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Sándor L, Paál G. Design space exploration of flow diverter hydraulic resistance parameters in sidewall intracranial aneurysms. Comput Methods Biomech Biomed Engin 2024; 27:931-942. [PMID: 37231591 DOI: 10.1080/10255842.2023.2215369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 05/07/2023] [Indexed: 05/27/2023]
Abstract
Intracranial aneurysms are nowadays treated with endovascular flow diverter devices to avoid sac rupture. This study explores how different linear and quadratic hydrodynamic resistance parameters reduce the flow in the sac for five patient-specific sidewall aneurysms.The 125 performed blood flow simulations included the stents using a Darcy-Forcheimer porous layer approach based on real-life stent characteristics. Time- and space-averaged velocity magnitudes were strongly affected by the linear coefficient with a power-law relationship. Quadratic coefficients alter the flow in a minor way due to the low-velocity levels in the aneurysm sac and neck region.
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Affiliation(s)
- Levente Sándor
- Faculty of Mechanical Engineering, Department of Hydrodynamic Systems, Budapest University of Technology and Economics, Budapest, Hungary
| | - György Paál
- Faculty of Mechanical Engineering, Department of Hydrodynamic Systems, Budapest University of Technology and Economics, Budapest, Hungary
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2
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Boite Y, Suaiden Klein T, de Andrade Medronho R, Wajnberg E. Numerical simulation of flow-diverting stent: comparison between branches in bifurcation brain aneurysm. Biomech Model Mechanobiol 2023; 22:1801-1814. [PMID: 37335373 DOI: 10.1007/s10237-023-01733-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 06/01/2023] [Indexed: 06/21/2023]
Abstract
The usage of flow-diverting stents in the treatment of intracranial aneurysms is widespread due to their high success and low complication rates. However, their use is still not officially recommended for bifurcation aneurysms, as there is a risk of generating ischemic complications due to the reduced blood flow to the jailed branch. Many works utilize computational fluid dynamics (CFD) to study how hemodynamic variables respond to flow diverter placement, but few seem to use it to verify flow variation between branches of bifurcation aneurysms and to aid in the choice of the best ramification for device placement. This investigation was performed in the present work, by comparing wall shear stress (WSS) and flowrates for a patient-specific scenario of a middle cerebral artery (MCA) aneurysm, considering device placement on each branch. A secondary objective was to follow a methodology that provides fast results, envisioning application to daily medical practice. The device was simplified as a homogeneous porous medium, and extreme porosity values were simulated for comparison. Results suggest that stent placement on either branch is both safe and effective, significantly reducing WSS and flow into the aneurysm while maintaining flow to the different ramifications within acceptable thresholds.
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Affiliation(s)
- Yasmin Boite
- Programa de Pós-Graduação em Engenharia de Processos Químicos e Bioquímicos da Escola de Química, UFRJ, LabCFD, Rua Moniz de Aragão, Bloco K, Rio de Janeiro, RJ, 21941972, Brazil.
| | - Tânia Suaiden Klein
- Programa de Pós-Graduação em Engenharia de Processos Químicos e Bioquímicos da Escola de Química, UFRJ, LabCFD, Rua Moniz de Aragão, Bloco K, Rio de Janeiro, RJ, 21941972, Brazil
| | - Ricardo de Andrade Medronho
- Programa de Pós-Graduação em Engenharia de Processos Químicos e Bioquímicos da Escola de Química, UFRJ, LabCFD, Rua Moniz de Aragão, Bloco K, Rio de Janeiro, RJ, 21941972, Brazil
| | - Eduardo Wajnberg
- Radiologia Intervencionista, Hospital Américas, Avenida Jorge Curi, 550, Rio de Janeiro, RJ, 22793334, Brazil
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3
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Khorasanizadeh M, Shutran M, Schirmer CM, Salem MM, Ringer AJ, Grandhi R, Mitha AP, Levitt MR, Jankowitz BT, Taussky P, Thomas AJ, Moore JM, Ogilvy CS. North American multicenter experience with the Flow Redirection Endoluminal Device in the treatment of intracranial aneurysms. J Neurosurg 2022; 138:933-943. [PMID: 36087324 DOI: 10.3171/2022.7.jns221371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 07/21/2022] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Flow diverters have revolutionized the endovascular treatment of intracranial aneurysms. Here, the authors present the first large-scale North American multicenter experience using the Flow Redirection Endoluminal Device (FRED) in the treatment of cerebral aneurysms. METHODS Consecutive cerebral aneurysms treated with FRED at 7 North American centers between June 2020 and November 2021 were included. Data collected included patient demographic characteristics, aneurysm characteristics, periprocedural and long-term complications, modified Rankin Scale (mRS) scores, and radiological follow-up. RESULTS In total, 133 aneurysms in 116 patients were treated with 123 FRED deployment procedures and included in this study. One hundred twenty-six aneurysms (94.7%) were unruptured, 117 (88.0%) saccular, and 123 (92.5%) located in anterior circulation. The mean (range) aneurysm maximal width and neck width sizes were 7.2 (1.5-42.5) mm and 4.1 (1.0-15.1) mm, respectively. Successful FRED deployment was achieved in 122 procedures (99.2%). Adjunctive coiling was used in 4 procedures (3.3%). Radiological follow-up was available for 101 aneurysms at a median duration of 7.0 months. At last follow-up, complete occlusion was observed in 55.4% of patients, residual neck in 8.9%, and filling aneurysm in 35.6%; among cases with radiological follow-up duration > 10 months, these values were 21/43 (48.8%), 3/43 (7.0%), and 19/43 (44.2%), respectively. On multivariate regression analysis, age (OR 0.93, p = 0.001) and aneurysm neck size (OR 0.83, p = 0.048) were negatively correlated with odds of complete occlusion at latest follow-up. The retreatment rate was 6/124 (4.8%). The overall complication rate was 31/116 (26.7%). Parent vessel occlusion, covered branch occlusion, and in-stent stenosis were detected in 9/99 (9.1%), 6/63 (9.5%), and 15/99 (15.2%) cases, respectively. The FRED-related, symptomatic, thromboembolic, and hemorrhagic complication rates were 22.4%, 12.9%, 6.9%, and 0.9% respectively. The morbidity rate was 10/116 patients (8.6%). There was 1 death due to massive periprocedural internal carotid artery stroke, and 3.6% of the patients had an mRS score > 2 at the last follow-up (vs 0.9% at baseline). CONCLUSIONS As the first large-scale North American multicenter FRED experience, this study confirmed the ease of successful FRED deployment but suggested lower efficacy and a higher rate of complications than reported by previous European and South American studies on FRED and other flow-diverting devices. The authors recommend judicious use of this device until future studies can better elucidate the long-term outcomes of FRED treatment.
