after stent implantation were within the normal blood pressure values. The stress and the factor of safety (FOS) analysis showed that the stress values reached by the stent are very far from the yield strength limit of the materials and that the stent is stiff enough to support the applied loads exported from the CFD results.
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Peng L, Chen J, Cheng Y, Lv N, Gao H, Bai B. The Hemodynamic Effect of Flow Diverter Treatment of Intracranial Bifurcation Aneurysms. J Med Biol Eng 2020; 40:851-7. [DOI: 10.1007/s40846-020-00570-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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13
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Saqr KM, Rashad S, Tupin S, Niizuma K, Hassan T, Tominaga T, Ohta M. What does computational fluid dynamics tell us about intracranial aneurysms? A meta-analysis and critical review. J Cereb Blood Flow Metab 2020; 40:1021-1039. [PMID: 31213162 PMCID: PMC7181089 DOI: 10.1177/0271678x19854640] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Despite the plethora of published studies on intracranial aneurysms (IAs) hemodynamic using computational fluid dynamics (CFD), limited progress has been made towards understanding the complex physics and biology underlying IA pathophysiology. Guided by 1733 published papers, we review and discuss the contemporary IA hemodynamics paradigm established through two decades of IA CFD simulations. We have traced the historical origins of simplified CFD models which impede the progress of comprehending IA pathology. We also delve into the debate concerning the Newtonian fluid assumption used to represent blood flow computationally. We evidently demonstrate that the Newtonian assumption, used in almost 90% of studies, might be insufficient to describe IA hemodynamics. In addition, some fundamental properties of the Navier-Stokes equation are revisited in supplementary material to highlight some widely spread misconceptions regarding wall shear stress (WSS) and its derivatives. Conclusively, our study draws a roadmap for next-generation IA CFD models to help researchers investigate the pathophysiology of IAs.
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Affiliation(s)
- Khalid M Saqr
- Biomedical Flow Dynamics Laboratory, Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan.,Department of Mechanical Engineering, College of Engineering and Technology, Arab Academy for Science, Technology and Maritime Transport, Alexandria, Egypt
| | - Sherif Rashad
- Department of Neurosurgical Engineering and Translational Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Simon Tupin
- Biomedical Flow Dynamics Laboratory, Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan
| | - Kuniyasu Niizuma
- Department of Neurosurgical Engineering and Translational Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Neurosurgical Engineering and Translational Neuroscience, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
| | - Tamer Hassan
- Department of Neurosurgery, Alexandria University School of Medicine, Azarita Medical Campus, Alexandria, Egypt
| | - Teiji Tominaga
- Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Makoto Ohta
- Biomedical Flow Dynamics Laboratory, Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan
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Li Y, Verrelli DI, Yang W, Qian Y, Chong W. A pilot validation of CFD model results against PIV observations of haemodynamics in intracranial aneurysms treated with flow-diverting stents. J Biomech 2020; 100:109590. [DOI: 10.1016/j.jbiomech.2019.109590] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 12/07/2019] [Accepted: 12/18/2019] [Indexed: 11/30/2022]
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15
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Csippa B, Gyürki D, Závodszky G, Szikora I, Paál G. Hydrodynamic Resistance of Intracranial Flow-Diverter Stents: Measurement Description and Data Evaluation. Cardiovasc Eng Technol 2020; 11:1-13. [PMID: 31797262 DOI: 10.1007/s13239-019-00445-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [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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16
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Xu L, Zhao B, Liu X, Liang F. Computational methods applied to analyze the hemodynamic effects of flow-diverter devices in the treatment of cerebral aneurysms: Current status and future directions. Medicine in Novel Technology and Devices 2019; 3:100018. [DOI: 10.1016/j.medntd.2019.100018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Yadollahi-Farsani H, Scougal E, Herrmann M, Wei W, Frakes D, Chong B. Numerical study of hemodynamics in brain aneurysms treated with flow diverter stents using porous medium theory. Comput Methods Biomech Biomed Engin 2019; 22:961-971. [DOI: 10.1080/10255842.2019.1609457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
| | - Erik Scougal
- School for Engineering of Matter Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Marcus Herrmann
- School for Engineering of Matter Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Wei Wei
- School for Engineering of Matter Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - David Frakes
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
- School of Electrical Computer and Energy Engineering, Arizona State University, Tempe, AZ, USA
| | - Brian Chong
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
- Department of Radiology, Mayo Clinic Hospital, Phoenix, AZ, USA
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Chua MMJ, Silveira L, Moore J, Pereira VM, Thomas AJ, Dmytriw AA. Flow diversion for treatment of intracranial aneurysms: Mechanism and implications. Ann Neurol 2019; 85:793-800. [PMID: 30973965 DOI: 10.1002/ana.25484] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 03/31/2019] [Accepted: 04/07/2019] [Indexed: 12/31/2022]
Abstract
Flow diverters are new generation stents that have recently garnered a large amount of interest for use in treatment of intracranial aneurysms. Flow diverters reduce blood flow into the aneurysm, with redirection along the path of the parent vessel. Flow stagnation into the aneurysm and neck coverage with subsequent endothelialization are the important synergistic mechanisms by which the therapy acts. Several studies have examined the mechanisms by which flow diverters subsequently lead to aneurysm occlusion. This review aims to provide a general overview of the flow diverters and their mechanism of action and potential implications. ANN NEUROL 2019;85:793-800.
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Affiliation(s)
| | | | - Justin Moore
- Boston University School of Medicine, Boston, MA.,Neurosurgical Service, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Vitor M Pereira
- Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Ajith J Thomas
- Neurosurgical Service, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Adam A Dmytriw
- Neurosurgical Service, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.,Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
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Catalán-echeverría B, Kelly M, Peeling L, Bergstrom D, Chen X, Malvè M. CFD-Based Comparison Study of a New Flow Diverting Stent and Commercially-Available Ones for the Treatment of Cerebral Aneurysms. Applied Sciences 2019; 9:1341. [DOI: 10.3390/app9071341] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [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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Chiu TL, Tang AYS, Tsang ACO, Leung GKK, Chow KW. A Computational Hemodynamics Analysis on the Correlation Between Energy Loss and Clinical Outcomes for Flow Diverters Treatment of Intracranial Aneurysm. J Med Biol Eng 2019; 39:27-42. [DOI: 10.1007/s40846-018-0376-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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21
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Li Y, Zhang M, Verrelli DI, Chong W, Ohta M, Qian Y. Numerical simulation of aneurysmal haemodynamics with calibrated porous-medium models of flow-diverting stents. J Biomech 2018; 80:88-94. [DOI: 10.1016/j.jbiomech.2018.08.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 05/18/2018] [Accepted: 08/22/2018] [Indexed: 11/27/2022]
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22
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Alkhalili K, Hannallah J, Cobb M, Chalouhi N, Philips JL, Echeverria AB, Jabbour P, Babiker MH, Frakes DH, Gonzalez LF. The Effect of Stents in Cerebral Aneurysms: A Review. Asian J Neurosurg 2018; 13:201-211. [PMID: 29682009 PMCID: PMC5898080 DOI: 10.4103/1793-5482.175639] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The etiology of up to 95% of cerebral aneurysms may be accounted for by hemodynamically-induced factors that create vascular injury. The purpose of this review is to describe key physical properties that stents have and how they affect cerebral aneurysms. We performed a two-step screening process. First, a structured search was performed using the PubMed database. The following search terms and keywords were used: “Hemodynamics,” “wall shear stress (WSS),” “velocity,” “viscosity,” “cerebral aneurysm,” “intracranial aneurysm,” “stent,” “flow diverter,” “stent porosity,” “stent geometry,” “stent configuration,” and “stent design.” Reports were considered if they included original data, discussed hemodynamic changes after stent-based treatment of cerebral aneurysms, examined the hemodynamic effects of stent deployment, and/or described the geometric characteristics of both stents and the aneurysms they were used to treat. The search strategy yielded a total of 122 articles, 61 were excluded after screening the titles and abstracts. Additional articles were then identified by cross-checking reference lists. The final collection of 97 articles demonstrates that the geometric characteristics and configurations of deployed stents influenced hemodynamic parameters such as aneurysmal WSS, inflow, and pressure. The geometric characteristics of the aneurysm and its position also had significant influences on intra-aneurysmal hemodynamics after treatment. In conclusion, changes in specific aneurysmal hemodynamic parameters that result from stenting relate to a number of factors including the geometric properties and configurations of deployed stents, the geometric properties of the aneurysm, and the pretreatment hemodynamics.
