1
|
Yi H, Yang Z, Bramlage L, Ludwig B. Using DFT on ultrasound measurements to determine patient-specific blood flow boundary conditions for computational hemodynamics of intracranial aneurysms. Comput Biol Med 2024; 176:108563. [PMID: 38761498 DOI: 10.1016/j.compbiomed.2024.108563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 04/01/2024] [Accepted: 05/05/2024] [Indexed: 05/20/2024]
Abstract
Boundary conditions (BCs) is one pivotal factor influencing the accuracy of hemodynamic predictions on intracranial aneurysms (IAs) using computational fluid dynamics (CFD) modeling. Unfortunately, a standard procedure to secure accurate BCs for hemodynamic modeling does not exist. To bridge such a knowledge gap, two representative patient-specific IA models (Case-I and Case-II) were reconstructed and their blood flow velocity waveforms in the internal carotid artery (ICA) were measured by ultrasonic techniques and modeled by discrete Fourier transform (DFT). Then, numerical investigations were conducted to explore the appropriate number of samples (N) for DFT modeling to secure the accurate BC by comparing a series of hemodynamic parameters using in-vitro validated CFD modeling. Subsequently, a comprehensive comparison in hemodynamic characteristics under patient-specific BCs and a generalized BC based on a one-dimensional (1D) model was conducted to reinforce the understanding that a patient-specific BC is pivotal for accurate hemodynamic risk evaluations on IA pathophysiology. In addition, the influence of the variance of heart rate/cardiac pulsatile period on hemodynamic characteristics in IA models was studied preliminarily. The results showed that N ≥ 16 for DFT model is a decent choice to secure the proper BC profile to calculate time-averaged hemodynamic parameters, while more data points such as N ≥ 36 can ensure the accuracy of instantaneous hemodynamic predictions. In addition, results revealed the generalized BC could overestimate or underestimate the hemodynamic risks on IAs significantly; thus, patient-specific BCs are highly recommended for hemodynamic modeling for IA risk evaluation. Furthermore, this study discovered the variance of heart rate has rare influences on hemodynamic characteristics in both instantaneous and time-averaged parameters under the assumption of an identical blood flow rate.
Collapse
Affiliation(s)
- Hang Yi
- Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH, 45435, USA
| | - Zifeng Yang
- Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH, 45435, USA.
| | - Luke Bramlage
- Division of NeuroInterventional Surgery, Department of Neurology, Wright State University/Premier Health-Clinical Neuroscience Institute, 30E. Apple St., Dayton, OH, 45409, USA; Boonshoft School of Medicine, Wright State University, Dayton, OH, 45435, USA
| | - Bryan Ludwig
- Division of NeuroInterventional Surgery, Department of Neurology, Wright State University/Premier Health-Clinical Neuroscience Institute, 30E. Apple St., Dayton, OH, 45409, USA; Boonshoft School of Medicine, Wright State University, Dayton, OH, 45435, USA
| |
Collapse
|
2
|
Csippa B, Sándor L, Závodszky G, Szikora I, Paál G. Comparison of Flow Reduction Efficacy of Nominal and Oversized Flow Diverters Using a Novel Measurement-assisted in Silico Method. Clin Neuroradiol 2024:10.1007/s00062-024-01404-4. [PMID: 38652163 DOI: 10.1007/s00062-024-01404-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 03/07/2024] [Indexed: 04/25/2024]
Abstract
PURPOSE The high efficacy of flow diverters (FD) in the case of wide-neck aneurysms is well demonstrated, yet new challenges have arisen because of reported posttreatment failures and the growing number of new generation of devices. Our aim is to present a measurement-supported in silico workflow that automates the virtual deployment and subsequent hemodynamic analysis of FDs. In this work, the objective is to analyze the effects of FD deployment variability of two manufacturers on posttreatment flow reduction. METHODS The virtual deployment procedure is based on detailed mechanical calibration of the flow diverters, while the flow representation is based on hydrodynamic resistance (HR) measurements. Computational fluid dynamic simulations resulted in 5 untreated and 80 virtually treated scenarios, including 2 FD designs in nominal and oversized deployment states. The simulated aneurysmal velocity reduction (AMVR) is correlated with the HR values and deployment scenarios. RESULTS The linear HR coefficient and AMVR revealed a power-law relationship considering all 80 deployments. In nominal deployment scenarios, a significantly larger average AMVR was obtained (60.3%) for the 64-wire FDs than for 48-wire FDs (51.9%). In oversized deployments, the average AMVR was almost the same for 64-wire and 48-wire device types, 27.5% and 25.7%, respectively. CONCLUSION The applicability of our numerical workflow was demonstrated, also in large-scale hemodynamic investigations. The study revealed a robust power-law relationship between a HR coefficient and AMVR. Furthermore, the 64 wire configurations in nominal sizing produced a significantly higher posttreatment flow reduction, replicating the results of other in vitro studies.
Collapse
Affiliation(s)
- Benjamin Csippa
- Department of Hydrodynamic Systems, Faculty of Mechanical Engineering,, Budapest University of Technology and Economics, Műegyetem rkp 1-3, 1111, Budapest, Hungary.
| | - Levente Sándor
- Department of Hydrodynamic Systems, Faculty of Mechanical Engineering,, Budapest University of Technology and Economics, Műegyetem rkp 1-3, 1111, Budapest, Hungary
| | - Gábor Závodszky
- Department of Hydrodynamic Systems, Faculty of Mechanical Engineering,, Budapest University of Technology and Economics, Műegyetem rkp 1-3, 1111, Budapest, Hungary
- Faculty of Science, Informatics Institute, Computational Science Lab, University of Amsterdam, Amsterdam, The Netherlands
| | - István Szikora
- National Institute of Mental Health, Neurology, and Neurosurgery, Department of Neurointerventions, Budapest, Hungary
| | - György Paál
- Department of Hydrodynamic Systems, Faculty of Mechanical Engineering,, Budapest University of Technology and Economics, Műegyetem rkp 1-3, 1111, Budapest, Hungary
| |
Collapse
|
3
|
Luisi CA, Witter TL, Nikoubashman O, Wiesmann M, Steinseifer U, Neidlin M. Evaluating the accuracy of cerebrovascular computational fluid dynamics modeling through time-resolved experimental validation. Sci Rep 2024; 14:8194. [PMID: 38589554 PMCID: PMC11001858 DOI: 10.1038/s41598-024-58925-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 04/03/2024] [Indexed: 04/10/2024] Open
Abstract
Accurate modeling of cerebral hemodynamics is crucial for better understanding the hemodynamics of stroke, for which computational fluid dynamics (CFD) modeling is a viable tool to obtain information. However, a comprehensive study on the accuracy of cerebrovascular CFD models including both transient arterial pressures and flows does not exist. This study systematically assessed the accuracy of different outlet boundary conditions (BCs) comparing CFD modeling and an in-vitro experiment. The experimental setup consisted of an anatomical cerebrovascular phantom and high-resolution flow and pressure data acquisition. The CFD model of the same cerebrovascular geometry comprised five sets of stationary and transient BCs including established techniques and a novel BC, the phase modulation approach. The experiment produced physiological hemodynamics consistent with reported clinical results for total cerebral blood flow, inlet pressure, flow distribution, and flow pulsatility indices (PI). The in-silico model instead yielded time-dependent deviations between 19-66% for flows and 6-26% for pressures. For cerebrovascular CFD modeling, it is recommended to avoid stationary outlet pressure BCs, which caused the highest deviations. The Windkessel and the phase modulation BCs provided realistic flow PI values and cerebrovascular pressures, respectively. However, this study shows that the accuracy of current cerebrovascular CFD models is limited.
Collapse
Affiliation(s)
- Claudio A Luisi
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Pauwelsstr. 20, 52074, Aachen, Germany
| | - Tom L Witter
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Pauwelsstr. 20, 52074, Aachen, Germany
| | - Omid Nikoubashman
- Clinic for Diagnostic and Interventional Neuroradiology, Medical Faculty, RWTH Aachen University, Pauwelstr. 30, 52074, Aachen, Germany
| | - Martin Wiesmann
- Clinic for Diagnostic and Interventional Neuroradiology, Medical Faculty, RWTH Aachen University, Pauwelstr. 30, 52074, Aachen, Germany
| | - Ulrich Steinseifer
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Pauwelsstr. 20, 52074, Aachen, Germany
| | - Michael Neidlin
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Pauwelsstr. 20, 52074, Aachen, Germany.
| |
Collapse
|
4
|
Zhou G, Wang J, Liu W, Gu W, Su M, Feng Y, Qin B, Zhu Y. An assessment of how the anterior cerebral artery anatomy impacts ACoA aneurysm formation based on CFD analysis. Br J Neurosurg 2024; 38:215-219. [PMID: 32988230 DOI: 10.1080/02688697.2020.1821867] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 06/26/2020] [Accepted: 09/04/2020] [Indexed: 12/27/2022]
Abstract
OBJECTIVE The aim of this study was to identify independent anatomic, morphologic and hemodynamic features of the ACoA (anterior communicating artery) complex that serve as risk factors for the occurrence of ACoA aneurysms. METHODS Fifteen consecutive patients with 15 ACoA aneurysms were included. Computational fluid dynamics (CFD) simulations based on patient-specific models were carried out using 3D time-of-flight magnetic resonance angiography (3D-TOF-MRA) images. A reverse reconstruction technique was used to generate a pre-aneurysm vessel anatomy. Geometric parameters and hemodynamic changes were compared and evaluated. RESULTS The overall prevalence of symmetric, dysplastic, and absent A1 segments were 53.3%, 26.7%, and 20%. The mean wall shear stress (WSS) of the absent group (AG) was significantly higher than that of the symmetric group (SG) and dysplastic group (DG). The absolute mean A1 artery flow rate (410.2 ± 88 versus 439.4 ± 101 mL/min; p = .45) of the aneurysm side was similar between the SG and DG but significantly higher in the AG (528.1 ± 77 mL/min; p < .05). The A1-A2 angles of the aneurysm side showed no significant differences among the 3 groups (p = .32). However, the mean A1-A2 angle on the aneurysm side was smaller than the contralateral A1-A2 angle (101.9 ± 9.1˚ versus 120.3 ± 7.7˚; p <.05). A regression analysis demonstrated that high WSS was significantly associated with a large A1-A2 ratio (R2=0.52; p <.05). CONCLUSIONS ACoA aneurysms are a high-WSS pathology. Severe flow impingement and the anatomic vasculature structures play a role in triggering the occurrence of ACoA aneurysms.
Collapse
Affiliation(s)
- Geng Zhou
- Department of Radiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Jienan Wang
- Department of Radiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Weidong Liu
- Department of Neurosurgery, Shanghai Punan Hospital, Shanghai, China
| | - Wenquan Gu
- Department of Neurosurgery, Shanghai Punan Hospital, Shanghai, China
| | - Ming Su
- Department of Radiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Yong Feng
- Shanghai Micro-Invention Medical Devices Co., Ltd, Shanghai, China
| | - Binjie Qin
- Department of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yueqi Zhu
- Department of Radiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| |
Collapse
|
5
|
Caddy HT, Thomas HJ, Kelsey LJ, Smith KJ, Doyle BJ, Green DJ. Comparison of computational fluid dynamics with transcranial Doppler ultrasound in response to physiological stimuli. Biomech Model Mechanobiol 2024; 23:255-269. [PMID: 37805938 PMCID: PMC10902019 DOI: 10.1007/s10237-023-01772-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 09/05/2023] [Indexed: 10/10/2023]
Abstract
Cerebrovascular haemodynamics are sensitive to multiple physiological stimuli that require synergistic response to maintain adequate perfusion. Understanding haemodynamic changes within cerebral arteries is important to inform how the brain regulates perfusion; however, methods for direct measurement of cerebral haemodynamics in these environments are challenging. The aim of this study was to assess velocity waveform metrics obtained using transcranial Doppler (TCD) with flow-conserving subject-specific three-dimensional (3D) simulations using computational fluid dynamics (CFD). Twelve healthy participants underwent head and neck imaging with 3 T magnetic resonance angiography. Velocity waveforms in the middle cerebral artery were measured with TCD ultrasound, while diameter and velocity were measured using duplex ultrasound in the internal carotid and vertebral arteries to calculate incoming cerebral flow at rest, during hypercapnia and exercise. CFD simulations were developed for each condition, with velocity waveform metrics extracted in the same insonation region as TCD. Exposure to stimuli induced significant changes in cardiorespiratory measures across all participants. Measured absolute TCD velocities were significantly higher than those calculated from CFD (P range < 0.001-0.004), and these data were not correlated across conditions (r range 0.030-0.377, P range 0.227-0.925). However, relative changes in systolic and time-averaged velocity from resting levels exhibited significant positive correlations when the distinct techniques were compared (r range 0.577-0.770, P range 0.003-0.049). Our data indicate that while absolute measures of cerebral velocity differ between TCD and 3D CFD simulation, physiological changes from resting levels in systolic and time-averaged velocity are significantly correlated between techniques.
Collapse
Affiliation(s)
- Harrison T Caddy
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia and the UWA Centre for Medical Research, The University of Western Australia, Perth, Australia
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Perth, Australia
| | - Hannah J Thomas
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Perth, Australia
| | - Lachlan J Kelsey
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia and the UWA Centre for Medical Research, The University of Western Australia, Perth, Australia
- School of Engineering, The University of Western Australia, Perth, Australia
| | - Kurt J Smith
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Perth, Australia
- Cerebrovascular Health, Exercise, and Environmental Research Sciences Laboratory, University of Victoria, Victoria, Canada
| | - Barry J Doyle
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia and the UWA Centre for Medical Research, The University of Western Australia, Perth, Australia.
