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Dier C, Sanchez S, Sagues E, Gudino A, Jaramillo R, Wendt L, Samaniego EA. Radiomic profiling of high-risk aneurysms with blebs: an exploratory study. J Neurointerv Surg 2024:jnis-2024-022133. [PMID: 39299742 DOI: 10.1136/jnis-2024-022133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Accepted: 08/27/2024] [Indexed: 09/22/2024]
Abstract
BACKGROUND Blebs significantly increase rupture risk of intracranial aneurysms. Radiomic analysis offers a robust characterization of the aneurysm wall. However, the unique radiomic profile of various compartments, including blebs, remains unexplored. Likewise, the correlation between these imaging markers and fluid/mechanical metrics is yet to be investigated. To address this, we analyzed the radiomic features (RFs) of bleb-containing aneurysms and their relationship with wall tension and shear stress metrics, aiming to enhance risk assessment. METHODS Aneurysms were imaged using high-resolution magnetic resonance imaging (MRI). A T1 and a T1 after contrast (T1+Gd) sequences were acquired. 3D models of aneurysm bodies and blebs were generated, and RFs were extracted. Aneurysms with and without blebs were matched based on location and size for analysis. Univariate regression models and Spearman's correlations were used to establish associations between bleb-dependent RFs and mechanical/fluid dynamics metrics. RESULTS Eighteen aneurysms with blebs were identified. Fifty-five RFs were significantly different between blebs and body within the same aneurysms. Of these RFs, 9% (5/55) were first-order, and 91% (50/55) were second-order features. After aneurysms with and without blebs were matched for location and size, five RFs 5% (5/93) were significantly different. Forty-one out of the 55 RFs different between bleb and body sac of the primary aneurysm were moderately and strongly correlated with mechanical and fluid dynamics metrics. CONCLUSION Aneurysm blebs exhibit distinct radiomic profiles compared with the main body of the aneurysm sac. The variability in bleb wall characteristics may arise from differing mechanical stresses and localized hemodynamics. Leveraging radiomic profiling could help identify regions with a heightened risk of rupture.
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Affiliation(s)
- Carlos Dier
- Neurology, University of Iowa, Iowa City, Iowa, USA
| | - Sebastian Sanchez
- Department of Neurology, Yale University, New Haven, Connecticut, USA
| | - Elena Sagues
- Neurology, University of Iowa, Iowa City, Iowa, USA
| | | | | | - Linder Wendt
- Institute for Clinical and Translational Science, University of Iowa Health Care, Iowa City, Iowa, USA
| | - Edgar A Samaniego
- Departments of Neurology, Neurosurgery and Radiology, University of Iowa, Iowa City, Iowa, USA
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Zhu S, Xu X, Zou R, Lu Z, Yan Y, Li S, Wu Y, Cai J, Li L, Xiang J, Huang Q. Nomograms for assessing the rupture risk of anterior choroid artery aneurysms based on clinical, morphological, and hemodynamic features. Front Neurol 2024; 15:1304270. [PMID: 38390597 PMCID: PMC10882079 DOI: 10.3389/fneur.2024.1304270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 01/17/2024] [Indexed: 02/24/2024] Open
Abstract
Background and purpose A notable prevalence of subarachnoid hemorrhage is evident among patients with anterior choroidal artery aneurysms in clinical practice. To evaluate the risk of rupture in unruptured anterior choroidal artery aneurysms, we conducted a comprehensive analysis of risk factors and subsequently developed two nomograms. Methods A total of 120 cases of anterior choroidal artery aneurysms (66 unruptured and 54 ruptured) from 4 medical institutions were assessed utilizing computational fluid dynamics (CFD) and digital subtraction angiography (DSA). The training set, consisting of 98 aneurysms from 3 hospitals, was established, with an additional 22 cases from the fourth hospital forming the external validation set. Statistical differences between the two data sets were thoroughly compared. The significance of 9 clinical baseline characteristics, 11 aneurysm morphology parameters, and 4 hemodynamic parameters concerning aneurysm rupture was evaluated within the training set. Candidate selection for constructing the nomogram models involved regression analysis and variance inflation factors. Discrimination, calibration, and