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A Patient-Specific Three-Dimensional Hemodynamic Model of the Circle of Willis. Cardiovasc Eng Technol 2017; 8:495-504. [PMID: 28913763 DOI: 10.1007/s13239-017-0330-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 09/04/2017] [Indexed: 10/18/2022]
Abstract
Circle of Willis (CoW) is one of the most important cerebral arteries in the human body and various attempts have been made to study the hemodynamic of blood flow in this vital part of the brain. In the present study, blood flow in a patient specific CoW is numerically modeled to predict disease-prone regions of the CoW. Medical images and computer aided design software are used to construct a realistic three-dimensional model of the CoW for this particular case. The arteries are considered as elastic conduits and the interactions between arterial walls and the blood flow are taken into account. Mooney-Rivlin hyperelastic model is used to describe the behavior of arterial walls and blood is considered as a non-Newtonian fluid obeying the Carreau model. An available experimental-based pulsatile velocity profile is used at the entrance of the CoW. The finite element-based commercial software, ADINA, is used to solve the governing equations. Blood pressure and velocity and arterial wall shear stress are calculated in different regions of the CoW. A simplified form of the model is also compared with the available published data. Results affirmed that the proposed computational model has the potential to capture the hemodynamic characteristics of the CoW. The computational results can be used to determine disease-prone locations for a given CoW.
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Sarrami-Foroushani A, Lassila T, Frangi AF. Virtual endovascular treatment of intracranial aneurysms: models and uncertainty. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2017; 9. [PMID: 28488754 DOI: 10.1002/wsbm.1385] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 01/09/2017] [Accepted: 02/07/2017] [Indexed: 01/11/2023]
Abstract
Virtual endovascular treatment models (VETMs) have been developed with the view to aid interventional neuroradiologists and neurosurgeons to pre-operatively analyze the comparative efficacy and safety of endovascular treatments for intracranial aneurysms. Based on the current state of VETMs in aneurysm rupture risk stratification and in patient-specific prediction of treatment outcomes, we argue there is a need to go beyond personalized biomechanical flow modeling assuming deterministic parameters and error-free measurements. The mechanobiological effects associated with blood clot formation are important factors in therapeutic decision making and models of post-treatment intra-aneurysmal biology and biochemistry should be linked to the purely hemodynamic models to improve the predictive power of current VETMs. The influence of model and parameter uncertainties associated to each component of a VETM is, where feasible, quantified via a random-effects meta-analysis of the literature. This allows estimating the pooled effect size of these uncertainties on aneurysmal wall shear stress. From such meta-analyses, two main sources of uncertainty emerge where research efforts have so far been limited: (1) vascular wall distensibility, and (2) intra/intersubject systemic flow variations. In the future, we suggest that current deterministic computational simulations need to be extended with strategies for uncertainty mitigation, uncertainty exploration, and sensitivity reduction techniques. WIREs Syst Biol Med 2017, 9:e1385. doi: 10.1002/wsbm.1385 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Ali Sarrami-Foroushani
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
| | - Toni Lassila
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
| | - Alejandro F Frangi
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
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Berg P, Saalfeld S, Voß S, Redel T, Preim B, Janiga G, Beuing O. Does the DSA reconstruction kernel affect hemodynamic predictions in intracranial aneurysms? An analysis of geometry and blood flow variations. J Neurointerv Surg 2017; 10:290-296. [PMID: 28465404 DOI: 10.1136/neurintsurg-2017-012996] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 03/29/2017] [Accepted: 04/13/2017] [Indexed: 11/04/2022]
Abstract
BACKGROUND Computational fluid dynamics (CFD) blood flow predictions in intracranial aneurysms promise great potential to reveal patient-specific flow structures. Since the workflow from image acquisition to the final result includes various processing steps, quantifications of the individual introduced potential error sources are required. METHODS Three-dimensional (3D) reconstruction of the acquired imaging data as input to 3D model generation was evaluated. Six different reconstruction modes for 3D digital subtraction angiography (DSA) acquisitions were applied to eight patient-specific aneurysms. Segmentations were extracted to compare the 3D luminal surfaces. Time-dependent CFD simulations were carried out in all 48 configurations to assess the velocity and wall shear stress (WSS) variability due to the choice of reconstruction kernel. RESULTS All kernels yielded good segmentation agreement in the parent artery; deviations of the luminal surface were present at the aneurysm neck (up to 34.18%) and in distal or perforating arteries. Observations included pseudostenoses as well as noisy surfaces, depending on the selected reconstruction kernel. Consequently, the hemodynamic predictions show a mean SD of 11.09% for the aneurysm neck inflow rate, 5.07% for the centerline-based velocity magnitude, and 17.83%/9.53% for the mean/max aneurysmal WSS, respectively. In particular, vessel sections distal to the aneurysms yielded stronger variations of the CFD values. CONCLUSIONS The choice of reconstruction kernel for DSA data influences the segmentation result, especially for small arteries. Therefore, if precise morphology measurements or blood flow descriptions are desired, a specific reconstruction setting is required. Furthermore, research groups should be encouraged to denominate the kernel types used in future hemodynamic studies.
