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Yang H, Cho KC, Hong I, Kim Y, Kim YB, Kim JJ, Oh JH. Influence of circle of Willis modeling on hemodynamic parameters in anterior communicating artery aneurysms and recommendations for model selection. Sci Rep 2024; 14:8476. [PMID: 38605063 PMCID: PMC11009257 DOI: 10.1038/s41598-024-59042-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 04/04/2024] [Indexed: 04/13/2024] Open
Abstract
Computational fluid dynamics (CFD) has been utilized to calculate hemodynamic parameters in anterior communicating artery aneurysm (AComA), which is located at a junction between left and right A1 and A2 segments. However, complete or half circle of Willis (CoW) models are used indiscriminately. This study aims to suggest recommendations for determining suitable CoW model. Five patient-specific CoW models with AComA were used, and each model was divided into complete, left-half, and right-half models. After validating the CFD using a flow experiment, the hemodynamic parameters and flow patterns in five AComAs were compared. In four out of five cases, inflow from one A1 side had a dominant influence on the AComA, while both left and right A1 sides affected the AComA in the remaining case. Also, the average difference in time-averaged wall shear stress between the complete and half models for four cases was 4.6%, but it was 62% in the other case. The differences in the vascular resistances of left and right A1 and A2 segments greatly influenced the flow patterns in the AComA. These results may help to enhance clinicians' understanding of blood flow in the brain, leading to improvements in diagnosis and treatment of cerebral aneurysms.
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Affiliation(s)
- Hyeondong Yang
- Department of Mechanical Engineering and BK21 FOUR ERICA-ACE Center, Hanyang University, 55 Hanyangdaehak-Ro, Sangnok-Gu, Ansan, 15588, Gyeonggi-Do, Korea
| | - Kwang-Chun Cho
- Department of Neurosurgery, College of Medicine, Yonsei University, Yongin Severance Hospital, Yongin, Gyeonggi-Do, Korea
| | - Ineui Hong
- Department of Mechanical Engineering and BK21 FOUR ERICA-ACE Center, Hanyang University, 55 Hanyangdaehak-Ro, Sangnok-Gu, Ansan, 15588, Gyeonggi-Do, Korea
| | - Yeonwoo Kim
- Department of Mechanical Engineering and BK21 FOUR ERICA-ACE Center, Hanyang University, 55 Hanyangdaehak-Ro, Sangnok-Gu, Ansan, 15588, Gyeonggi-Do, Korea
| | - Yong Bae Kim
- Department of Neurosurgery, College of Medicine, Yonsei University, Severance Hospital, 50-1 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, Korea
| | - Jung-Jae Kim
- Department of Neurosurgery, College of Medicine, Yonsei University, Severance Hospital, 50-1 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, Korea.
- Department of Anatomy, Graduate School of Medicine, Korea University, 13 Jongam-Ro, Seongbuk-Gu, Seoul, 02841, Korea.
| | - Je Hoon Oh
- Department of Mechanical Engineering and BK21 FOUR ERICA-ACE Center, Hanyang University, 55 Hanyangdaehak-Ro, Sangnok-Gu, Ansan, 15588, Gyeonggi-Do, Korea.
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Goetz A, Jeken-Rico P, Chau Y, Sédat J, Larcher A, Hachem E. Analysis of Intracranial Aneurysm Haemodynamics Altered by Wall Movement. Bioengineering (Basel) 2024; 11:269. [PMID: 38534544 DOI: 10.3390/bioengineering11030269] [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: 01/31/2024] [Revised: 02/27/2024] [Accepted: 03/06/2024] [Indexed: 03/28/2024] Open
Abstract
Computational fluid dynamics is intensively used to deepen our understanding of aneurysm growth and rupture in an attempt to support physicians during therapy planning. Numerous studies assumed fully rigid vessel walls in their simulations, whose sole haemodynamics may fail to provide a satisfactory criterion for rupture risk assessment. Moreover, direct in vivo observations of intracranial aneurysm pulsation were recently reported, encouraging the development of fluid-structure interaction for their modelling and for new assessments. In this work, we describe a new fluid-structure interaction functional setting for the careful evaluation of different aneurysm shapes. The configurations consist of three real aneurysm domes positioned on a toroidal channel. All geometric features, employed meshes, flow quantities, comparisons with the rigid wall model and corresponding plots are provided for the sake of reproducibility. The results emphasise the alteration of flow patterns and haemodynamic descriptors when wall deformations were taken into account compared with a standard rigid wall approach, thereby underlining the impact of fluid-structure interaction modelling.
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Affiliation(s)
- Aurèle Goetz
- Computing and Fluids Research Group, CEMEF, Mines Paris PSL, 06904 Sophia Antipolis, France
| | - Pablo Jeken-Rico
- Computing and Fluids Research Group, CEMEF, Mines Paris PSL, 06904 Sophia Antipolis, France
| | - Yves Chau
- Department of Neuro-Interventional and Vascular Interventional, University Hospital of Nice, 06000 Nice, France
| | - Jacques Sédat
- Department of Neuro-Interventional and Vascular Interventional, University Hospital of Nice, 06000 Nice, France
| | - Aurélien Larcher
- Computing and Fluids Research Group, CEMEF, Mines Paris PSL, 06904 Sophia Antipolis, France
| | - Elie Hachem
- Computing and Fluids Research Group, CEMEF, Mines Paris PSL, 06904 Sophia Antipolis, France
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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.
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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
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Irfan M, Malik KM, Ahmad J, Malik G. StrokeNet: An automated approach for segmentation and rupture risk prediction of intracranial aneurysm. Comput Med Imaging Graph 2023; 108:102271. [PMID: 37556901 DOI: 10.1016/j.compmedimag.2023.102271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/19/2023] [Accepted: 07/05/2023] [Indexed: 08/11/2023]
Abstract
Intracranial Aneurysms (IA) present a complex challenge for neurosurgeons as the risks associated with surgical intervention, such as Subarachnoid Hemorrhage (SAH) mortality and morbidity, may outweigh the benefits of aneurysmal occlusion in some cases. Hence, there is a critical need for developing techniques that assist physicians in assessing the risk of aneurysm rupture to determine which aneurysms require treatment. However, a reliable IA rupture risk prediction technique is currently unavailable. To address this issue, this study proposes a novel approach for aneurysm segmentation and multidisciplinary rupture prediction using 2D Digital Subtraction Angiography (DSA) images. The proposed method involves training a fully connected convolutional neural network (CNN) to segment aneurysm regions in DSA images, followed by extracting and fusing different features using a multidisciplinary approach, including deep features, geometrical features, Fourier descriptor, and shear pressure on the aneurysm wall. The proposed method also adopts a fast correlation-based filter approach to drop highly correlated features from the set of fused features. Finally, the selected fused features are passed through a Decision Tree classifier to predict the rupture severity of the associated aneurysm into four classes: Mild, Moderate, Severe, and Critical. The proposed method is evaluated on a newly developed DSA image dataset and on public datasets to assess its generalizability. The system's performance is also evaluated on DSA images annotated by expert neurosurgeons for the rupture risk assessment of the segmented aneurysm. The proposed system outperforms existing state-of-the-art segmentation methods, achieving an 85 % accuracy against annotated DSA images for the risk assessment of aneurysmal rupture.