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Affiliation(s)
- Kenan Alkhalili
- Department of Surgery, University of Arizona, Tucson, Arizona, USA
| | - Jack Hannallah
- Department of Surgery, University of Arizona, Tucson, Arizona, USA
| | - Mary Cobb
- Division of Neurosurgery, Duke University, Durham, NC, USA
| | - Nohra Chalouhi
- Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jessica L Philips
- Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Pascal Jabbour
- Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - David H Frakes
- Division of Neurosurgery, Duke University, Durham, NC, USA
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Bhogal P, AlMatter M, Hellstern V, Ganslandt O, Bäzner H, Henkes H, Aguilar-Pérez M. The Combined Use of Intraluminal and Intrasaccular Flow Diversion for the Treatment of Intracranial Aneurysms: Report of 25 Cases. Neurointervention 2018; 13:20-31. [PMID: 29535895 PMCID: PMC5847887 DOI: 10.5469/neuroint.2018.13.1.20] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 02/23/2018] [Accepted: 02/26/2018] [Indexed: 11/29/2022] Open
Abstract
PURPOSE The Medina Embolic Device (MED) is a new intrasaccular device with promising early results. Previously we documented our initial experience of this device both alone and in combination with other devices including flow diverter stents (FDS). We sought to determine the effect of the MED + FDS strategy for the treatment of selected aneurysms. MATERIALS AND METHODS We performed a retrospective analysis of prospectively collected data to identify all patients with aneurysms treated using both the MED and intraluminal FDS. We present our technical success rate, early and mid-term angiographic follow-up, and clinical outcome data. RESULTS We identified 25 non-consecutive patients. The treatment was staged in 9 patients and in a single session 16 patients. The average age was 61±12.8 years (range 40-82). The average fundus height was 11±3.6 mm and average fundus width was 10.1±3.4 mm. In the staged cohort (n=9) at delayed angiography (mean 10 mths) 8 aneurysms (89%) showed complete exclusion (mRRC 1) and in one patient there was a parent vessel occlusion. In the simultaneous cohort delayed angiography (n=10, mean 8.1 months) demonstrated complete occlusion (mRRC 1) in 6 aneurysms (60%), 3 neck remnants (mRRC 2) (30%) and 1 patient (10%) showed persistent aneurysmal filling (mRRC 3a). There were 5 complications with permanent morbidity (mRS >2) in two patients. There were no mortalities. CONCLUSION The MED can be successfully used in combination with intraluminal FDS and in selected aneurysms this may represent an alternative to FDS and adjunctive coiling.
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Affiliation(s)
- Pervinder Bhogal
- Neuroradiological Clinic, Neurocenter, Klinikum Stuttgart, Germany
| | | | | | | | - Hansjörg Bäzner
- Neurological Clinic, Neurocenter, Klinikum Stuttgart, Germany
| | - Hans Henkes
- Neuroradiological Clinic, Neurocenter, Klinikum Stuttgart, Germany
- Medical Faculty, University Duisburg-Essen, Germany
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Durka MJ, Wong IH, Kallmes DF, Pasalic D, Mut F, Jagani M, Blanco PJ, Cebral JR, Robertson AM. A data-driven approach for addressing the lack of flow waveform data in studies of cerebral arterial flow in older adults. Physiol Meas 2018; 39:015006. [PMID: 29205172 DOI: 10.1088/1361-6579/aa9f46] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Blood flow waveforms-essential data for hemodynamic modeling-are often in practice unavailable to researchers. The objectives of this work were to assess the variability among the waveforms for a clinically relevant older population, and develop data-based methods for addressing the missing waveform data for hemodynamic studies. APPROACH We analyzed 272 flow waveforms from the internal carotid arteries of older patients (73 ± 13 yr) with moderate cardiovascular disease, and used these data to develop methods to guide new approaches for hemodynamic studies. MAIN RESULTS Profound variations in waveform parameters were found within the aged population that were not seen in published data for young subjects. Common features in the aged population relative to the young included a larger systole-to-diastole flow rate ratio, increased flow during late systole, and absence of a dicrotic notch. Eight waveforms were identified that collectively represent the range of waveforms in the older population. A relationship between waveform shape and flow rate was obtained that, in conjunction with equations relating flow rate to diameter, can be used to provide individualized waveforms for patient-specific geometries. The dependence of flow rate on diameter was statistically different between male and female patients. SIGNIFICANCE It was shown that a single archetypal waveform cannot well-represent the diverse waveforms found within an aged population, although this approach is frequently used in studies of flow in the cerebral vasculature. Motivated by these results, we provided a set of eight waveforms that can be used to assess the hemodynamic uncertainty associated with the lack of patient-specific waveform data. We also provided a methodology for generating individualized waveforms when patient gender, age, and cardiovascular disease state are known. These data-driven approaches can be used to devise more relevant in vitro or in silico intra-cranial hemodynamic studies for older patients.