- School of Engineering, The University of Western Australia, Perth, Australia.
| | - Daniel J Green
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Perth, Australia
| |
Collapse
|
6
|
Korte J, Klopp ES, Berg P. Multi-Dimensional Modeling of Cerebral Hemodynamics: A Systematic Review. Bioengineering (Basel) 2024; 11:72. [PMID: 38247949 PMCID: PMC10813503 DOI: 10.3390/bioengineering11010072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 12/23/2023] [Accepted: 01/06/2024] [Indexed: 01/23/2024] Open
Abstract
The Circle of Willis (CoW) describes the arterial system in the human brain enabling the neurovascular blood supply. Neurovascular diseases like intracranial aneurysms (IAs) can occur within the CoW and carry the risk of rupture, which can lead to subarachnoid hemorrhage. The assessment of hemodynamic information in these pathologies is crucial for their understanding regarding detection, diagnosis and treatment. Multi-dimensional in silico approaches exist to evaluate these hemodynamics based on patient-specific input data. The approaches comprise low-scale (zero-dimensional, one-dimensional) and high-scale (three-dimensional) models as well as multi-scale coupled models. The input data can be derived from medical imaging, numerical models, literature-based assumptions or from measurements within healthy subjects. Thus, the most realistic description of neurovascular hemodynamics is still controversial. Within this systematic review, first, the models of the three scales (0D, 1D, 3D) and second, the multi-scale models, which are coupled versions of the three scales, were discussed. Current best practices in describing neurovascular hemodynamics most realistically and their clinical applicablility were elucidated. The performance of 3D simulation entails high computational expenses, which could be reduced by analyzing solely the region of interest in detail. Medical imaging to establish patient-specific boundary conditions is usually rare, and thus, lower dimensional models provide a realistic mimicking of the surrounding hemodynamics. Multi-scale coupling, however, is computationally expensive as well, especially when taking all dimensions into account. In conclusion, the 0D-1D-3D multi-scale approach provides the most realistic outcome; nevertheless, it is least applicable. A 1D-3D multi-scale model can be considered regarding a beneficial trade-off between realistic results and applicable performance.
Collapse
Affiliation(s)
- Jana Korte
- Research Campus STIMULATE, University of Magdeburg, 39106 Magdeburg, Germany
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, 39106 Magdeburg, Germany
| | - Ehlar Sophie Klopp
- Research Campus STIMULATE, University of Magdeburg, 39106 Magdeburg, Germany
- Department of Medical Engineering, University of Magdeburg, 39106 Magdeburg, Germany
| | - Philipp Berg
- Research Campus STIMULATE, University of Magdeburg, 39106 Magdeburg, Germany
- Department of Medical Engineering, University of Magdeburg, 39106 Magdeburg, Germany
| |
Collapse
|
7
|
Gaidzik F, Korte J, Saalfeld S, Janiga G, Berg P. Image-based hemodynamic simulations for intracranial aneurysms: the impact of complex vasculature. Int J Comput Assist Radiol Surg 2024:10.1007/s11548-023-03045-3. [PMID: 38206468 DOI: 10.1007/s11548-023-03045-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 12/06/2023] [Indexed: 01/12/2024]
Abstract
PURPOSE Hemodynamics play an important role in the assessment of intracranial aneurysm (IA) development and rupture risk. The purpose of this study was to examine the impact of complex vasculatures onto the intra-vessel and intra-aneurysmal blood flow. METHODS Complex segmentation of a subject-specific, 60-outlet and 3-inlet circle of Willis model captured with 7T magnetic resonance imaging was performed. This model was trimmed to a 10-outlet model version. Two patient-specific IAs were added onto both models yielding two pathological versions, and image-based blood flow simulations of the four resulting cases were carried out. To capture the differences between complex and trimmed model, time-averaged and centerline velocities were compared. The assessment of intra-saccular blood flow within the IAs involved the evaluation of wall shear stresses (WSS) at the IA wall and neck inflow rates (NIR). RESULTS Lower flow values are observed in the majority of the complex model. However, at specific locations (left middle cerebral artery 0.5 m/s, left posterior cerebral artery 0.25 m/s), higher flow rates were visible when compared to the trimmed counterpart. Furthermore, at the centerlines the total velocity values reveal differences up to 0.15 m/s. In the IAs, the reduction in the neck inflow rate and WSS in the complex model was observed for the first IA (IA-A δNIRmean = - 0.07ml/s, PCA.l δWSSmean = - 0.05 Pa). The second IA featured an increase in the neck inflow rate and WSS (IA-B δNIRmean = 0.04 ml/s, PCA.l δWSSmean = 0.07 Pa). CONCLUSION Both the magnitude and shape of the flow distribution vary depending on the model's complexity. The magnitude is primarily influenced by the global vessel model, while the shape is determined by the local structure. Furthermore, intra-aneurysmal flow strongly depends on the location in the vessel tree, emphasizing the need for complex model geometries for realistic hemodynamic assessment and rupture risk analysis.
Collapse
Affiliation(s)
- Franziska Gaidzik
- Research Campus STIMULATE, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany.
- Laboratory of Fluid Dynamics and Technical Flows, Forschungscampus STIMULATE, Otto-von-Guericke-University Magdeburg, Universitätsplatz 2, 39106, Magdeburg, Germany.
| | - Jana Korte
- Research Campus STIMULATE, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
- Laboratory of Fluid Dynamics and Technical Flows, Forschungscampus STIMULATE, Otto-von-Guericke-University Magdeburg, Universitätsplatz 2, 39106, Magdeburg, Germany
| | - Sylvia Saalfeld
- Research Campus STIMULATE, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
- Laboratory of Simulation and Graphics, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
| | - Gábor Janiga
- Research Campus STIMULATE, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
- Laboratory of Fluid Dynamics and Technical Flows, Forschungscampus STIMULATE, Otto-von-Guericke-University Magdeburg, Universitätsplatz 2, 39106, Magdeburg, Germany
| | - Philipp Berg
- Research Campus STIMULATE, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
- Department of Medical Engineering, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
| |
Collapse
|
8
|
Weiss AJ, Panduro AO, Schwarz EL, Sexton ZA, Lan IS, Geisbush TR, Marsden AL, Telischak NA. A matched-pair case control study identifying hemodynamic predictors of cerebral aneurysm growth using computational fluid dynamics. Front Physiol 2023; 14:1300754. [PMID: 38162830 PMCID: PMC10757566 DOI: 10.3389/fphys.2023.1300754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 11/29/2023] [Indexed: 01/03/2024] Open
Abstract
Introduction: Initiation and progression of cerebral aneurysms is known to be driven by complex interactions between biological and hemodynamic factors, but the hemodynamic mechanism which drives aneurysm growth is unclear. We employed robust modeling and computational methods, including temporal and spatial convergence studies, to study hemodynamic characteristics of cerebral aneurysms and identify differences in these characteristics between growing and stable aneurysms. Methods: Eleven pairs of growing and non-growing cerebral aneurysms, matched in both size and location, were modeled from MRA and CTA images, then simulated using computational fluid dynamics (CFD). Key hemodynamic characteristics, including wall shear stress (WSS), oscillatory shear index (OSI), and portion of the aneurysm under low shear, were evaluated. Statistical analysis was then performed using paired Wilcoxon rank sum tests. Results: The portion of the aneurysm dome under 70% of the parent artery mean wall shear stress was higher in growing aneurysms than in stable aneurysms and had the highest significance among the tested metrics (p = 0.08). Other metrics of area under low shear had similar levels of significance. Discussion: These results align with previously observed hemodynamic trends in cerebral aneurysms, indicating a promising direction for future study of low shear area and aneurysm growth. We also found that mesh resolution significantly affected simulated WSS in cerebral aneurysms. This establishes that robust computational modeling methods are necessary for high fidelity results. Together, this work demonstrates that complex hemodynamics are at play within cerebral aneurysms, and robust modeling and simulation methods are needed to further study this topic.
Collapse
Affiliation(s)
- Allyson J. Weiss
- Department of Mechanical Engineering, Stanford University, Stanford, CA, United States
| | - Aaron O. Panduro
- Department of Biochemistry, California State University, Fresno, CA, United States
| | - Erica L. Schwarz
- Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Zachary A. Sexton
- Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Ingrid S. Lan
- Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Thomas. R. Geisbush
- Department of Radiology, School of Medicine, Stanford University, Stanford, CA, United States
| | - Alison L. Marsden
- Department of Bioengineering, Stanford University, Stanford, CA, United States
- Department of Pediatrics, School of Medicine, Stanford University, Stanford, CA, United States
| | - Nicholas A. Telischak
- Department of Radiology, School of Medicine, Stanford University, Stanford, CA, United States
| |
Collapse
|
9
|
MacDonald DE, Cancelliere NM, Pereira VM, Steinman DA. Sensitivity of hostile hemodynamics to aneurysm geometry via unsupervised shape interpolation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 241:107762. [PMID: 37598472 DOI: 10.1016/j.cmpb.2023.107762] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 06/19/2023] [Accepted: 08/10/2023] [Indexed: 08/22/2023]
Abstract
BACKGROUND AND OBJECTIVE Vessel geometry and hemodynamics are intrinsically linked, whereby geometry determines hemodynamics, and hemodynamics influence vascular remodeling. Both have been used for testing clinical outcomes, but geometry/morphology generally has less uncertainty than hemodynamics derived from medical image-based computational fluid dynamics (CFD). To provide clinical utility, CFD-based hemodynamic parameters must be robust to modeling errors and/or uncertainties, but must also provide useful information not more-easily extracted from shape alone. The objective of this study was to methodically assess the response of hemodynamic parameters to gradual changes in shape created using an unsupervised 3D shape interpolation method. METHODS We trained the neural network NeuroMorph on 3 patient-derived intracranial aneurysm surfaces (labelled A, B, C), and then generated 3 distinct morph sequences (A→B, B→C, C→A) each containing 10 interpolated surfaces. From high-fidelity CFD simulation of these, we calculated a variety of common reduced hemodynamic parameters, including many previously associated with aneurysm rupture, and analyzed their responses to changes in shape, and their correlations. RESULTS The interpolated surfaces demonstrate complex, gradual changes in branch angles, vessel diameters, and aneurysm morphology. CFD simulation showed gradual changes in aneurysm jetting characteristics and wall-shear stress (WSS) patterns, but demonstrated a range of responses from the reduced hemodynamic parameters. Spatially and temporally averaged parameters including time-averaged WSS, time-averaged velocity, and low-shear area (LSA) showed low variation across all morph sequences, while parameters of flow complexity such as oscillatory shear, spectral broadening, and spectral bandedness indices showed high variation between slightly-altered neighboring surfaces. Correlation analysis revealed a great deal of mutual information with easier-to-measure shape-based parameters. CONCLUSIONS In the absence of large clinical datasets, unsupervised shape interpolation provides an ideal laboratory for exploring the delicate balance between robustness and sensitivity of nominal hemodynamic predictors of aneurysm rupture. Parameters like time-averaged WSS and LSA that are highly "robust" may, as a result, be effectively redundant to morphological predictors, whereas more sensitive parameters may be too uncertain for practical clinical use. Understanding these sensitivities may help identify parameters that are capable of providing added value to rupture risk assessment.
Collapse
Affiliation(s)
- Daniel E MacDonald
- Department of Mechanical & Industrial Engineering, University of Toronto, 5 King's College Rd, Toronto, Ontario M5S 3G8, Canada
| | - Nicole M Cancelliere
- Department of Neurosurgery, St. Michael's Hospital, 36 Queen St E, Toronto, Ontario M5B 1W8, Canada
| | - Vitor M Pereira
- Department of Neurosurgery, St. Michael's Hospital, 36 Queen St E, Toronto, Ontario M5B 1W8, Canada
| | - David A Steinman
- Department of Mechanical & Industrial Engineering, University of Toronto, 5 King's College Rd, Toronto, Ontario M5S 3G8, Canada.
| |
Collapse
|
10
|
Che Y, Zhao J, Zhang X, Luo M, Cao X, Zheng L, Shu C. Hemodynamics of different configurations of the left subclavian artery parallel stent graft for thoracic endovascular aortic repair. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 241:107741. [PMID: 37544164 DOI: 10.1016/j.cmpb.2023.107741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/26/2023] [Accepted: 07/30/2023] [Indexed: 08/08/2023]
Abstract
BACKGROUND AND OBJECTIVE Parallel (chimney and periscope) graft technique is an effective approach for left subclavian artery (LSA) reconstruction in patients treated by thoracic endovascular aortic repair (TEVAR) for the inadequate landing zone. However, certain stent graft (SG) configurations may promote thrombosis and reduce distal blood flow, increasing risks of cerebral infarction and reintervention. METHODS In this paper, we first attempt to systematically evaluate the hemodynamic performances of different parallel graft techniques as potential determinants of complication risks. Based on the patient-specific 3D aortic geometry undergoing parallel graft technique, fifteen models in total for five kinds of LSA branched SG configurations (Forward, Backward, Extended, Elliptical and Periscopic) were designed virtually, and the hemodynamic discrepancies between them were analyzed by computational fluid dynamics. RESULTS Results show that flow rate of patients undergoing periscope technique reduces by half compared with chimney technique, suggesting that periscope SG may cause more serious flow obstruction to LSA, leading to stroke. For chimney stent structure, the extension length 0has little influence on energy loss and other parameters. Conversely, hemodynamic differences between the retrograde curvature and the antegrade curvature are significant (time average WSS: 47.07%), so the retrograde curvature might prompt SG displacement. Furthermore, the flatter chimney SG induces more aggressive hemodynamic forces, among which the difference of the maximum WSS between the flatter SG and nearly round SG reaches 65.56%, leading to the greater risk of vascular wall damage. CONCLUSIONS Results obtained might provide suggestions for physicians to formulate appropriate parallel graft technique schemes in TEVAR.