clinical utility of the models in both training and validation sets were assessed using area under curves (AUC), calibration plots, and decision curve analysis (DCA). The DeLong test, net reclassification index (NRI), and integrated discrimination improvement (IDI) were employed to compare the effectiveness of classification across models. Results Two nomogram models were ultimately constructed: model 1, incorporating clinical, morphological, and hemodynamic parameters (C + M + H), and model 2, relying primarily on clinical and morphological parameters (C + M). Multivariate analysis identified smoking, size ratio (SR), normalized wall shear stress (NWSS), and average oscillatory shear index (OSIave) as optimal candidates for model development. In the training set, model 1 (C + M + H) achieved an AUC of 0.795 (95% CI: 0.706 ~ 0.884), demonstrating a sensitivity of 95.6% and a specificity of 54.7%. Model 2 (C + M) had an AUC of 0.706 (95% CI: 0.604 ~ 0.808), with corresponding sensitivity and specificity of 82.4 and 50.3%, respectively. Similarly, AUCs for models 1 and 2 in the external validation set were calculated to be 0.709 and 0.674, respectively. Calibration plots illustrated a consistent correlation between model evaluations and real-world observations in both sets. DCA demonstrated that the model incorporating hemodynamic parameters offered higher clinical benefits. In the training set, NRI (0.224, p = 0.007), IDI (0.585, p = 0.002), and DeLong test (change = 0.089, p = 0.008) were all significant. In the external validation set, NRI, IDI, and DeLong test statistics were 0.624 (p = 0.063), 0.572 (p = 0.044), and 0.035 (p = 0.047), respectively. Conclusion Multidimensional nomograms have the potential to enhance risk assessment and patient-specific treatment of anterior choroidal artery aneurysms. Validated by an external cohort, the model incorporating clinical, morphological, and hemodynamic features may provide improved classification of rupture states.
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Affiliation(s)
- Shijie Zhu
- Department of Neurovascular Center, Changhai Hospital, Naval Medical University, Shanghai, China
| | - Xiaolong Xu
- Department of Neurovascular Center, Changhai Hospital, Naval Medical University, Shanghai, China
| | - Rong Zou
- ArteryFlow Technology Co., Ltd., Hangzhou, Zhejiang, China
| | - Zhiwen Lu
- Department of Neurovascular Center, Changhai Hospital, Naval Medical University, Shanghai, China
| | - Yazhou Yan
- Department of Neurosurgery, 971 Hospital of People's Liberation Army (PLA), Qingdao, China
| | - Siqi Li
- Department of Neurovascular Center, Changhai Hospital, Naval Medical University, Shanghai, China
| | - Yina Wu
- Department of Neurovascular Center, Changhai Hospital, Naval Medical University, Shanghai, China
| | - Jing Cai
- Department of Neurosurgery, Linyi People's Hospital, Linyi, China
| | - Li Li
- Cerebrovascular Department of Interventional Center, Henan Provincial People's Hospital, Zhengzhou, China
| | - Jianping Xiang
- ArteryFlow Technology Co., Ltd., Hangzhou, Zhejiang, China
| | - Qinghai Huang
- Department of Neurovascular Center, Changhai Hospital, Naval Medical University, Shanghai, China
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Cheng L, Huang Y, Yao H, Luo J, Zhang L, Fu R, Lv J, Yang B, Yan L. Wall Shear Stress Reduction Activates Angiotensin II to Facilitate Aneurysmal Subarachnoid Hemorrhage in Intracranial Aneurysms Through MicroRNA-29/The Growth Factor-Beta Receptor Type II/Smad3 Axis. World Neurosurg 2023; 176:e314-e326. [PMID: 37230243 DOI: 10.1016/j.wneu.2023.05.056] [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: 03/15/2023] [Revised: 05/16/2023] [Accepted: 05/17/2023] [Indexed: 05/27/2023]
Abstract