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Affiliation(s)
- MirHojjat Khorasanizadeh
- 1Neurosurgical Service, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Max Shutran
- 1Neurosurgical Service, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | | | - Mohamed M Salem
- 3Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Andrew J Ringer
- 4Mayfield Clinic, TriHealth Neuroscience Institute, Good Samaritan Hospital, Cincinnati, Ohio
| | - Ramesh Grandhi
- 5Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah
| | - Alim P Mitha
- 6Department of Clinical Neurosciences, Foothills Medical Centre, University of Calgary, Calgary, Alberta, Canada
| | - Michael R Levitt
- 7Department of Neurological Surgery, University of Washington, Seattle, Washington; and
| | - Brian T Jankowitz
- 3Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Philipp Taussky
- 5Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah
| | - Ajith J Thomas
- 8Department of Neurological Surgery, Cooper University Health Care, Cooper Medical School of Rowan University, Camden, New Jersey
| | - Justin M Moore
- 1Neurosurgical Service, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Christopher S Ogilvy
- 1Neurosurgical Service, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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4
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Chen D, Lakghomi B, Lawryshyn Y. Evaluation of using a porous medium approach to simulate flat-sheet membrane bioreactors. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2022; 86:746-762. [PMID: 36038974 DOI: 10.2166/wst.2022.235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The porous medium approach has been applied by others to study the global hydrodynamics in hollow-fiber (HF) membrane bioreactors (MBR). This study explores the usability of the porous medium approach for flat-sheet (FS) MBR and introduces a CFD-based numerical calibration of the porous parameters. Two key modeling strategies are suggested to ensure the pressure prediction accuracy: (1) use SST k - ω turbulence model incorporated with an intermittency transition model (SSIT); (2) considerate two-phase flow during the calibration. The results showed that SSIT significantly improved the pressure prediction of the flow between two sheets. Also, unlike HF MBR, the gas phase was observed to be non-negligible during the calibration for FS MBR. The numerically calibrated porous parameters were then applied in a three-dimensional simplified model (SPM), where multiple membrane sheets were treated as one porous zone. The SPM was compared with a realistic model (RM), where all membrane sheets were simulated directly. A similar pressure distribution was observed in both models; however, local flow characteristics (i.e., the acceleration of the flow entering the module zone) were not reflected in the SPM. Hence, it is recommended to use the porous medium approach for global hydrodynamics investigation when the local flow characteristics are not of interest.
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Affiliation(s)
- Danmei Chen
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, ON M5S 3E5, Canada E-mail:
| | - Babak Lakghomi
- Fibracast Ltd, 525 Glover Rd, Hannon, ON L0R 1P0, Canada
| | - Yuri Lawryshyn
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, ON M5S 3E5, Canada E-mail:
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Tikhvinskii D, Kuianova J, Kislitsin D, Orlov K, Gorbatykh A, Parshin D. Numerical Assessment of the Risk of Abnormal Endothelialization for Diverter Devices: Clinical Data Driven Numerical Study. J Pers Med 2022; 12:652. [PMID: 35455768 PMCID: PMC9025183 DOI: 10.3390/jpm12040652] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 12/07/2022] Open
Abstract
Numerical modeling is an effective tool for preoperative planning. The present work is devoted to a retrospective analysis of neurosurgical treatments for the occlusion of cerebral aneurysms using flow-diverters and hemodynamic factors affecting stent endothelization. Several different geometric approaches have been considered for virtual flow-diverters deployment. A comparative analysis of hemodynamic parameters as a result of computational modeling has been carried out basing on the four clinical cases: one successful treatment, one with no occlusion and two with in stent stenosis. For the first time, a quantitative assessment of both: the limiting magnitude of shear stresses that are necessary for the occurrence of in stent stenosis (MaxWSS > 1.23) and for conditions in which endothelialization is insufficiently active and occlusion of the cervical part of the aneurysm does not occur (MaxWSS < 1.68)—has been statistacally proven (p < 0.01).
