Image-Based Computational and Experimental Biomedical Flows

A special issue of Fluids (ISSN 2311-5521). This special issue belongs to the section "Non-Newtonian and Complex Fluids".

Deadline for manuscript submissions: closed (15 December 2023) | Viewed by 23167

Special Issue Editor

1. Department of Mechanical and Energy Engineering, Indiana University–Purdue University Indianapolis (IUPUI), Indianapolis, IN 46202, USA
2. Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
Interests: image-based computational and experimental fluid dynamics; GPU accelerated lattice Boltzmann method; DNS and LES of turbulence; multiphase flows; pulsatile flows; pore-scale porous media flows

Special Issue Information

Dear Colleagues,

Advances in medical imaging, computerized image processing, 3D printing, and computational and experimental fluid dynamics now make it possible to anatomically reconstruct 3D human organ geometries to access realistic 4D (space and time) biomedical flows, such as blood flow in human vessels and airflow in human airways. Such a capability gives rise to a promising field of medical diagnostics and therapeutics in a patient-specific environment. Data obtained from image-based computational and experimental biomedical flows, the majority of which are not readily available from the current standard clinical measurements, are promising to offer key insights into disease progression and subsequent physiological response, thus aiding in clinical decision making for various cardiovascular and respiratory diseases.

This Special Issue of Fluids is dedicated to collecting the most recent progress in the techniques of computational and experimental fluid dynamics in various image-based flow domains for the noninvasive quantification of 4D pressure, velocity, and shear stress in vessels and airways, together with verification, validation, and uncertain quantification. Highlights are the state-of-the-art theoretical and experimental representations of biomedical systems, sophisticated computational modeling, and fast computation, as well as novel methods for extracting medically meaningful information from computationally and/or experimentally obtained data toward new physiological indices and/or biomarkers.

Dr. Huidan (Whitney) Yu
Guest Editor

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Keywords

  • medical imaging
  • computational fluid dynamics
  • experimental fluid dynamics
  • biomedical flows
  • blood flows
  • cardiovascular diseases
  • respiratory diseases

Published Papers (13 papers)