Collapse
Affiliation(s)
- Yue Che
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China
| | - Jiawei Zhao
- Department of Vascular Surgery, Fuwai Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100037, China
| | - Xuelan Zhang
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China; School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 10083, China.
| | - Mingyao Luo
- Department of Vascular Surgery, Fuwai Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100037, China; Department of Vascular Surgery, Fuwai Yunnan Cardiovascular Hospital, Affiliated Cardiovascular Hospital of Kunming Medical University, Kunming 650102, China.
| | - Xiran Cao
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China
| | - Liancun Zheng
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China
| | - Chang Shu
- Department of Vascular Surgery, Fuwai Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100037, China; Department of Vascular Surgery, Second Xiangya Hospital, Central South University, Number 139, Renmin Road, Changsha 410011, China.
| |
Collapse
|
11
|
Korte J, Voß S, Janiga G, Beuing O, Behme D, Saalfeld S, Berg P. Is Accurate Lumen Segmentation More Important than Outlet Boundary Condition in Image-Based Blood Flow Simulations for Intracranial Aneurysms? Cardiovasc Eng Technol 2023; 14:617-630. [PMID: 37582997 PMCID: PMC10602961 DOI: 10.1007/s13239-023-00675-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 07/17/2023] [Indexed: 08/17/2023]
Abstract
PURPOSE Image-based blood flow simulations are increasingly used to investigate the hemodynamics in intracranial aneurysms (IAs). However, a strong variability in segmentation approaches as well as the absence of individualized boundary conditions (BCs) influence the quality of these simulation results leading to imprecision and decreased reliability. This study aims to analyze these influences on relevant hemodynamic parameters within IAs. METHODS As a follow-up study of an international multiple aneurysms challenge, the segmentation results of five IAs differing in size and location were investigated. Specifically, five possible outlet BCs were considered in each of the IAs. These are comprised of the zero-pressure condition (BC1), a flow distribution based on Murray's law with the exponents n = 2 (BC2) and n = 3 (BC3) as well as two advanced flow-splitting models considering the real vessels by including circular cross sections (BC4) or anatomical cross sections (BC5), respectively. In total, 120 time-dependent blood flow simulations were analyzed qualitatively and quantitatively, focusing on five representative intra-aneurysmal flow and five shear parameters such as vorticity and wall shear stress. RESULTS The outlet BC variation revealed substantial differences. Higher shear stresses (up to Δ9.69 Pa), intrasaccular velocities (up to Δ0.15 m/s) and vorticities (up to Δ629.22 1/s) were detected when advanced flow-splitting was applied compared to the widely used zero-pressure BC. The tendency of outlets BCs to over- or underestimate hemodynamic parameters is consistent across different segmentations of a single aneurysm model. Segmentation-induced variability reaches Δ19.58 Pa, Δ0.42 m/s and Δ957.27 1/s, respectively. Excluding low fidelity segmentations, however, (a) reduces the deviation drastically (>43%) and (b) leads to a lower impact of the outlet BC on hemodynamic predictions. CONCLUSION With a more realistic lumen segmentation, the influence of the BC on the resulting hemodynamics is decreased. A realistic lumen segmentation can be ensured, e.g., by using high-resolved 2D images. Furthermore, the selection of an advanced outflow-splitting model is advised and the use of a zero-pressure BC and BC based on Murray's law with exponent n = 3 should be avoided.
Collapse
Affiliation(s)
- Jana Korte
- Forschungscampus STIMULATE, University of Magdeburg, Magdeburg, Germany.
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany.
| | - Samuel Voß
- Forschungscampus STIMULATE, University of Magdeburg, Magdeburg, Germany
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - Gábor Janiga
- Forschungscampus STIMULATE, University of Magdeburg, Magdeburg, Germany
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - Oliver Beuing
- Department of Radiology, AMEOS Hospital, Bernburg, Germany
| | - Daniel Behme
- Department of Neuroradiology, University Hospital of Magdeburg, Magdeburg, Germany
| | - Sylvia Saalfeld
- Forschungscampus STIMULATE, University of Magdeburg, Magdeburg, Germany
- Department of Computer Science and Automation, Ilmenau University of Technology, Ilmenau , Germany
| | - Philipp Berg
- Forschungscampus STIMULATE, University of Magdeburg, Magdeburg, Germany
- Department of Medical Engineering, University of Magdeburg, Magdeburg, Germany
| |
Collapse
|
12
|
Wang X, Liu H, Xu M, Chen C, Ma L, Dai F. Efficacy assessment of superficial temporal artery-middle cerebral artery bypass surgery in treating moyamoya disease from a hemodynamic perspective: a pilot study using computational modeling and perfusion imaging. Acta Neurochir (Wien) 2023; 165:613-623. [PMID: 36595057 DOI: 10.1007/s00701-022-05455-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 12/05/2022] [Indexed: 01/04/2023]
Abstract
BACKGROUND Superficial temporal artery-middle cerebral artery (STA-MCA) bypass is a common surgery in treating moyamoya disease (MMD) with occluded MCA. Computational fluid dynamics (CFD) simulation might provide a simple, non-invasive, and low-cost tool to evaluate the efficacy of STA-MCA surgery. AIM We aim to quantitatively investigate the treatment efficacy of STA-MCA surgery in improving the blood flow of MMD patients using CFD simulation. METHODS This retrospective study included 11 MMD patients with occlusion around proximal MCA who underwent STA-MCA bypass surgery. CFD simulation was performed using patient-specific blood pressure and postoperative artery geometry. The volumetric flow rates of STA and the bypass, average flow velocity in the proximal segment of transcranial bypass, transcranial pressure drop, and transcranial flow resistance were measured and compared with a postoperative increment of cerebral blood flow (CBF) in MCA territories derived from perfusion imaging. Per-branch pressure drop from model inlet to bypass branch outlet was calculated. RESULTS The volumetric flow rates of STA and the bypass were 80.84 ± 14.54 mL/min and 46.03 ± 4.21 mL/min. Average flow velocity in proximal bypass, transcranial pressure drop, and transcranial flow resistance were 0.19 ± 0.07 m/s, 3.72 ± 3.10 mmHg, and 6.54 ± 5.65 10-8 Pa s m-3. Postoperative mean increment of CBF in MCA territories was 16.03 ± 11.72 mL·100 g-1·min-1. Per-branch pressure drop was 10.96 ± 5.59 mmHg and 7.26 ± 4.25 mmHg in branches with and without stenosis. CONCLUSIONS CFD simulation results are consistent with CBF observation in verifying the efficacy of STA-MCA bypass, where postoperative stenosis may influence the hemodynamics.
Collapse
Affiliation(s)
- Xinhong Wang
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, Zhejiang Province, China.
| | - Haipeng Liu
- Research Centre for Intelligent Healthcare, Coventry University, Coventry, CV1 5FB, UK.
| | - Mengxi Xu
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, Zhejiang Province, China
| | - Cong Chen
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, Zhejiang Province, China
| | - Linlin Ma
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, Zhejiang Province, China
| | - Fangyu Dai
- Department of Neurology, Zhoushan Hospital, Wenzhou Medical University, Zhoushan, 316000, Zhejiang Province, China
| |
Collapse
|
13
|
Aneurysm Neck Overestimation has a Relatively Modest Impact on Simulated Hemodynamics. Cardiovasc Eng Technol 2022; 14:252-263. [PMID: 36517696 DOI: 10.1007/s13239-022-00652-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 11/29/2022] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Overestimation of intracranial aneurysm neck width by 3D angiography is a recognized clinical problem, and has long been a concern for image-based computational fluid dynamics (CFD). Recently, it was demonstrated that neck overestimation in 3D rotational angiography (3DRA) could be corrected via segmentation with upsampled resolution and gradient enhancement (SURGE). Our aim was to leverage this approach to determine whether and how neck overestimation actually impacts CFD-derived hemodynamics. MATERIALS AND METHODS A subset of 17 cases having the largest neck errors from a consecutive clinical sample of 60 was segmented from 3DRA using both standard watershed and SURGE methods. High-fidelity, pulsatile CFD was performed, and a variety of scalar hemodynamic parameters that have been associated with aneurysm growth and/or rupture status were derived. RESULTS With a few exceptions, flow and wall shear stress (WSS) patterns were qualitatively similar between neck-overestimated and corrected models. Sac-averaged WSS values were significantly lower after neck correction (p = 0.0005) but were highly correlated with their neck-overestimated counterparts (R2 = 0.98). Jet impingement was significantly more concentrated in the neck-corrected vs. -uncorrected models (p = 0.0011), and only moderately correlated (R2 = 0.61). Parameters quantifying velocity or WSS fluctuations were not significantly different after neck correction, but this reflected their poorer correlations (R2 < 0.4). Nevertheless, for all hemodynamic parameters, median absolute differences were < 26%, and no parameter had more than 5/17 cases with absolute differences > 50%. CONCLUSION Differences in hemodynamics due to neck width overestimation were found to be at most equal to, and often less than, those reported for other sources of error/uncertainty in intracranial aneurysm CFD, such as solver settings or assumed inflow rates.
Collapse
|
14
|
Oliveira IL, Cardiff P, Baccin CE, Gasche JL. A numerical investigation of the mechanics of intracranial aneurysms walls: Assessing the influence of tissue hyperelastic laws and heterogeneous properties on the stress and stretch fields. J Mech Behav Biomed Mater 2022; 136:105498. [PMID: 36257146 DOI: 10.1016/j.jmbbm.2022.105498] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/14/2022] [Accepted: 09/27/2022] [Indexed: 11/06/2022]
Abstract
Numerical simulations have been extensively used in the past two decades for the study of intracranial aneurysms (IAs), a dangerous disease that occurs in the arteries that reach the brain and affect overall 3.2% of a population without comorbidity with up to 60% mortality rate, in case of rupture. The majority of those studies, though, assumed a rigid-wall model to simulate the blood flow. However, to also study the mechanics of IAs walls, it is important to assume a fluid-solid interaction (FSI) modeling. Progress towards more reliable FSI simulations is limited because FSI techniques pose severe numerical difficulties, but also due to scarce data on the mechanical behavior and material constants of IA tissue. Additionally, works that have investigated the impact of different wall modeling choices for patient-specific IAs geometries are a few and often with limited conclusions. Thus our present study investigated the effect of different modeling approaches to simulate the motion of an IA. We used three hyperelastic laws - the Yeoh law, the three-parameter Mooney-Rivlin law, and a Fung-like law with a single parameter - and two different ways of modeling the wall thickness and tissue mechanical properties - one assumed that both were uniform while the other accounted for the heterogeneity of the wall by using a "hemodynamics-driven" approach in which both thickness and material constants varied spatially with the cardiac-cycle-averaged hemodynamics. Pulsatile numerical simulations, with patient-specific vascular geometries harboring IAs, were carried out using the one-way fluid-solid interaction solution strategy implemented in solids4foam, an extension of OpenFOAM®, in which the blood flow is solved and applied as the driving force of the wall motion. We found that different wall morphology models yield smaller absolute differences in the mechanical response than different hyperelastic laws. Furthermore, the stretch levels of IAs walls were more sensitive to the hyperelastic and material constants than the stress. These findings could be used to guide modeling decisions on IA simulations, since the computational behavior of each law was different, for example, with the Yeoh law being the fastest to converge.
Collapse
Affiliation(s)
- I L Oliveira
- São Paulo State University (UNESP), School of Engineering, Ilha Solteira, Mechanical Engineering Department, Thermal Sciences Building, Avenida Brasil, 56, Ilha Solteira - SP, Brazil.
| | - P Cardiff
- University College Dublin (UCD), School of Mechanical and Materials Engineering, Dublin, Ireland.
| | - C E Baccin
- Interventional Neuroradiology/Endovascular Neurosurgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States.
| | - J L Gasche
- São Paulo State University (UNESP), School of Engineering, Ilha Solteira, Mechanical Engineering Department, Brazil.
| |
Collapse
|
15
|
Hemodynamic Analysis Shows High Wall Shear Stress Is Associated with Intraoperatively Observed Thin Wall Regions of Intracranial Aneurysms. J Cardiovasc Dev Dis 2022; 9:jcdd9120424. [PMID: 36547421 PMCID: PMC9780790 DOI: 10.3390/jcdd9120424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/23/2022] [Accepted: 11/26/2022] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Studying the relationship between hemodynamics and local intracranial aneurysm (IA) pathobiology can help us understand the natural history of IA. We characterized the relationship between the IA wall appearance, using intraoperative imaging, and the hemodynamics from CFD simulations. METHODS Three-dimensional geometries of 15 IAs were constructed and used for CFD. Two-dimensional intraoperative images were subjected to wall classification using a machine learning approach, after which the wall type was mapped onto the 3D surface. IA wall regions included thick (white), normal (purple-crimson), and thin/translucent (red) regions. IA-wide and local statistical analyses were performed to assess the relationship between hemodynamics and wall type. RESULTS Thin regions of the IA sac had significantly higher WSS, Normalized WSS, WSS Divergence and Transverse WSS, compared to both normal and thick regions. Thicker regions tended to co-locate with significantly higher RRT than thin regions. These trends were observed on a local scale as well. Regression analysis showed a significant positive correlation between WSS and thin regions and a significant negative correlation between WSSD and thick regions. CONCLUSION Hemodynamic simulation results were associated with the intraoperatively observed IA wall type. We consistently found that elevated WSS and WSSNorm were associated with thin regions of the IA wall rather than thick and normal regions.
Collapse
|
16
|
Li B, Liu T, Liu J, Liu Y, Cao B, Zhao X, Wang W, Shi M, Zhang L, Xu K, Chen M, Wen C, Zhang M. Reliability of using generic flow conditions to quantify aneurysmal haemodynamics: A comparison against simulations incorporating boundary conditions measured in vivo. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 225:107034. [PMID: 35914441 DOI: 10.1016/j.cmpb.2022.107034] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 07/06/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVES Initiation, growth, and rupture of intracranial aneurysms are believed to be closely related to their local haemodynamic environment. While haemodynamics can be characterised by use of computational fluid dynamics (CFD), its reliability depends heavily upon accurate assumption of the boundary conditions. Herein, we compared the simulated aneurysmal haemodynamics obtained by use of generic boundary conditions against those obtained under flow conditions measured in vivo. METHODS We prospectively recruited 19 patients with intracranial aneurysms requiring 3-dimensional rotational angiography, during which blood pressure at the internal carotid artery was probed by catheter and flowrate measured by a dedicated software tool. Using these flow conditions measured in vivo, we quantified the aneurysmal haemodynamics for each patient by CFD, and then compared the results with those derived from a generic condition reported in the literature, in terms of the time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and percentage of the intra-aneurysmal flow (PIAF). In addition, the effects on aneurysmal haemodynamics of different outflow strategies (splitting method vs. Murray's Law) and simulation schemes (transient vs. steady-state) relative to each flow condition were also assessed. RESULTS Differences in the simulated TAWSS (-6.08 ± 10.64 Pa, p = 0.001), OSI (0.06 ± 0.13, p = 0.001), and PIAF (-0.05 ± 0.20, p = 0.012) between the patient-specific and generic boundary conditions were found to be statistically significant, in contrast to that in the RRT (49 ± 307 Pa-1, p = 0.062). Outflow strategies did not yield statistically significant differences in any of the investigated parameters (all p > 0.05); rather, the resulting parameters were found to be in good correlations (all r > 0.71, p < 0.001). Difference between the aneurysmal TAWSS and the WSS derived from cycle-averaged flowrate condition was found to be minor (0.66 ± 1.36 Pa, p = 0.000), so was that between PIAFs obtained respectively from the transient and steady-state simulations (0.02 ± 0.05, p = 0.000). CONCLUSIONS Incorporating into simulation the patient-specific boundary conditions is critical for CFD to characterise aneurysmal haemodynamics, while outflow strategies may not introduce significant uncertainties. Steady-state simulation incorporating the cycle-averaged flow condition may produce unbiased WSS and PIAF compared to the transient analysis.