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Affiliation(s)
- Denis Tikhvinskii
- Lavrentyev Institute of Hydrodynamics SB RAS, Lavrentiev Avenue 15, 630090 Novosibirsk, Russia; (D.T.); (J.K.)
| | - Julia Kuianova
- Lavrentyev Institute of Hydrodynamics SB RAS, Lavrentiev Avenue 15, 630090 Novosibirsk, Russia; (D.T.); (J.K.)
| | - Dmitrii Kislitsin
- Neurosurgery Department, Meshalkin National Medical Research Center, 630055 Novosibirsk, Russia; (D.K.); (K.O.); (A.G.)
| | - Kirill Orlov
- Neurosurgery Department, Meshalkin National Medical Research Center, 630055 Novosibirsk, Russia; (D.K.); (K.O.); (A.G.)
| | - Anton Gorbatykh
- Neurosurgery Department, Meshalkin National Medical Research Center, 630055 Novosibirsk, Russia; (D.K.); (K.O.); (A.G.)
| | - Daniil Parshin
- Lavrentyev Institute of Hydrodynamics SB RAS, Lavrentiev Avenue 15, 630090 Novosibirsk, Russia; (D.T.); (J.K.)
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Nada A, Fakhr M, Elwakad M, Ali M. A Finite Element Based Analysis of a Hemodynamics Efficient Flow Stent Suitable for Different Abdominal Aneurysm Shapes. J Biomech Eng 2022; 144:1137925. [PMID: 35237800 DOI: 10.1115/1.4053999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Indexed: 11/08/2022]
Abstract
This research aimed to examine the impact of a proposed flow stent (PFS) on different abdominal artery shapes. For that purpose, a finite element-based model using the computational fluid dynamics (CFD) method is developed. The effect of PFS intervention on the hemodynamic efficiency is estimated by all of the significant criteria used for the evaluation of aneurysm occlusion and possible rupture; the flow velocity, pressure, wall shear stress (WSS), and WSS-related indices. Results showed that PFS intervention preserves the effects of high flow rate and decreases irregular flow recirculation in the sac of the aneurysm. The flow velocity decreases inside the aneurysm sac in the range of 55% to 80%. The time-averaged wall shear stress (TAWSS) was reduced from 42% to 53% by FPS deployment. The simulation results implies that PFS could heal an aneurysm efficiently with a mechanism that causes the development of thrombus and ultimately leads to aneurysm resorption.
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Affiliation(s)
- Ayat Nada
- Department of Computers and Systems, Electronics Research Institute, Cairo, Egypt
| | - Mahmoud Fakhr
- Department of Computers and Systems, Electronics Research Institute, Cairo, Egypt
| | - Mohamed Elwakad
- Department of Biomedical Engineering, Faculty of Engineering & Technology, Future University, Cairo, Egypt
| | - Mohamed Ali
- Department of Biomedical Engineering, Faculty of Engineering, Helwan University, Cairo, Egypt
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Chivukula V, White R, Shields A, Davies J, Mokin M, Bednarek DR, Rudin S, Ionita C. Leveraging Patient-Specific Simulated Angiograms to Characterize Cerebral Aneurysm Hemodynamics using Computational Fluid Dynamics. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2022; 12036:120360S. [PMID: 35983495 PMCID: PMC9385184 DOI: 10.1117/12.2611473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Cerebral aneurysms (CA) affect nearly 6% of the US population and its rupture is one of the major causes of hemorrhagic stroke. Neurointerventionalists performing endovascular therapy (ET) to treat CA rely on qualitative image sequences obtained under fluoroscopy guidance alone, and do not have access to crucial quantitative information regarding blood flow before, during and after treatment - partially contributing to a failure rate of up to 30%. Computational fluid dynamics (CFD) is a powerful tool that can provide a wealth of quantitative data; however, CFD has found limited utility in the clinic due to the challenges in obtaining hemodynamic boundary conditions for each patient. In this work, we present a novel CFD-based simulated angiogram approach (SAA) that resolves the blood flow physics and interaction between blood and injected contrast agent to extract quantitative hemodynamic parameters which can be used to design real-time parametric imaging analysis. The SAA enables correlating contrast agent transport to the underlying hemodynamic conditions via time-density curves (TDC) obtained at several points in the region of interest. The ability of the TDC and the SAA to provide critical hemodynamic parameters in and around CA anatomies, such as washout and local flow changes is explored and presented. This provides invaluable quantitative data to the clinician at the time of intervention, since it incorporates the physics of blood flow and correlates the contrast transport to hemodynamic parameters quantitatively - thereby enabling the clinician to take informed decisions that improve treatment outcomes.