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Affiliation(s)
- Muhammad Irfan
- SMILES LAB, Department of Computer Science and Engineering, Oakland University, Rochester, MI, 48309, USA
| | - Khalid Mahmood Malik
- SMILES LAB, Department of Computer Science and Engineering, Oakland University, Rochester, MI, 48309, USA.
| | - Jamil Ahmad
- Department of Computer Vision, Mohamed Bin Zayed University of Artificial Intelligence (MBZUAI), Abu Dhabi, United Arab Emirates
| | - Ghaus Malik
- Executive Vice-Chair at Department of Neurosurgery, Henry Ford Health System, Detroit, MI, USA
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Zhai X, Hu P, Wang Y, Zhang H, Cao L, Huang T, Lu J, Luo Y. Association of local solid mechanical, hemodynamic and morphological characteristics with ruptured intracranial aneurysm. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023; 39:e3674. [PMID: 36541137 DOI: 10.1002/cnm.3674] [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: 07/05/2022] [Revised: 10/31/2022] [Accepted: 12/17/2022] [Indexed: 06/17/2023]
Abstract
The rupture of intracranial aneurysms (IAs) is a complicated phenomenon of which the mechanism is not fully understood. The purpose of this study is to associate local solid mechanical, hemodynamic, and morphological characteristics with rupture regions through statistical means, in an attempt to identify the parameters that are indicative of rupture propensity for IAs. Twenty patient-specific ruptured IA models were reconstructed from digital subtraction angiography (DSA), and applied in the analysis of wall tension, wall shear stress (WSS) and curvature. The precise rupture locations were marked out through intraoperative videos. Pearson correlation analysis was employed to investigate the correlations of these three parameters with patient characteristics and global geometric features. Univariate and multivariate logistic regression analysis were further performed on wall tension, WSS and curvature with regards to rupture and nonrupture regions. Receiver operating characteristic (ROC) analysis defining area under the curve (AUC) was performed on these three parameters. The univariate model of wall tension (AUC, 0.9750), WSS (AUC, 0.9300), curvature (0.8150) and their combined multivariate model (AUC, 0.9875) all present high AUC values. The wall tension, WSS and curvature are acceptable parameters relating to rupture regions. The rupture odd is more sensitive to the wall tension and WSS than curvature. Each logistic model is capable in discriminating ruptures from nonrupture regions, while the multivariate model is the most efficient.
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Affiliation(s)
- Xiaodong Zhai
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- China International Neuroscience Institute (China-INI), Beijing, China
| | - Peng Hu
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- China International Neuroscience Institute (China-INI), Beijing, China
| | - Yadong Wang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- China International Neuroscience Institute (China-INI), Beijing, China
| | - Hongqi Zhang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- China International Neuroscience Institute (China-INI), Beijing, China
| | - Lan Cao
- Boea Wisdom (Hangzhou) Network Technology Co., Ltd., Hangzhou, Zhejiang, China
| | - Tianming Huang
- Boea Wisdom (Hangzhou) Network Technology Co., Ltd., Hangzhou, Zhejiang, China
| | - Jia Lu
- Department of Mechanical Engineering, The University of Iowa, Iowa City, Iowa, USA
| | - Yuanming Luo
- Department of Mechanical Engineering, The University of Iowa, Iowa City, Iowa, USA
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6
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Influence of blood viscosity models and boundary conditions on the computation of hemodynamic parameters in cerebral aneurysms using computational fluid dynamics. Acta Neurochir (Wien) 2023; 165:471-482. [PMID: 36624234 DOI: 10.1007/s00701-022-05467-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 12/21/2022] [Indexed: 01/11/2023]
Abstract
BACKGROUND Computational fluid dynamics (CFD) is widely used to calculate hemodynamic parameters that are known to influence cerebral aneurysms. However, the boundary conditions for CFD are chosen without any specific criteria. Our objective is to establish the recommendations for setting the analysis conditions for CFD analysis of the cerebral aneurysm. METHOD The plug and the Womersley flow were the inlet boundary conditions, and zero and pulsatile pressures were the outlet boundary conditions. In addition, the difference in the assumption of viscosity was analyzed with respect to the flow rate. The CFD process used in our research was validated using particle image velocimetry experiment data from Tupin et al.'s work to ensure the accuracy of the simulations. RESULTS It was confirmed that if the entrance length was sufficiently secured, the inlet and outlet boundary conditions did not affect the CFD results. In addition, it was observed that the difference in the hemodynamic parameter between Newtonian and non-Newtonian fluid decreased as the flow rate increased. Furthermore, it was confirmed that similar tendencies were evaluated when these recommendations were utilized in the patient-specific cerebral aneurysm models. CONCLUSIONS These results may help conduct standardized CFD analyses regardless of the research group.
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7
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Lampropoulos DS, Boutopoulos ID, Bourantas GC, Miller K, Zampakis PE, Loukopoulos VC. Hemodynamics of anterior circulation intracranial aneurysms with daughter blebs: investigating the multidirectionality of blood flow fields. Comput Methods Biomech Biomed Engin 2023; 26:113-125. [PMID: 35297711 DOI: 10.1080/10255842.2022.2048374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Recent advances in diagnostic neuroradiological imaging, allowed the detection of unruptured intracranial aneurysms (IAs). The shape - irregular or multilobular - of the aneurysmal dome, is considered as a possible rupture risk factor, independently of the size, the location and patient medical background. Disturbed blood flow fields in particular is thought to play a key role in IAs progression. However, there is an absence of widely-used hemodynamic indices to quantify the extent of a multi-directional disturbed flow. We simulated blood flow in twelve patient-specific anterior circulation unruptured intracranial aneurysms with daughter blebs utilizing the spectral/hp element framework Nektar++. We simulated three cardiac cycles using a volumetric flow rate waveform while we considered blood as a Newtonian fluid. To investigate the multidirectionality of the blood flow fields, besides the time-averaged wall shear stress (TAWSS), we calculated the oscillatory shear index (OSI), the relative residence time (RRT) and the time-averaged cross flow index (TACFI). Our CFD simulations suggest that in the majority of our vascular models there is a formation of complex intrasaccular flow patterns, resulting to low and highly oscillating WSS, especially in the area of the daughter blebs. The existence of disturbed multi-directional blood flow fields is also evident by the distributions of the RRT and the TACFI. These findings further support the theory that IAs with daughter blebs are linked to a potentially increased rupture risk.
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Affiliation(s)
| | | | - George C Bourantas
- Intelligent Systems for Medicine Laboratory, The University of Western Australia, Perth, Western Australia, Australia
| | - Karol Miller
- Intelligent Systems for Medicine Laboratory, The University of Western Australia, Perth, Western Australia, Australia.,Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Petros E Zampakis
- Department of Diagnostic and Interventional Neuroradiology, University of Patras, Patras, Greece
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Chitwood CA, Shih ED, Amili O, Larson AS, Ogle BM, Alford PW, Grande AW. Biology and Hemodynamics of Aneurysm Rupture. Neurosurg Clin N Am 2022; 33:431-441. [DOI: 10.1016/j.nec.2022.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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9
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Ivantsits M, Goubergrits L, Kuhnigk JM, Huellebrand M, Bruening J, Kossen T, Pfahringer B, Schaller J, Spuler A, Kuehne T, Jia Y, Li X, Shit S, Menze B, Su Z, Ma J, Nie Z, Jain K, Liu Y, Lin Y, Hennemuth A. Detection and analysis of cerebral aneurysms based on X-ray rotational angiography - the CADA 2020 challenge. Med Image Anal 2021; 77:102333. [PMID: 34998111 DOI: 10.1016/j.media.2021.102333] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 10/12/2021] [Accepted: 12/07/2021] [Indexed: 01/10/2023]
Abstract
The Cerebral Aneurysm Detection and Analysis (CADA) challenge was organized to support the development and benchmarking of algorithms for detecting, analyzing, and risk assessment of cerebral aneurysms in X-ray rotational angiography (3DRA) images. 109 anonymized 3DRA datasets were provided for training, and 22 additional datasets were used to test the algorithmic solutions. Cerebral aneurysm detection was assessed using the F2 score based on recall and precision, and the fit of the delivered bounding box was assessed using the distance to the aneurysm. The segmentation quality was measured using the Jaccard index and a combination of different surface distance measures. Systematic errors were analyzed using volume correlation and bias. Rupture risk assessment was evaluated using the F2 score. 158 participants from 22 countries registered for the CADA challenge. The U-Net-based detection solutions presented by the community show similar accuracy compared to experts (F2 score 0.92), with a small number of missed aneurysms with diameters smaller than 3.5 mm. In addition, the delineation of these structures, based on U-Net variations, is excellent, with a Jaccard score of 0.92. The rupture risk estimation methods achieved an F2 score of 0.71. The performance of the detection and segmentation solutions is equivalent to that of human experts. The best results are obtained in rupture risk estimation by combining different image-based, morphological, and computational fluid dynamic parameters using machine learning methods. Furthermore, we evaluated the best methods pipeline, from detecting and delineating the vessel dilations to estimating the risk of rupture. The chain of these methods achieves an F2-score of 0.70, which is comparable to applying the risk prediction to the ground-truth delineation (0.71).