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Affiliation(s)
- Michael J Durka
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
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25
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Karmonik C, Anderson JR, Elias S, Klucznik R, Diaz O, Zhang YJ, Grossman RG, Britz GW. Four-Dimensional Phase Contrast Magnetic Resonance Imaging Protocol Optimization Using Patient-Specific 3-Dimensional Printed Replicas for In Vivo Imaging Before and After Flow Diverter Placement. World Neurosurg 2017; 105:775-82. [DOI: 10.1016/j.wneu.2017.06.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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26
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Verrelli DI, Yang W, Chong W, Ohta M. Sensitivity study on modelling a flow-diverting stent as a porous medium using computational fluid dynamics. Annu Int Conf IEEE Eng Med Biol Soc 2017; 2017:3389-3392. [PMID: 29060624 DOI: 10.1109/embc.2017.8037583] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The flow-diverting (FD) stent has become a commonly used endovascular device to treat cerebral aneurysms. This discourages blood from entering the aneurysm, thereby reducing the likelihood of aneurysm rupture. Using computational fluid dynamics (CFD) to simulate the aneurysmal haemodynamics after FD treatment could help clinicians predict the stent effectiveness prior to the real procedure in the patient. As an alternative to modelling the stent as a fine wire mesh, modelling the FD stent as a porous medium was established to save computational time, and has also been proved capable of predicting the same haemodynamics as obtained using the real FD stent geometry. The flow resistance effect of a porous-medium stent may differ with respect to its morphology or permeability; however, the flow resistance effect after adjusting these parameters had not been clarified. In this study, we analysed the haemodynamic changes caused by alterations of porous-medium thickness and permeability, thereby providing future porous-medium stent simulations with important information on the respective parametric sensitivities. We found significant sensitivity to permeability. Results were insensitive to thickness when permeability was adjusted beforehand to compensate. We also compared our results with observations from an in-vitro model, and found good agreement. This supports adoption of porous-medium models in future work.
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Abstract
Background The importance of both porosity and pore density of a flow diverter is well recognized in treatment of intracranial aneurysms; however, understanding of the effect of individual wire (wire number and size) is critical in improving device design and use. Methods A total of 10 multi-layered flow diverters with different wire numbers (32, 48, 56, and 72) and sizes (30, 35, and 40 µm) were implanted into identical patient-specific middle cerebral artery aneurysm models. Digital subtraction angiography was acquired at 30 f/s and X-ray signals at three selected regions of interest were compared to determine the amount of intra-aneurysmal flow. Results Flow reduction ranged from 19% for a high porosity (82%) and low pore density (5 pores/mm2) to nearly 80% for a low porosity (49%) and high pore density (36 pores/mm2). An increase in the wire number from 32 to 72 lowers intra-aneurysmal flow and redirects the flow jet; however, the effect of wire size is not observed. Conclusions In our in vitro angiographic study, flow jet is influenced by the wire number in a device qualitatively; quantitatively, intra-aneurysmal flow is affected by both the porosity and pore density. A 2.5 mm device performs better in flow diversion of a middle cerebral artery (MCA) aneurysm than a 3 mm device with the same wire size and wire number, but thicker wires do not lead to better flow diversion.
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Affiliation(s)
- Liang-Der Jou
- Department of Neurosurgery, Houston Methodist Hospital, Houston, TX, USA
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28
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Zhang M, Li Y, Zhao X, Verrelli DI, Chong W, Ohta M, Qian Y. Haemodynamic effects of stent diameter and compaction ratio on flow-diversion treatment of intracranial aneurysms: A numerical study of a successful and an unsuccessful case. J Biomech 2017; 58:179-186. [PMID: 28576622 DOI: 10.1016/j.jbiomech.2017.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 04/02/2017] [Accepted: 05/05/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND Compacting a flow-diverting (FD) stent is an emerging technique to create a denser configuration of wires across the aneurysm ostium. However, quantitative analyses of post-stenting haemodynamics affected by the compaction level of different stent sizes remain inconclusive. OBJECTIVE To compare the aneurysmal haemodynamic alterations after virtual FD treatments with different device diameters at different compaction ratios. METHODS We virtually implanted three sizes of FD stent, with each size deployed at four compaction ratios, into two patient aneurysms previously treated with the Silk+FD-one successful case and the other unsuccessful. Wire configurations of the FD in the 24 treatment scenarios were examined, and aneurysmal haemodynamic alterations were resolved by computational fluid dynamics (CFD) simulations. We investigated the aneurysmal flow patterns, aneurysmal average velocity (AAV), mass flowrate (MF), and energy loss (EL) in each scenario. RESULTS Compactions of the stent in the successful case resulted in a greater metal coverage rate than that achieved in the unsuccessful one. A 25% increment in compaction ratio further decreased the AAV (12%), MF (11%), and EL (9%) in both cases (average values). The averaged maximum differences attributable to device size were 10% (AAV), 8% (MF), and 9% (EL). CONCLUSIONS Both stent size and compaction level could markedly affect the FD treatment outcomes. It is therefore important to individualise the treatment plan by selecting the optimal stent size and deployment procedure. CFD simulation can be used to investigate the treatment outcomes, thereby assisting doctors in choosing a favourable treatment plan.
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Affiliation(s)
- Mingzi Zhang
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia; Graduate School of Engineering, Tohoku University, Sendai, Miyagi, Japan
| | - Yujie Li
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia; Graduate School of Engineering, Tohoku University, Sendai, Miyagi, Japan
| | - Xi Zhao
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - David I Verrelli
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Winston Chong
- Neuroradiology Department, Monash Medical Centre, Melbourne, Victoria, Australia; Department of Surgery, School of Clinical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Makoto Ohta
- Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan
| | - Yi Qian
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia.
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Zenteno M, Lee A, Bejarano JLH, Satyarthee GD, Alvis-Miranda HR, Moscote-Salazar LR. When flow diverters fail: short review and a case illustration of a device failure. Romanian Neurosurgery 2016. [DOI: 10.1515/romneu-2016-0075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
The ultimate aims of treatment of the intracranial aneurysms are reconstruction the vessel wall and correcting the hemodynamic disturbance. A flow diverter (FD) is a stent placed inside lumen of the parent artery with aim to blood flow reduction into the aneurysms sac to the extent of almost stagnation leading to gradual onset of progressive thrombosis and neointimal lining of arterial wall remodeling to maintain blood outflow into perforators the side and branches. Flow diverter is considered as an effective treatment for fusiform, wide-necked, large and giant intracranial unruptured aneurysms. However, FD implantation may also be associated with growth and rupture of residual aneurysms. The most frequent complication of endovascular aneurysms management is thromboembolic events and less common are intra and postoperative hemorrhagic aneurysmal rupture. Authors report a case where a lack of operation of the device as illustration is presented to demonstrate the shortcomings of this new type of devices.