Collapse
Affiliation(s)
- Bao Li
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Tao Liu
- Neurosurgery Department, Medical School of Nanjing University Affiliated Drum Tower Hospital, No. 321 Zhongshan Road, Gulou, Nanjing, Jiangsu, China.
| | - Jincheng Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Youjun Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Boqiang Cao
- Nanjing Drum Tower Hospital, Clinical College of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xi Zhao
- Philips Healthcare China, Shanghai 200072, China
| | - Wenxin Wang
- Philips Healthcare China, Shanghai 200072, China
| | - Mengchao Shi
- Philips Healthcare China, Shanghai 200072, China
| | - Liyuan Zhang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Ke Xu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Mingyan Chen
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Chuanqi Wen
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Mingzi Zhang
- Macquarie Medical School, Faculty of Medicine, Health, and Human Sciences, Macquarie University, Sydney, NSW 2109, Australia.
| |
Collapse
|
17
|
Patient-specific computational haemodynamics associated with the surgical creation of an arteriovenous fistula. Med Eng Phys 2022; 105:103814. [DOI: 10.1016/j.medengphy.2022.103814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 11/22/2022]
|
18
|
Zhang M, Hou X, Qian Y, Chong W, Zhang X, Duan CZ, Ou C. Evaluation of aneurysm rupture risk based upon flowrate-independent hemodynamic parameters: a multi-center pilot study. J Neurointerv Surg 2022:neurintsurg-2022-018691. [PMID: 35688619 DOI: 10.1136/neurintsurg-2022-018691] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/21/2022] [Indexed: 01/07/2023]
Abstract
BACKGROUND Specifying generic flow boundary conditions in aneurysm hemodynamic simulations yields a great degree of uncertainty for the evaluation of aneurysm rupture risk. Herein, we proposed the use of flowrate-independent parameters in discriminating unstable aneurysms and compared their prognostic performance against that of conventional absolute parameters. METHODS This retrospective study included 186 aneurysms collected from three international centers, with the stable aneurysms having a minimum follow-up period of 24 months. The flowrate-independent aneurysmal wall shear stress (WSS) and energy loss (EL) were defined as the coefficients of the second-order polynomials characterizing the relationships between the respective parameters and the parent-artery flows. Performance of the flowrate-independent parameters in discriminating unstable aneurysms with the logistic regression, Adaboost, and support-vector machine (SVM) methods was quantified and compared against that of the conventional parameters, in terms of sensitivity, specificity, and area under the curve (AUC). RESULTS In discriminating unstable aneurysms, the proposed flowrate-independent EL achieved the highest sensitivity (0.833, 95% CI 0.586 to 0.964) and specificity (0.833, 95% CI 0.672 to 0.936) on the SVM, with the AUC outperforming the conventional EL by 0.133 (95% CI 0.039 to 0.226, p=0.006). Likewise, the flowrate-independent WSS outperformed the conventional WSS in terms of the AUC (difference: 0.137, 95% CI 0.033 to 0.241, p=0.010). CONCLUSION The flowrate-independent hemodynamic parameters surpassed their conventional counterparts in predicting the stability of aneurysms, which may serve as a promising set of hemodynamic metrics to be used for the prediction of aneurysm rupture risk when physiologically real vascular boundary conditions are unavailable.
Collapse
Affiliation(s)
- Mingzi Zhang
- Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Xiaoxi Hou
- Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Yi Qian
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Winston Chong
- Neuroradiology Department, Monash Medical Centre, Melbourne, Victoria, Australia
| | - Xin Zhang
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Chuan-Zhi Duan
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Chubin Ou
- Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, New South Wales, Australia .,Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| |
Collapse
|
19
|
He Y, Northrup H, Le H, Cheung AK, Berceli SA, Shiu YT. Medical Image-Based Computational Fluid Dynamics and Fluid-Structure Interaction Analysis in Vascular Diseases. Front Bioeng Biotechnol 2022; 10:855791. [PMID: 35573253 PMCID: PMC9091352 DOI: 10.3389/fbioe.2022.855791] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 04/08/2022] [Indexed: 01/17/2023] Open
Abstract
Hemodynamic factors, induced by pulsatile blood flow, play a crucial role in vascular health and diseases, such as the initiation and progression of atherosclerosis. Computational fluid dynamics, finite element analysis, and fluid-structure interaction simulations have been widely used to quantify detailed hemodynamic forces based on vascular images commonly obtained from computed tomography angiography, magnetic resonance imaging, ultrasound, and optical coherence tomography. In this review, we focus on methods for obtaining accurate hemodynamic factors that regulate the structure and function of vascular endothelial and smooth muscle cells. We describe the multiple steps and recent advances in a typical patient-specific simulation pipeline, including medical imaging, image processing, spatial discretization to generate computational mesh, setting up boundary conditions and solver parameters, visualization and extraction of hemodynamic factors, and statistical analysis. These steps have not been standardized and thus have unavoidable uncertainties that should be thoroughly evaluated. We also discuss the recent development of combining patient-specific models with machine-learning methods to obtain hemodynamic factors faster and cheaper than conventional methods. These critical advances widen the use of biomechanical simulation tools in the research and potential personalized care of vascular diseases.
Collapse
Affiliation(s)
- Yong He
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, United States
| | - Hannah Northrup
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Ha Le
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Alfred K. Cheung
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
- Veterans Affairs Salt Lake City Healthcare System, Salt Lake City, UT, United States
| | - Scott A. Berceli
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, United States
- Vascular Surgery Section, Malcom Randall Veterans Affairs Medical Center, Gainesville, FL, United States
| | - Yan Tin Shiu
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
- Veterans Affairs Salt Lake City Healthcare System, Salt Lake City, UT, United States
- *Correspondence: Yan Tin Shiu,
| |
Collapse
|
20
|
Veeturi SS, Rajabzadeh-Oghaz H, Pintér NK, Waqas M, Hasan DM, Snyder KV, Siddiqui AH, Tutino VM. Aneurysm risk metrics and hemodynamics are associated with greater vessel wall enhancement in intracranial aneurysms. ROYAL SOCIETY OPEN SCIENCE 2021; 8:211119. [PMID: 34804573 PMCID: PMC8580418 DOI: 10.1098/rsos.211119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 09/27/2021] [Indexed: 06/13/2023]
Abstract
Vessel wall enhancement (VWE) in contrast-enhanced magnetic resonance imaging (MRI) is a potential biomarker for intracranial aneurysm (IA) risk stratification. In this study, we investigated the relationship between VWE features, risk metrics, morphology and hemodynamics in 41 unruptured aneurysms. We reconstructed the IA geometries from MR angiography and mapped pituitary stalk-normalized MRI intensity on the aneurysm surface using an in-house tool. For each case, we calculated the maximum intensity (CRstalk) and IA risk (via size and the rupture resemblance score (RRS)). We performed correlation analysis to assess relationships between CRstalk and IA risk metrics (size and RRS), as well as each parameter encompassed in RRS, i.e. aneurysmal size ratio (SR), normalized wall shear stress (WSS) and oscillatory shear index. We found that CRstalk had a strong correlation (Pearson correlation coefficient, PCC = 0.630) with size and a moderate correlation (PCC = 0.472) with RRS, indicating an association between VWE and IA risk. Furthermore, CRstalk had a weak negative correlation with normalized WSS (PCC = -0.320) and a weak positive correlation with SR (PCC = 0.390). Local voxel-based analysis showed only a weak negative correlation between normalized WSS and contrast-enhanced MRI signal intensity (PCC = -0.240), suggesting that if low-normalized WSS induces enhancement-associated pathobiology, the effect is not localized.
Collapse
Affiliation(s)
- Sricharan S. Veeturi
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY, USA
| | - Hamidreza Rajabzadeh-Oghaz
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Neurosurgery, University at Buffalo, Buffalo, NY, USA
| | | | - Muhammad Waqas
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Neurosurgery, University at Buffalo, Buffalo, NY, USA
| | - David M. Hasan
- Department of Neurosurgery, University of Iowa Health Care, Iowa City, IA, USA
| | - Kenneth V. Snyder
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Neurosurgery, University at Buffalo, Buffalo, NY, USA
| | - Adnan H. Siddiqui
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Neurosurgery, University at Buffalo, Buffalo, NY, USA
| | - Vincent M. Tutino
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY, USA
- Department of Pathology and Anatomical Sciences, University at Buffalo, Buffalo, NY, USA
- DENT Neurologic Institute, Buffalo, NY, USA
| |
Collapse
|
21
|
Cornelissen BMW, Leemans EL, Slump CH, van den Berg R, Marquering HA, Majoie CBLM. Hemodynamic changes after intracranial aneurysm growth. J Neurosurg 2021:1-7. [PMID: 34715660 DOI: 10.3171/2021.6.jns204155] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 06/07/2021] [Indexed: 11/06/2022]
Abstract
OBJECTIVE For accurate risk assessment of unruptured intracranial aneurysms, it is important to understand the underlying mechanisms that lead to rupture. It is known that hemodynamic anomalies contribute to aneurysm growth and rupture, and that growing aneurysms carry higher rupture risks. However, it is unknown how growth affects hemodynamic characteristics. In this study, the authors assessed how hemodynamic characteristics change over the course of aneurysm growth. METHODS The authors included patients with observed aneurysm growth on longitudinal MRA in the period between 2012 and 2016. Patient-specific vascular models were created from baseline and follow-up images. Subsequently, intraaneurysmal hemodynamic characteristics were computed using computational fluid dynamics. The authors computed the normalized wall shear stress, oscillatory shear index, and low shear area to quantify hemodynamic characteristics. Differences between baseline and follow-up measurements were analyzed using paired t-tests. RESULTS Twenty-five patients with a total of 31 aneurysms were included. The aneurysm volume increased by a median (IQR) of 26 (9-39) mm3 after a mean follow-up period of 4 (range 0.4-10.9) years. The median wall shear stress decreased significantly after growth. Other hemodynamic parameters did not change significantly, although large individual changes with large variability were observed. CONCLUSIONS Hemodynamic characteristics change considerably after aneurysm growth. On average, wall shear stress values decrease after growth, but there is a large variability in hemodynamic changes between aneurysms.
Collapse
Affiliation(s)
- Bart M W Cornelissen
- 1Department of Radiology and Nuclear Medicine, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam.,2Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam; and.,3Technical Medical Center, University of Twente, Enschede, The Netherlands
| | - Eva L Leemans
- 1Department of Radiology and Nuclear Medicine, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam.,2Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam; and
| | - Cornelis H Slump
- 3Technical Medical Center, University of Twente, Enschede, The Netherlands
| | - René van den Berg
- 1Department of Radiology and Nuclear Medicine, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam
| | - Henk A Marquering
- 1Department of Radiology and Nuclear Medicine, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam.,2Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam; and
| | - Charles B L M Majoie
- 1Department of Radiology and Nuclear Medicine, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam
| |
Collapse
|
22
|
Khan MO, Toro Arana V, Najafi M, MacDonald DE, Natarajan T, Valen-Sendstad K, Steinman DA. On the prevalence of flow instabilities from high-fidelity computational fluid dynamics of intracranial bifurcation aneurysms. J Biomech 2021; 127:110683. [PMID: 34454331 DOI: 10.1016/j.jbiomech.2021.110683] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/31/2021] [Accepted: 08/09/2021] [Indexed: 11/27/2022]
Abstract
High-fidelity computational fluid dynamics (HF-CFD) has revealed the potential for high-frequency flow instabilities (aka "turbulent-like" flow) in intracranial aneurysms, consistent with classic in vivo and in vitro reports of bruits and/or wall vibrations. However, HF-CFD has typically been performed on limited numbers of cases, often with unphysiological inflow conditions or focused on sidewall-type aneurysms where flow instabilities may be inherently less prevalent. Here we report HF-CFD of 50 bifurcation aneurysm cases from the open-source Aneurisk model repository. These were meshed using quadratic finite elements having an average effective spatial resolution of 0.065 mm, and solved under physiologically-pulsatile flow conditions using a well-validated, minimally-dissipative solver with 20,000 time-steps per cardiac cycle Flow instability was quantified using the recently introduced spectral power index (SPI), which quantifies, from 0 to 1, the power associated with velocity fluctuations above those of the driving inflow waveform. Of the 50 cases, nearly half showed regions within the sac having SPI up to 0.5, often with non-negligible power into the 100's of Hz, and roughly 1/3 had sac-averaged SPI > 0.1. High SPI did not significantly predict rupture status in this cohort. Proper orthogonal decomposition of cases with highest SPIavg revealed time-varying energetics consistent with transient turbulence. Our reported prevalence of high-frequency flow instabilities in HF-CFD modelling of aneurysms suggests that care must be taken to avoid routinely overlooking them if we are to understand the highly dynamic mechanical forces to which some aneurysm walls may be exposed, and their prevalence in vivo.