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Affiliation(s)
- Matthias Ivantsits
- Charit Universittsmedizin Berlin, Augustenburger Pl. 1, Berlin 13353, Germany.
| | - Leonid Goubergrits
- Charit Universittsmedizin Berlin, Augustenburger Pl. 1, Berlin 13353, Germany; Einstein Center Digital Future, Wilhelmstrae 67, Berlin 10117, Germany
| | | | - Markus Huellebrand
- Charit Universittsmedizin Berlin, Augustenburger Pl. 1, Berlin 13353, Germany; Fraunhofer MEVIS, Am Fallturm 1, Bremen 28359, Germany
| | - Jan Bruening
- Charit Universittsmedizin Berlin, Augustenburger Pl. 1, Berlin 13353, Germany
| | - Tabea Kossen
- Charit Universittsmedizin Berlin, Augustenburger Pl. 1, Berlin 13353, Germany
| | - Boris Pfahringer
- Charit Universittsmedizin Berlin, Augustenburger Pl. 1, Berlin 13353, Germany
| | - Jens Schaller
- Charit Universittsmedizin Berlin, Augustenburger Pl. 1, Berlin 13353, Germany
| | - Andreas Spuler
- Helios Hospital Berlin-Buch, Schwanebecker Chaussee 50, Berlin 13125, Germany
| | - Titus Kuehne
- Charit Universittsmedizin Berlin, Augustenburger Pl. 1, Berlin 13353, Germany; German Heart Centre Berlin, Augustenburger Pl. 1, Berlin 13353, Germany; DZHK (German Centre for Cardiovascular Research), Berlin, Germany
| | - Yizhuan Jia
- Mediclouds Medical Technology, Beijing, China
| | - Xuesong Li
- School of Computer Science and Technology, Beijing Institute of Technology, Beijing, China
| | - Suprosanna Shit
- Departments of Informatics, Technical University Munich, Germany; TranslaTUM Center for Translational Cancer Research, Munich, Germany
| | - Bjoern Menze
- Departments of Informatics, Technical University Munich, Germany; TranslaTUM Center for Translational Cancer Research, Munich, Germany; Department of Quantitative Biomedicine of UZH, Zurich, Switzerland
| | - Ziyu Su
- School of Computer Science and Technology, Beijing Institute of Technology, Beijing, China
| | - Jun Ma
- Department of Mathematics, Nanjing University of Science and Technology, Nanjing, China
| | - Ziwei Nie
- Department of Mathematics, Nanjing University, Nanjing, China
| | - Kartik Jain
- Faculty of Engineering Technology, University of Twente, P.O. Box 217, Enschede 7500, AE, the Netherlands
| | - Yanfei Liu
- Jarvis Lab, Tencent, Shenzhen, China; Shenzhen United Imaging Research Institute of Innovative Medical Equipment Innovation Research, Shenzhen, China
| | - Yi Lin
- Jarvis Lab, Tencent, Shenzhen, China
| | - Anja Hennemuth
- Charit Universittsmedizin Berlin, Augustenburger Pl. 1, Berlin 13353, Germany; Fraunhofer MEVIS, Am Fallturm 1, Bremen 28359, Germany; German Heart Centre Berlin, Augustenburger Pl. 1, Berlin 13353, Germany; DZHK (German Centre for Cardiovascular Research), Berlin, Germany
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10
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Shi L, Laramee RS, Chen G. Integral Curve Clustering and Simplification for Flow Visualization: A Comparative Evaluation. IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2021; 27:1967-1985. [PMID: 31514143 DOI: 10.1109/tvcg.2019.2940935] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Unsupervised clustering techniques have been widely applied to flow simulation data to alleviate clutter and occlusion in the resulting visualization. However, there is an absence of systematic guidelines for users to evaluate (both quantitatively and visually) the appropriate clustering technique and similarity measures for streamline and pathline curves. In this work, we provide an overview of a number of prevailing curve clustering techniques. We then perform a comprehensive experimental study to qualitatively and quantitatively compare these clustering techniques coupled with popular similarity measures used in the flow visualization literature. Based on our experimental results, we derive empirical guidelines for selecting the appropriate clustering technique and similarity measure given the requirements of the visualization task. We believe our work will inform the task of generating meaningful reduced representations for large-scale flow data and inspire the continuous investigation of a more refined guidance on clustering technique selection.
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Soldozy S, Norat P, Elsarrag M, Chatrath A, Costello JS, Sokolowski JD, Tvrdik P, Kalani MYS, Park MS. The biophysical role of hemodynamics in the pathogenesis of cerebral aneurysm formation and rupture. Neurosurg Focus 2020; 47:E11. [PMID: 31261115 DOI: 10.3171/2019.4.focus19232] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 04/18/2019] [Indexed: 11/06/2022]
Abstract
The pathogenesis of intracranial aneurysms remains complex and multifactorial. While vascular, genetic, and epidemiological factors play a role, nascent aneurysm formation is believed to be induced by hemodynamic forces. Hemodynamic stresses and vascular insults lead to additional aneurysm and vessel remodeling. Advanced imaging techniques allow us to better define the roles of aneurysm and vessel morphology and hemodynamic parameters, such as wall shear stress, oscillatory shear index, and patterns of flow on aneurysm formation, growth, and rupture. While a complete understanding of the interplay between these hemodynamic variables remains elusive, the authors review the efforts that have been made over the past several decades in an attempt to elucidate the physical and biological interactions that govern aneurysm pathophysiology. Furthermore, the current clinical utility of hemodynamics in predicting aneurysm rupture is discussed.
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12
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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.
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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
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13
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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.
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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
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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.
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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
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Lipp SN, Niedert EE, Cebull HL, Diorio TC, Ma JL, Rothenberger SM, Stevens Boster KA, Goergen CJ. Computational Hemodynamic Modeling of Arterial Aneurysms: A Mini-Review. Front Physiol 2020; 11:454. [PMID: 32477163 PMCID: PMC7235429 DOI: 10.3389/fphys.2020.00454] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 04/09/2020] [Indexed: 01/02/2023] Open
Abstract
Arterial aneurysms are pathological dilations of blood vessels, which can be of clinical concern due to thrombosis, dissection, or rupture. Aneurysms can form throughout the arterial system, including intracranial, thoracic, abdominal, visceral, peripheral, or coronary arteries. Currently, aneurysm diameter and expansion rates are the most commonly used metrics to assess rupture risk. Surgical or endovascular interventions are clinical treatment options, but are invasive and associated with risk for the patient. For aneurysms in locations where thrombosis is the primary concern, diameter is also used to determine the level of therapeutic anticoagulation, a treatment that increases the possibility of internal bleeding. Since simple diameter is often insufficient to reliably determine rupture and thrombosis risk, computational hemodynamic simulations are being developed to help assess when an intervention is warranted. Created from subject-specific data, computational models have the potential to be used to predict growth, dissection, rupture, and thrombus-formation risk based on hemodynamic parameters, including wall shear stress, oscillatory shear index, residence time, and anomalous blood flow patterns. Generally, endothelial damage and flow stagnation within aneurysms can lead to coagulation, inflammation, and the release of proteases, which alter extracellular matrix composition, increasing risk of rupture. In this review, we highlight recent work that investigates aneurysm geometry, model parameter assumptions, and other specific considerations that influence computational aneurysm simulations. By highlighting modeling validation and verification approaches, we hope to inspire future computational efforts aimed at improving our understanding of aneurysm pathology and treatment risk stratification.