OBJECTIVE We tried to broaden our knowledge of the possible role of wall shear stress (WSS) in the occurrence of intracranial aneurysms (IAs). METHODS Genes implicated in IAs and genes related to WSS were predicted through in silico analysis. Rat models of IAs were established, in which the expression patterns of angiotensin II (Ang II) were characterized, and WSS was assessed. Vascular endothelial cells isolated from rats bearing IAs were treated with microRNA-29 (miR-29) mimic/inhibitor, small interfering RNA-TGF-β receptor type II (TGFBR2)/overexpressed TGFBR2, Ang II, or angiotensin-converting enzyme (ACE) inhibitor. Then, the endothelial-to-mesenchymal transition (EndMT) was evaluated by flow cytometry. Finally, the volume of IAs and risk of subarachnoid hemorrhage were analyzed in vivo in response to miR-29 gain of function. RESULTS WSS was decreased in the IA bearing arteries, which showed a positive correlation with ACE and Ang II in the vascular tissues of IA rats. Reduced miR-29 and increased ACE, Ang II, and TGFBR2 were detected in the vascular tissues of IA rats. Ang II inhibited miR-29, which targeted TGFBR2. Downregulated TGFBR2 was accompanied by suppression of Smad3 phosphorylation. Through impairing miR-29-dependent inhibition of TGFBR2, Ang II enhanced EndMT. In vivo data confirmed that treatment of miR-29 agomir delayed the formation of IA and decreased the risk of subarachnoid hemorrhage. CONCLUSIONS The current study provided evidence that WSS reduction could activate Ang II, reduce miR-29 expression, and activate the TGFBR2/Smad3 axis, thus promoting EndMT and accelerating the progression of IAs.
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Affiliation(s)
- Longhai Cheng
- Department of Neurosurgery, Taihe Hospital, Hubei University of Medicine, Shiyan, P.R. China
| | - Yan Huang
- Department of Neurosurgery, Taihe Hospital, Hubei University of Medicine, Shiyan, P.R. China
| | - Hong Yao
- Department of Neurosurgery, Taihe Hospital, Hubei University of Medicine, Shiyan, P.R. China
| | - Jie Luo
- Department of Neurosurgery, Taihe Hospital, Hubei University of Medicine, Shiyan, P.R. China
| | - Li Zhang
- Department of Neurosurgery, Taihe Hospital, Hubei University of Medicine, Shiyan, P.R. China
| | - Rui Fu
- Department of Neurosurgery, Taihe Hospital, Hubei University of Medicine, Shiyan, P.R. China
| | - Junti Lv
- Department of Neurosurgery, Taihe Hospital, Hubei University of Medicine, Shiyan, P.R. China.
| | - Bowen Yang
- Department of Neurosurgery, Taihe Hospital, Hubei University of Medicine, Shiyan, P.R. China
| | - Lidong Yan
- Department of Neurosurgery, Taihe Hospital, Hubei University of Medicine, Shiyan, P.R. China
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Raghuram A, Galloy A, Nino M, Sanchez S, Hasan D, Raghavan S, Samaniego EA. Comprehensive morphomechanical analysis of brain aneurysms. Acta Neurochir (Wien) 2023; 165:461-470. [PMID: 36595056 DOI: 10.1007/s00701-022-05476-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 12/21/2022] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Brain aneurysms comprise different compartments that undergo unique biological processes. A detailed multimodal analysis incorporating 3D aneurysm wall enhancement (AWE), computational fluid dynamics (CFD), and finite element analysis (FEA) data can provide insights into the aneurysm wall biology. METHODS Unruptured aneurysms were prospectively imaged with 7 T high-resolution MRI (HR-MRI). 3D AWE color maps of the entire aneurysm wall were generated and co-registered with contour plots of morphomechanical parameters derived from CFD and FEA. A multimodal analysis of the entire aneurysm was performed using 3D circumferential AWE (3D-CAWE), wall tension (WT), time-averaged wall shear stress (TAWSS), wall shear stress gradient (WSSG), and oscillatory shear index (OSI). A detailed compartmental analysis of each aneurysm's dome, bleb, and neck was also performed. RESULTS Twenty-six aneurysms were analyzed. 3D-CAWE + aneurysms had higher WT (p = 0.03) and higher TAWSS (p = 0.045) than 3D-CAWE- aneurysms. WT, TAWSS, and WSSG were lower in areas of focal AWE in the aneurysm dome compared to the neck (p = 0.009, p = 0.049, and p = 0.040, respectively), whereas OSI was higher in areas of focal AWE compared to the neck (p = 0.020). When compared to areas of no AWE of the aneurysm sac (AWE = 0.92 vs. 0.49, p = 0.001), blebs exhibited lower WT (1.6 vs. 2.45, p = 0.010), lower TAWSS (2.6 vs. 6.34), lower OSI (0.0007 vs. 0.0010), and lower WSSG (2900 vs. 5306). Fusiform aneurysms had a higher 3D-CAWE and WT than saccular aneurysms (p = 0.046 and p = 0.003, respectively). CONCLUSIONS Areas of focal high AWE in the sac and blebs are associated with low wall tension, low wall shear stress, and low flow conditions (TAWSS and WSSG). Conversely, the neck had average AWE, high wall tension, high wall shear stress, and high flow conditions. The aneurysm dome and the aneurysm neck have different morphomechanical environments, with increased mechanical load at the neck.