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Affiliation(s)
- V Chivukula
- Biomedical Engineering, Florida Institute of Technology
| | - R White
- Biomedical Engineering, Florida Institute of Technology
| | - A Shields
- Medical Physics, State University of New York at Buffalo
- Canon Stroke and Vascular Research Center, State University of New York at Buffalo
| | - J Davies
- Department of Neurosurgery, State University of New York at Buffalo
| | - M Mokin
- Department of Neurology and Neurosurgery, University of South Florida
| | - D R Bednarek
- Medical Physics, State University of New York at Buffalo
- Canon Stroke and Vascular Research Center, State University of New York at Buffalo
| | - S Rudin
- Medical Physics, State University of New York at Buffalo
- Canon Stroke and Vascular Research Center, State University of New York at Buffalo
- Department of Neurosurgery, State University of New York at Buffalo
| | - C Ionita
- Medical Physics, State University of New York at Buffalo
- Canon Stroke and Vascular Research Center, State University of New York at Buffalo
- Department of Neurosurgery, State University of New York at Buffalo
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8
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Wang Z, Putra NK, Anzai H, Ohta M. Endothelial Cell Distribution After Flow Exposure With Two Stent Struts Placed in Different Angles. Front Physiol 2022; 12:733547. [PMID: 35095542 PMCID: PMC8793281 DOI: 10.3389/fphys.2021.733547] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 10/14/2021] [Indexed: 12/30/2022] Open
Abstract
Stent implantation has been a primary treatment for stenosis and other intravascular diseases. However, the struts expansion procedure might cause endothelium lesion and the structure of the struts could disturb the blood flow environment near the wall of the blood vessel. These changes could damage the vascular innermost endothelial cell (EC) layer and pose risks of restenosis and post-deployment thrombosis. This research aims to investigate the effect of flow alterations on EC distribution in the presence of gap between two struts within the parallel flow chamber. To study how the gap presence impacts EC migration and the endothelialization effect on the surface of the struts, two struts were placed with specific orientations and positions on the EC layer in the flow chamber. After a 24-h exposure under wall shear stress (WSS), we observed the EC distribution conditons especially in the gap area. We also conducted computational fluid dynamics (CFD) simulations to calculate the WSS distribution. High EC-concentration areas on the bottom plate corresponded to the high WSS by the presence of gap between the two struts. To find the relation between the WSS and EC distributions on the fluorescence images, WSS condition by CFD simulation could be helpful for the EC distribution. The endothelialization rate, represented by EC density, on the downstream sides of both struts was higher than that on the upstream sides. These observations were made in the flow recirculation at the gap area between two struts. On two side surfaces between the gaps, meaning the downstream at the first and the upstream at the second struts, EC density differences on the downstream surfaces of the first strut were higher than on the upstream surfaces of the second strut. Finally, EC density varied along the struts when the struts were placed at tilted angles. These results indicate that, by the presence of gap between the struts, ECs distribution could be predicted in both perpendicular and tiled positions. And tiled placement affect ECs distribution on the strut side surfaces.
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Affiliation(s)
- Zi Wang
- Institute of Fluid Science, Tohoku University, Sendai, Japan
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
| | - Narendra Kurnia Putra
- Instrumentation and Control Research Group, Faculty of Industrial Technology, Institut Teknologi Bandung, Bandung, Indonesia
| | - Hitomi Anzai
- Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Makoto Ohta
- Institute of Fluid Science, Tohoku University, Sendai, Japan
- *Correspondence: Makoto Ohta,
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Li Y, Zhang M, Tupin S, Mitsuzuka K, Nakayama T, Anzai H, Ohta M. Flush Flow Behaviour Affected by the Morphology of Intravascular Endoscope: A Numerical Simulation and Experimental Study. Front Physiol 2021; 12:733767. [PMID: 34867440 PMCID: PMC8640206 DOI: 10.3389/fphys.2021.733767] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 10/15/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Whilst intravascular endoscopy can be used to identify lesions and assess the deployment of endovascular devices, it requires temporary blockage of the local blood flow during observation, posing a serious risk of ischaemia. Objective: To aid the design of a novel flow-blockage-free intravascular endoscope, we explored changes in the haemodynamic behaviour of the flush flow with respect to the flow injection speed and the system design. Methods: We first constructed the computational models for three candidate endoscope designs (i.e., Model A, B, and C). Using each of the three endoscopes, flow patterns in the target vessels (straight, bent, and twisted) under three different sets of boundary conditions (i.e., injection speed of the flush flow and the background blood flowrate) were then resolved through use of computational fluid dynamics and in vitro flow experiments. The design of endoscope and its optimal operating condition were evaluated in terms of the volume fraction within the vascular segment of interest, as well as the percentage of high-volume-fraction area (PHVFA) corresponding to three cross-sectional planes distal to the microcatheter tip. Results: With a mild narrowing at the endoscope neck, Model B exhibited the highest PHVFA, irrespective of location of the cross-sectional plane, compared with Models A and C which, respectively, had no narrowing and a moderate narrowing. The greatest difference in the PHVFA between the three models was observed on the cross-sectional plane 2 mm distal to the tip of the microcatheter (Model B: 33% vs. Model A: 18%). The background blood flowrate was found to have a strong impact on the resulting volume fraction of the flush flow close to the vascular wall, with the greatest difference being 44% (Model A). Conclusion: We found that the haemodynamic performance of endoscope Model B outperformed that of Models A and C, as it generated a flush flow that occupied the largest volume within the vascular segment of interest, suggesting that the endoscope design with a diameter narrowing of 30% at the endoscope neck might yield images of a better quality.