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Affiliation(s)
- Sarah N Lipp
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Elizabeth E Niedert
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Hannah L Cebull
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Tyler C Diorio
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Jessica L Ma
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Sean M Rothenberger
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Kimberly A Stevens Boster
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States.,School of Mechanical Engineering, Purdue University, West Lafayette, IN, United States
| | - Craig J Goergen
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
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Lassila T, Sarrami-Foroushani A, Hejazi S, Frangi AF. Population-specific modelling of between/within-subject flow variability in the carotid arteries of the elderly. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3271. [PMID: 31691518 DOI: 10.1002/cnm.3271] [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: 01/03/2019] [Revised: 09/12/2019] [Accepted: 09/22/2019] [Indexed: 06/10/2023]
Abstract
Computational fluid dynamics models are increasingly proposed for assisting the diagnosis and management of vascular diseases. Ideally, patient-specific flow measurements are used to impose flow boundary conditions. When patient-specific flow measurements are unavailable, mean values of flow measurements across small cohorts are used as normative values. In reality, both the between-subjects and within-subject flow variabilities are large. Consequently, neither one-shot flow measurements nor mean values across a cohort are truly indicative of the flow regime in a given person. We develop models for both the between-subjects and within-subject variability of internal carotid flow. A log-linear mixed effects model is combined with a Gaussian process to model the between-subjects flow variability, while a lumped parameter model of cerebral autoregulation is used to model the within-subject flow variability in response to heart rate and blood pressure changes. The model parameters are identified from carotid ultrasound measurements in a cohort of 103 elderly volunteers. We use the models to study intracranial aneurysm flow in 54 subjects under rest and exercise and conclude that OSI, a common wall shear-stress derived quantity in vascular CFD studies, may be too sensitive to flow fluctuations to be a reliable biomarker.
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Affiliation(s)
- Toni Lassila
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds
| | - Ali Sarrami-Foroushani
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds
| | - SeyedMostafa Hejazi
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds
| | - Alejandro F Frangi
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds
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17
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Transient flow prediction in an idealized aneurysm geometry using data assimilation. Comput Biol Med 2019; 115:103507. [DOI: 10.1016/j.compbiomed.2019.103507] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/27/2019] [Accepted: 10/12/2019] [Indexed: 01/01/2023]
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18
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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.
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Computational methods applied to analyze the hemodynamic effects of flow-diverter devices in the treatment of cerebral aneurysms: Current status and future directions. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2019. [DOI: 10.1016/j.medntd.2019.100018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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20
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Meuschke M, Oeltze-Jafra S, Beuing O, Preim B, Lawonn K. Classification of Blood Flow Patterns in Cerebral Aneurysms. IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2019; 25:2404-2418. [PMID: 29994310 DOI: 10.1109/tvcg.2018.2834923] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present a Cerebral Aneurysm Vortex Classification (CAVOCLA) that allows to classify blood flow in cerebral aneurysms. Medical studies assume a strong relation between the progression and rupture of aneurysms and flow patterns. To understand how flow patterns impact the vessel morphology, they are manually classified according to predefined classes. However, manual classifications are time-consuming and exhibit a high inter-observer variability. In contrast, our approach is more objective and faster than manual methods. The classification of integral lines, representing steady or unsteady blood flow, is based on a mapping of the aneurysm surface to a hemisphere by calculating polar-based coordinates. The lines are clustered and for each cluster a representative is calculated. Then, the polar-based coordinates are transformed to the representative as basis for the classification. Classes are based on the flow complexity. The classification results are presented by a detail-on-demand approach using a visual transition from the representative over an enclosing surface to the associated lines. Based on seven representative datasets, we conduct an informal interview with five domain experts to evaluate the system. They confirmed that CAVOCLA allows for a robust classification of intra-aneurysmal flow patterns. The detail-on-demand visualization enables an efficient exploration and interpretation of flow patterns.
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21
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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.
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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
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22
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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.
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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
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Novel feature-based visualization of the unsteady blood flow in intracranial aneurysms with the help of proper orthogonal decomposition (POD). Comput Med Imaging Graph 2019; 73:30-38. [DOI: 10.1016/j.compmedimag.2019.01.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 12/07/2018] [Accepted: 01/11/2019] [Indexed: 11/22/2022]
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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
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Real-World Variability in the Prediction of Intracranial Aneurysm Wall Shear Stress: The 2015 International Aneurysm CFD Challenge. Cardiovasc Eng Technol 2018; 9:544-564. [PMID: 30203115 PMCID: PMC6290689 DOI: 10.1007/s13239-018-00374-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Accepted: 08/11/2018] [Indexed: 11/04/2022]
Abstract
Purpose Image-based computational fluid dynamics (CFD) is widely used to predict intracranial aneurysm wall shear stress (WSS), particularly with the goal of improving rupture risk assessment. Nevertheless, concern has been expressed over the variability of predicted WSS and inconsistent associations with rupture. Previous challenges, and studies from individual groups, have focused on individual aspects of the image-based CFD pipeline. The aim of this Challenge was to quantify the total variability of the whole pipeline. Methods 3D rotational angiography image volumes of five middle cerebral artery aneurysms were provided to participants, who were free to choose their segmentation methods, boundary conditions, and CFD solver and settings. Participants were asked to fill out a questionnaire about their solution strategies and experience with aneurysm CFD, and provide surface distributions of WSS magnitude, from which we objectively derived a variety of hemodynamic parameters. Results A total of 28 datasets were submitted, from 26 teams with varying levels of self-assessed experience. Wide variability of segmentations, CFD model extents, and inflow rates resulted in interquartile ranges of sac average WSS up to 56%, which reduced to < 30% after normalizing by parent artery WSS. Sac-maximum WSS and low shear area were more variable, while rank-ordering of cases by low or high shear showed only modest consensus among teams. Experience was not a significant predictor of variability. Conclusions Wide variability exists in the prediction of intracranial aneurysm WSS. While segmentation and CFD solver techniques may be difficult to standardize across groups, our findings suggest that some of the variability in image-based CFD could be reduced by establishing guidelines for model extents, inflow rates, and blood properties, and by encouraging the reporting of normalized hemodynamic parameters.
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Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH): Phase I: Segmentation. Cardiovasc Eng Technol 2018; 9:565-581. [DOI: 10.1007/s13239-018-00376-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/20/2018] [Indexed: 10/28/2022]
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Botti L, Paliwal N, Conti P, Antiga L, Meng H. Modeling hemodynamics in intracranial aneurysms: Comparing accuracy of CFD solvers based on finite element and finite volume schemes. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e3111. [PMID: 29858530 PMCID: PMC6378953 DOI: 10.1002/cnm.3111] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 05/25/2018] [Accepted: 05/27/2018] [Indexed: 06/08/2023]
Abstract
Image-based computational fluid dynamics (CFD) has shown potential to aid in the clinical management of intracranial aneurysms, but its adoption in the clinical practice has been missing, partially because of lack of accuracy assessment and sensitivity analysis. To numerically solve the flow-governing equations, CFD solvers generally rely on 2 spatial discretization schemes: finite volume (FV) and finite element (FE). Since increasingly accurate numerical solutions are obtained by different means, accuracies and computational costs of FV and FE formulations cannot be compared directly. To this end, in this study, we benchmark 2 representative CFD solvers in simulating flow in a patient-specific intracranial aneurysm model: (1) ANSYS Fluent, a commercial FV-based solver, and (2) VMTKLab multidGetto, a discontinuous Galerkin (dG) FE-based solver. The FV solver's accuracy is improved by increasing the spatial mesh resolution (134k, 1.1m, 8.6m, and 68.5m tetrahedral element meshes). The dGFE solver accuracy is increased by increasing the degree of polynomials (first, second, third, and fourth degree) on the base 134k tetrahedral element mesh. Solutions from best FV and dGFE approximations are used as baseline for error quantification. On average, velocity errors for second-best approximations are approximately 1 cm/s for a [0,125] cm/s velocity magnitude field. Results show that high-order dGFE provides better accuracy per degree of freedom but worse accuracy per Jacobian nonzero entry as compared with FV. Cross-comparison of velocity errors demonstrates asymptotic convergence of both solvers to the same numerical solution. Nevertheless, the discrepancy between underresolved velocity fields suggests that mesh independence is reached following different paths.