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Affiliation(s)
| | - Adam Galloy
- Roy J Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | - Marco Nino
- Roy J Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | | | - David Hasan
- Department of Neurosurgery, Duke University, Durham, NC, USA
| | - Suresh Raghavan
- Roy J Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | - Edgar A Samaniego
- Department of Neurology, University of Iowa, Iowa City, IA, USA. .,Department of Neurosurgery, University of Iowa, Iowa City, IA, USA. .,Department of Radiology, University of Iowa, Iowa City, IA, USA. .,Current Institution, The University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA, 52246, USA.
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Saqr KM, Rashad S, Tupin S, Niizuma K, Hassan T, Tominaga T, Ohta M. What does computational fluid dynamics tell us about intracranial aneurysms? A meta-analysis and critical review. J Cereb Blood Flow Metab 2020; 40:1021-1039. [PMID: 31213162 PMCID: PMC7181089 DOI: 10.1177/0271678x19854640] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Despite the plethora of published studies on intracranial aneurysms (IAs) hemodynamic using computational fluid dynamics (CFD), limited progress has been made towards understanding the complex physics and biology underlying IA pathophysiology. Guided by 1733 published papers, we review and discuss the contemporary IA hemodynamics paradigm established through two decades of IA CFD simulations. We have traced the historical origins of simplified CFD models which impede the progress of comprehending IA pathology. We also delve into the debate concerning the Newtonian fluid assumption used to represent blood flow computationally. We evidently demonstrate that the Newtonian assumption, used in almost 90% of studies, might be insufficient to describe IA hemodynamics. In addition, some fundamental properties of the Navier-Stokes equation are revisited in supplementary material to highlight some widely spread misconceptions regarding wall shear stress (WSS) and its derivatives. Conclusively, our study draws a roadmap for next-generation IA CFD models to help researchers investigate the pathophysiology of IAs.
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Affiliation(s)
- Khalid M Saqr
- Biomedical Flow Dynamics Laboratory, Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan.,Department of Mechanical Engineering, College of Engineering and Technology, Arab Academy for Science, Technology and Maritime Transport, Alexandria, Egypt
| | - Sherif Rashad
- Department of Neurosurgical Engineering and Translational Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Simon Tupin
- Biomedical Flow Dynamics Laboratory, Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan
| | - Kuniyasu Niizuma
- Department of Neurosurgical Engineering and Translational Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Neurosurgical Engineering and Translational Neuroscience, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
| | - Tamer Hassan
- Department of Neurosurgery, Alexandria University School of Medicine, Azarita Medical Campus, Alexandria, Egypt
| | - Teiji Tominaga
- Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Makoto Ohta
- Biomedical Flow Dynamics Laboratory, Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan
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Rayz VL, Cohen-Gadol AA. Hemodynamics of Cerebral Aneurysms: Connecting Medical Imaging and Biomechanical Analysis. Annu Rev Biomed Eng 2020; 22:231-256. [PMID: 32212833 DOI: 10.1146/annurev-bioeng-092419-061429] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the last two decades, numerous studies have conducted patient-specific computations of blood flow dynamics in cerebral aneurysms and reported correlations between various hemodynamic metrics and aneurysmal disease progression or treatment outcomes. Nevertheless, intra-aneurysmal flow analysis has not been adopted in current clinical practice, and hemodynamic factors usually are not considered in clinical decision making. This review presents the state of the art in cerebral aneurysm imaging and image-based modeling, discussing the advantages and limitations of each approach and focusing on the translational value of hemodynamic analysis. Combining imaging and modeling data obtained from different flow modalities can improve the accuracy and fidelity of resulting velocity fields and flow-derived factors that are thought to affect aneurysmal disease progression. It is expected that predictive models utilizing hemodynamic factors in combination with patient medical history and morphological data will outperform current risk scores and treatment guidelines. Possible future directions include novel approaches enabling data assimilation and multimodality analysis of cerebral aneurysm hemodynamics.