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Affiliation(s)
- Yujie Li
- Institute of Fluid Science, Tohoku University, Sendai, Japan.,Centre of Health Research, Torrens University Australia, Pyrmont, NSW, Australia
| | - Mingzi Zhang
- Institute of Fluid Science, Tohoku University, Sendai, Japan.,Faculty of Medicine, Health, and Human Sciences, Macquarie Medical School, Macquarie University, Sydney, NSW, Australia
| | - Simon Tupin
- Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Kohei Mitsuzuka
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
| | - Toshio Nakayama
- Nara College, National Institute of Technology, Yamatokoriyama, Japan
| | - Hitomi Anzai
- Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Makoto Ohta
- Institute of Fluid Science, Tohoku University, Sendai, Japan
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10
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Mu Z, Liu L, Sun Y, Gao B, Lv H, Zhao P, Liu Y, Wang Z. Multiphysics coupling numerical simulation of flow-diverting stents in the treatment of patients with pulsatile tinnitus. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3526. [PMID: 34463060 DOI: 10.1002/cnm.3526] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
Patients with pulsatile tinnitus (PT) have unstable treatment effects after resurfacing surgery. Flow-diverting stents (FDS) are proposed as a potential method for the treatment of PT, but the therapeutic effect is not clear. This study aimed to investigate the efficacy of FDS in the treatment of patients with PT induced by sigmoid sinus diverticulum (SSD) and sigmoid sinus wall dehiscence (SSWD). In addition, we aimed to explore the treatment mechanism of PT. Transient-state multiphysics coupling numerical simulation method based on computed tomography angiography of five patients was used to clarify the biomechanical and acoustic states before and after FDS placement. FDS was placed to prevent the blood flow from impacting the vessel wall in the SSD and SSWD areas. Low blood flow velocity (<0.0391 m/s), high relative residence time (>10 Pa-1 ), and low wall shear stress of SSD might lead to thrombosis after FDS placement. The average pressure on the SSWD area of each patient decreased by 13.77%, 18.82%, 29.23%, 19.03%, and 11.20%. The average displacement of the vessel wall on the SSWD area showed acute pulsation and decreased by 15.29%, 14.64%, 30.22%, 41.03%, and 21.28%. The average sound pressure level at the tympanum decreased by 14.01%, 9.33%, 17.66%, 18.88%, and 25.18%, respectively. In brief, FDS was placed to avoid blood flow impacting vessels and reduce the vibration of vessels in the short term, thereby attenuating the degree of PT. The long-term prognosis was that the SSWD area was blocked after SSD thrombosis. Therefore, FDS might be an effective method for the treatment of PT induced by SSD and SSWD. This study would provide a theoretical basis for the treatment of PT and an exploration of FDS design in the treatment of PT.
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Affiliation(s)
- Zhenxia Mu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Li Liu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Yufeng Sun
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Bin Gao
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Han Lv
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Pengfei Zhao
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Youjun Liu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Zhenchang Wang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
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11
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Cerebral aneurysm flow diverter modeled as a thin inhomogeneous porous medium in hemodynamic simulations. Comput Biol Med 2021; 139:104988. [PMID: 34717230 DOI: 10.1016/j.compbiomed.2021.104988] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 10/11/2021] [Accepted: 10/24/2021] [Indexed: 11/24/2022]
Abstract
Rapid and accurate simulation of cerebral aneurysm flow modifications by flow diverters (FDs) can help improving patient-specific intervention and predicting treatment outcome. However, when FD devices are explicitly represented in computational fluid dynamics (CFD) simulations, flow around the stent wires must be resolved, leading to high computational cost. Classic porous medium (PM) methods can reduce computational expense but cannot capture the inhomogeneous FD wire distribution once implanted on a cerebral artery and thus cannot accurately model the post-stenting aneurysmal flow. We report a novel approach that models the FD flow modification as a thin inhomogeneous porous medium (iPM). It improves over the classic PM approaches in two ways. First, the FD is more appropriately treated as a thin screen, which is more accurate than the classic 3D-PM-based Darcy-Forchheimer relation. Second, pressure drop is calculated cell-by-cell using the local FD geometric parameters across an inhomogeneous PM. We applied the iPM technique to simulating the post-stenting hemodynamics of three patient-specific aneurysms. To test its accuracy and speed, we compared the results from the iPM technique against CFD simulations with explicit FD devices. The iPM CFD ran 500% faster than the explicit CFD while achieving 94%-99% accuracy; thus, iPM is a promising clinical bedside modeling tool to assist endovascular interventions with FD and stents.
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12
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Li G, Song X, Wang H, Liu S, Ji J, Guo Y, Qiao A, Liu Y, Wang X. Prediction of Cerebral Aneurysm Hemodynamics With Porous-Medium Models of Flow-Diverting Stents via Deep Learning. Front Physiol 2021; 12:733444. [PMID: 34603085 PMCID: PMC8484706 DOI: 10.3389/fphys.2021.733444] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 08/19/2021] [Indexed: 11/26/2022] Open
Abstract
The interventional treatment of cerebral aneurysm requires hemodynamics to provide proper guidance. Computational fluid dynamics (CFD) is gradually used in calculating cerebral aneurysm hemodynamics before and after flow-diverting (FD) stent placement. However, the complex operation (such as the construction and placement simulation of fully resolved or porous-medium FD stent) and high computational cost of CFD hinder its application. To solve these problems, we applied aneurysm hemodynamics point cloud data sets and a deep learning network with double input and sampling channels. The flexible point cloud format can represent the geometry and flow distribution of different aneurysms before and after FD stent (represented by porous medium layer) placement with high resolution. The proposed network can directly analyze the relationship between aneurysm geometry and internal hemodynamics, to further realize the flow field prediction and avoid the complex operation of CFD. Statistical analysis shows that the prediction results of hemodynamics by our deep learning method are consistent with the CFD method (error function <13%), but the calculation time is significantly reduced 1,800 times. This study develops a novel deep learning method that can accurately predict the hemodynamics of different cerebral aneurysms before and after FD stent placement with low computational cost and simple operation processes.