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Research

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15 pages, 9682 KiB  
Article
V Flow Measurements of Pulsatile Flow in Femoral-Popliteal Bypass Proximal Anastomosis Compared with CFD Simulation
by Andrey Yukhnev, Ludmila Tikhomolova, Yakov Gataulin, Alexandra Marinova, Evgueni Smirnov, Andrey Vrabiy, Andrey Suprunovich and Gennady Khubulava
Fluids 2024, 9(3), 64; https://doi.org/10.3390/fluids9030064 - 04 Mar 2024
Viewed by 548
Abstract
This paper presents the experience of using the V Flow high-frame-rate ultrasound vector imaging method to study the pulsatile velocity fields in the area of the proximal anastomosis for femoral popliteal bypass surgery in vitro and in vivo. A representative (average) anastomosis model [...] Read more.
This paper presents the experience of using the V Flow high-frame-rate ultrasound vector imaging method to study the pulsatile velocity fields in the area of the proximal anastomosis for femoral popliteal bypass surgery in vitro and in vivo. A representative (average) anastomosis model and the experimental setup designed for in vitro studies covering forward and reverse flow phases throughout the cycle are described. The results of the measurements are presented for areas with a relatively uniform velocity distribution and for areas with pronounced spatial inhomogeneities due to the jet or recirculating nature of the flow. The results of ultrasonic studies of the velocity field of the three-dimensional pulsatile flow in vitro and in vivo are compared with the data of numerical simulations carried out for the average and personalized models based on the Navier–Stokes equations. Acceptable consistency between the results of experimental and numerical studies is demonstrated. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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16 pages, 21022 KiB  
Article
Evaluating the Impact of Domain Boundaries on Hemodynamics in Intracranial Aneurysms within the Circle of Willis
by Pablo Jeken-Rico, Aurèle Goetz, Philippe Meliga, Aurélien Larcher, Yigit Özpeynirci and Elie Hachem
Fluids 2024, 9(1), 1; https://doi.org/10.3390/fluids9010001 - 21 Dec 2023
Viewed by 1237
Abstract
Hemodynamic simulations are increasingly used to study vascular diseases such as Intracranial Aneurysms (IA) and to further develop treatment options. However, due to limited data, certain aspects must rely on heuristics, especially at the simulation’s distal ends. In the literature, Murray’s Law is [...] Read more.
Hemodynamic simulations are increasingly used to study vascular diseases such as Intracranial Aneurysms (IA) and to further develop treatment options. However, due to limited data, certain aspects must rely on heuristics, especially at the simulation’s distal ends. In the literature, Murray’s Law is often used to model the outflow split based on vessel cross-section area; however, this poses challenges for the communicating arteries in the Circle of Willis (CoW). In this study, we contribute by assessing the impact of Murray’s Law in patient-specific geometries featuring IA at the posterior communication. We simulate different domain extensions representing common modelling choices and establish Full CoW simulations as a baseline to evaluate the effect of these modelling assumptions on hemodynamic indicators, focusing on IA growth and rupture-related factors such as the Wall Shear Stress (WSS) and Oscillatory Shear Index (OSI). Our findings reveal qualitative alterations in hemodynamics when not modeling posterior communication. Comparisons between computing the anterior circulation and computing the whole Circle of Willis reveal that quantitative changes in WSS may reach up to 80%, highlighting the significance of modelling choices in assessing IA risks and treatment strategies. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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15 pages, 4969 KiB  
Article
Blood Flow Simulation of Aneurysmatic and Sane Thoracic Aorta Using OpenFOAM CFD Software
by Francesco Duronio and Andrea Di Mascio
Fluids 2023, 8(10), 272; https://doi.org/10.3390/fluids8100272 - 02 Oct 2023
Cited by 1 | Viewed by 1801
Abstract
Cardiovascular diseases still represent one of the most deadly pathologies worldwide. Knowledge of the blood flow dynamics within the cardio-vascular system is crucial in preventing these diseases and analysing their physiology and physio-pathology. CFD simulations are highly effective in guiding clinical predictions and, [...] Read more.
Cardiovascular diseases still represent one of the most deadly pathologies worldwide. Knowledge of the blood flow dynamics within the cardio-vascular system is crucial in preventing these diseases and analysing their physiology and physio-pathology. CFD simulations are highly effective in guiding clinical predictions and, more importantly, allow the evaluation of physical and clinical parameters that are difficult to measure with common diagnostic techniques. Therefore, in particular, this study is focused on investigating the hemodynamics of the thoracic aorta. Real aortic geometries regarding a sane and diseased patient presenting an aneurysm were considered. CFD simulations were performed with the OpenFOAM C++ library using patient-specific pulsatile blood flow waveforms and implementing the Windkessel pressure boundary condition for the artery outflow. The adopted methodology was preliminarily verified for assessing the numerical uncertainty and convergence. Then, the CFD results were evaluated against experimental data concerning pressure and velocity of the thoracic aorta measured with standard diagnostic techniques. The normal aorta’s blood flow was also compared against the pattern regarding the patient-specific aortic aneurysm. Parameters such as wall pressure, wall shear stress (WSS) and velocity distribution were investigated and discussed. The research highlighted that the blood flow in the aorta is strongly affected by the aneurysm onset, with the growth of recirculation zones being potentially hazardous. The outcomes of the investigation finally demonstrate how CFD simulation tools, capturing the detailed physics of the aortic flow, are powerful tools for supporting clinical activities of the cardio-vascular system. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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15 pages, 3047 KiB  
Article
A Mock Circulation Loop to Characterize In Vitro Hemodynamics in Human Systemic Arteries with Stenosis
by Weichen Hong, Huidan Yu, Jun Chen, John Talamantes, Dave M. Rollins, Xin Fang, Jianyun Long, Chenke Xu and Alan P. Sawchuk
Fluids 2023, 8(7), 198; https://doi.org/10.3390/fluids8070198 - 29 Jun 2023
Cited by 1 | Viewed by 1180
Abstract
Vascular disease is the leading cause of morbidity and mortality and a major cause of disability for Americans, and arterial stenosis is its most common form in systemic arteries. Hemodynamic characterization in a stenosed arterial system plays a crucial role in the diagnosis [...] Read more.
Vascular disease is the leading cause of morbidity and mortality and a major cause of disability for Americans, and arterial stenosis is its most common form in systemic arteries. Hemodynamic characterization in a stenosed arterial system plays a crucial role in the diagnosis of its lesion severity and the decision-making process for revascularization, but it is not readily available in the current clinical measurements. The newly emerged image-based computational hemodynamics (ICHD) technique provides great potential to characterize the hemodynamics with fine temporospatial resolutions in realistic human vessels, but medical data is rather limited for validation requirements. We present an image-based experimental hemodynamics (IEHD) technique through a mock circulation loop (MCL) to bridge this critical gap. The MCL mimics blood circulation in human stenosed systemic arterial systems that can be either 3D-printed silicone, artificial, or cadaver arteries and thus enables in vitro measurement of hemodynamics. In this work, we focus on the development and validation of the MCL for the in vitro measurement of blood pressure in stenosed silicone arteries anatomically extracted from medical imaging data. Five renal and six iliac patient cases are studied. The pressure data from IEHD were compared with those from ICHD and medical measurement. The good agreements demonstrate the reliability of IEHD. We also conducted two parametric studies to demonstrate the medical applicability of IEHD. One was the cardiovascular response to MCL parameters. We found that blood pressure has a linear correlation with stroke volume and heart rate. Another was the effect of arterial stenosis, characterized by the volumetric reduction (VR) of the arterial lumen, on the trans-stenotic pressure gradient (TSPG). We parametrically varied the stenosis degree and measured the corresponding TSPG. The TSPG-VR curve provides a critical VR that can be used to assess the true hemodynamic severity of the stenosis. Meanwhile, the TSPG at VR = 0 can predict the potential pressure improvement after revascularization. Unlike the majority of existing MCLs that are mainly used to test medical devices involving heart function, this MCL is unique in its specific focus on pressure measurement in stenosed human systemic arteries. Meanwhile, rigorous hemodynamic characterization through concurrent IEHD and ICHD will significantly enhance our current understanding of the pathophysiology of stenosis and contribute to advancements in the medical treatment of arterial stenosis. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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23 pages, 3685 KiB  
Article
Repaired Tetralogy of Fallot Pressure Assessment: Insights from 4D-Flow Pressure Mapping
by Safia Ihsan Ali, David Patton, Kimberley A. Myers and Julio Garcia
Fluids 2023, 8(7), 196; https://doi.org/10.3390/fluids8070196 - 29 Jun 2023
Viewed by 1020
Abstract
Tetralogy of Fallot (TOF) is the most prevalent cyanotic congenital heart defect (CHD) that alters normal blood flow through the heart and accounts for 10% of all CHD. Pulmonary stenosis and regurgitation are common in adults who have undergone TOF repair (rTOF) and [...] Read more.