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Affiliation(s)
- Vitaliy L Rayz
- Weldon School of Biomedical Engineering and School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, USA;
| | - Aaron A Cohen-Gadol
- Department of Neurosurgery, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.,Goodman Campbell Brain and Spine, Carmel, Indiana 46032, USA
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Schönfeld MH, Forkert ND, Fiehler J, Cho YD, Han MH, Kang HS, Peach TW, Byrne JV. Hemodynamic Differences Between Recurrent and Nonrecurrent Intracranial Aneurysms: Fluid Dynamics Simulations Based on MR Angiography. J Neuroimaging 2019; 29:447-453. [PMID: 30891876 DOI: 10.1111/jon.12612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE Although the role of wall shear stress (WSS) in the initiation, growth, and rupture of intracranial aneurysms has been well studied, its influence on aneurysm recurrence after endovascular treatment requires further investigation. We aimed to compare WSS at necks of recurrent and nonrecurrent aneurysms. METHODS Nine recurrent coil-embolized aneurysms were identified and matched with nine nonrecurrent aneurysms. Patient-specific vessel geometries reconstructed from follow-up 3-D time-of-flight magnetic resonance angiography were analyzed using computational fluid dynamics (CFD) simulations. Absolute WSS and the percentage of abnormally low and high WSS at the aneurysm neck compared to the near artery were measured. RESULTS The median percentage of abnormal WSS at the aneurysm neck was 49.3% for recurrent and 34.7% for nonrecurrent aneurysms (P = .011). The area under the receiver-operating-characteristic curve for distinguishing these aneurysms according to the percentage of abnormal WSS was .86 (95% CI .62 to .98). The optimal cut-off value of 45.1% resulted in a sensitivity and a specificity of 88.89% (95% CI 51.8% to 99.7%). CONCLUSION Our findings indicate that necks of recurrent aneurysms are exposed to abnormal WSS to a larger extent. Abnormal WSS may serve as a metric to distinguish them from nonrecurrent aneurysms with CFD simulations a priori.
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Affiliation(s)
- Michael Hinrich Schönfeld
- Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Nils Daniel Forkert
- Department of Radiology and Hotchkiss Brain Institute, University of Calgary, Calgary, Canada
| | - Jens Fiehler
- Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Young Dae Cho
- Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea
| | - Moon Hee Han
- Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea
| | - Hyun-Seung Kang
- Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea
| | - Thomas William Peach
- Department of Mechanical Engineering, University College London, London, UK.,Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK
| | - James Vincent Byrne
- Oxford Neurovascular & Neuroradiology Research Unit, Oxford Radcliffe Hospital, Oxford, UK
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Hodis S. Correlation of flow complexity parameter with aneurysm rupture status. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e3131. [PMID: 30021249 DOI: 10.1002/cnm.3131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 07/07/2018] [Indexed: 05/22/2023]
Abstract
Ruptured aneurysms are known to have complex flow patterns and concentrated inflow jet, but a quantifiable measure for the degree of flow complexity in patient-specific geometries has not been established. Previously, we proposed a flow complexity parameter that provides a quantitative description of the complexity of flow patterns through calculated curvature and torsion of the flow field. The purpose of the current study was to provide an analytic solution of the flow complexity parameter and assess a possible correlation with the rupture status of cerebral aneurysms by analyzing the parameter on five ruptured and five unruptured aneurysms from anterior communicating artery. We analyzed the flow complexity parameter in jet and non-jet regions in order to measure the concentration of the jet flow and the complexity of the non-jet flow. We found that on average, in a ruptured case the jet region is significantly less complex (4.5 times) than the jet region in an unruptured case, while the non-jet region is significantly more complex (3.5 times) than the non-jet region in an unruptured case. We also found a strong positive correlation of the non-jet complexity with dome volume in ruptured cases, but no correlation of jet complexity with dome volume. These findings suggest that a ruptured aneurysm has more than 4 times more concentrated inflow jet and more than 3 times more complex flow patterns in non-jet region than an unruptured aneurysm. This newly implemented kinematic parameter provides a measurable degree of complexity of flow patterns in cerebral aneurysms that can better assess aneurysm rupture risk.