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Affiliation(s)
- Lorenzo Botti
- Department of Engineering and Applied Sciences, University of Bergamo, Bergamo, Italy
| | - Nikhil Paliwal
- Toshiba Stroke and Vascular Research Center, University of Buffalo, Buffalo, NY, USA
- Department of Neurosurgery, University at Buffalo, Buffalo, NY, USA
| | - Pierangelo Conti
- Department of Engineering and Applied Sciences, University of Bergamo, Bergamo, Italy
| | | | - Hui Meng
- Toshiba Stroke and Vascular Research Center, University of Buffalo, Buffalo, NY, USA
- Department of Neurosurgery, University at Buffalo, Buffalo, NY, USA
- Department of Mechanical and Aerospace Engineering, University of Buffalo, Buffalo, NY, USA
- Department of Biomedical Engineering, University at Buffalo, Buffalo, NY, USA
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Roloff C, Stucht D, Beuing O, Berg P. Comparison of intracranial aneurysm flow quantification techniques: standard PIV vs stereoscopic PIV vs tomographic PIV vs phase-contrast MRI vs CFD. J Neurointerv Surg 2018; 11:275-282. [DOI: 10.1136/neurintsurg-2018-013921] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 06/22/2018] [Accepted: 06/29/2018] [Indexed: 12/21/2022]
Abstract
Image-based hemodynamic simulations to assess the rupture risk or improve the treatment planning of intracranial aneurysms have become popular recently. However, due to strong modeling assumptions and limitations, the acceptance of numerical approaches remains limited. Therefore, validation using experimental methods is mandatory.In this study, a unique compilation of four in-vitro flow measurements (three particle image velocimetry approaches using a standard (PIV), stereoscopic (sPIV), and tomographic (tPIV) setup, as well as a phase-contrast magnetic resonance imaging (PC-MRI) measurement) were compared with a computational fluid dynamics (CFD) simulation. This was carried out in a patient-specific silicone phantom model of an internal carotid artery aneurysm under steady flow conditions. To evaluate differences between each technique, a similarity index (SI) with respect to the velocity vectors and the average velocity magnitude differences among all involved modalities were computed.The qualitative comparison reveals that all techniques are able to provide a reasonable description of the global flow structures. High quantitative agreement in terms of SI and velocity magnitude differences was found between all PIV methods and CFD. However, quantitative differences were observed between PC-MRI and the other techniques. Deeper analysis revealed that the limited resolution of the PC-MRI technique is a major contributor to the experienced differences and leads to a systematic underestimation of overall velocity magnitude levels inside the vessel. This confirms the necessity of using highly resolving flow measurement techniques, such as PIV, in an in-vitro environment to individually verify the validity of the numerically obtained hemodynamic results.
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Chnafa C, Brina O, Pereira VM, Steinman DA. Better Than Nothing: A Rational Approach for Minimizing the Impact of Outflow Strategy on Cerebrovascular Simulations. AJNR Am J Neuroradiol 2018; 39:337-343. [PMID: 29269407 DOI: 10.3174/ajnr.a5484] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 10/13/2017] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Computational fluid dynamics simulations of neurovascular diseases are impacted by various modeling assumptions and uncertainties, including outlet boundary conditions. Many studies of intracranial aneurysms, for example, assume zero pressure at all outlets, often the default ("do-nothing") strategy, with no physiological basis. Others divide outflow according to the outlet diameters cubed, nominally based on the more physiological Murray's law but still susceptible to subjective choices about the segmented model extent. Here we demonstrate the limitations and impact of these outflow strategies, against a novel "splitting" method introduced here. MATERIALS AND METHODS With our method, the segmented lumen is split into its constituent bifurcations, where flow divisions are estimated locally using a power law. Together these provide the global outflow rate boundary conditions. The impact of outflow strategy on flow rates was tested for 70 cases of MCA aneurysm with 0D simulations. The impact on hemodynamic indices used for rupture status assessment was tested for 10 cases with 3D simulations. RESULTS Differences in flow rates among the various strategies were up to 70%, with a non-negligible impact on average and oscillatory wall shear stresses in some cases. Murray-law and splitting methods gave flow rates closest to physiological values reported in the literature; however, only the splitting method was insensitive to arbitrary truncation of the model extent. CONCLUSIONS Cerebrovascular simulations can depend strongly on the outflow strategy. The default zero-pressure method should be avoided in favor of Murray-law or splitting methods, the latter being released as an open-source tool to encourage the standardization of outflow strategies.
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Affiliation(s)
- C Chnafa
- From the Biomedical Simulation Laboratory (C.C., D.A.S.), Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - O Brina
- Joint Division of Medical Imaging (O.B., V.M.P.), Department of Medical Imaging and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University Health Network, and University of Toronto, Toronto, Ontario, Canada
| | - V M Pereira
- Joint Division of Medical Imaging (O.B., V.M.P.), Department of Medical Imaging and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University Health Network, and University of Toronto, Toronto, Ontario, Canada
| | - D A Steinman
- From the Biomedical Simulation Laboratory (C.C., D.A.S.), Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
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Chnafa C, Bouillot P, Brina O, Delattre BMA, Vargas MI, Lovblad KO, Pereira VM, Steinman DA. Vessel calibre and flow splitting relationships at the internal carotid artery terminal bifurcation. Physiol Meas 2017; 38:2044-2057. [DOI: 10.1088/1361-6579/aa92bf] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Xiang J, Varble N, Davies JM, Rai AT, Kono K, Sugiyama SI, Binning MJ, Tawk RG, Choi H, Ringer AJ, Snyder KV, Levy EI, Hopkins LN, Siddiqui AH, Meng H. Initial Clinical Experience with AView-A Clinical Computational Platform for Intracranial Aneurysm Morphology, Hemodynamics, and Treatment Management. World Neurosurg 2017; 108:534-542. [PMID: 28919570 DOI: 10.1016/j.wneu.2017.09.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 12/17/2022]
Abstract
BACKGROUND The management of intracranial aneurysm (IA) is challenging. Clinicians often rely on varied and intuitively disparate ways of evaluating rupture risk that may only partially take into account complex hemodynamic and morphologic factors. We developed a prototype of a clinically oriented, streamlined, computational platform, AView, for rapid assessment of hemodynamics and morphometrics in clinical settings. To show the potential clinical utility of AView, we report our initial multicenter experience highlighting the possible advantages of morphologic and hemodynamic analysis of IAs. METHODS AView software was deployed across 8 medical centers (6 in the United States, 2 in Japan). Eight clinicians were trained and used the AView software between September 2012 and January 2013. RESULTS We present 12 illustrative cases that show the potential clinical utility of AView. For all, morphology and hemodynamics, flow visualization, and rupture resemblance score (a surrogate for rupture risk) were provided. In 3 cases, AView could confirm the clinicians' decision to treat; in 3 cases, it could suggest which aneurysms may be at greater risk among multiple aneurysms; in 5 cases, AView could provide additional information for use during treatment decisions for ambiguous situations. In one stent-assisted coiling case, flow visualization predicted that the intuitive choice for stent placement could have resulted in sacrifice of an anterior cerebral artery due to blockage by coils and led clinicians to reconsider treatment plans. CONCLUSIONS AView has the potential to confirm decisions to treat IAs, suggest which among multiple aneurysms to treat, and guide treatment decisions. Furthermore, the flow visualization it affords can inform aneurysm treatment planning and potentially avoid poor outcomes.
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Affiliation(s)
- Jianping Xiang
- Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Neurosurgery, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - Nicole Varble
- Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Mechanical and Aerospace Engineering, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - Jason M Davies
- Department of Neurosurgery, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Biomedical Informatics, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - Ansaar T Rai
- Department of Neurosurgery, West Virginia University, Morgantown, West Virginia, USA
| | - Kenichi Kono
- Department of Neurosurgery, Wakayama Rosai Hospital, Wakayama, Japan
| | | | - Mandy J Binning
- Capital Institute of Neurosciences, Capital Health Systems, Trenton, New Jersey, USA
| | - Rabih G Tawk
- Department of Neurosurgery, Mayo Clinic, Jacksonville, Florida, USA
| | - Hoon Choi
- Department of Neurosurgery, SUNY Upstate University Hospital, Syracuse, New York, USA
| | - Andrew J Ringer
- Department of Neurosurgery, Mayfield Clinic, TriHealth Health System, Cincinnati, Ohio, USA
| | - Kenneth V Snyder
- Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Neurosurgery, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Radiology, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - Elad I Levy
- Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Neurosurgery, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Radiology, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - L Nelson Hopkins
- Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Neurosurgery, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Radiology, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - Adnan H Siddiqui
- Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Neurosurgery, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Radiology, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - Hui Meng
- Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Neurosurgery, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Mechanical and Aerospace Engineering, University at Buffalo, State University of New York, Buffalo, New York, USA; Department of Biomedical Engineering, University at Buffalo, State University of New York, Buffalo, New York, USA.