Collapse
Affiliation(s)
- M O Khan
- Cardiovascular Imaging, Modelling and Biomechanics Lab, Department of Electrical, Computer and Biomedical Engineering, Ryerson University, Ontario, Canada.
| | - V Toro Arana
- Stanford University School of Medicine, Stanford, CA, USA
| | - M Najafi
- Biomedical Simulation Laboratory, Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - D E MacDonald
- Biomedical Simulation Laboratory, Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - T Natarajan
- Biomedical Simulation Laboratory, Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Ontario, Canada; Simula Research Laboratory, Lysaker Norway
| | | | - D A Steinman
- Biomedical Simulation Laboratory, Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
23
|
Swiatek VM, Neyazi B, Roa JA, Zanaty M, Samaniego EA, Ishii D, Lu Y, Sandalcioglu IE, Saalfeld S, Berg P, Hasan DM. Aneurysm Wall Enhancement Is Associated With Decreased Intrasaccular IL-10 and Morphological Features of Instability. Neurosurgery 2021; 89:664-671. [PMID: 34245147 PMCID: PMC8578742 DOI: 10.1093/neuros/nyab249] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 05/08/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND High-resolution vessel wall imaging plays an increasingly important role in assessing the risk of aneurysm rupture. OBJECTIVE To introduce an approach toward the validation of the wall enhancement as a direct surrogate parameter for aneurysm stability. METHODS A total of 19 patients harboring 22 incidental intracranial aneurysms were enrolled in this study. The aneurysms were dichotomized according to their aneurysm-to-pituitary stalk contrast ratio using a cutoff value of 0.5 (nonenhancing < 0.5; enhancing ≥ 0.5). We evaluated the association of aneurysm wall enhancement with morphological characteristics, hemodynamic features, and inflammatory chemokines directly measured inside the aneurysm. RESULTS Differences in plasma concentration of chemokines and inflammatory molecules, morphological, and hemodynamic parameters were analyzed using the Welch test or Mann-Whitney U test. The concentration ΔIL-10 in the lumen of intracranial aneurysms with low wall enhancement was significantly increased compared to aneurysms with strong aneurysm wall enhancement (P = .014). The analysis of morphological and hemodynamic parameters showed significantly increased values for aneurysm volume (P = .03), aneurysm area (P = .044), maximal diameter (P = .049), and nonsphericity index (P = .021) for intracranial aneurysms with strong aneurysm wall enhancement. None of the hemodynamic parameters reached statistical significance; however, the total viscous shear force computed over the region of low wall shear stress showed a strong tendency toward significance (P = .053). CONCLUSION Aneurysmal wall enhancement shows strong associations with decreased intrasaccular IL-10 and established morphological indicators of aneurysm instability.
Collapse
Affiliation(s)
- Vanessa M Swiatek
- Deparment of Neurosurgery, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| | - Belal Neyazi
- Deparment of Neurosurgery, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| | - Jorge A Roa
- Deparment of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
- Deparment of Neurology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Mario Zanaty
- Deparment of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Edgar A Samaniego
- Deparment of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
- Deparment of Neurology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Daizo Ishii
- Deparment of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Yongjun Lu
- Deparment of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - I Erol Sandalcioglu
- Deparment of Neurosurgery, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| | - Sylvia Saalfeld
- Deparment of Simulation and Graphics, University of Magdeburg, Magdeburg, Saxony Anhalt, Germany
- Research Campus STIMULATE, Magdeburg, Saxony Anhalt, Germany
| | - Philipp Berg
- Research Campus STIMULATE, Magdeburg, Saxony Anhalt, Germany
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Saxony Anhalt, Germany
| | - David M Hasan
- Deparment of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| |
Collapse
|
24
|
Berg P, Behrendt B, Voß S, Beuing O, Neyazi B, Sandalcioglu IE, Preim B, Saalfeld S. VICTORIA: VIrtual neck Curve and True Ostium Reconstruction of Intracranial Aneurysms. Cardiovasc Eng Technol 2021; 12:454-465. [PMID: 34100225 PMCID: PMC8354974 DOI: 10.1007/s13239-021-00535-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 03/17/2021] [Indexed: 11/24/2022]
Abstract
Purpose For the status evaluation of intracranial aneurysms (IAs), morphological and hemodynamic parameters can provide valuable information. For their extraction, a separation of the aneurysm sac from its parent vessel is required that yields the neck curve and the ostium. However, manual and subjective neck curve and ostium definitions might lead to inaccurate IA assessments. Methods The research project VICTORIA was initiated, allowing users to interactively define the neck curve of five segmented IA models using a web application. The submitted results were qualitatively and quantitatively compared to identify the minimum, median and maximum aneurysm surface area. Finally, image-based blood flow simulations were carried out to assess the effect of variable neck curve definitions on relevant flow- and shear-related parameters. Results In total, 55 participants (20 physicians) from 18 countries participated in VICTORIA. For relatively simple aneurysms, a good agreement with respect to the neck curve definition was found. However, differences among the participants increased with increasing complexity of the aneurysm. Furthermore, it was observed that the majority of participants excluded any small arteries occurring in the vicinity of an aneurysm. This can lead to non-negligible deviations among the flow- and shear-related parameters, which need to be carefully evaluated, if quantitative analysis is desired. Finally, no differences between participants with medical and non-medical background could be observed. Conclusions VICTORIAs findings reveal the complexity of aneurysm neck curve definition, especially for bifurcation aneurysms. Standardization appears to be mandatory for future sac-vessel-separations. For hemodynamic simulations a careful neck curve definition is crucial to avoid inaccuracies during the quantitative flow analysis. Supplementary Information The online version contains supplementary material available at 10.1007/s13239-021-00535-w.
Collapse
Affiliation(s)
- Philipp Berg
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - Benjamin Behrendt
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - Samuel Voß
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - Oliver Beuing
- Department of Radiology, AMEOS Hospital, Bernburg, Germany
| | - Belal Neyazi
- Department of Neurosurgery, University Hospital of Magdeburg, Magdeburg, Germany
| | | | - Bernhard Preim
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - Sylvia Saalfeld
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany.
| |
Collapse
|
25
|
Johnston L, Allen R, Hall Barrientos P, Mason A, Kazakidi A. Hemodynamic Abnormalities in the Aorta of Turner Syndrome Girls. Front Cardiovasc Med 2021; 8:670841. [PMID: 34141729 PMCID: PMC8203817 DOI: 10.3389/fcvm.2021.670841] [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: 02/22/2021] [Accepted: 05/06/2021] [Indexed: 01/15/2023] Open
Abstract
Congenital abnormalities in girls and women with Turner syndrome (TS), alongside an underlying predisposition to obesity and hypertension, contribute to an increased risk of cardiovascular disease and ultimately reduced life expectancy. We observe that children with TS present a greater variance in aortic arch morphology than their healthy counterparts, and hypothesize that their hemodynamics is also different. In this study, computational fluid dynamic (CFD) simulations were performed for four TS girls, and three age-matched healthy girls, using patient-specific inlet boundary conditions, obtained from phase-contrast MRI data. The visualization of multidirectional blood flow revealed an increase in vortical flow in the arch, supra-aortic vessels, and descending aorta, and a correlation between the presence of aortic abnormalities and disturbed flow. Compared to the relatively homogeneous pattern of time-averaged wall shear stress (TAWSS) on the healthy aortae, a highly heterogeneous distribution with elevated TAWSS values was observed in the TS geometries. Visualization of further shear stress parameters, such as oscillatory shear index (OSI), normalized relative residence time (RRTn), and transverse WSS (transWSS), revealed dissimilar heterogeneity in the oscillatory and multidirectional nature of the aortic flow. Taking into account the young age of our TS cohort (average age 13 ± 2 years) and their obesity level (75% were obese or overweight), which is believed to accelerate the initiation and progression of endothelial dysfunction, these findings may be an indication of atherosclerotic disease manifesting earlier in life in TS patients. Age, obesity and aortic morphology may, therefore, play a key role in assessing cardiovascular risk in TS children.
Collapse
Affiliation(s)
- Lauren Johnston
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - Ruth Allen
- Department of Radiology, Royal Hospital for Children, Glasgow, United Kingdom
| | | | - Avril Mason
- Department of Paediatric Endocrinology, Royal Hospital for Children, Queen Elizabeth University Hospital, Glasgow, United Kingdom
| | - Asimina Kazakidi
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
| |
Collapse
|
26
|
Oliveira IL, Santos GB, Gasche JL, Militzer J, Baccin CE. Non-Newtonian Blood Modeling in Intracranial Aneurysm Hemodynamics: Impact on the Wall Shear Stress and Oscillatory Shear Index Metrics for Ruptured and Unruptured Cases. J Biomech Eng 2021; 143:1104430. [PMID: 33729441 DOI: 10.1115/1.4050539] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Indexed: 11/08/2022]
Abstract
When simulating blood flow in intracranial aneurysms (IAs), the Newtonian model seems to be ubiquitous. However, analyzing the results from the few studies on this subject, the doubt remains on whether it is necessary to use non-Newtonian models in computational fluid dynamics (CFD) simulations of cerebral vascular flows. The objective of this study is to investigate whether different rheology models would influence the hemodynamic parameters related to the wall shear stress (WSS) for ruptured and unruptured IA cases, especially because ruptured aneurysms normally have morphological features, such as lobular regions and blebs, that could trigger non-Newtonian phenomena in the blood flow due to low shear rates. Using CFD in an open-source framework, we simulated four ruptured and four unruptured patient-specific aneurysms to assess the influence of the blood modeling on the main hemodynamic variables associated with aneurysm formation, growth, and rupture. Results for WSS and oscillatory shear index (OSI) and their metrics were obtained using Casson and Carreau-Yasuda non-Newtonian models and were compared with those obtained using the Newtonian model. We found that all differences between non-Newtonian and the Newtonian models were consistent among all cases irrespective of their rupture status. We further found that the WSS at peak systole is overestimated by more than 50% by using the non-Newtonian models, but its metrics based on time and surface averaged values are less affected-the maximum relative difference among the cases is 7% for the Casson model. On the other hand, the surface-averaged OSI is underestimated by more than 30% by the non-Newtonian models. These results suggest that it is recommended to investigate different blood rheology models in IAs simulations when specific parameters to characterize the flow are needed, such as peak-systole WSS and OSI.
Collapse
Affiliation(s)
- Iago L Oliveira
- Mechanical Engineering Department, São Paulo State University (UNESP), Ilha Solteira, São Paulo 15385-000, Brazil
| | - Gabriel B Santos
- Mechanical Engineering Department, São Paulo State University (UNESP), Ilha Solteira, São Paulo 15385-000, Brazil
| | - José L Gasche
- Mechanical Engineering Department, São Paulo State University (UNESP), Ilha Solteira, São Paulo 15385-000, Brazil
| | - Julio Militzer
- Department of Mechanical Engineering, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Carlos E Baccin
- Interventional Neuroradiology, Hospital Israelita Albert Einstein, São Paulo, São Paulo 05652-900, Brazil
| |
Collapse
|
27
|
Le TB. Dynamic modes of inflow jet in brain aneurysms. J Biomech 2021; 116:110238. [PMID: 33485144 DOI: 10.1016/j.jbiomech.2021.110238] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 01/04/2021] [Indexed: 01/27/2023]
Abstract
The transition of the inflow jet to turbulence is crucial in understanding the pathology of brain aneurysms. Previous works Le et al. (2010, 2013) have shown evidence for a highly dynamic inflow jet in the ostium of brain aneurysms. While it is highly desired to investigate this inflow jet dynamics in clinical practice, the constraints on spatial and temporal resolutions of in vivo data do not allow a detailed analysis of this transition. In this work, Dynamic Mode Decomposition (DMD) is used to identify the most energetic modes of the inflow jet in patient-specific models of internal carotid aneurysms via the utilization of high-resolution simulation data. It is hypothesized that dynamic modes are not solely controlled by the blood flow waveform at the parent artery. They are also dependent on jet-wall interaction phenomena. DMD analysis shows that the spatial extent of low- frequency modes corresponds well to the most energetic areas of the inflow jet. The high-frequency modes are short-lived and correspond to the flow separation at the proximal neck and the jet's impingement onto the aneurysmal wall. Low-frequency modes can be reconstructed at relatively low spatial and temporal resolutions comparable to ones of in vivo data. The current results suggest that DMD can be practically useful in analyzing blood flow patterns of brain aneurysms with in vivo data.
Collapse
Affiliation(s)
- Trung Bao Le
- Department of Civil and Environmental Engineering, North Dakota State University, CIE 201, 1410 North 14th Avenue, Fargo, ND 58105-5285, United States; NDSU-UND Biomedical Engineering Program, United States; Center for Cellular Biointerfaces in Science and Engineering, United States.
| |
Collapse
|
28
|
Holmgren M, Støverud KH, Zarrinkoob L, Wåhlin A, Malm J, Eklund A. Middle cerebral artery pressure laterality in patients with symptomatic ICA stenosis. PLoS One 2021; 16:e0245337. [PMID: 33417614 PMCID: PMC7793245 DOI: 10.1371/journal.pone.0245337] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/28/2020] [Indexed: 11/18/2022] Open
Abstract
An internal carotid artery (ICA) stenosis can potentially decrease the perfusion pressure to the brain. In this study, computational fluid dynamics (CFD) was used to study if there was a hemispheric pressure laterality between the contra- and ipsilateral middle cerebral artery (MCA) in patients with a symptomatic ICA stenosis. We further investigated if this MCA pressure laterality (ΔPMCA) was related to the hemispheric flow laterality (ΔQ) in the anterior circulation, i.e., ICA, proximal MCA and the proximal anterior cerebral artery (ACA). Twenty-eight patients (73±6 years, range 59–80 years, 21 men) with symptomatic ICA stenosis were included. Flow rates were measured using 4D flow MRI data (PC-VIPR) and vessel geometries were obtained from computed tomography angiography. The ΔPMCA was calculated from CFD, where patient-specific flow rates were applied at all input- and output boundaries. The ΔPMCA between the contra- and ipsilateral side was 6.4±8.3 mmHg (p<0.001) (median 3.9 mmHg, range -1.3 to 31.9 mmHg). There was a linear correlation between the ΔPMCA and ΔQICA (r = 0.85, p<0.001) and ΔQACA (r = 0.71, p<0.001), respectively. The correlation to ΔQMCA was weaker (r = 0.47, p = 0.011). In conclusion, the MCA pressure laterality obtained with CFD, is a promising physiological biomarker that can grade the hemodynamic disturbance in patients with a symptomatic ICA stenosis.