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Quicken S, Donders WP, van Disseldorp EMJ, Gashi K, Mees BME, van de Vosse FN, Lopata RGP, Delhaas T, Huberts W. Application of an Adaptive Polynomial Chaos Expansion on Computationally Expensive Three-Dimensional Cardiovascular Models for Uncertainty Quantification and Sensitivity Analysis. J Biomech Eng 2016; 138:2554136. [DOI: 10.1115/1.4034709] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Indexed: 11/08/2022]
Abstract
When applying models to patient-specific situations, the impact of model input uncertainty on the model output uncertainty has to be assessed. Proper uncertainty quantification (UQ) and sensitivity analysis (SA) techniques are indispensable for this purpose. An efficient approach for UQ and SA is the generalized polynomial chaos expansion (gPCE) method, where model response is expanded into a finite series of polynomials that depend on the model input (i.e., a meta-model). However, because of the intrinsic high computational cost of three-dimensional (3D) cardiovascular models, performing the number of model evaluations required for the gPCE is often computationally prohibitively expensive. Recently, Blatman and Sudret (2010, “An Adaptive Algorithm to Build Up Sparse Polynomial Chaos Expansions for Stochastic Finite Element Analysis,” Probab. Eng. Mech., 25(2), pp. 183–197) introduced the adaptive sparse gPCE (agPCE) in the field of structural engineering. This approach reduces the computational cost with respect to the gPCE, by only including polynomials that significantly increase the meta-model’s quality. In this study, we demonstrate the agPCE by applying it to a 3D abdominal aortic aneurysm (AAA) wall mechanics model and a 3D model of flow through an arteriovenous fistula (AVF). The agPCE method was indeed able to perform UQ and SA at a significantly lower computational cost than the gPCE, while still retaining accurate results. Cost reductions ranged between 70–80% and 50–90% for the AAA and AVF model, respectively.
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Affiliation(s)
- Sjeng Quicken
- Department of Biomedical Engineering, School for Cardiovascular Diseases (CARIM), Maastricht University, Universiteitssingel 50, Maastricht 6229 ER, The Netherlands e-mail:
| | - Wouter P. Donders
- Department of Biomedical Engineering, School for Mental Health and Neuroscience (MHENS), Maastricht University, Universiteitssingel 50, Maastricht 6229 ER, The Netherlands e-mail:
| | - Emiel M. J. van Disseldorp
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands e-mail:
| | - Kujtim Gashi
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands e-mail:
| | - Barend M. E. Mees
- Department of Vascular Surgery, Maastricht University Medical Center, P.O. Box 5800, Maastricht 6202 AZ, The Netherlands e-mail:
| | - Frans N. van de Vosse
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands e-mail:
| | - Richard G. P. Lopata
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands e-mail:
| | - Tammo Delhaas
- Department of Biomedical Engineering, School for Cardiovascular Diseases (CARIM), Maastricht University, Universiteitssingel 50, Maastricht 6229 ER, The Netherlands e-mail:
| | - Wouter Huberts
- Department of Biomedical Engineering, School for Cardiovascular Diseases (CARIM), Maastricht University, Universiteitssingel 50, Maastricht 6229 ER, The Netherlands e-mail:
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Morales HG, Bonnefous O, Geers AJ, Brina O, Pereira VM, Spelle L, Moret J, Larrabide I. Does Arterial Flow Rate Affect the Assessment of Flow-Diverter Stent Performance? AJNR Am J Neuroradiol 2016; 37:2293-2298. [PMID: 27633810 DOI: 10.3174/ajnr.a4933] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 07/20/2016] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Our aim was to assess the performance of flow-diverter stents. The pre- and end-of-treatment angiographies are commonly compared. However, the arterial flow rate may change between acquisitions; therefore, a better understanding of its influence on the local intra-aneurysmal hemodynamics before and after flow-diverter stent use is required. MATERIALS AND METHODS Twenty-five image-based aneurysm models extracted from 3D rotational angiograms were conditioned for computational fluid dynamics simulations. Pulsatile simulations were performed at different arterial flow rates, covering a wide possible range of physiologic flows among 1-5 mL/s. The effect of flow-diverter stents on intra-aneurysmal hemodynamics was numerically simulated with a porous medium model. Spatiotemporal-averaged intra-aneurysmal flow velocity and flow rate were calculated for each case to quantify the hemodynamics after treatment. The short-term flow-diverter stent performance was characterized by the relative velocity reduction inside the aneurysm. RESULTS Spatiotemporal-averaged intra-aneurysmal flow velocity before and after flow-diverter stent use is linearly proportional to the mean arterial flow rate (minimum R2 > 0.983 of the linear regression models for untreated and stented models). Relative velocity reduction asymptotically decreases with increasing mean arterial flow rate. When the most probable range of arterial flow rate was considered (3-5 mL/s), instead of the wide possible flow range, the mean SD of relative velocity reduction was reduced from 3.6% to 0.48%. CONCLUSIONS Both intra-aneurysmal aneurysm velocity and flow-diverter stent performance depend on the arterial flow rate. The performance could be considered independent of the arterial flow rates within the most probable range of physiologic flows.
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Affiliation(s)
- H G Morales
- From Medisys-Philips Research (H.G.M., O.Bonnefous), Paris, France
| | - O Bonnefous
- From Medisys-Philips Research (H.G.M., O.Bonnefous), Paris, France
| | - A J Geers
- Centre for Cardiovascular Science (A.J.G.), University of Edinburgh, Edinburgh, Scotland.,Department of Information and Communication Technologies (A.J.G.), Universitat Pompeu Fabra, Barcelona, Spain
| | - O Brina
- Department of Information Neuroradiology (O.Brina), University Hospital of Geneva, Geneva, Switzerland
| | - V M Pereira
- Department of Medical Imaging and Department of Surgery (V.M.P.), University Health Network, Toronto, Ontario, Canada
| | - L Spelle
- Interventional Neuroradiology (L.S., J.M.), Beaujon University Hospital, Clichy, France.,Paris Diderot University (L.S.), Paris, France
| | - J Moret
- Interventional Neuroradiology (L.S., J.M.), Beaujon University Hospital, Clichy, France
| | - I Larrabide
- PLADEMA-CONICET (I.L.), Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina
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Briganti F, Leone G, Ugga L, Marseglia M, Solari D, Caranci F, Mariniello G, Maiuri F, Cappabianca P. Safety and efficacy of flow re-direction endoluminal device (FRED) in the treatment of cerebral aneurysms: a single center experience. Acta Neurochir (Wien) 2016; 158:1745-55. [PMID: 27357157 DOI: 10.1007/s00701-016-2875-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 06/07/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Experience with the endovascular treatment of cerebral aneurysms by the Flow Re-Direction Endoluminal Device (FRED) is still limited. The aim of this study is to discuss the results and complications of this new flow diverter device (FDD). METHODS Between November 2013 and April 2015, 20 patients (15 female and five male) harboring 24 cerebral aneurysms were treated with FRED FDD in a single center. RESULTS Complete occlusion was obtained in 20/24 aneurysms (83 %) and partial occlusion in four (17 %). Intraprocedural technical complication occurred in one case (4 %) and post-procedural complications in three (12 %). None reported neurological deficits (mRS = 0). All FRED were patent at follow-up. No early or delayed aneurysm rupture, no subarachnoid (SAH) or intraparenchymal hemorrhage (IPH) no ischemic complications and no deaths occurred. CONCLUSIONS Endovascular treatment with FRED FDD is a safe treatment for unruptured cerebral aneurysms, resulting in a high rate of occlusion. The FRED is substantially equivalent to the other known FDDs, which show similar functions and technical profiles.