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Affiliation(s)
- P Berg
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - S Saalfeld
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - S Voß
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - T Redel
- Siemens Healthcare GmbH, Forchheim, Germany
| | - B Preim
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - G Janiga
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - O Beuing
- Institute of Neuroradiology, University Hospital Magdeburg, Magdeburg, Germany
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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] [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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Otani T, Ii S, Shigematsu T, Fujinaka T, Hirata M, Ozaki T, Wada S. Computational study for the effects of coil configuration on blood flow characteristics in coil-embolized cerebral aneurysm. Med Biol Eng Comput 2016; 55:697-710. [DOI: 10.1007/s11517-016-1541-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 06/29/2016] [Indexed: 11/28/2022]
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Larrabide I, Geers AJ, Morales HG, Bijlenga P, Rüfenacht DA. Change in aneurysmal flow pulsatility after flow diverter treatment. Comput Med Imaging Graph 2016; 50:2-8. [DOI: 10.1016/j.compmedimag.2015.01.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Revised: 12/16/2014] [Accepted: 01/19/2015] [Indexed: 11/30/2022]
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Physical and computational fluid dynamics models for the hemodynamics of the artiodactyl carotid rete. J Theor Biol 2015; 386:122-31. [DOI: 10.1016/j.jtbi.2015.09.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 09/09/2015] [Accepted: 09/11/2015] [Indexed: 11/23/2022]
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Unraveling the relationship between arterial flow and intra-aneurysmal hemodynamics. J Biomech 2015; 48:585-591. [DOI: 10.1016/j.jbiomech.2015.01.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 01/06/2015] [Accepted: 01/07/2015] [Indexed: 11/21/2022]
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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] [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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Chung B, Cebral JR. CFD for Evaluation and Treatment Planning of Aneurysms: Review of Proposed Clinical Uses and Their Challenges. Ann Biomed Eng 2014; 43:122-38. [DOI: 10.1007/s10439-014-1093-6] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 08/08/2014] [Indexed: 11/29/2022]
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ISHII TAKURO, NAYA YUKIO, YAMANISHI TOMONORI, IGARASHI TATSUO. URINE FLOW DYNAMICS THROUGH THE URETHRA IN PATIENTS WITH BLADDER OUTLET OBSTRUCTION. J MECH MED BIOL 2014. [DOI: 10.1142/s0219519414500523] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Voiding dysfunction is a common disease among the elderly male population. However, few studies have elucidated the flow dynamics of the disease mechanism. We attempted to clarify the fluid dynamics of urine in the prostatic urethra (PU) in patients with bladder outlet obstruction (BOO), a common disease associated with voiding dysfunction. A model of normal PU and three phase models following the BOO progression were prepared using 3D CAD software tracing cystourethroscopic images. In fluid dynamics computation, the normal detrusor pressure was applied to the bladder side in each model. Results of fluid simulation were compared for flow trajectory line, fluid energy dynamics using Bernoulli's principle and pressure loss coefficient. In the BOO model, a large vortex was observed adjacent to the bladder outlet (BO) with increased hydraulic energy loss during the passage through the tract. In contrast, opening of the BO eliminated the vortex with reduction of hydraulic energy loss. These results corresponded with clinical data measured by catheterized pressure sensors inserted into the urethra, and those of urethral diameter measured by urethrography. Fluid dynamics simulation using CAD models can clarify the mechanism of voiding dysfunction in a less invasive and more acceptable way in patients with BOO.
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Affiliation(s)
- TAKURO ISHII
- Division of Medical System Engineering, Graduate School of Engineering, Chiba University, 1-33 Yayoi-Cho, Inage Ward, Chiba, 263-8522, Japan
| | - YUKIO NAYA
- Department of Urology, Teikyo University, Chiba Medical Center, 3426-3 Anesaki, Ichihara City, Chiba, 299-0111, Japan
| | - TOMONORI YAMANISHI
- Department of Urology, Dokkyo Medical University, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, Japan
| | - TATSUO IGARASHI
- Center for Frontier Medical Engineering, Chiba University, 1-33 Yayoi-cho, Inage ward, Chiba, 263-8522, Japan
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Morales HG, Bonnefous O. Peak systolic or maximum intra-aneurysmal hemodynamic condition? Implications on normalized flow variables. J Biomech 2014; 47:2362-70. [DOI: 10.1016/j.jbiomech.2014.04.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/25/2014] [Accepted: 04/17/2014] [Indexed: 10/25/2022]
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