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Affiliation(s)
- Simona Hodis
- Department of Mathematics, Texas A&M University-Kingsville, Kingsville, Texas
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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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Suzuki T, Ioan Nita C, Rapaka S, Takao H, Mihalef V, Fujimura S, Dahmani C, Sharma P, Mamori H, Ishibashi T, Redel T, Yamamoto M, Murayama Y. Verification of a research prototype for hemodynamic analysis of cerebral aneurysms. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2016:2921-2924. [PMID: 28268925 DOI: 10.1109/embc.2016.7591341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Owing to its clinical importance, there has been a growing body of research on understanding the hemodynamics of cerebral aneurysms. Traditionally, this work has been performed using general-purpose, state-of-the-art commercial solvers. This has meant requiring engineering expertise for making appropriate choices on the geometric discretization, time-step selection, choice of boundary conditions etc. Recently, a CFD research prototype has been developed (Siemens Healthcare GmbH, Prototype - not for diagnostic use) for end-to-end analysis of aneurysm hemodynamics. This prototype enables anatomical model preparation, hemodynamic computations, advanced visualizations and quantitative analysis capabilities. In this study, we investigate the accuracy of the hemodynamic solver in the prototype against a commercially available CFD solver ANSYS CFX 16.0 (ANSYS Inc., Canonsburg, PA, www.ansys.com) retrospectively on a sample of twenty patient-derived aneurysm models, and show good agreement of hemodynamic parameters of interest.
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11
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Miraucourt O, Salmon S, Szopos M, Thiriet M. Blood flow in the cerebral venous system: modeling and simulation. Comput Methods Biomech Biomed Engin 2016; 20:471-482. [PMID: 27802781 DOI: 10.1080/10255842.2016.1247833] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The development of a software platform incorporating all aspects, from medical imaging data, through three-dimensional reconstruction and suitable meshing, up to simulation of blood flow in patient-specific geometries, is a crucial challenge in biomedical engineering. In the present study, a fully three-dimensional blood flow simulation is carried out through a complete rigid macrovascular circuit, namely the intracranial venous network, instead of a reduced order simulation and partial vascular network. The biomechanical modeling step is carefully analyzed and leads to the description of the flow governed by the dimensionless Navier-Stokes equations for an incompressible viscous fluid. The equations are then numerically solved with a free finite element software using five meshes of a realistic geometry obtained from medical images to prove the feasibility of the pipeline. Some features of the intracranial venous circuit in the supine position such as asymmetric behavior in merging regions are discussed.
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Affiliation(s)
- Olivia Miraucourt
- a Laboratoire de Mathématiques, EA 4535 FR CNRS ARC 3399 , Université de Reims Champagne-Ardenne, UFR Sciences Exactes et Naturelles , Reims Cedex 2 , France
| | - Stéphanie Salmon
- a Laboratoire de Mathématiques, EA 4535 FR CNRS ARC 3399 , Université de Reims Champagne-Ardenne, UFR Sciences Exactes et Naturelles , Reims Cedex 2 , France
| | - Marcela Szopos
- b Université de Strasbourg , CNRS, IRMA UMR 7501 , F-67000 Strasbourg , France
| | - Marc Thiriet
- c Laboratoire J.-L. Lions , UMR 7598 CNRS/Université Pierre et Marie Curie-Paris 6 , Paris , France .,d INRIA, Equipe-projet REO , Le Chesnay , France
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Ramachandran M, Retarekar R, Raghavan ML, Berkowitz B, Dickerhoff B, Correa T, Lin S, Johnson K, Hasan D, Ogilvy C, Rosenwasser R, Torner J, Bogason E, Stapleton CJ, Harbaugh RE. Assessment of image-derived risk factors for natural course of unruptured cerebral aneurysms. J Neurosurg 2016; 124:288-95. [DOI: 10.3171/2015.2.jns142265] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECT
The goal of this prospective longitudinal study was to test whether image-derived metrics can differentiate unruptured aneurysms that will become unstable (grow and/or rupture) from those that will remain stable.