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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] [What about the content of this article? (0)] [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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Abstract
BACKGROUND The direction and magnitude of intra-aneurysmal flow jet are significant risk factors of subarachnoid hemorrhage, and the change of flow jet during an endovascular procedure has been used for prediction of aneurysm occlusion or whether an additional flow diverter (FD) is warranted. However, evaluation of flow jets is often unreliable due to a large variation of flow jet on the digital subtraction angiograms, and this flow pattern variation may result in incorrect clinical diagnosis Therefore, factors contributing to the variation in flow jet are examined at an in vitro setting, and the findings can help us to understand the nature of flow jet and devise a better plan to quantify the aneurysmal hemodynamics accurately. METHODS Intra-aneurysmal flows in three patient-specific aneurysms between 11 and 25 mm were investigated in vitro, and a FD was deployed in each aneurysm model. X-ray imaging of these models were performed at injection rates between 0.2 and 2 mL/s. Pulsatile blood pump and aneurysm model were imaged together to determine the timing of flow jet. RESULTS The contrast bolus arrives at the aneurysm early at high contrast injection rates. The flow patterns with slow injection rates exhibit strong inertia that is associated with the systole flow. Flow jets arrive at the aneurysms at the peak systole when the bolus is injected at 0.2 mL/s. The contrast-to-signal ratio is the highest at the injection rate of 0.5 mL/s. Effect of flow diversion can only be assessed at an injection rate greater than 0.5 mL/s. CONCLUSIONS Intra-aneurysmal flow jet is highly dependent on the injection rate of the contrast agent. For the internal carotid artery (ICA) aneurysms, the systolic flows can be visualized at slow injection rates (<0.5 mL/s), while the diastolic flow jets are visible at higher injection rates (>1 mL/s). Dependence of flow jet on the contrast injection rate has serious clinical implications and needs to be considered during diagnostic procedures; a protocol with a consistent injection rate is highly recommended.
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Affiliation(s)
- Liang-der Jou
- Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas 77030, USA
| | - Virendra R Desai
- Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas 77030, USA
| | - Garvin W Britz
- Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas 77030, USA
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Ou C, Huang W, Yuen MMF. A computational model based on fibrin accumulation for the prediction of stasis thrombosis following flow-diverting treatment in cerebral aneurysms. Med Biol Eng Comput 2016; 55:89-99. [PMID: 27106753 DOI: 10.1007/s11517-016-1501-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 03/27/2016] [Indexed: 01/09/2023]
Abstract
Flow diverters, the specially designed low porosity stents, have been used to redirect blood flow from entering aneurysm, which induces flow stasis in aneurysm and promote thrombosis for repairing aneurysm. However, it is not clear how thrombus develops following flow-diversion treatment. Our objective was to develop a computation model for the prediction of stasis-induced thrombosis following flow-diversion treatment in cerebral aneurysms. We proposed a hypothesis to initiate coagulation following flow-diversion treatment. An experimental model was used by ligating rat's right common carotid artery (RCCA) to create flow-stasis environment. Thrombus formed in RCCA as a result of flow stasis. The fibrin distributions in different sections along the axial length of RCCA were measured. The fibrin distribution predicted by our computational model displayed a trend of increase from the proximal neck to the distal tip, consistent with the experimental results on rats. The model was applied on a saccular aneurysm treated with flow diverter to investigate thrombus development following flow diversion. Thrombus was predicted to form inside the sac, and the aneurysm was occluded with only a small remnant neck remained. Our model can serve as a tool to evaluate flow-diversion treatment outcome and optimize the design of flow diverters.
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Affiliation(s)
- Chubin Ou
- Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Wei Huang
- Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Matthew Ming-Fai Yuen
- Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
- Division of Biomedical Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
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Zhong J, Long Y, Yan H, Meng Q, Zhao J, Zhang Y, Yang X, Li H. Fast Virtual Stenting with Active Contour Models in Intracranical Aneurysm. Sci Rep 2016; 6:21724. [PMID: 26876026 PMCID: PMC4753686 DOI: 10.1038/srep21724] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 01/28/2016] [Indexed: 11/09/2022] Open
Abstract
Intracranial stents are becoming increasingly a useful option in the treatment of intracranial aneurysms (IAs). Image simulation of the releasing stent configuration together with computational fluid dynamics (CFD) simulation prior to intervention will help surgeons optimize intervention scheme. This paper proposed a fast virtual stenting of IAs based on active contour model (ACM) which was able to virtually release stents within any patient-specific shaped vessel and aneurysm models built on real medical image data. In this method, an initial stent mesh was generated along the centerline of the parent artery without the need for registration between the stent contour and the vessel. Additionally, the diameter of the initial stent volumetric mesh was set to the maximum inscribed sphere diameter of the parent artery to improve the stenting accuracy and save computational cost. At last, a novel criterion for terminating virtual stent expanding that was based on the collision detection of the axis aligned bounding boxes was applied, making the stent expansion free of edge effect. The experiment results of the virtual stenting and the corresponding CFD simulations exhibited the efficacy and accuracy of the ACM based method, which are valuable to intervention scheme selection and therapy plan confirmation.
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Affiliation(s)
- Jingru Zhong
- Capital Medical University, Department of Biomedical Engineering, Beijing, 100069, China
| | - Yunling Long
- Capital Medical University, Department of Biomedical Engineering, Beijing, 100069, China
| | - Huagang Yan
- Capital Medical University, Department of Biomedical Engineering, Beijing, 100069, China
| | - Qianqian Meng
- Capital Medical University, Department of Biomedical Engineering, Beijing, 100069, China
| | - Jing Zhao
- Capital Medical University, Department of Biomedical Engineering, Beijing, 100069, China
| | - Ying Zhang
- Capital Medical University, Beijing Tiantan Hospital, Beijing Neurosurgical Institute, Department of Interventional Neuroradiology, Beijing, 100050, China
| | - Xinjian Yang
- Capital Medical University, Beijing Tiantan Hospital, Beijing Neurosurgical Institute, Department of Interventional Neuroradiology, Beijing, 100050, China
| | - Haiyun Li
- Capital Medical University, Department of Biomedical Engineering, Beijing, 100069, China
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Karmonik C, Anderson JR, Beilner J, Ge JJ, Partovi S, Klucznik RP, Diaz O, Zhang YJ, Britz GW, Grossman RG, Lv N, Huang Q. Relationships and redundancies of selected hemodynamic and structural parameters for characterizing virtual treatment of cerebral aneurysms with flow diverter devices. J Biomech 2015; 49:2112-2117. [PMID: 26654675 DOI: 10.1016/j.jbiomech.2015.11.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 11/13/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND PURPOSE To quantify the relationship and to demonstrate redundancies between hemodynamic and structural parameters before and after virtual treatment with a flow diverter device (FDD) in cerebral aneurysms. METHODS Steady computational fluid dynamics (CFD) simulations were performed for 10 cerebral aneurysms where FDD treatment with the SILK device was simulated by virtually reducing the porosity at the aneurysm ostium. Velocity and pressure values proximal and distal to and at the aneurysm ostium as well as inside the aneurysm were quantified. In addition, dome-to-neck ratios and size ratios were determined. Multiple correlation analysis (MCA) and hierarchical cluster analysis (HCA) were conducted to demonstrate dependencies between both structural and hemodynamic parameters. RESULTS Velocities in the aneurysm were reduced by 0.14m/s on average and correlated significantly (p<0.05) with velocity values in the parent artery (average correlation coefficient: 0.70). Pressure changes in the aneurysm correlated significantly with pressure values in the parent artery and aneurysm (average correlation coefficient: 0.87). MCA found statistically significant correlations between velocity values and between pressure values, respectively. HCA sorted velocity parameters, pressure parameters and structural parameters into different hierarchical clusters. HCA of aneurysms based on the parameter values yielded similar results by either including all (n=22) or only non-redundant parameters (n=2, 3 and 4). CONCLUSION Hemodynamic and structural parameters before and after virtual FDD treatment show strong inter-correlations. Redundancy of parameters was demonstrated with hierarchical cluster analysis.