Tetralogy of Fallot (TOF) is the most prevalent cyanotic congenital heart defect (CHD) that alters normal blood flow through the heart and accounts for 10% of all CHD. Pulmonary stenosis and regurgitation are common in adults who have undergone TOF repair (rTOF) and can impact the load on the right ventricle, blood flow pressure, and pulmonary hemodynamics. Pressure mapping, obtained through 4D-flow magnetic resonance imaging (4D-flow MRI), has been applied to identify abnormal heart hemodynamics in CHD. Hence, the aim of this research was to compare pressure drop and relative pressures between patients with repaired TOF (rTOF) and healthy volunteers. An in vitro validation was performed, followed by an in vivo validation. We hypothesized that pressure drop is a more stable pressure mapping method than relative pressures to detect altered hemodynamics. A total of 36 subjects, 18 rTOF patients and 18 controls underwent cardiac MRI scans and 4D-flow MRI. Pressure drops and relative pressures in the MPA were higher in rTOF patients compared to the controls (p < 0.05). Following the in vitro validation, pressure drops proved to be a more stable pressure mapping method than relative pressures, as the flow loses its laminarity and becomes more turbulent. In conclusion, this study demonstrated that flow hemodynamics in rTOF can exhibit altered pressure maps. Pressure mapping can help provide further insight into rTOF patients’ hemodynamics to improve patient care and clinical decisions. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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18 pages, 5111 KiB  
Article
Hemodynamic Investigation of the Flow Diverter Treatment of Intracranial Aneurysm
by Maria Antonietta Boniforti, Roberto Magini and Tania Orosco Salinas
Fluids 2023, 8(7), 189; https://doi.org/10.3390/fluids8070189 - 24 Jun 2023
Cited by 1 | Viewed by 1535
Abstract
Flow diverter stents (FDS) are increasingly used for the treatment of complex intracranial aneurysms such as fusiform, giant, or wide-neck aneurysms. The primary goal of these devices is to reconstruct the diseased vascular segment by diverting blood flow from the aneurysm. The resulting [...] Read more.
Flow diverter stents (FDS) are increasingly used for the treatment of complex intracranial aneurysms such as fusiform, giant, or wide-neck aneurysms. The primary goal of these devices is to reconstruct the diseased vascular segment by diverting blood flow from the aneurysm. The resulting intra-aneurysmal flow reduction promotes progressive aneurysm thrombosis and healing of the disease. In the present study, a numerical investigation was performed for modeling blood flow inside a patient-specific intracranial aneurysm virtually treated with FDS. The aim of the study is to investigate the effects of FDS placement prior to the actual endovascular treatment and to compare the effectiveness of devices differing in porosity. Numerical simulations were performed under pulsatile flow conditions, taking into account the non-Newtonian behavior of blood. Two possible post-operative conditions with virtual stent deployment were simulated. Hemodynamic parameters were calculated and compared between the pre-operative (no stent placement) and post-operative (virtual stent placement) aneurysm models. FDS placement significantly reduced intra-aneurysmal flow velocity and increased the Relative Residence Time (RRT) on the aneurysm, thus promoting thrombus formation within the dilatation and aneurysm occlusion. The results highlighted an increase in the effectiveness of FDS as its porosity increased. The proposed analysis provides pre-operative knowledge on the impact of FDS on intracranial hemodynamics, allowing the selection of the most effective treatment for the specific patient. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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33 pages, 1360 KiB  
Article
Modelling The Hemodynamics of Coronary Ischemia
by Abdulaziz Al Baraikan, Krzysztof Czechowicz, Paul D. Morris, Ian Halliday, Rebecca C. Gosling, Julian P. Gunn, Andrew J. Narracott, Gareth Williams, Pankaj Garg, Maciej Malawski, Frans van de Vosse, Angela Lungu, Dan Rafiroiu and David Rodney Hose
Fluids 2023, 8(5), 159; https://doi.org/10.3390/fluids8050159 - 17 May 2023
Cited by 2 | Viewed by 1542
Abstract
Acting upon clinical patient data, acquired in the pathway of percutaneous intervention, we deploy hierarchical, multi-stage, data-handling protocols and interacting low- and high-order mathematical models (chamber elastance, state-space system and CFD models), to establish and then validate a framework to quantify the burden [...] Read more.
Acting upon clinical patient data, acquired in the pathway of percutaneous intervention, we deploy hierarchical, multi-stage, data-handling protocols and interacting low- and high-order mathematical models (chamber elastance, state-space system and CFD models), to establish and then validate a framework to quantify the burden of ischaemia. Our core tool is a compartmental, zero-dimensional model of the coupled circulation with four heart chambers, systemic and pulmonary circulations and an optimally adapted windkessel model of the coronary arteries that reflects the diastolic dominance of coronary flow. We guide the parallel development of protocols and models by appealing to foundational physiological principles of cardiac energetics and a parameterisation (stenotic Bernoulli resistance and micro-vascular resistance) of patients’ coronary flow. We validate our process first with results which substantiate our protocols and, second, we demonstrate good correspondence between model operation and patient data. We conclude that our core model is capable of representing (patho)physiological states and discuss how it can potentially be deployed, on clinical data, to provide a quantitative assessment of the impact, on the individual, of coronary artery disease. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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15 pages, 2924 KiB  
Article
Hemodynamic Assessment of the Pathological Left Ventricle Function under Rest and Exercise Conditions
by Jana Korte, Thomas Rauwolf, Jan-Niklas Thiel, Andreas Mitrasch, Paulina Groschopp, Michael Neidlin, Alexander Schmeißer, Rüdiger Braun-Dullaeus and Philipp Berg