Collapse
Affiliation(s)
| | | | - Laleh Zarrinkoob
- Department of Clinical Science, Neurosciences, Umeå University, Umeå, Sweden.,Department of Surgical and Perioperative Sciences, Umeå University, Umeå, Sweden
| | - Anders Wåhlin
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.,Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden
| | - Jan Malm
- Department of Clinical Science, Neurosciences, Umeå University, Umeå, Sweden
| | - Anders Eklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.,Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden
| |
Collapse
|
29
|
Neyazi B, Swiatek VM, Skalej M, Beuing O, Stein KP, Hattingen J, Preim B, Berg P, Saalfeld S, Sandalcioglu IE. Rupture risk assessment for multiple intracranial aneurysms: why there is no need for dozens of clinical, morphological and hemodynamic parameters. Ther Adv Neurol Disord 2020; 13:1756286420966159. [PMID: 33403004 PMCID: PMC7739206 DOI: 10.1177/1756286420966159] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 09/21/2020] [Indexed: 12/23/2022] Open
Abstract
Introduction: A multitude of approaches have been postulated for assessing the risk of intracranial aneurysm rupture. However, the amount of potential predictive factors is not applicable in clinical practice and they are rejected in favor of the more practical PHASES score. For the subgroup of multiple intracranial aneurysms (MIAs), the PHASES score might severely underestimate the rupture risk, as only the aneurysm with the largest diameter is considered for risk evaluation. Methods: In this study, we investigated 38 patients harboring a total number of 87 MIAs with respect to their morphological and hemodynamical characteristics. For the determination of the best suited parameters regarding their predictive power for aneurysm rupture, we conducted three phases of statistical evaluation. The statistical analysis aimed to identify parameters that differ significantly between ruptured and unruptured aneurysms, show smallest possible correlations among each other and have a high impact on rupture risk prediction. Results: Significant differences between ruptured and unruptured aneurysms were found in 16 out of 49 parameters. The lowest correlation were found for gamma, aspect ratio (AR1), aneurysm maximal relative residence time (Aneurysm_RRT_max) and aneurysm mean relative residence time. The data-driven parameter selection yielded a significant correlation of only two parameters (AR1 and the Aneurysm_RRT_max) with rupture state (area under curve = 0.75). Conclusion: A high number of established morphological and hemodynamical parameters seem to have no or only low effect on prediction of aneurysm rupture in patients with MIAs. For best possible rupture risk assessment of patients with MIAs, only the morphological parameter AR1 and the hemodynamical parameter Aneurysm_RRT_max need to be included in the prediction model.
Collapse
Affiliation(s)
- Belal Neyazi
- Department of Neurosurgery, Otto-von-Guericke University, Leipziger Straße 44, Magdeburg, Saxony Anhalt 39120, Germany
| | - Vanessa M Swiatek
- Department of Neurosurgery, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| | - Martin Skalej
- Department of Neuroradiology, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| | - Oliver Beuing
- Department of Neuroradiology, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| | - Klaus-Peter Stein
- Department of Neurosurgery, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| | - Jörg Hattingen
- Institute of Neuroradiology, KRH Klinikum Nordstadt, Hanover, Niedersachsen, Germany
| | - Bernhard Preim
- Department of Simulation and Graphics, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| | - Philipp Berg
- Department of Fluid Dynamics and Technical Flows, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| | - Sylvia Saalfeld
- Department of Simulation and Graphics, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| | - I Erol Sandalcioglu
- Department of Neurosurgery, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany
| |
Collapse
|
30
|
Boumpouli M, Danton MHD, Gourlay T, Kazakidi A. Blood flow simulations in the pulmonary bifurcation in relation to adult patients with repaired tetralogy of Fallot. Med Eng Phys 2020; 85:123-138. [PMID: 33081959 DOI: 10.1016/j.medengphy.2020.09.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 07/01/2020] [Accepted: 09/25/2020] [Indexed: 10/23/2022]
Abstract
Understanding the haemodynamic environment of the pulmonary bifurcation is important in adults with repaired conotruncal congenital heart disease. In these patients, dysfunction of the pulmonary valve and narrowing of the branch pulmonary arteries are common and can have serious clinical consequences. The aim of this study was to numerically investigate the underlying blood flow characteristics in the pulmonary trunk under a range of simplified conditions. For that, an in-depth analysis was conducted in idealised two-dimensional geometries that facilitate parametric investigation of healthy and abnormal conditions. Subtle variations in morphology influenced the haemodynamic environment and wall shear stress distribution. The pressure in the left pulmonary artery was generally higher than that in the right and main arteries, but was markedly reduced in the presence of a local stenosis. Different downstream pressure conditions altered the branch flow ratio, from 50:50% to more realistic 60:40% ratios in the right and left pulmonary artery, respectively. Despite some simplifications, this study highlights some previously undocumented aspects of the flow in bifurcating geometries, by clarifying the role of the stagnation point location on wall shear stress and differential branch pressures. In addition, measurements of the mean pressure ratios in the pulmonary bifurcation are discussed in the context of a new haemodynamic index which could potentially contribute to the assessment of left pulmonary artery stenosis in tetralogy of Fallot patients. Further studies are required to confirm the results in patient-specific models with personalised physiological flow conditions.
Collapse
Affiliation(s)
- Maria Boumpouli
- Department of Biomedical Engineering, University of Strathclyde, 106 Rottenrow East, Glasgow G4 0NW, United Kingdom
| | - Mark H D Danton
- Department of Biomedical Engineering, University of Strathclyde, 106 Rottenrow East, Glasgow G4 0NW, United Kingdom; Scottish Adult Congenital Cardiac Service, Golden Jubilee National Hospital, Clydebank G81 4DY, United Kingdom
| | - Terence Gourlay
- Department of Biomedical Engineering, University of Strathclyde, 106 Rottenrow East, Glasgow G4 0NW, United Kingdom
| | - Asimina Kazakidi
- Department of Biomedical Engineering, University of Strathclyde, 106 Rottenrow East, Glasgow G4 0NW, United Kingdom.
| |
Collapse
|
31
|
Steinman DA, Pereira VM. How patient specific are patient-specific computational models of cerebral aneurysms? An overview of sources of error and variability. Neurosurg Focus 2020; 47:E14. [PMID: 31261118 DOI: 10.3171/2019.4.focus19123] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 04/12/2019] [Indexed: 01/20/2023]
Abstract
Computational modeling of cerebral aneurysms, derived from clinical 3D angiography, has become widespread over the past 15 years. While such "image-based" or "patient-specific" models have shown promise for the assessment of rupture risk, much debate remains about their reliability in light of necessary modeling assumptions and incomplete or uncertain model input parameters derived from the clinic. The aims of this review were to walk through the various steps of this so-called patient-specific modeling pipeline and to highlight evidence supporting those steps that we can or cannot rely on. The relative importance of the different sources of error and variability on hemodynamic predictions is summarized, with recommendations to standardize for those that can be avoided and to pay closer attention those to that cannot.
Collapse
Affiliation(s)
- David A Steinman
- 1Department of Mechanical and Industrial Engineering and Institute of Biomaterials and Biomedical Engineering, University of Toronto; and
| | - Vitor M Pereira
- 2Divisions of Neuroradiology and Neurosurgery, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| |
Collapse
|
32
|
Berg P, Saalfeld S, Voß S, Beuing O, Janiga G. A review on the reliability of hemodynamic modeling in intracranial aneurysms: why computational fluid dynamics alone cannot solve the equation. Neurosurg Focus 2020; 47:E15. [PMID: 31261119 DOI: 10.3171/2019.4.focus19181] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 04/09/2019] [Indexed: 12/23/2022]
Abstract
Computational blood flow modeling in intracranial aneurysms (IAs) has enormous potential for the assessment of highly resolved hemodynamics and derived wall stresses. This results in an improved knowledge in important research fields, such as rupture risk assessment and treatment optimization. However, due to the requirement of assumptions and simplifications, its applicability in a clinical context remains limited.This review article focuses on the main aspects along the interdisciplinary modeling chain and highlights the circumstance that computational fluid dynamics (CFD) simulations are embedded in a multiprocess workflow. These aspects include imaging-related steps, the setup of realistic hemodynamic simulations, and the analysis of multidimensional computational results. To condense the broad knowledge, specific recommendations are provided at the end of each subsection.Overall, various individual substudies exist in the literature that have evaluated relevant technical aspects. In this regard, the importance of precise vessel segmentations for the simulation outcome is emphasized. Furthermore, the accuracy of the computational model strongly depends on the specific research question. Additionally, standardization in the context of flow analysis is required to enable an objective comparison of research findings and to avoid confusion within the medical community. Finally, uncertainty quantification and validation studies should always accompany numerical investigations.In conclusion, this review aims for an improved awareness among physicians regarding potential sources of error in hemodynamic modeling for IAs. Although CFD is a powerful methodology, it cannot provide reliable information, if pre- and postsimulation steps are inaccurately carried out. From this, future studies can be critically evaluated and real benefits can be differentiated from results that have been acquired based on technically inaccurate procedures.
Collapse
Affiliation(s)
- Philipp Berg
- 1Department of Fluid Dynamics and Technical Flows.,2Research CampusSTIMULATE, and
| | - Sylvia Saalfeld
- 2Research CampusSTIMULATE, and.,3Department of Simulation and Graphics, University of Magdeburg; and
| | - Samuel Voß
- 1Department of Fluid Dynamics and Technical Flows.,2Research CampusSTIMULATE, and
| | - Oliver Beuing
- 2Research CampusSTIMULATE, and.,4Department of Neuroradiology, University Hospital Magdeburg, Magdeburg, Germany
| | - Gábor Janiga
- 1Department of Fluid Dynamics and Technical Flows.,2Research CampusSTIMULATE, and
| |
Collapse
|
33
|
Najafi M, Cancelliere NM, Brina O, Bouillot P, Vargas MI, Delattre BM, Pereira VM, Steinman DA. How patient-specific do internal carotid artery inflow rates need to be for computational fluid dynamics of cerebral aneurysms? J Neurointerv Surg 2020; 13:459-464. [PMID: 32732256 DOI: 10.1136/neurintsurg-2020-015993] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 11/03/2022]
Abstract
BACKGROUND Computational fluid dynamics (CFD) has become a popular tool for studying 'patient-specific' blood flow dynamics in cerebral aneurysms; however, rarely are the inflow boundary conditions patient-specific. We aimed to test the impact of widespread reliance on generalized inflow rates. METHODS Internal carotid artery (ICA) flow rates were measured via 2D cine phase-contrast MRI for 24 patients scheduled for endovascular therapy of an ICA aneurysm. CFD models were constructed from 3D rotational angiography, and pulsatile inflow rates imposed as measured by MRI or estimated using an average older-adult ICA flow waveform shape scaled by a cycle-average flow rate (Qavg) derived from the patient's ICA cross-sectional area via an assumed inlet velocity. RESULTS There was good overall qualitative agreement in the magnitudes and spatial distributions of time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and spectral power index (SPI) using generalized versus patient-specific inflows. Sac-averaged quantities showed moderate to good correlations: R2=0.54 (TAWSS), 0.80 (OSI), and 0.68 (SPI). Using patient-specific Qavg to scale the generalized waveform shape resulted in near-perfect agreement for TAWSS, and reduced bias, but not scatter, for SPI. Patient-specific waveform had an impact only on OSI correlations, which improved to R2=0.93. CONCLUSIONS Aneurysm CFD demonstrates the ability to stratify cases by nominal hemodynamic 'risk' factors when employing an age- and vascular-territory-specific recipe for generalized inflow rates. Qavg has a greater influence than waveform shape, suggesting some improvement could be achieved by including measurement of patient-specific Qavg into aneurysm imaging protocols.
Collapse
Affiliation(s)
- Mehdi Najafi
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Nicole M Cancelliere
- Joint Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada
| | - Olivier Brina
- Department for Diagnostic and Interventional Neuroradiology, Hôpitaux Universitaires de Geneve, Geneva, Switzerland
| | - Pierre Bouillot
- Department for Diagnostic and Interventional Neuroradiology, Hôpitaux Universitaires de Geneve, Geneva, Switzerland
| | - Maria I Vargas
- Department for Diagnostic and Interventional Neuroradiology, Hôpitaux Universitaires de Geneve, Geneva, Switzerland
| | - Benedicte Ma Delattre
- Department for Diagnostic and Interventional Neuroradiology, Hôpitaux Universitaires de Geneve, Geneva, Switzerland
| | - Vitor M Pereira
- Joint Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada
- Department of Neurosurgery, Toronto Western Hospital, Toronto, Ontario, Canada
| | - David A Steinman
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
34
|
Larsen N, Flüh C, Saalfeld S, Voß S, Hille G, Trick D, Wodarg F, Synowitz M, Jansen O, Berg P. Multimodal validation of focal enhancement in intracranial aneurysms as a surrogate marker for aneurysm instability. Neuroradiology 2020; 62:1627-1635. [PMID: 32681192 PMCID: PMC7666674 DOI: 10.1007/s00234-020-02498-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 07/13/2020] [Indexed: 11/09/2022]
Abstract
Purpose Circumferential enhancement on MR vessel wall imaging has been proposed as a biomarker of a higher risk of rupture in intracranial aneurysms. Focal enhancement is frequently encountered in unruptured aneurysms, but its implication for risk stratification and patient management remains unclear. This study investigates the association of focal wall enhancement with hemodynamic and morphological risk factors and histologic markers of wall inflammation and degeneration. Methods Patients with an unruptured middle cerebral artery aneurysm who underwent 3D rotational angiography and 3T MR vessel wall imaging showing focal wall enhancement were included. Hemodynamic parameters were calculated based on flow simulations and compared between enhanced regions and the entire aneurysm surface. Morphological parameters were semiautomatically extracted and quantitatively associated with wall enhancement. Histological analysis included detection of vasa vasorum, CD34, and myeloperoxidase staining in a subset of patients. Results Twenty-two aneurysms were analyzed. Enhanced regions were significantly associated with lower AWSS, lower maxOSI, and increased LSA. In multivariate analysis, higher ellipticity index was an independent predictor of wall enhancement. Histologic signs of inflammation and degeneration and higher PHASES score were significantly associated with focal enhancement. Conclusion Focal wall enhancement is colocalized with hemodynamic factors that have been related to a higher rupture risk. It is correlated with morphological factors linked to rupture risk, higher PHASES score, and histologic markers of wall destabilization. The results support the hypothesis that focal enhancement could serve as a surrogate marker for aneurysm instability.