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Affiliation(s)
- C Karmonik
- MRI Core, Houston Methodist Research Institute, Houston, TX, USA; Cerebrovascular Center, Neurosurgery, Houston Methodist, Houston, TX, USA.
| | - J R Anderson
- MRI Core, Houston Methodist Research Institute, Houston, TX, USA
| | | | - J J Ge
- Siemens AX, Shanghai, China
| | - S Partovi
- Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH, USA
| | - R P Klucznik
- Cerebrovascular Center, Radiology, Houston Methodist, Houston, TX, USA
| | - O Diaz
- Cerebrovascular Center, Radiology, Houston Methodist, Houston, TX, USA
| | - Y J Zhang
- Cerebrovascular Center, Neurosurgery, Houston Methodist, Houston, TX, USA
| | - G W Britz
- Cerebrovascular Center, Neurosurgery, Houston Methodist, Houston, TX, USA
| | - R G Grossman
- Cerebrovascular Center, Neurosurgery, Houston Methodist, Houston, TX, USA
| | - N Lv
- Neurosurgery, The Affiliated Changhai Hospital of Second Military Medical University, Shanghai, China
| | - Q Huang
- Neurosurgery, The Affiliated Changhai Hospital of Second Military Medical University, Shanghai, China
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Xu J, Wu Z, Yu Y, Lv N, Wang S, Karmonik C, Liu JM, Huang Q. Combined Effects of Flow Diverting Strategies and Parent Artery Curvature on Aneurysmal Hemodynamics: A CFD Study. PLoS One 2015; 10:e0138648. [PMID: 26398847 PMCID: PMC4580450 DOI: 10.1371/journal.pone.0138648] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 09/02/2015] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Flow diverters (FD) are increasingly being considered for treating large or giant wide-neck aneurysms. Clinical outcome is highly variable and depends on the type of aneurysm, the flow diverting device and treatment strategies. The objective of this study was to analyze the effect of different flow diverting strategies together with parent artery curvature variations on altering intra-aneurysmal hemodynamics. METHODS Four ideal intracranial aneurysm models with different parent artery curvature were constructed. Computational fluid dynamics (CFD) simulations of the hemodynamics before and after applying five types of flow diverting strategies (single FD, single FD with 5% and 10% packing density of coils, two FDs with 25% and 50% overlapping rate) were performed. Changes in pressure, wall shear stress (WSS), relative residence time (RRT), inflow velocity and inflow volume rate were calculated and compared. RESULTS Each flow diverting strategy resulted in enhancement of RRT and reduction of normalized mean WSS, inflow volume rate and inflow velocity in various levels. Among them, 50% overlapped FD induced most effective hemodynamic changes in RRT and inflow volume rate. The mean pressure only slightly decreased after treatment. Regardless of the kind of implantation of FD, the mean pressure, inflow volume rate and inflow velocity increased and the RRT decreased as the curvature of the parent artery increased. CONCLUSIONS Of all flow diverting strategies, overlapping FDs induced most favorable hemodynamic changes. Hemodynamics alterations post treatment were substantially influenced by parent artery curvature. Our results indicate the need of an individualized flow diverting strategy that is tailored for a specific aneurysm.
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Affiliation(s)
- Jinyu Xu
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Zhichen Wu
- School of International Relations and Public Affairs, Fudan University, Shanghai, China
| | - Ying Yu
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Nan Lv
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Shengzhang Wang
- Department of Mechanics and Engineering Science, Fudan University, Shanghai, China
| | - Christof Karmonik
- Cerebrovascular Center, Department of Neurosurgery, Houston Methodist Hospital, Houston, TX, United States of America
| | - Jian-Min Liu
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China
- * E-mail: (JL); (QH)
| | - Qinghai Huang
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China
- * E-mail: (JL); (QH)
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Tang AYS, Chung WC, Liu ETY, Qu JQ, Tsang ACO, Leung GKK, Leung KM, Yu ACH, Chow KW. Computational Fluid Dynamics Study of Bifurcation Aneurysms Treated with Pipeline Embolization Device: Side Branch Diameter Study. J Med Biol Eng 2015; 35:293-304. [PMID: 26167140 PMCID: PMC4491114 DOI: 10.1007/s40846-015-0046-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 08/16/2014] [Indexed: 11/17/2022]
Abstract
An intracranial aneurysm, abnormal swelling of the cerebral artery, may lead to undesirable rates of mortality and morbidity upon rupture. Endovascular treatment involves the deployment of a flow-diverting stent that covers the aneurysm orifice, thereby reducing the blood flow into the aneurysm and mitigating the risk of rupture. In this study, computational fluid dynamics analysis is performed on a bifurcation model to investigate the change in hemodynamics with various side branch diameters. The condition after the deployment of a pipeline embolization device is also simulated. Hemodynamic factors such as flow velocity, pressure, and wall shear stress are studied. Aneurysms with a larger side branch vessel might have greater risk after treatment in terms of hemodynamics. Although a stent could lead to flow reduction entering the aneurysm, it would drastically alter the flow rate inside the side branch vessel. This may result in side-branch hypoperfusion subsequent to stenting. In addition, two patient-specific bifurcation aneurysms are tested, and the results show good agreement with the idealized models. Furthermore, the peripheral resistance of downstream vessels is investigated by varying the outlet pressure conditions. This quantitative analysis can assist in treatment planning and therapeutic decision-making.