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Berg P, Beuing O. Multiple intracranial aneurysms: a direct hemodynamic comparison between ruptured and unruptured vessel malformations. Int J Comput Assist Radiol Surg 2017; 13:83-93. [PMID: 28733907 DOI: 10.1007/s11548-017-1643-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 07/11/2017] [Indexed: 11/27/2022]
Abstract
PURPOSE Despite numerous studies addressing the rupture risk of intracranial aneurysms that have been published, the assessment thereof still remains challenging. Image-based simulations enable a precise prediction of patient-specific blood flow information. However, those approaches normally consider only small segments of the complete cerebral vasculature. METHODS To test the validity of the consideration of single aneurysms in one computational setup, domains of the complete anterior and posterior circulations with multiple intracranial aneurysms (MIA) were simulated. Six patients with MIA were investigated, while 3D surfaces of eleven unruptured and six ruptured aneurysms were segmented. The segmentations were used for the determination of morphological parameters and also for image-based blood flow simulations used to characterize the hemodynamic properties of each aneurysm. RESULTS In the geometric comparison, neck aspect ratios of unruptured and ruptured aneurysms did not differ significantly. In contrast, size ratios, aspect ratios, surface areas, volumes, and non-sphericity indices were significantly higher in the ruptured cases. The analysis of hemodynamic parameters demonstrated that in each patient, the ruptured aneurysm exhibited the lowest averaged wall shear stresses and highest oscillatory shears. Unstable flow was also detected in ruptured aneurysms based on increased oscillatory velocity. CONCLUSION In this small study involving patients with MIA, different morphologies and flow patterns were observed between ruptured and unruptured aneurysms. The analysis of the hemodynamics in such patients revealed a good agreement with studies that only considered single malformations. Additionally, complex flow patterns are detected in ruptured cases, which require deeper investigation.
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Affiliation(s)
- Philipp Berg
- Laboratory of Fluid Dynamics and Technical Flows, University of Magdeburg "Otto von Guericke", Universitätsplatz 2, 39106, Magdeburg, Germany.
| | - Oliver Beuing
- Institute of Neuroradiology, University Hospital Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany
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Sarrami-Foroushani A, Lassila T, Frangi AF. Virtual endovascular treatment of intracranial aneurysms: models and uncertainty. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2017; 9. [PMID: 28488754 DOI: 10.1002/wsbm.1385] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 01/09/2017] [Accepted: 02/07/2017] [Indexed: 01/11/2023]
Abstract
Virtual endovascular treatment models (VETMs) have been developed with the view to aid interventional neuroradiologists and neurosurgeons to pre-operatively analyze the comparative efficacy and safety of endovascular treatments for intracranial aneurysms. Based on the current state of VETMs in aneurysm rupture risk stratification and in patient-specific prediction of treatment outcomes, we argue there is a need to go beyond personalized biomechanical flow modeling assuming deterministic parameters and error-free measurements. The mechanobiological effects associated with blood clot formation are important factors in therapeutic decision making and models of post-treatment intra-aneurysmal biology and biochemistry should be linked to the purely hemodynamic models to improve the predictive power of current VETMs. The influence of model and parameter uncertainties associated to each component of a VETM is, where feasible, quantified via a random-effects meta-analysis of the literature. This allows estimating the pooled effect size of these uncertainties on aneurysmal wall shear stress. From such meta-analyses, two main sources of uncertainty emerge where research efforts have so far been limited: (1) vascular wall distensibility, and (2) intra/intersubject systemic flow variations. In the future, we suggest that current deterministic computational simulations need to be extended with strategies for uncertainty mitigation, uncertainty exploration, and sensitivity reduction techniques. WIREs Syst Biol Med 2017, 9:e1385. doi: 10.1002/wsbm.1385 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Ali Sarrami-Foroushani
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
| | - Toni Lassila
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
| | - Alejandro F Frangi
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
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Berg P, Saalfeld S, Voß S, Redel T, Preim B, Janiga G, Beuing O. Does the DSA reconstruction kernel affect hemodynamic predictions in intracranial aneurysms? An analysis of geometry and blood flow variations. J Neurointerv Surg 2017; 10:290-296. [PMID: 28465404 DOI: 10.1136/neurintsurg-2017-012996] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 03/29/2017] [Accepted: 04/13/2017] [Indexed: 11/04/2022]
Abstract
BACKGROUND Computational fluid dynamics (CFD) blood flow predictions in intracranial aneurysms promise great potential to reveal patient-specific flow structures. Since the workflow from image acquisition to the final result includes various processing steps, quantifications of the individual introduced potential error sources are required. METHODS Three-dimensional (3D) reconstruction of the acquired imaging data as input to 3D model generation was evaluated. Six different reconstruction modes for 3D digital subtraction angiography (DSA) acquisitions were applied to eight patient-specific aneurysms. Segmentations were extracted to compare the 3D luminal surfaces. Time-dependent CFD simulations were carried out in all 48 configurations to assess the velocity and wall shear stress (WSS) variability due to the choice of reconstruction kernel. RESULTS All kernels yielded good segmentation agreement in the parent artery; deviations of the luminal surface were present at the aneurysm neck (up to 34.18%) and in distal or perforating arteries. Observations included pseudostenoses as well as noisy surfaces, depending on the selected reconstruction kernel. Consequently, the hemodynamic predictions show a mean SD of 11.09% for the aneurysm neck inflow rate, 5.07% for the centerline-based velocity magnitude, and 17.83%/9.53% for the mean/max aneurysmal WSS, respectively. In particular, vessel sections distal to the aneurysms yielded stronger variations of the CFD values. CONCLUSIONS The choice of reconstruction kernel for DSA data influences the segmentation result, especially for small arteries. Therefore, if precise morphology measurements or blood flow descriptions are desired, a specific reconstruction setting is required. Furthermore, research groups should be encouraged to denominate the kernel types used in future hemodynamic studies.
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Affiliation(s)
- P Berg
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - S Saalfeld
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - S Voß
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - T Redel
- Siemens Healthcare GmbH, Forchheim, Germany
| | - B Preim
- Department of Simulation and Graphics, University of Magdeburg, Magdeburg, Germany
| | - G Janiga
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - O Beuing
- Institute of Neuroradiology, University Hospital Magdeburg, Magdeburg, Germany
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Impact of Using Conventional Inlet/Outlet Boundary Conditions on Haemodynamic Metrics in a Subject-Specific Rabbit Aorta. Proc Inst Mech Eng H 2017; 232:103-113. [DOI: 10.1177/0954411917699237] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Computational fluid dynamics is a tool capable of accurately measuring metrics currently used to predict the behaviour of cardiovascular diseases. This study quantifies the impact various commonly used inlet and outlet boundary conditions have on various shear rate–based haemodynamic metrics currently used for predicting the localisation of cardiovascular diseases. Simulations are conducted on an accurately represented rabbit aorta configuration and comparison has been made against available in vivo data. The boundary conditions studied include two different inlet profiles, three outlet boundary conditions, and steady-state versus pulsatile flow cases. Large variations were found in the results, particularly when using different outlet boundary conditions, and the discrepancies were evaluated both quantitatively and qualitatively. The results clearly highlight the importance of the type of boundary condition used when simulating complex cardiovascular models. By restricting the attention to the flow within the aorta and the intercostal branches, the results suggest that prescribing transient simulation and fully developed flow at the inlet are not required. Furthermore, assuming the widely accepted low wall shear stress theory of Caro, it was found that Murray’s law–based outlet boundary condition returns the most physiologically accurate results when compared to in vivo data.
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Meuschke M, Voss S, Beuing O, Preim B, Lawonn K. Combined Visualization of Vessel Deformation and Hemodynamics in Cerebral Aneurysms. IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2017; 23:761-770. [PMID: 27875190 DOI: 10.1109/tvcg.2016.2598795] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present the first visualization tool that combines patient-specific hemodynamics with information about the vessel wall deformation and wall thickness in cerebral aneurysms. Such aneurysms bear the risk of rupture, whereas their treatment also carries considerable risks for the patient. For the patient-specific rupture risk evaluation and treatment analysis, both morphological and hemodynamic data have to be investigated. Medical researchers emphasize the importance of analyzing correlations between wall properties such as the wall deformation and thickness, and hemodynamic attributes like the Wall Shear Stress and near-wall flow. Our method uses a linked 2.5D and 3D depiction of the aneurysm together with blood flow information that enables the simultaneous exploration of wall characteristics and hemodynamic attributes during the cardiac cycle. We thus offer medical researchers an effective visual exploration tool for aneurysm treatment risk assessment. The 2.5D view serves as an overview that comprises a projection of the vessel surface to a 2D map, providing an occlusion-free surface visualization combined with a glyph-based depiction of the local wall thickness. The 3D view represents the focus upon which the data exploration takes place. To support the time-dependent parameter exploration and expert collaboration, a camera path is calculated automatically, where the user can place landmarks for further exploration of the properties. We developed a GPU-based implementation of our visualizations with a flexible interactive data exploration mechanism. We designed our techniques in collaboration with domain experts, and provide details about the evaluation.