Collapse
Affiliation(s)
- Naomi Larsen
- Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein Campus Kiel, Arnold-Heller-Str. 3, Haus D, 24105, Kiel, Germany.
| | - Charlotte Flüh
- Department of Neurosurgery, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Sylvia Saalfeld
- Forschungscampus STIMULATE, University of Magdeburg, Magdeburg, Germany.,Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - Samuel Voß
- Forschungscampus STIMULATE, University of Magdeburg, Magdeburg, Germany.,Institute of Fluid Dynamics and Thermodynamics, University of Magdeburg, Magdeburg, Germany
| | - Georg Hille
- Forschungscampus STIMULATE, University of Magdeburg, Magdeburg, Germany.,Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - David Trick
- Institute of Pathology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Fritz Wodarg
- Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein Campus Kiel, Arnold-Heller-Str. 3, Haus D, 24105, Kiel, Germany
| | - Michael Synowitz
- Department of Neurosurgery, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Olav Jansen
- Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein Campus Kiel, Arnold-Heller-Str. 3, Haus D, 24105, Kiel, Germany
| | - Philipp Berg
- Forschungscampus STIMULATE, University of Magdeburg, Magdeburg, Germany.,Institute of Fluid Dynamics and Thermodynamics, University of Magdeburg, Magdeburg, Germany
| |
Collapse
|
35
|
Sun L, Wang J, Li M, Li M, Zhu Y. The contribution of wall shear stress insult to the growth of small unruptured cerebral aneurysms in longitudinal 3D-TOF-MRA. J Neurol Sci 2020; 413:116798. [DOI: 10.1016/j.jns.2020.116798] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 03/11/2020] [Accepted: 03/20/2020] [Indexed: 12/23/2022]
|
36
|
Bergersen AW, Kjeldsberg HA, Valen-Sendstad K. A framework for automated and objective modification of tubular structures: Application to the internal carotid artery. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3330. [PMID: 32125768 DOI: 10.1002/cnm.3330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 02/26/2020] [Accepted: 02/27/2020] [Indexed: 06/10/2023]
Abstract
Patient-specific medical image-based computational fluid dynamics has been widely used to reveal fundamental insight into mechanisms of cardiovascular disease, for instance, correlating morphology to adverse vascular remodeling. However, segmentation of medical images is laborious, error-prone, and a bottleneck in the development of large databases that are needed to capture the natural variability in morphology. Instead, idealized models, where morphological features are parameterized, have been used to investigate the correlation with flow features, but at the cost of limited understanding of the complexity of cardiovascular flows. To combine the advantages of both approaches, we developed a tool that preserves the patient-specificness inherent in medical images while allowing for parametric alteration of the morphology. In our open-source framework morphMan we convert the segmented surface to a Voronoi diagram, modify the diagram to change the morphological features of interest, and then convert back to a new surface. In this paper, we present algorithms for modifying bifurcation angles, location of branches, cross-sectional area, vessel curvature, shape of bends, and surface roughness. We show qualitative and quantitative validation of the algorithms, performing with an accuracy exceeding 97% in general, and proof-of-concept on combining the tool with computational fluid dynamics. By combining morphMan with appropriate clinical measurements, one could explore the morphological parameter space and resulting hemodynamic response using only a handful of segmented surfaces, effectively minimizing the main bottleneck in image-based computational fluid dynamics.
Collapse
Affiliation(s)
- Aslak W Bergersen
- Department of Computational Physiology, Simula Research Laboratory, Fornebu, Akershus, Norway
| | - Henrik A Kjeldsberg
- Department of Computational Physiology, Simula Research Laboratory, Fornebu, Akershus, Norway
| | - Kristian Valen-Sendstad
- Department of Computational Physiology, Simula Research Laboratory, Fornebu, Akershus, Norway
| |
Collapse
|
37
|
Rajabzadeh-Oghaz H, van Ooij P, Veeturi SS, Tutino VM, Zwanenburg JJ, Meng H. Inter-patient variations in flow boundary conditions at middle cerebral artery from 7T PC-MRI and influence on Computational Fluid Dynamics of intracranial aneurysms. Comput Biol Med 2020; 120:103759. [PMID: 32421656 DOI: 10.1016/j.compbiomed.2020.103759] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 04/03/2020] [Accepted: 04/08/2020] [Indexed: 11/26/2022]
Abstract
BACKGROUND Computational fluid dynamics(CFD) of intracranial aneurysms requires flow boundary conditions(BCs) as inputs. Patient-specific BCs are usually unavailable and substituted by literature-derived generic BCs. Therefore, we investigated inter-patient BC variations and their influence on middle cerebral artery aneurysmal hemodynamics. METHOD We retrospectively collected CT angiography and 7-T Phase-Contrast(PC)-MRI data from eight middle-cerebral-artery bifurcation aneurysms to reconstruct the geometry and measure the arterial flowrates, respectively. The coefficient of variation(CoV) was calculated for the inlet flowrate and the pulsatility index(PI). The outflow split estimated by Murray's law was compared with PC-MRI measurements. For each aneurysm, we performed seven simulations: "baseline" using PC-MRI-derived BCs and the other six with changing BCs to explore the influence of BC variations on hemodynamics. RESULTS From PC-MRI, the inlet flowrate was 1.94 ± 0.71 cm3/s(CoV = 36%) and PI was 0.37 ± 0.13(CoV = 34%). The outflow split estimated by Murray's law deviated by 15.3% compared to PC-MRI. Comparing to "baseline" models, ±36% variations in inlet flowrate caused -61% to +89% changes in time-averaged wall shear stress(WSS), -37% to +32% in normalized WSS(NWSS; by parent-artery), and -42% to +126% in oscillatory shear index(OSI). The ±34% variations in PI caused, -46% to +67% in OSI. Applying ±15% variations in outflow split led to inflow jet deflection and -41% to +52% changes in WSS, -41% to +47% in NWSS, and -44% to +144% in OSI. CONCLUSION Inflow rate and outflow split have a drastic impact on hemodynamics of intracranial aneurysms. Inlet waveform has a negligible impact on WSS and NWSS but major impact on OSI. CFD-based models need to consider such sensitivity.
Collapse
Affiliation(s)
- Hamidreza Rajabzadeh-Oghaz
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, USA; Canon Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, NY, USA; Department of Neurosurgery, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Pim van Ooij
- Department of Radiology& Nuclear Medicine, Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, the Netherlands
| | - Sricharan S Veeturi
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, USA; Canon Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Vincent M Tutino
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, USA; Canon Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, NY, USA; Department of Neurosurgery, University at Buffalo, The State University of New York, Buffalo, NY, USA; Department of Pathology and Anatomical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA; Department of Biomedical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Jaco Jm Zwanenburg
- Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Hui Meng
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, USA; Canon Stroke and Vascular Research Center, University at Buffalo, The State University of New York, Buffalo, NY, USA.
| |
Collapse
|
38
|
Park CS, Hartung G, Alaraj A, Du X, Charbel FT, Linninger AA. Quantification of blood flow patterns in the cerebral arterial circulation of individual (human) subjects. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3288. [PMID: 31742921 DOI: 10.1002/cnm.3288] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 10/04/2019] [Accepted: 11/15/2019] [Indexed: 06/10/2023]
Abstract
There is a growing research interest in quantifying blood flow distribution for the entire cerebral circulation to sharpen diagnosis and improve treatment options for cerebrovascular disease of individual patients. We present a methodology to reconstruct subject-specific cerebral blood flow patterns in accordance with physiological and fluid mechanical principles and optimally informed by in vivo neuroimage data of cerebrovascular anatomy and arterial blood flow rates. We propose an inverse problem to infer blood flow distribution across the visible portion of the arterial network that best matches subject-specific anatomy and a given set of volumetric flow measurements. The optimization technique also mitigates the effect of uncertainties by reconciling incomplete flow data and by dissipating unavoidable acquisition errors associated with medical imaging data.
Collapse
Affiliation(s)
- Chang S Park
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
| | - Grant Hartung
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
| | - Ali Alaraj
- Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois
| | - Xinjian Du
- Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois
| | - Fady T Charbel
- Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois
| | - Andreas A Linninger
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
- Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois
| |
Collapse
|
39
|
Cancelliere NM, Najafi M, Brina O, Bouillot P, Vargas MI, Lovblad KO, Krings T, Pereira VM, Steinman DA. 4D-CT angiography versus 3D-rotational angiography as the imaging modality for computational fluid dynamics of cerebral aneurysms. J Neurointerv Surg 2019; 12:626-630. [DOI: 10.1136/neurintsurg-2019-015389] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 11/06/2019] [Accepted: 11/07/2019] [Indexed: 11/03/2022]
Abstract
Background and purposeComputational fluid dynamics (CFD) can provide valuable information regarding intracranial hemodynamics. Patient-specific models can be segmented from various imaging modalities, which may influence the geometric output and thus hemodynamic results. This study aims to compare CFD results from aneurysm models segmented from three-dimensional rotational angiography (3D-RA) versus novel four-dimensional CT angiography (4D-CTA).MethodsFourteen patients with 16 cerebral aneurysms underwent novel 4D-CTA followed by 3D-RA. Endoluminal geometries were segmented from each modality using an identical workflow, blinded to the other modality, to produce 28 'original' models. Each was then minimally edited a second time to match length of branches, producing 28 additional 'matched' models. CFD simulations were performed using estimated flow rates for 'original' models (representing real-world experience) and patient-specific flow rates from 4D-CTA for 'matched' models (to control for influence of modality alone).ResultsOverall, geometric and hemodynamic results were consistent between models segmented from 3D-RA and 4D-CTA, with correlations improving after matching to control for operator-introduced variability. Despite smaller 4D-CTA parent artery diameters (3.49±0.97 mm vs 3.78±0.92 mm for 3D-RA; p=0.005) and sac volumes (157 (37–750 mm3) vs 173 (53–770 mm3) for 3D-RA; p=0.0002), sac averages of time-averaged wall shear stress (TAWSS), oscillatory shear (OSI), and high frequency fluctuations (measured by spectral power index, SPI) were well correlated between 3D-RA and 4D-CTA 'matched' control models (TAWSS, R2=0.91; OSI, R2=0.79; SPI, R2=0.90).ConclusionsOur study shows that CFD performed using 4D-CTA models produces reliable geometric and hemodynamic information in the intracranial circulation. 4D-CTA may be considered as a follow-up imaging tool for hemodynamic assessment of cerebral aneurysms.
Collapse
|
40
|
Bergersen AW, Chnafa C, Gallo D, Piccinelli M, Steinman DA, Valen-Sendstad K. Automated and objective removal of bifurcation aneurysms: Incremental improvements, and validation against healthy controls. J Biomech 2019; 96:109342. [PMID: 31630772 DOI: 10.1016/j.jbiomech.2019.109342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 09/09/2019] [Accepted: 09/11/2019] [Indexed: 12/01/2022]
Abstract
Abnormal hemodynamic stresses are thought to correlate with aneurysm initiation, growth, and rupture. We have previously investigated the role of wall shear stress (WSS) and WSS gradients (WSSG) in search for a mechanistic link to formation of sidewall aneurysms using an automated and objective tool for aneurysm removal and arterial reconstruction in combination with computational fluid dynamics (CFD). However, we warned against the use of the tool for bifurcation type aneurysms because of a potential unrealistic reconstruction of the apex. We hypothesized that inclusion of additional morphological features from the surrounding vasculature could overcome these constraints. We extended the previously published method for removal and reconstruction of the bifurcation vasculature based on diverging and converging points of the parent and daughter artery centerlines, to also include two new centerlines between the daughter vessels, one of them passed through the bifurcation center. Validation was performed by comparing the efficacy of the two algorithms, using ten healthy models of the internal carotid artery terminus as ground truth. Qualitative results showed that the bifurcation apexes became smoother relative to the original algorithm; more consistent with the reference models. This was reflected quantitatively by a reduced maximum distance between the reference and reconstructed surfaces, although not statistically significant. Furthermore, the modified algorithm also quantitatively improved CFD derived WSS and WSSG, especially the latter. In conclusion, the modified algorithm does not perfectly reconstruct the bifurcation apex, but provides an incremental improvement, especially important for the derived hemodynamic metrics of interest in vascular pathobiology.
Collapse
Affiliation(s)
- Aslak W Bergersen
- Department of Computational Physiology, Simula Research Laboratory, Lysaker, Norway
| | - Christophe Chnafa
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Diego Gallo
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino, Italy
| | - Marina Piccinelli
- Department of Radiology and Imaging Sciences, Emory University, GA, USA
| | - David A Steinman
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | | |
Collapse
|
41
|
Natarajan T, MacDonald DE, Najafi M, Coppin PW, Steinman DA. Spectral decomposition and illustration-inspired visualisation of highly disturbed cerebrovascular blood flow dynamics. COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING-IMAGING AND VISUALIZATION 2019. [DOI: 10.1080/21681163.2019.1647461] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Thangam Natarajan
- Biomedical Simulation laboratory, University of Toronto, Toronto, Canada
| | | | - Mehdi Najafi
- Biomedical Simulation laboratory, University of Toronto, Toronto, Canada
| | - Peter W. Coppin
- Perceptual Artifacts Laboratory, Ontario College of Art and Design University, Toronto, Canada
| | - David A. Steinman
- Biomedical Simulation laboratory, University of Toronto, Toronto, Canada
| |
Collapse
|
42
|
Voß S, Beuing O, Janiga G, Berg P. Stent-induced vessel deformation after intracranial aneurysm treatment – A hemodynamic pilot study. Comput Biol Med 2019; 111:103338. [DOI: 10.1016/j.compbiomed.2019.103338] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 06/18/2019] [Accepted: 06/18/2019] [Indexed: 12/13/2022]
|
43
|
Flow-splitting-based computation of outlet boundary conditions for improved cerebrovascular simulation in multiple intracranial aneurysms. Int J Comput Assist Radiol Surg 2019; 14:1805-1813. [PMID: 31363984 DOI: 10.1007/s11548-019-02036-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 07/18/2019] [Indexed: 01/20/2023]
Abstract
PURPOSE Image-based hemodynamic simulations have great potential for precise blood flow predictions in intracranial aneurysms. Due to model assumptions and simplifications with respect to boundary conditions, clinical acceptance remains limited. METHODS Within this study, we analyzed the influence of outflow-splitting approaches on multiple aneurysm studies and present a new outflow-splitting approach that takes the precise morphological vessel cross sections into account. We provide a detailed comparison of five outflow strategies considering eight intracranial aneurysms: zero-pressure configuration (1), a flow splitting inspired by Murray's law with a square (2) and a cubic (3) vessel diameter, a flow splitting incorporating vessel bifurcations based on circular vessel cross sections (4) and our novel flow splitting including vessel bifurcations and anatomical vessel cross sections (5). Other boundary conditions remain constant. For each simulation and each aneurysm, we conducted an evaluation based on common hemodynamic parameters, e.g., normalized wall shear stress and inflow concentration index. RESULTS The comparison of five outflow strategies for image-based simulations shows a large variability regarding the parameters of interest. Qualitatively, our strategy based on anatomical cross sections yields a more uniform flow rate distribution with increased aneurysm inflow rates. The commonly used zero-pressure approach shows the largest variations, especially for more distal aneurysms. A rank ordering of multiple aneurysms in one patient might still be possible, since the ordering appeared to be independent of the outflow strategy. CONCLUSIONS The results reveal that outlet boundary conditions have a crucial impact on image-based blood flow simulations, especially for multiple aneurysm studies. We could confirm the advantages of the more complex outflow-splitting model (4) including an incremental improvement (5) compared to strategies (1), (2) and (3) for this application scenario. Furthermore, we discourage from using zero-pressure configurations that lack a physiological basis.