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Affiliation(s)
- Gaoyang Li
- Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Xiaorui Song
- Department of Radiology, Shandong First Medical University and Shandong Academy of Medical Sciences, Tai'an, China
| | - Haoran Wang
- Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Siwei Liu
- Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Jiayuan Ji
- Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Yuting Guo
- Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Aike Qiao
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Youjun Liu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Xuezheng Wang
- Department of Radiology, Shandong First Medical University and Shandong Academy of Medical Sciences, Tai'an, China
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Method of creating 3D models of small caliber cerebral arteries basing on anatomical specimens. J Biomech 2021; 125:110590. [PMID: 34214861 DOI: 10.1016/j.jbiomech.2021.110590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/17/2021] [Accepted: 06/20/2021] [Indexed: 11/20/2022]
Abstract
The cerebral circulation is a common site of vascular lesions and concurrent hemodynamic accidents, which often lead to serious neurological disabilities. Recent advances in understanding pathogenesis, improving diagnostics and developing new treatment methods for these conditions result from an interdisciplinary approach to the problem - linking clinical sciences, basic medical sciences and hemodynamical analyses. Most common techniques used in such studies include computational fluid dynamics, which allows for development of 3D models of cerebral vasculature, basing on radiological studies. However, these methods remain flawed, mainly because of their spatial resolution, which is not high enough to visualize the smallest arterial branches (perforating branches) in the models. That leaves the perforators (<1.0 mm) out of most of the contemporary studies, whilst their clinical importance is widely recognized in clinical practice. Obstruction of these vessels by atherosclerotic plaques, thrombi or implantation of flow diverting stents may result in neurological complications such as paralysis or coma. Our research team has recently developed a new method of creating 3D models of the cerebral arterial system based on anatomical specimens and micro computed tomography (micro-CT). We have infused fresh brainstem vasculature specimens with contrast medium, subsequently scanned them using an industrial-grade micro-CT system and finally, created spatial models, which included branches of diameter less than 0.1 mm. None of the current methods have been able to produce models of detail as high as this, which allows us to presume, that our procedure may open up new opportunities for hemodynamical studies within cerebral circulation and beyond.
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14
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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] [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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Zhang M, Tupin S, Anzai H, Kohata Y, Shojima M, Suzuki K, Okamoto Y, Tanaka K, Yagi T, Fujimura S, Ohta M. Implementation of computer simulation to assess flow diversion treatment outcomes: systematic review and meta-analysis. J Neurointerv Surg 2020; 13:164-170. [PMID: 33097626 PMCID: PMC7848055 DOI: 10.1136/neurintsurg-2020-016724] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/11/2020] [Accepted: 09/17/2020] [Indexed: 12/31/2022]
Abstract
Introduction Despite a decade of research into virtual stent deployment and the post-stenting aneurysmal hemodynamics, the hemodynamic factors which correlate with successful treatment remain inconclusive. We aimed to examine the differences in various post-treatment hemodynamic parameters between successfully and unsuccessfully treated cases, and to quantify the additional flow diversion achievable through stent compaction or insertion of a second stent. Methods A systematic review and meta-analysis were performed on eligible studies published from 2000 to 2019. We first classified cases according to treatment success (aneurysm occlusion) and then calculated the pooled standardized mean differences (SMD) of each available parameter to examine their association with clinical outcomes. Any additional flow diversion arising from the two common strategies for improving the stent wire density was quantified by pooling the results of such studies. Results We found that differences in the aneurysmal inflow rate (SMD −6.05, 95% CI −10.87 to −1.23, p=0.01) and energy loss (SMD −5.28, 95% CI −7.09 to −3.46, p<0.001) between the successfully and unsuccessfully treated groups were indicative of statistical significance, in contrast to wall shear stress (p=0.37), intra-aneurysmal average velocity (p=0.09), vortex core-line length (p=0.46), and shear rate (p=0.09). Compacting a single stent could achieve additional flow diversion comparable to that by dual-stent implantation. Conclusions Inflow rate and energy loss have shown promise as identifiers to discriminate between successful and unsuccessful treatment, pending future research into their diagnostic performance to establish optimal cut-off values.