Fluids 2023, 8(2), 71; https://doi.org/10.3390/fluids8020071 - 16 Feb 2023
Cited by 1 | Viewed by 1077
Abstract
Purpose: The analysis of pathological human left ventricular hemodynamics using high-resolved image-based blood flow simulations shows a major potential for examining mitral valve insufficiency (MI) under exercise conditions. Since capturing and simulating the patient-specific movement of the left ventricle (LV) during rest and [...] Read more.
Purpose: The analysis of pathological human left ventricular hemodynamics using high-resolved image-based blood flow simulations shows a major potential for examining mitral valve insufficiency (MI) under exercise conditions. Since capturing and simulating the patient-specific movement of the left ventricle (LV) during rest and exercise is challenging, this study aims to propose a workflow to analyze the hemodynamics within the pathologically moving LV. Methods: Patient-specific ultrasound (US) data of ten patients with MI in different stages were captured with three-dimensional real-time echocardiography. US measurements were performed while patients were resting and while doing handgrip exercise (2–4 min work). Patient-specific hemodynamic simulations were carried out based on the captured ventricular wall movement. Velocity and kinetic energy were analyzed for rest and exercise and for the different MI stages. Results: The results reveal a dependency of the kinetic energy over time in the ventricular volume curves. Concerning the comparison between rest and exercise, the left ventricular function reveals lower systolic kinetic energy under exercise (kinetic energy normalized by EDV; mean ± standard deviation: rest = 0.16 ± 0.14; exercise = 0.06 ± 0.05; p-value = 0.04). Comparing patients with non-limiting (MI I) and mild/moderate (MI II/III) MI, lower velocities (mean ± standard deviation: non-limiting = 0.10 ± 0.03; mild/moderate = 0.06 ± 0.02; p-value = 0.01) and lower diastolic kinetic energy (kinetic energy normalized by EDV; mean ± standard deviation: non-limiting = 0.45 ± 0.30; mild/moderate = 0.20 ± 0.19; p-value = 0.03) were found for the latter. Conclusion: With the proposed workflow, the hemodynamics within LVs with MI can be analyzed under rest and exercise. The results reveal the importance of the patient-specific wall movement when analyzing intraventricular hemodynamics. These findings can be further used within patient-specific simulations, based on varying the imaging and segmentation methods. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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16 pages, 5451 KiB  
Article
Image-Based Numerical Investigation in an Impending Abdominal Aneurysm Rupture
by Maria Antonietta Boniforti, Maria Chiara Cesaroni, Roberto Magini, Edoardo Pasqui and Gianmarco de Donato
Fluids 2022, 7(8), 269; https://doi.org/10.3390/fluids7080269 - 05 Aug 2022
Cited by 2 | Viewed by 1646
Abstract
Blood flow dynamics plays a crucial role in the growth and rupture of abdominal aortic aneurysms. The aim of this study was to analyze the possibility of predicting aneurysmal rupture by numerical investigations based on diagnostic images. The blood flow dynamics was analyzed [...] Read more.
Blood flow dynamics plays a crucial role in the growth and rupture of abdominal aortic aneurysms. The aim of this study was to analyze the possibility of predicting aneurysmal rupture by numerical investigations based on diagnostic images. The blood flow dynamics was analyzed in a patient-specific abdominal aortic aneurysm, reconstructed from CT images of an aneurysm while it was rupturing. The patient-specific geometry was virtually repaired in order to obtain a non-ruptured model representative of the geometry immediately preceding the rupture. To reproduce physiological conditions, numerical simulations were performed under pulsatile flow conditions, and blood was modelled as a non-Newtonian fluid, using the Carreau rheological model. Hemodynamic parameters that influence the rupture of the aneurysm were investigated, and their possible association with vascular disease was discussed. The results of the numerical simulations indicated regions of slow recirculation and low values of Time Averaged Wall Shear Stress (TAWSS) in the region of rupture. Unlike literature results, a high Oscillatory Shear Index (OSI) was not clearly found in this region. Nevertheless, just in the region where the rupture will occur, high values of Endothelial Cell Activation Potential index (ECAP) were found. This index is therefore extremely significant for assessing the vulnerability of the aortic wall and locating the critical rupture region. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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13 pages, 4427 KiB  
Article
CFD to Quantify Idealized Intra-Aneurysmal Blood Flow in Response to Regular and Flow Diverter Stent Treatment
by Augusto Fava Sanches, Suprosanna Shit, Yigit Özpeynirci and Thomas Liebig
Fluids 2022, 7(8), 254; https://doi.org/10.3390/fluids7080254 - 28 Jul 2022
Viewed by 1743
Abstract
Cerebral aneurysms are pathological dilatations of the vessels supplying the brain. They carry a certain risk of rupture, which in turn, results in a high risk of mortality and morbidity. Flow diverters (FDs) are high-density meshed stents which are implanted in the vessel [...] Read more.