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Affiliation(s)
- Abraham Yik-Sau Tang
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, 999077 China
| | - Wai-Choi Chung
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, 999077 China
| | - Eric Tian-Yang Liu
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, 999077 China
| | - Jie-Qiong Qu
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, 999077 China
| | - Anderson Chun-On Tsang
- Division of Neurosurgery, Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong, 999077 China
| | - Gilberto Ka-Kit Leung
- Division of Neurosurgery, Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong, 999077 China
| | - Kar-Ming Leung
- Department of Neurosurgery, Kwong Wah Hospital, Waterloo Road, Hong Kong, 999077 China
| | - Alfred Cheuk-Hang Yu
- Medical Engineering Program, Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, 999077 China
| | - Kwok-Wing Chow
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, 999077 China
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Ohta M, Anzai H, Miura Y, Nakayama T. Parametric study of porous media as substitutes for flow-diverter stent. Biomaterials and Biomedical Engineering 2015. [DOI: 10.12989/bme.2015.2.2.111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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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] [What about the content of this article? (0)] [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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Hu P, Qian Y, Zhang Y, Zhang HQ, Li Y, Chong W, Ling F. Blood flow reduction of covered small side branches after flow diverter treatment: A computational fluid hemodynamic quantitative analysis. J Biomech 2015; 48:895-8. [DOI: 10.1016/j.jbiomech.2015.02.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 11/15/2014] [Accepted: 02/17/2015] [Indexed: 10/23/2022]
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Yamaguchi R, Tanaka G, Liu H, Ujiie H. Repression of wall shear stress inside cerebral aneurysm at bifurcation of anterior cerebral artery by stents. Heart Vessels 2015; 31:622-7. [PMID: 25813684 DOI: 10.1007/s00380-015-0665-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 03/20/2015] [Indexed: 10/23/2022]
Abstract
The effect of a simple bare metal stent on repression of wall shear stress inside a model cerebral aneurysm was experimentally investigated by two-dimensional particle image velocimetry in vitro. The flow model simulated a cerebral aneurysm induced at the apex of bifurcation between the anterior cerebral artery and the anterior communicating artery. Wall shear stress was investigated using both stented and non-stented models to assess the simple stent characteristics. The flow behavior inside the stented aneurysm sac was unusual and wall shear stress was much smaller inside the aneurysm sac. Stent placement effectively repressed the temporal and spatial variations and the magnitude of wall shear stress. Hence, there is an effective possibility that would retard the progress of cerebral aneurysms by even simple stent.
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Affiliation(s)
- Ryuhei Yamaguchi
- Graduate School of Engineering, Chiba University, 1-33 Yayoicho, Inage-ku, Chiba, 263-8522, Japan.
| | - Gaku Tanaka
- Graduate School of Engineering, Chiba University, 1-33 Yayoicho, Inage-ku, Chiba, 263-8522, Japan
| | - Hao Liu
- Graduate School of Engineering, Chiba University, 1-33 Yayoicho, Inage-ku, Chiba, 263-8522, Japan
| | - Hiroshi Ujiie
- Department of Neurosurgery, Tokyo Rosai Hospital, 4-13-21 Oomori, Ohta-ku, Tokyo, 337-8570, Japan
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Tsang ACO, Lai SSM, Chung WC, Tang AYS, Leung GKK, Poon AKK, Yu ACH, Chow KW. Blood flow in intracranial aneurysms treated with Pipeline embolization devices: computational simulation and verification with Doppler ultrasonography on phantom models. Ultrasonography 2015; 34:98-108. [PMID: 25754367 PMCID: PMC4372715 DOI: 10.14366/usg.14063] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 01/30/2015] [Accepted: 01/31/2015] [Indexed: 12/19/2022] Open
Abstract
Purpose: The aim of this study was to validate a computational fluid dynamics (CFD) simulation of flow-diverter treatment through Doppler ultrasonography measurements in patient-specific models of intracranial bifurcation and side-wall aneurysms. Methods: Computational and physical models of patient-specific bifurcation and sidewall aneurysms were constructed from computed tomography angiography with use of stereolithography, a three-dimensional printing technology. Flow dynamics parameters before and after flow-diverter treatment were measured with pulse-wave and color Doppler ultrasonography, and then compared with CFD simulations. Results: CFD simulations showed drastic flow reduction after flow-diverter treatment in both aneurysms. The mean volume flow rate decreased by 90% and 85% for the bifurcation aneurysm and the side-wall aneurysm, respectively. Velocity contour plots from computer simulations before and after flow diversion closely resembled the patterns obtained by color Doppler ultrasonography. Conclusion: The CFD estimation of flow reduction in aneurysms treated with a flow-diverting stent was verified by Doppler ultrasonography in patient-specific phantom models of bifurcation and side-wall aneurysms. The combination of CFD and ultrasonography may constitute a feasible and reliable technique in studying the treatment of intracranial aneurysms with flow-diverting stents.
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Affiliation(s)
- Anderson Chun On Tsang
- Department of Surgery, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Simon Sui Man Lai
- Departments of Electrical and Electronic Engineering, University of Hong Kong, Hong Kong
| | - Wai Choi Chung
- Departments of Mechanical Engineering, University of Hong Kong, Hong Kong
| | | | - Gilberto Ka Kit Leung
- Department of Surgery, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Alexander Kai Kei Poon
- Departments of Electrical and Electronic Engineering, University of Hong Kong, Hong Kong
| | - Alfred Cheuk Hang Yu
- Departments of Electrical and Electronic Engineering, University of Hong Kong, Hong Kong
| | - Kwok Wing Chow
- Departments of Mechanical Engineering, University of Hong Kong, Hong Kong
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Karunanithi K, Han C, Lee C, Shi W, Duan L, Qian Y. Identification of a hemodynamic parameter for assessing treatment outcome of EDAS in Moyamoya disease. J Biomech 2015; 48:304-9. [DOI: 10.1016/j.jbiomech.2014.11.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/19/2014] [Accepted: 11/21/2014] [Indexed: 11/22/2022]
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Hodis S, Ding YH, Dai D, Lingineni R, Mut F, Cebral J, Kallmes D, Kadirvel R. Relationship between aneurysm occlusion and flow diverting device oversizing in a rabbit model. J Neurointerv Surg 2014; 8:94-8. [PMID: 25387731 DOI: 10.1136/neurintsurg-2014-011487] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 10/24/2014] [Indexed: 11/03/2022]
Abstract
BACKGROUND AND PURPOSE Implanted, actual flow diverter pore density is thought to be strongly influenced by proper matching between the device size and parent artery diameter. The objective of this study was to characterize the correlation between device sizing, metal coverage, and the resultant occlusion of aneurysms following flow diverter treatment in a rabbit model. METHODS Rabbit saccular aneurysms were treated with flow diverters (iso-sized to proximal parent artery, 0.5 mm oversized, or 1.0 mm oversized, respectively, n=6 for each group). Eight weeks after implantation, the angiographic degree of aneurysm occlusion was graded (complete, near-complete, or incomplete). The ostium of the explanted aneurysm covered with the flow diverter struts was photographed. Based on gross anatomic findings, the metal coverage and pore density at the ostium of the aneurysm were calculated and correlated with the degree of aneurysm occlusion. RESULTS Angiographic results showed there were no statistically significant differences in aneurysm geometry and occlusion among groups. The mean parent artery diameter to flow diverter diameter ratio was higher in the 1.0 mm oversized group than in the other groups. Neither the percentage metal coverage nor the pore density showed statistically significant differences among groups. Aneurysm occlusion was inversely correlated with the ostium diameter, irrespective of the size of the device implanted. CONCLUSIONS Device sizing alone does not predict resultant pore density or metal coverage following flow diverter implantation in the rabbit aneurysm model. Aneurysm occlusion was not impacted by either metal coverage or pore density, but was inversely correlated with the diameter of the ostium.