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Affiliation(s)
- Mingzi Zhang
- Biomedical Flow Dynamics Laboratory, Tohoku University Institute of Fluid Science, Sendai, Miyagi, Japan
| | - Simon Tupin
- Biomedical Flow Dynamics Laboratory, Tohoku University Institute of Fluid Science, Sendai, Miyagi, Japan
| | - Hitomi Anzai
- Biomedical Flow Dynamics Laboratory, Tohoku University Institute of Fluid Science, Sendai, Miyagi, Japan
| | - Yutaro Kohata
- Biomedical Flow Dynamics Laboratory, Tohoku University Institute of Fluid Science, Sendai, Miyagi, Japan
| | - Masaaki Shojima
- Department of Neurosurgery, Saitama Medical University Saitama Medical Center, Kawagoe, Saitama, Japan
| | - Kosuke Suzuki
- Department of Mechanical and Electrical Engineering, Nagoya Institute of Technology, Nagoya, Aichi, Japan
| | - Yoshihiro Okamoto
- Division of Medical Devices, National Institute of Health Sciences, Kawasaki, Kanagawa, Japan
| | - Katsuhiro Tanaka
- Department of Neurosurgery, Mie Central Medical Center, Tsu, Mie, Japan
| | - Takanobu Yagi
- Center for Advanced Biomedical Sciences (TWIns), Waseda University, Shinjuku, Tokyo, Japan
| | - Soichiro Fujimura
- Department of Innovation for Medical Information Technology, Jikei University School of Medicine, Minato, Tokyo, Japan.,Graduate School of Mechanical Engineering, Tokyo University of Science, Shinjuku, Tokyo, Japan
| | - Makoto Ohta
- Biomedical Flow Dynamics Laboratory, Tohoku University Institute of Fluid Science, Sendai, Miyagi, Japan .,ElyTMaX, CNRS - Université de Lyon - Tohoku University, International Joint Unit, Tohoku University, Sendai, Miyagi, Japan
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Beppu M, Tsuji M, Ishida F, Shirakawa M, Suzuki H, Yoshimura S. Computational Fluid Dynamics Using a Porous Media Setting Predicts Outcome after Flow-Diverter Treatment. AJNR Am J Neuroradiol 2020; 41:2107-2113. [PMID: 33004340 DOI: 10.3174/ajnr.a6766] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 07/07/2020] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Knowledge about predictors of the outcome of flow-diverter treatment is limited. The aim of this study was to predict the angiographic occlusion status after flow-diverter treatment with computational fluid dynamics using porous media modeling for decision-making in the treatment of large wide-neck aneurysms. MATERIALS AND METHODS A total of 27 patients treated with flow-diverter stents were retrospectively analyzed through computational fluid dynamics using pretreatment patient-specific 3D rotational angiography. These patients were classified into no-filling and contrast-filling groups based on the O'Kelly-Marotta scale. The patient characteristics, morphologic variables, and hemodynamic parameters were evaluated for understanding the outcomes of the flow-diverter treatment. RESULTS The patient characteristics and morphologic variables were similar between the 2 groups. Flow velocity, wall shear stress, shear rate, modified aneurysmal inflow rate coefficient, and residual flow volume were significantly lower in the no-filling group. A novel parameter, called the normalized residual flow volume, was developed and defined as the residual flow volume normalized by the dome volume. The receiver operating characteristic curve analyses demonstrated that the normalized residual flow volume with an average flow velocity of ≥8.0 cm/s in the aneurysmal dome was the most effective in predicting the flow-diverter treatment outcomes. CONCLUSIONS It was established in this study that the hemodynamic parameters could predict the angiographic occlusion status after flow-diverter treatment.
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Affiliation(s)
- M Beppu
- From the Department of Neurosurgery (M.B., M.S., S.Y.), Hyogo College of Medicine, Hygo, Japan
| | - M Tsuji
- Department of Neurosurgery (M.T., F.I.), National Hospital Organization Mie Chuo Medical Center, Tsu, Mie, Japan
| | - F Ishida
- Department of Neurosurgery (M.T., F.I.), National Hospital Organization Mie Chuo Medical Center, Tsu, Mie, Japan
| | - M Shirakawa
- From the Department of Neurosurgery (M.B., M.S., S.Y.), Hyogo College of Medicine, Hygo, Japan
| | - H Suzuki
- Department of Neurosurgery (H.S.), Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - S Yoshimura
- From the Department of Neurosurgery (M.B., M.S., S.Y.), Hyogo College of Medicine, Hygo, Japan
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Li Y, Yoneyama Y, Isoda H, Terada M, Kosugi T, Kosugi T, Zhang M, Ohta M. Haemodynamics in a patient-specific intracranial aneurysm according to experimental and numerical approaches: A comparison of PIV, CFD and PC-MRI. Technol Health Care 2020; 29:253-267. [PMID: 32568138 DOI: 10.3233/thc-202252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The haemodynamics determined by different approaches for studying fluid dynamics - i.e. computational fluid dynamics (CFD), particle image velocimetry (PIV), and phase-contrast magnetic resonance imaging (PC-MRI) - have rarely been thoroughly compared; nor have the factors that affect accuracy and precision in each method. As each method has its own advantages and limitations, this knowledge is important for future studies to be able to achieve valid analyses of fluid flows. OBJECTIVE To gauge the capacity of these methods for analysing aneurysmal flows, we compared the haemodynamic behaviours determined by each method within a patient-specific aneurysm model. METHODS An in vitro silicone aneurysm model was fabricated for PIV and PC-MRI, and an in silico aneurysm model with the same geometry was reconstructed for CFD. With the same fluid model prepared numerically and physically, CFD, PIV and PC-MRI were performed to study aneurysmal haemodynamics. RESULTS 2D velocity vectors and magnitudes show good agreement between PIV and CFD, and 3D flow patterns show good similarity between PC-MRI and CFD. CONCLUSIONS These findings give confidence to future haemodynamic studies using CFD technology. For the first time, the morphological inconsistency between the PCMRI model and others is found to affect the measurement of local flow patterns.