Cerebral aneurysms are pathological dilatations of the vessels supplying the brain. They carry a certain risk of rupture, which in turn, results in a high risk of mortality and morbidity. Flow diverters (FDs) are high-density meshed stents which are implanted in the vessel segment harboring an intracranial aneurysm to cover the entrance of the aneurysm, thus reducing the blood flow into the aneurysm, promoting thrombosis formation and stable occlusion, which prevents rupture or growth of the aneurysm. In the present study, the blood flow in an idealized aneurysm, treated with an FD stent and a regular stent (RS), were modeled and analyzed considering their design, surface area porosity, and flow reduction to investigate the quantitative and qualitative effect of the stent on intra-aneurysmal hemodynamics. CFD simulations were conducted before and after treatment. Significant reductions were observed for most hemodynamic variables with the use of stents, during both the peak systolic and late diastolic cardiac cycles. FD reduces the intra-aneurysmal wall shear stress (WSS), inflow, and aneurysmal flow velocity, and increases the turnover time when compared to the RS; therefore, the possibility of aneurysm thrombotic occlusion is likely to increase, reducing the risk of rupture in cerebral aneurysms. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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16 pages, 6742 KiB  
Article
Fluid Flow and Structural Numerical Analysis of a Cerebral Aneurysm Model
by Maria Sabrina Souza, Andrews Souza, Violeta Carvalho, Senhorinha Teixeira, Carla S. Fernandes, Rui Lima and João Ribeiro
Fluids 2022, 7(3), 100; https://doi.org/10.3390/fluids7030100 - 07 Mar 2022
Cited by 5 | Viewed by 2568
Abstract
Intracranial aneurysms (IA) are dilations of the cerebral arteries and, in most cases, have no symptoms. However, it is a very serious pathology, with a high mortality rate after rupture. Several studies have been focused only on the hemodynamics of the flow within [...] Read more.
Intracranial aneurysms (IA) are dilations of the cerebral arteries and, in most cases, have no symptoms. However, it is a very serious pathology, with a high mortality rate after rupture. Several studies have been focused only on the hemodynamics of the flow within the IA. However, besides the effect of the flow, the development and rupture of the IA are also associated with a combination of other factors such as the wall mechanical behavior. Thus, the objective of this work was to analyze, in addition to the flow behavior, the biomechanical behavior of the aneurysm wall. For this, CFD simulations were performed for different Reynolds numbers (1, 100, 500 and 1000) and for two different rheological models (Newtonian and Carreau). Subsequently, the pressure values of the fluid simulations were exported to the structural simulations in order to qualitatively observe the deformations, strains, normal stresses and shear stress generated in the channel wall. For the structural simulations, a hyperelastic constitutive model (5-parameter Mooney–Rivlin) was used. The results show that with the increase in the Reynolds number (Re), the recirculation phenomenon is more pronounced, which is not seen for Re = 1. The higher the Re, the higher the strain, displacement, normal and shear stresses values. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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15 pages, 2460 KiB  
Article
Inlet and Outlet Boundary Conditions and Uncertainty Quantification in Volumetric Lattice Boltzmann Method for Image-Based Computational Hemodynamics
by Huidan Yu, Monsurul Khan, Hao Wu, Chunze Zhang, Xiaoping Du, Rou Chen, Xin Fang, Jianyun Long and Alan P. Sawchuk
Fluids 2022, 7(1), 30; https://doi.org/10.3390/fluids7010030 - 10 Jan 2022
Cited by 8 | Viewed by 3207
Abstract
Inlet and outlet boundary conditions (BCs) play an important role in newly emerged image-based computational hemodynamics for blood flows in human arteries anatomically extracted from medical images. We developed physiological inlet and outlet BCs based on patients’ medical data and integrated them into [...] Read more.
Inlet and outlet boundary conditions (BCs) play an important role in newly emerged image-based computational hemodynamics for blood flows in human arteries anatomically extracted from medical images. We developed physiological inlet and outlet BCs based on patients’ medical data and integrated them into the volumetric lattice Boltzmann method. The inlet BC is a pulsatile paraboloidal velocity profile, which fits the real arterial shape, constructed from the Doppler velocity waveform. The BC of each outlet is a pulsatile pressure calculated from the three-element Windkessel model, in which three physiological parameters are tuned by the corresponding Doppler velocity waveform. Both velocity and pressure BCs are introduced into the lattice Boltzmann equations through Guo’s non-equilibrium extrapolation scheme. Meanwhile, we performed uncertainty quantification for the impact of uncertainties on the computation results. An application study was conducted for six human aortorenal arterial systems. The computed pressure waveforms have good agreement with the medical measurement data. A systematic uncertainty quantification analysis demonstrates the reliability of the computed pressure with associated uncertainties in the Windkessel model. With the developed physiological BCs, the image-based computation hemodynamics is expected to provide a computation potential for the noninvasive evaluation of hemodynamic abnormalities in diseased human vessels. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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Review