Collapse
|
44
|
Voß S, Beuing O, Janiga G, Berg P. Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH)-Phase Ib: Effect of morphology on hemodynamics. PLoS One 2019; 14:e0216813. [PMID: 31100101 PMCID: PMC6524809 DOI: 10.1371/journal.pone.0216813] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 04/29/2019] [Indexed: 12/16/2022] Open
Abstract
Background Image-based blood flow simulations have been increasingly applied to investigate intracranial aneurysm (IA) hemodynamics. However, the acceptance among physicians remains limited due to the high variability in the underlying assumptions and quality of results. Methods To evaluate the vessel segmentation as one of the most important sources of error, the international Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH) was announced. 26 research groups from 13 different countries segmented three datasets, which contained five IAs in total. Based on these segmentations, 73 time-dependent blood flow simulations under consistent conditions were carried out. Afterwards, relevant flow and shear parameters (e.g., neck inflow rate, parent vessel flow rate, spatial mean velocity, and wall shear stress) were analyzed both qualitatively and quantitatively. Results Regarding the entire vasculature, the variability of the segmented vessel radius is 0.13 mm, consistent and independent of the local vessel radius. However, the centerline velocity shows increased variability in more distal vessels. Focusing on the aneurysms, clear differences in morphological and hemodynamic parameters were observed. The quantification of the segmentation-induced variability showed approximately a 14% difference among the groups for the parent vessel flow rate. Regarding the mean aneurysmal velocity and the neck inflow rate, a variation of 30% and 46% was observed, respectively. Finally, time-averaged wall shear stresses varied between 28% and 51%, depending on the aneurysm in question. Conclusions MATCH reveals the effect of state-of-the-art segmentation algorithms on subsequent hemodynamic simulations for IA research. The observed variations may lead to an inappropriate interpretation of the simulation results and thus, can lead to inappropriate conclusions by physicians. Therefore, accurate segmentation of the region of interest is necessary to obtain reliable and clinically helpful flow information.
Collapse
Affiliation(s)
- Samuel Voß
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
- Forschungscampus STIMULATE, Magdeburg, Germany
- * E-mail:
| | - Oliver Beuing
- Forschungscampus STIMULATE, Magdeburg, Germany
- Institute of Neuroradiology, University Hospital Magdeburg, Magdeburg, Germany
| | - Gábor Janiga
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
- Forschungscampus STIMULATE, Magdeburg, Germany
| | - Philipp Berg
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
- Forschungscampus STIMULATE, Magdeburg, Germany
| |
Collapse
|
45
|
Berg P, Voß S, Janiga G, Saalfeld S, Bergersen AW, Valen-Sendstad K, Bruening J, Goubergrits L, Spuler A, Chiu TL, Tsang ACO, Copelli G, Csippa B, Paál G, Závodszky G, Detmer FJ, Chung BJ, Cebral JR, Fujimura S, Takao H, Karmonik C, Elias S, Cancelliere NM, Najafi M, Steinman DA, Pereira VM, Piskin S, Finol EA, Pravdivtseva M, Velvaluri P, Rajabzadeh-Oghaz H, Paliwal N, Meng H, Seshadhri S, Venguru S, Shojima M, Sindeev S, Frolov S, Qian Y, Wu YA, Carlson KD, Kallmes DF, Dragomir-Daescu D, Beuing O. Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH)-phase II: rupture risk assessment. Int J Comput Assist Radiol Surg 2019; 14:1795-1804. [PMID: 31054128 DOI: 10.1007/s11548-019-01986-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 04/23/2019] [Indexed: 01/10/2023]
Abstract
PURPOSE Assessing the rupture probability of intracranial aneurysms (IAs) remains challenging. Therefore, hemodynamic simulations are increasingly applied toward supporting physicians during treatment planning. However, due to several assumptions, the clinical acceptance of these methods remains limited. METHODS To provide an overview of state-of-the-art blood flow simulation capabilities, the Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH) was conducted. Seventeen research groups from all over the world performed segmentations and hemodynamic simulations to identify the ruptured aneurysm in a patient harboring five IAs. Although simulation setups revealed good similarity, clear differences exist with respect to the analysis of aneurysm shape and blood flow results. Most groups (12/71%) included morphological and hemodynamic parameters in their analysis, with aspect ratio and wall shear stress as the most popular candidates, respectively. RESULTS The majority of groups (7/41%) selected the largest aneurysm as being the ruptured one. Four (24%) of the participating groups were able to correctly select the ruptured aneurysm, while three groups (18%) ranked the ruptured aneurysm as the second most probable. Successful selections were based on the integration of clinically relevant information such as the aneurysm site, as well as advanced rupture probability models considering multiple parameters. Additionally, flow characteristics such as the quantification of inflow jets and the identification of multiple vortices led to correct predictions. CONCLUSIONS MATCH compares state-of-the-art image-based blood flow simulation approaches to assess the rupture risk of IAs. Furthermore, this challenge highlights the importance of multivariate analyses by combining clinically relevant metadata with advanced morphological and hemodynamic quantification.
Collapse
Affiliation(s)
| | - Samuel Voß
- University of Magdeburg, Magdeburg, Germany
| | | | | | | | | | | | | | | | | | | | | | - Benjamin Csippa
- Budapest University of Technology and Economics, Budapest, Hungary
| | - György Paál
- Budapest University of Technology and Economics, Budapest, Hungary
| | - Gábor Závodszky
- Budapest University of Technology and Economics, Budapest, Hungary
| | | | | | | | | | | | | | - Saba Elias
- Houston Methodist Research Institute, Houston, TX, USA
| | | | | | | | | | - Senol Piskin
- The University of Texas at San Antonio, San Antonio, TX, USA
| | - Ender A Finol
- The University of Texas at San Antonio, San Antonio, TX, USA
| | | | | | | | | | - Hui Meng
- State University of New York, Buffalo, NY, USA
| | | | | | | | | | | | - Yi Qian
- Macquarie University, Sydney, Australia
| | | | | | | | | | | |
Collapse
|
46
|
Puiseux T, Sewonu A, Meyrignac O, Rousseau H, Nicoud F, Mendez S, Moreno R. Reconciling PC-MRI and CFD: An in-vitro study. NMR IN BIOMEDICINE 2019; 32:e4063. [PMID: 30747461 DOI: 10.1002/nbm.4063] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 11/16/2018] [Accepted: 12/18/2018] [Indexed: 05/25/2023]
Abstract
Several well-resolved 4D Flow MRI acquisitions of an idealized rigid flow phantom featuring an aneurysm, a curved channel as well as a bifurcation were performed under pulsatile regime. The resulting hemodynamics were processed to remove MRI artifacts. Subsequently, they were compared with CFD predictions computed on the same flow domain, using an in-house high-order low dissipative flow solver. Results show that reaching a good agreement is not straightforward but requires proper treatments of both techniques. Several sources of discrepancies are highlighted and their impact on the final correlation evaluated. While a very poor correlation (r2 = 0.63) is found in the entire domain between raw MRI and CFD data, correlation as high as r2 = 0.97 is found when artifacts are removed by post-processing the MR data and down sampling the CFD results to match the MRI spatial and temporal resolutions. This work demonstrates that, in a well-controlled environment, both PC-MRI and CFD might bring reliable and correlated flow quantities when a proper methodology to reduce the errors is followed.
Collapse
Affiliation(s)
- Thomas Puiseux
- IMAG, Univ Montpellier, CNRS, Montpellier, France
- ALARA Expertise, Strasbourg, France
| | - Anou Sewonu
- ALARA Expertise, Strasbourg, France
- I2MC, INSERM U1048, Toulouse, France
| | - Olivier Meyrignac
- I2MC, INSERM U1048, Toulouse, France
- Department of Radiology, CHU de Toulouse, Toulouse, France
| | - Hervé Rousseau
- I2MC, INSERM U1048, Toulouse, France
- Department of Radiology, CHU de Toulouse, Toulouse, France
| | | | - Simon Mendez
- IMAG, Univ Montpellier, CNRS, Montpellier, France
| | - Ramiro Moreno
- ALARA Expertise, Strasbourg, France
- I2MC, INSERM U1048, Toulouse, France
| |
Collapse
|
47
|
Park CS, Alaraj A, Du X, Charbel FT, Linninger AA. An efficient full space-time discretization method for subject-specific hemodynamic simulations of cerebral arterial blood flow with distensible wall mechanics. J Biomech 2019; 87:37-47. [PMID: 30876734 DOI: 10.1016/j.jbiomech.2019.02.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/17/2019] [Accepted: 02/15/2019] [Indexed: 02/07/2023]
Abstract
A computationally inexpensive mathematical solution approach using orthogonal collocations for space discretization with temporal Fourier series is proposed to compute subject-specific blood flow in distensible vessels of large cerebral arterial networks. Several models of wall biomechanics were considered to assess their impact on hemodynamic predictions. Simulations were validated against in vivo blood flow measurements in six human subjects. The average root-mean-square relative differences were found to be less than 4.3% for all subjects with a linear elastic wall model. This discrepancy decreased further in a viscoelastic Kelvin-Voigt biomechanical wall. The results provide support for the use of collocation-Fourier series approach to predict clinically relevant blood flow distribution and collateral blood supply in large portions of the cerebral circulation at reasonable computational costs. It thus opens the possibility of performing computationally inexpensive subject-specific simulations that are robust and fast enough to predict clinical results in real time on the same day.
Collapse
Affiliation(s)
- Chang Sub Park
- Department of Bioengineering, University of Illinois at Chicago, USA
| | - Ali Alaraj
- Department of Neurosurgery, University of Illinois at Chicago, USA
| | - Xinjian Du
- Department of Neurosurgery, University of Illinois at Chicago, USA
| | - Fady T Charbel
- Department of Neurosurgery, University of Illinois at Chicago, USA
| | - Andreas A Linninger
- Department of Bioengineering, University of Illinois at Chicago, USA; Department of Neurosurgery, University of Illinois at Chicago, USA.
| |
Collapse
|
48
|
Shimano K, Serigano S, Ikeda N, Yuchi T, Shiratori S, Nagano H. Understanding of boundary conditions imposed at multiple outlets in computational haemodynamic analysis of cerebral aneurysm. ACTA ACUST UNITED AC 2019. [DOI: 10.17106/jbr.33.32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Kenjiro Shimano
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Shota Serigano
- Graduate School of Integrative Science and Engineering, Tokyo City University
| | - Naoki Ikeda
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Tomoki Yuchi
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Suguru Shiratori
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Hideaki Nagano
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| |
Collapse
|
49
|
Steinman DA, Gallo D, Morbiducci U, Wasserman BA. Letter by Steinman et al Regarding Article, "Wall Shear Stress and T1 Contrast Ratio Are Associated With Embolic Signals During Carotid Exposure in Endarterectomy". Stroke 2018; 49:e341. [PMID: 30571448 DOI: 10.1161/strokeaha.118.023197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- David A Steinman
- Department of Mechanical and Industrial Engineering, University of Toronto, Canada
| | - Diego Gallo
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Italy
| | - Umberto Morbiducci
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Italy
| | - Bruce A Wasserman
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Hospital, Baltimore, MD
| |
Collapse
|
50
|
Suzuki T, Takao H, Fujimura S, Otani K, Uchiyama Y, Tanaka K, Ishibashi T, Mamori H, Murayama Y, Yamamoto M. Multivariate Analysis For Predicting Internal Carotid (IC) And Middle Cerebral (MC) Aneurysmal Rupture By Hemodynamic Parameters. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2018:1339-1342. [PMID: 30440639 DOI: 10.1109/embc.2018.8512450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Currently, aneurysmal rupture can hardly be predicted and the search for an objective and precise indicator is ongoing. The objective of this study was to find a rupture prediction indicator (RPI) based on hemodynamic parameters of unruptured aneurysms focusing on the internal carotid (IC) and middle cerebral (MC) arteries. Computational fluid dynamics simulations were performed and hemodynamic parameters were calculated using three-dimensional C-arm computed tomography (3D C-arm CT) images of a total of 137 unruptured aneurysms (69 IC and 68 MC artery aneurysms) with known outcomes of rupture or unrupture. Multivariate analysis was applied to build an RPI model. The final RPI models contained the pressure-loss coefficient at the time maximum (TMAXPLc). Ruptured aneurysms were found to have lower TMAXPLc than unruptured aneurysms. The mean values were 1.002 (95%CI 0.827 to 1.177) and 1.466 (95%CI 1.352 to 1.579), respectively (P=0.002). TMAXPLc may thus be a useful parameter for rupture prediction of IC and MC artery aneurysms.
Collapse
|