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Affiliation(s)
- Yujie Li
- Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan
| | - Yuuya Yoneyama
- Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.,Department of Radiology, Fujita Health University Hospital, Toyoake, Aichi, Japan
| | - Haruo Isoda
- Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.,Brain and Mind Research Center, Nagoya University, Nagoya, Aichi, Japan
| | - Masaki Terada
- Department of Diagnostic Radiological Technology, Iwata City Hospital, Iwata, Shizuoka, Japan
| | - Takafumi Kosugi
- Renaissance of Technology Corporation, Hamamatsu, Shizuoka, Japan
| | - Takashi Kosugi
- Renaissance of Technology Corporation, Hamamatsu, Shizuoka, Japan
| | - Mingzi Zhang
- Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan
| | - Makoto Ohta
- 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] [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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Evaluating the Effect of the Number of Wire of Flow Diverter Stents on the Nonstagnated Region Formation in an Aneurysm Sac Using Lagrangian Coherent Structure and Hyperbolic Time Analysis. World Neurosurg 2020; 133:e666-e682. [DOI: 10.1016/j.wneu.2019.09.116] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/21/2019] [Accepted: 09/23/2019] [Indexed: 01/18/2023]
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21
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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. [DOI: 10.1016/j.medntd.2019.100018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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22
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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] [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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Zhang K, Wang ZL, Gao BL, Xue JY, Li TX, Zhao TY, Cai DY, He YK. Use of a First Large-Sized Coil Versus Conventional Coils for Embolization of Cerebral Aneurysms: Effects on Packing Density, Coil Length, and Durable Occlusion. World Neurosurg 2019; 127:e685-e691. [PMID: 30946999 DOI: 10.1016/j.wneu.2019.03.242] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 03/22/2019] [Accepted: 03/23/2019] [Indexed: 01/09/2023]
Abstract
OBJECTIVE To investigate effects of using a large-sized coil first on embolizing cerebral aneurysms compared with conventional coils. MATERIALS AND METHODS Forty-six patients with 51 saccular intracranial aneurysms who underwent embolization with a large-sized coil first were enrolled as the large-sized coil group. There were 33 female and 13 male patients with a mean age of 56.9 ± 8.8 years. The treatment modality was coiling alone in 30 aneurysms and stent-assisted coiling in 21. Meanwhile, 50 patients with 53 intracranial aneurysms who were treated with conventional-sized coils were selected as the control conventional-sized coil group, including 36 female and 14 male patients with a mean age of 54.6 ± 5.8 years. The treatment modality was coiling alone in 29 aneurysms and stent-assisted coiling in 24 aneurysms. The occlusion rate, percent packing volume, total coil number and length, and follow-up occlusion rate were compared between the 2 groups. RESULTS Significantly (P < 0.001) decreased percent packing volume (19.54% ± 6.44% vs. 27.39% ± 5.68%), decreased coil number (2.98 ± 1.09 vs. 6.38 ± 1.65), and length (26.20 ± 26.57 vs. 44.35 ± 35.88 cm) were achieved in the large versus the conventional coil group. At angiographic follow-up of 8 months, only 1 aneurysm (2.2%) recurred in the large coil group compared with 5 aneurysms recurrent (11.1%) in the conventional coil group. CONCLUSIONS The use of a large-sized coil as the first one for embolizing cerebral aneurysms may be a better embolization strategy because it achieves similar initial occlusion rates, decreased packing density, decreased coil numbers and lengths, and reduced recurrence prevalence at follow-up.
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Affiliation(s)
- Kun Zhang
- Henan Provincial Cerebrovascular Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zhengzhou, Henan Province, China
| | - Zi-Liang Wang
- Henan Provincial Cerebrovascular Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zhengzhou, Henan Province, China
| | - Bu-Lang Gao
- Henan Provincial Cerebrovascular Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zhengzhou, Henan Province, China
| | - Jiang-Yu Xue
- Henan Provincial Cerebrovascular Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zhengzhou, Henan Province, China.
| | - Tian-Xiao Li
- Henan Provincial Cerebrovascular Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zhengzhou, Henan Province, China
| | - Tong-Yuan Zhao
- Henan Provincial Cerebrovascular Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zhengzhou, Henan Province, China
| | - Dong-Yang Cai
- Henan Provincial Cerebrovascular Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zhengzhou, Henan Province, China
| | - Ying-Kun He
- Henan Provincial Cerebrovascular Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zhengzhou, Henan Province, China
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CFD-Based Comparison Study of a New Flow Diverting Stent and Commercially-Available Ones for the Treatment of Cerebral Aneurysms. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9071341] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Flow-diverting stents (FDSs) show considerable promise for the treatment of cerebral aneurysms by diverting blood flow away from the aneurysmal sacs, however, post-treatment complications such as failure of occlusion and subarachnoid haemorrhaging remain and vary with the FDS used. Based on computational fluid dynamics (CFD), this study aimed to investigate the performance of a new biodegradable stent as compared to two metallic commercially available FDSs. CFD models were developed for an idealized cerebral artery with a sidewall aneurysmal sac treated by deploying the aforementioned stents of different porosities (90, 80, and 70 % ) respectively. By using these models, the simulation and analysis were performed, with a focus on comparing the local hemodynamics or the blood flow in the stented arteries as compared to the one without the stent deployment. For the comparison, we computed and compared the flow velocity, wall shear stress (WSS) and pressure distributions, as well as the WSS related indices, all of which are of important parameters for studying the occlusion and potential rupture of the aneurysm. Our results illustrate that the WSS decreases within the aneurysmal sac on the treated arteries, which is more significant for the stents with lower porosity or finer mesh. Our results also show that the maximum WSS near the aneurysmal neck increases regardless of the stents used. In addition, the WSS related indices including the time-average WSS, oscillatory shear index and relative residence time show different distributions, depending on the FDSs. Together, we found that the finer mesh stents provide more flow reduction and smaller region characterized by high oscillatory shear index, while the new stent has a higher relative residence time.
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