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23 pages, 2270 KiB  
Review
Advancements and Opportunities in Characterizing Patient-Specific Wall Shear Stress Imposed by Coronary Artery Stenting
by John F. LaDisa, Jr., Arash Ghorbannia, David S. Marks, Peter Mason and Hiromasa Otake
Fluids 2022, 7(10), 325; https://doi.org/10.3390/fluids7100325 - 11 Oct 2022
Cited by 3 | Viewed by 2752
Abstract
The success of drug-eluting stents (DES) is limited by restenosis and, to a lesser extent, late stent thrombosis. Mechanical stimuli have been implicated in these outcomes, with indices of wall shear stress (WSS) determined from computational simulations being reported most frequently. The current [...] Read more.
The success of drug-eluting stents (DES) is limited by restenosis and, to a lesser extent, late stent thrombosis. Mechanical stimuli have been implicated in these outcomes, with indices of wall shear stress (WSS) determined from computational simulations being reported most frequently. The current work summarizes state-of-the-art computational approaches applicable to patient-specific models aimed at further understanding changes in WSS indexes imposed by stent implantation. We begin with a review of best practices involved in the process and then summarize the literature related to stent-induced WSS alterations. Image-based reconstruction methods are also discussed, along with the latest generation boundary conditions that replicate cardiac physiology and downstream vasculature in the setting of coronary artery disease. The influence of existing material property data on WSS results obtained with geometries reconstructed from finite element modeling and fluid structure interaction (FSI) simulations is reviewed, along with the novel approaches being used to provide coronary artery plaque data that are currently missing from the literature. We also consider the use of machine learning tools that have the potential for impact when assessing the role of adverse stent-induced WSS in suboptimal clinical outcomes. We conclude by focusing on challenging cases that involve DES implantation, which may benefit from recent advancements in patient-specific computational modeling. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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