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Daughter Sac Formation Related to Blood Inflow Jet in an Intracranial Aneurysm. World Neurosurg 2016; 96:396-402. [DOI: 10.1016/j.wneu.2016.09.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 09/08/2016] [Accepted: 09/08/2016] [Indexed: 10/21/2022]
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Can A, Du R. Association of Hemodynamic Factors With Intracranial Aneurysm Formation and Rupture: Systematic Review and Meta-analysis. Neurosurgery 2016; 78:510-20. [PMID: 26516819 DOI: 10.1227/neu.0000000000001083] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Recent evidence suggests a link between the magnitude and distribution of hemodynamic factors and the formation and rupture of intracranial aneurysms. However, there are many conflicting results. OBJECTIVE To quantify the effect of hemodynamic factors on aneurysm formation and their association with ruptured aneurysms. METHODS We performed a systematic review and meta-analysis through October 2014. Analysis of the effects of hemodynamic factors on aneurysm formation was performed by pooling the results of studies that compared geometrical models of intracranial aneurysms and "preaneurysm" models where the aneurysm was artificially removed. Furthermore, we calculated pooled standardized mean differences between ruptured and unruptured aneurysms to quantify the association of hemodynamic factors with ruptured aneurysms. Standard PRISMA guidelines were followed. RESULTS The hemodynamic factors that showed high positive correlations with location of aneurysm formation were high wall shear stress (WSS) and high gradient oscillatory number, with pooled proportions of 78.8% and 85.7%, respectively. Positive correlations were largely seen in bifurcation aneurysms, whereas negative correlations were seen in sidewall aneurysms. Mean and normalized WSS were significantly lower and low shear area significantly higher in ruptured aneurysms. CONCLUSION Pooled analyses of computational fluid dynamics models suggest that an increase in WSS and gradient oscillatory number may contribute to aneurysm formation, whereas low WSS is associated with ruptured aneurysms. The location of the aneurysm at the bifurcation or sidewall may influence the correlation of these hemodynamic factors.
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Affiliation(s)
- Anil Can
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
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Sugiyama SI, Niizuma K, Sato K, Rashad S, Kohama M, Endo H, Endo T, Matsumoto Y, Ohta M, Tominaga T. Blood Flow Into Basilar Tip Aneurysms. Stroke 2016; 47:2541-7. [DOI: 10.1161/strokeaha.116.013555] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 08/15/2016] [Indexed: 12/28/2022]
Abstract
Background and Purpose—
Hemodynamic forces may play a role in the recanalization of coiled aneurysms. The purpose of this study was to investigate the influence of presurgical hemodynamics on the efficacy of coil embolization for basilar tip aneurysms.
Methods—
We identified 82 patients who underwent endovascular coil embolization for basilar tip aneurysms with a follow-up of >1 year. Presurgical hemodynamics were investigated using computational fluid dynamics with 3-dimensional data derived from rotational angiography. During postprocessing, we quantified the rate of net flow entering the aneurysm through its neck and calculated the proportion of the aneurysmal inflow rate to the basilar artery flow rate. In addition, we investigated the correlation between the basilar bifurcation configuration and the hemodynamics.
Results—
Twenty-five of the 82 patients were excluded because of difficult vascular geometry reconstruction. Among the 57 examined patients, angiographic recanalization was observed in 19 patients (33.3%). The proportion of the aneurysmal inflow rate to the basilar artery flow rate and a coil packing density <30% were independent and significant predictors for the recanalization of coiled aneurysms. Additional investigation revealed that a small branch angle formed by the basilar artery and the posterior cerebral artery increased blood flow into the aneurysm.
Conclusions—
The proportion of the aneurysmal inflow rate to the basilar artery flow rate, influenced by the basilar bifurcation configuration, was an independent and significant predictor for recanalization after coil embolization in basilar tip aneurysms.
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Affiliation(s)
- Shin-ichiro Sugiyama
- From the Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan (S.-i.S., K.N., S.R., T.T.); Graduate School of Biomedical Engineering (S.-i.S., M.O.) and Institute of Fluid Science (M.O.), Tohoku University, Sendai, Japan; and Department of Neuroanesthesia (S.-i.S., M.K.), Department of Neuroendovascular Therapy (K.S., Y.M.), and Department of Neurosurgery (H.E., T.E.), Kohnan Hospital, Sendai, Japan
| | - Kuniyasu Niizuma
- From the Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan (S.-i.S., K.N., S.R., T.T.); Graduate School of Biomedical Engineering (S.-i.S., M.O.) and Institute of Fluid Science (M.O.), Tohoku University, Sendai, Japan; and Department of Neuroanesthesia (S.-i.S., M.K.), Department of Neuroendovascular Therapy (K.S., Y.M.), and Department of Neurosurgery (H.E., T.E.), Kohnan Hospital, Sendai, Japan
| | - Kenichi Sato
- From the Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan (S.-i.S., K.N., S.R., T.T.); Graduate School of Biomedical Engineering (S.-i.S., M.O.) and Institute of Fluid Science (M.O.), Tohoku University, Sendai, Japan; and Department of Neuroanesthesia (S.-i.S., M.K.), Department of Neuroendovascular Therapy (K.S., Y.M.), and Department of Neurosurgery (H.E., T.E.), Kohnan Hospital, Sendai, Japan
| | - Sherif Rashad
- From the Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan (S.-i.S., K.N., S.R., T.T.); Graduate School of Biomedical Engineering (S.-i.S., M.O.) and Institute of Fluid Science (M.O.), Tohoku University, Sendai, Japan; and Department of Neuroanesthesia (S.-i.S., M.K.), Department of Neuroendovascular Therapy (K.S., Y.M.), and Department of Neurosurgery (H.E., T.E.), Kohnan Hospital, Sendai, Japan
| | - Misaki Kohama
- From the Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan (S.-i.S., K.N., S.R., T.T.); Graduate School of Biomedical Engineering (S.-i.S., M.O.) and Institute of Fluid Science (M.O.), Tohoku University, Sendai, Japan; and Department of Neuroanesthesia (S.-i.S., M.K.), Department of Neuroendovascular Therapy (K.S., Y.M.), and Department of Neurosurgery (H.E., T.E.), Kohnan Hospital, Sendai, Japan
| | - Hidenori Endo
- From the Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan (S.-i.S., K.N., S.R., T.T.); Graduate School of Biomedical Engineering (S.-i.S., M.O.) and Institute of Fluid Science (M.O.), Tohoku University, Sendai, Japan; and Department of Neuroanesthesia (S.-i.S., M.K.), Department of Neuroendovascular Therapy (K.S., Y.M.), and Department of Neurosurgery (H.E., T.E.), Kohnan Hospital, Sendai, Japan
| | - Toshiki Endo
- From the Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan (S.-i.S., K.N., S.R., T.T.); Graduate School of Biomedical Engineering (S.-i.S., M.O.) and Institute of Fluid Science (M.O.), Tohoku University, Sendai, Japan; and Department of Neuroanesthesia (S.-i.S., M.K.), Department of Neuroendovascular Therapy (K.S., Y.M.), and Department of Neurosurgery (H.E., T.E.), Kohnan Hospital, Sendai, Japan
| | - Yasushi Matsumoto
- From the Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan (S.-i.S., K.N., S.R., T.T.); Graduate School of Biomedical Engineering (S.-i.S., M.O.) and Institute of Fluid Science (M.O.), Tohoku University, Sendai, Japan; and Department of Neuroanesthesia (S.-i.S., M.K.), Department of Neuroendovascular Therapy (K.S., Y.M.), and Department of Neurosurgery (H.E., T.E.), Kohnan Hospital, Sendai, Japan
| | - Makoto Ohta
- From the Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan (S.-i.S., K.N., S.R., T.T.); Graduate School of Biomedical Engineering (S.-i.S., M.O.) and Institute of Fluid Science (M.O.), Tohoku University, Sendai, Japan; and Department of Neuroanesthesia (S.-i.S., M.K.), Department of Neuroendovascular Therapy (K.S., Y.M.), and Department of Neurosurgery (H.E., T.E.), Kohnan Hospital, Sendai, Japan
| | - Teiji Tominaga
- From the Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan (S.-i.S., K.N., S.R., T.T.); Graduate School of Biomedical Engineering (S.-i.S., M.O.) and Institute of Fluid Science (M.O.), Tohoku University, Sendai, Japan; and Department of Neuroanesthesia (S.-i.S., M.K.), Department of Neuroendovascular Therapy (K.S., Y.M.), and Department of Neurosurgery (H.E., T.E.), Kohnan Hospital, Sendai, Japan
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Berg P, Vos S, Becker M, Serowy S, Redel T, Janiga G, Skalej M, Beuing O. Bringing hemodynamic simulations closer to the clinics: a CFD prototype study for intracranial aneurysms. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2016:3302-3305. [PMID: 28269011 DOI: 10.1109/embc.2016.7591434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Computational Fluid Dynamics enables the investigation of patient-specific hemodynamics for rupture predictions and treatment support of intracranial aneurysms. However, due to numerous simplifications to decrease the computations effort, clinical applicability is limited until now. To overcome this situation a clinical research software prototype was tested that can be easily operated by attending physicians. In order to evaluate the accuracy of this prototype, four patient-specific intracranial aneurysms were investigated using four different spatial resolutions. The results demonstrate that physicians were able to generate hemodynamic predictions within several minutes at low spatial resolution. However, depending on the parameter of interest and the desired accuracy, higher resolutions are required, which will lead to an increase of computational times that still look very attractive towards clinical usability. The study shows that the next step towards an applicable individualized therapy for patients harboring intracranial aneurysms can be done. However, further in vivo validations are required to guarantee realistic predictions in future studies.