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Affiliation(s)
- Simona Hodis
- Neuroradiology Research Laboratory, Mayo Clinic, Rochester, Minnesota, USA
| | - Yong-Hong Ding
- Neuroradiology Research Laboratory, Mayo Clinic, Rochester, Minnesota, USA
| | - Daying Dai
- Neuroradiology Research Laboratory, Mayo Clinic, Rochester, Minnesota, USA
| | - Ravi Lingineni
- Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, USA
| | - Fernando Mut
- Center for Computational Fluid Dynamics, College of Sciences, George Mason University, Fairfax, Virginia, USA
| | - Juan Cebral
- Center for Computational Fluid Dynamics, College of Sciences, George Mason University, Fairfax, Virginia, USA
| | - David Kallmes
- Neuroradiology Research Laboratory, Mayo Clinic, Rochester, Minnesota, USA
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Kerl HU, Boll H, Fiebig T, Figueiredo G, Förster A, Nölte IS, Nonn A, Groden C, Brockmann MA. Implantation of pipeline flow-diverting stents reduces aneurysm inflow without relevantly affecting static intra-aneurysmal pressure. Neurosurgery 2014; 74:321-34; discussion 334. [PMID: 24549048 DOI: 10.1227/neu.0000000000000253] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Flow-diverting stent (FDS) implantation is an endovascular treatment option for intracranial aneurysms. However, little is known about the hemodynamic effects. OBJECTIVE To assess the effect of stent compression on FDS porosity, to evaluate the influence of single and overlapping implantation of FDS on intra-aneurysmal flow profiles, and to correlate stent porosity with changes in static mean intra-aneurysmal pressure. METHODS Intra-aneurysmal time-density curves were recorded in a pulsatile in vitro flow model before and after implantation of FDSs (Pipeline Embolization Device; ev3) in 7 different types of aneurysm models. Reductions in the maximum contrast inflow and time to maximum intra-aneurysmal contrast were calculated. Micro--computed tomography was performed, and compression-related FDS porosity was measured. The influence of FDS placement on mean static intra-aneurysmal pressure was measured. RESULTS FDS compression resulted in an almost linear reduction in stent porosity. Stent porosity (struts per 1 mm) correlated significantly with the reduction of aneurysm contrast inflow (R = 0.81, P < .001) and delay until maximum contrast (R = 0.34, P = .001). Circulating intra-aneurysmal high-velocity flow was terminated in all sidewall models after implantation of a single stent. Superimposition of 2 stents reduced maximum intra-aneurysmal contrast by 69.1 ± 3.1% (mean ± SD) in narrow-necked sidewall aneurysm models, whereas no substantial reduction in maximum intra-aneurysmal contrast was observed in wide-necked sidewall aneurysm models. Intra-aneurysmal mean static pressure did not correlate with FDS porosity or number of implanted stents. CONCLUSION Implantation of FDS effectively reduces aneurysm inflow in a porosity-dependent way without relevantly affecting static mean intra-aneurysmal pressure. ABBREVIATIONS FDS, flow-diverting stentMAP, mean arterial pressurePED, Pipeline Embolization Device.
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Affiliation(s)
- Hans U Kerl
- *University of Heidelberg, Medical Faculty Mannheim, Department of Neuroradiology, Mannheim, Germany; ‡University Hospital of the RWTH Aachen, Department of Diagnostic and Interventional Neuroradiology, Aachen, Germany
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Cebral JR, Mut F, Raschi M, Hodis S, Ding YH, Erickson BJ, Kadirvel R, Kallmes DF. Analysis of hemodynamics and aneurysm occlusion after flow-diverting treatment in rabbit models. AJNR Am J Neuroradiol 2014; 35:1567-73. [PMID: 24722302 DOI: 10.3174/ajnr.a3913] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Predicting the outcome of flow diversion treatment of cerebral aneurysms remains challenging. Our aim was to investigate the relationship between hemodynamic conditions created immediately after flow diversion and subsequent occlusion of experimental aneurysms in rabbits. MATERIALS AND METHODS The hemodynamic environment before and after flow-diversion treatment of elastase-induced aneurysms in 20 rabbits was modeled by using image-based computational fluid dynamics. Local aneurysm occlusion was quantified by using a voxelization technique on 3D images acquired 8 weeks after treatment. Global and local voxel-by-voxel hemodynamic variables were used to statistically compare aneurysm regions that later thrombosed to regions that remained patent. RESULTS Six aneurysms remained patent at 8 weeks, while 14 were completely or nearly completely occluded. Patent aneurysms had statistically larger neck sizes (P = .0015) and smaller mean transit times (P = .02). The velocity, vorticity, and shear rate were approximately 2.8 times (P < .0001) larger in patent regions-that is, they had larger "flow activity" than regions that progressed to occlusion. Statistical models based on local hemodynamic variables were capable of predicting local occlusion with good precision (84% accuracy), especially away from the neck (92%-94%). Predictions near the neck were poorer (73% accuracy). CONCLUSIONS These results suggests that the dominant healing mechanism of occlusion within the aneurysm dome is related to slow-flow-induced thrombosis, while near the neck, other processes could be at play simultaneously.
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Affiliation(s)
- J R Cebral
- From the Center for Computational Fluid Dynamics (J.R.C., F.M., M.R.), College of Sciences, George Mason University, Fairfax, Virginia
| | - F Mut
- From the Center for Computational Fluid Dynamics (J.R.C., F.M., M.R.), College of Sciences, George Mason University, Fairfax, Virginia
| | - M Raschi
- From the Center for Computational Fluid Dynamics (J.R.C., F.M., M.R.), College of Sciences, George Mason University, Fairfax, Virginia
| | - S Hodis
- Departments of Radiology (S.H., Y.-H.D., B.J.E., R.K., D.F.K.)
| | - Y-H Ding
- Departments of Radiology (S.H., Y.-H.D., B.J.E., R.K., D.F.K.)
| | - B J Erickson
- Departments of Radiology (S.H., Y.-H.D., B.J.E., R.K., D.F.K.)
| | - R Kadirvel
- Departments of Radiology (S.H., Y.-H.D., B.J.E., R.K., D.F.K.)
| | - D F Kallmes
- Departments of Radiology (S.H., Y.-H.D., B.J.E., R.K., D.F.K.)Neurosurgery (D.F.K.), Mayo Clinic, Rochester, Minnesota
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