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Imai Y, Omori T, Shimogonya Y, Yamaguchi T, Ishikawa T. Numerical methods for simulating blood flow at macro, micro, and multi scales. J Biomech 2016; 49:2221-2228. [DOI: 10.1016/j.jbiomech.2015.11.047] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 11/07/2015] [Indexed: 02/04/2023]
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Basic Principles of Hemodynamics and Cerebral Aneurysms. World Neurosurg 2016; 88:311-319. [DOI: 10.1016/j.wneu.2016.01.031] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 01/03/2016] [Accepted: 01/05/2016] [Indexed: 11/18/2022]
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Berg P, Roloff C, Beuing O, Voss S, Sugiyama SI, Aristokleous N, Anayiotos AS, Ashton N, Revell A, Bressloff NW, Brown AG, Jae Chung B, Cebral JR, Copelli G, Fu W, Qiao A, Geers AJ, Hodis S, Dragomir-Daescu D, Nordahl E, Bora Suzen Y, Owais Khan M, Valen-Sendstad K, Kono K, Menon PG, Albal PG, Mierka O, Münster R, Morales HG, Bonnefous O, Osman J, Goubergrits L, Pallares J, Cito S, Passalacqua A, Piskin S, Pekkan K, Ramalho S, Marques N, Sanchi S, Schumacher KR, Sturgeon J, Švihlová H, Hron J, Usera G, Mendina M, Xiang J, Meng H, Steinman DA, Janiga G. The Computational Fluid Dynamics Rupture Challenge 2013—Phase II: Variability of Hemodynamic Simulations in Two Intracranial Aneurysms. J Biomech Eng 2015; 137:121008. [DOI: 10.1115/1.4031794] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Indexed: 11/08/2022]
Abstract
With the increased availability of computational resources, the past decade has seen a rise in the use of computational fluid dynamics (CFD) for medical applications. There has been an increase in the application of CFD to attempt to predict the rupture of intracranial aneurysms, however, while many hemodynamic parameters can be obtained from these computations, to date, no consistent methodology for the prediction of the rupture has been identified. One particular challenge to CFD is that many factors contribute to its accuracy; the mesh resolution and spatial/temporal discretization can alone contribute to a variation in accuracy. This failure to identify the importance of these factors and identify a methodology for the prediction of ruptures has limited the acceptance of CFD among physicians for rupture prediction. The International CFD Rupture Challenge 2013 seeks to comment on the sensitivity of these various CFD assumptions to predict the rupture by undertaking a comparison of the rupture and blood-flow predictions from a wide range of independent participants utilizing a range of CFD approaches. Twenty-six groups from 15 countries took part in the challenge. Participants were provided with surface models of two intracranial aneurysms and asked to carry out the corresponding hemodynamics simulations, free to choose their own mesh, solver, and temporal discretization. They were requested to submit velocity and pressure predictions along the centerline and on specified planes. The first phase of the challenge, described in a separate paper, was aimed at predicting which of the two aneurysms had previously ruptured and where the rupture site was located. The second phase, described in this paper, aims to assess the variability of the solutions and the sensitivity to the modeling assumptions. Participants were free to choose boundary conditions in the first phase, whereas they were prescribed in the second phase but all other CFD modeling parameters were not prescribed. In order to compare the computational results of one representative group with experimental results, steady-flow measurements using particle image velocimetry (PIV) were carried out in a silicone model of one of the provided aneurysms. Approximately 80% of the participating groups generated similar results. Both velocity and pressure computations were in good agreement with each other for cycle-averaged and peak-systolic predictions. Most apparent “outliers” (results that stand out of the collective) were observed to have underestimated velocity levels compared to the majority of solutions, but nevertheless identified comparable flow structures. In only two cases, the results deviate by over 35% from the mean solution of all the participants. Results of steady CFD simulations of the representative group and PIV experiments were in good agreement. The study demonstrated that while a range of numerical schemes, mesh resolution, and solvers was used, similar flow predictions were observed in the majority of cases. To further validate the computational results, it is suggested that time-dependent measurements should be conducted in the future. However, it is recognized that this study does not include the biological aspects of the aneurysm, which needs to be considered to be able to more precisely identify the specific rupture risk of an intracranial aneurysm.
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Affiliation(s)
- Philipp Berg
- University of Magdeburg, Magdeburg 39106, Germany
| | | | - Oliver Beuing
- University Hospital of Magdeburg, Magdeburg 39120, Germany
| | - Samuel Voss
- University of Magdeburg, Magdeburg 39106, Germany
| | | | | | | | - Neil Ashton
- The University of Manchester, Manchester M60 1QD, UK
| | | | | | | | | | | | | | - Wenyu Fu
- Beijing University of Technology, Beijing 100124, China
| | - Aike Qiao
- Beijing University of Technology, Beijing 100124, China
| | | | - Simona Hodis
- Texas A&M University, Kingsville, TX 78363
- Mayo Clinic, Rochester, MN 55905
| | | | | | | | | | | | - Kenichi Kono
- Wakayama Rosai Hospital, Wakayama 640-8505, Japan
| | - Prahlad G. Menon
- Sun Yat-sen University—Carnegie Mellon University Joint Institute of Engineering, Pittsburgh, PA 15219
| | - Priti G. Albal
- Sun Yat-sen University—Carnegie Mellon University Joint Institute of Engineering, Pittsburgh, PA 15219
| | - Otto Mierka
- University of Dortmund, Dortmund 44227, Germany
| | | | | | | | - Jan Osman
- Charité-Universitätsmedizin Berlin, Berlin 13353, Germany
| | | | | | | | | | | | | | - Susana Ramalho
- blueCAPE Lda—CAE Solutions, Milharado 2665-305, Portugal
| | - Nelson Marques
- blueCAPE Lda—CAE Solutions, Milharado 2665-305, Portugal
| | | | | | | | | | | | - Gabriel Usera
- Universidad de la República, Montevideo 11300, Uruguay
| | | | - Jianping Xiang
- University at Buffalo—State University of New York, Buffalo, NY 14203
| | - Hui Meng
- University at Buffalo—State University of New York, Buffalo, NY 14203
| | | | - Gábor Janiga
- University of Magdeburg, Magdeburg 39106, Germany
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