METHODS
One hundred seventy-eight patients harboring 198 unruptured cerebral aneurysms for whom clinical observation and follow-up with imaging surveillance was recommended at 4 clinical centers were prospectively recruited into this study. Imaging data (predominantly CT angiography) at initial presentation was recorded. Computational geometry was used to estimate numerous metrics of aneurysm morphology that described the size and shape of the aneurysm. The nonlinear, finite element method was used to estimate uniform pressure-induced peak wall tension. Computational fluid dynamics was used to estimate blood flow metrics. The median follow-up period was 645 days. Longitudinal outcome data on these aneurysm patients—whether their aneurysms grew or ruptured (the unstable group) or remained unchanged (the stable group)—was documented based on follow-up at 4 years after the beginning of recruitment.
RESULTS
Twenty aneurysms (10.1%) grew, but none ruptured. One hundred forty-nine aneurysms (75.3%) remained stable and 29 (14.6%) were lost to follow-up. None of the metrics—including aneurysm size, nonsphericity index, peak wall tension, and low shear stress area—differentiated the stable from unstable groups with statistical significance.
CONCLUSIONS
The findings in this highly selected group do not support the hypothesis that image-derived metrics can predict aneurysm growth in patients who have been selected for observation and imaging surveillance. If aneurysm shape is a significant determinant of invasive versus expectant management, selection bias is a key limitation of this study.
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Affiliation(s)
| | | | | | | | | | - Tatiana Correa
- 1Department of Biomedical Engineering, University of Iowa
| | - Steve Lin
- 1Department of Biomedical Engineering, University of Iowa
| | - Kevin Johnson
- 2Department of Neurosurgery, University of Iowa Hospitals and Clinics; and
| | - David Hasan
- 2Department of Neurosurgery, University of Iowa Hospitals and Clinics; and
| | - Christopher Ogilvy
- 3Department of Surgery, Division of Neurosurgery, Beth Israel Deaconess Medical Center; and
| | - Robert Rosenwasser
- 4Department of Neurosurgery, Jefferson University Hospital, Philadelphia
| | - James Torner
- 5Department of Epidemiology, University of Iowa, Iowa City, Iowa
| | - Einar Bogason
- 6Department of Neurosurgery, Penn State University, Hershey; and
| | | | - Robert E. Harbaugh
- 6Department of Neurosurgery, Penn State University, Hershey; and
- 8Department of Engineering Science and Mechanics, Pennsylvania State University, State College, Pennsylvania
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The effect of inlet waveforms on computational hemodynamics of patient-specific intracranial aneurysms. J Biomech 2014; 47:3882-90. [PMID: 25446264 DOI: 10.1016/j.jbiomech.2014.09.034] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 09/05/2014] [Accepted: 09/29/2014] [Indexed: 12/28/2022]
Abstract
Due to the lack of patient-specific inlet flow waveform measurements, most computational fluid dynamics (CFD) simulations of intracranial aneurysms usually employ waveforms that are not patient-specific as inlet boundary conditions for the computational model. The current study examined how this assumption affects the predicted hemodynamics in patient-specific aneurysm geometries. We examined wall shear stress (WSS) and oscillatory shear index (OSI), the two most widely studied hemodynamic quantities that have been shown to predict aneurysm rupture, as well as maximal WSS (MWSS), energy loss (EL) and pressure loss coefficient (PLc). Sixteen pulsatile CFD simulations were carried out on four typical saccular aneurysms using 4 different waveforms and an identical inflow rate as inlet boundary conditions. Our results demonstrated that under the same mean inflow rate, different waveforms produced almost identical WSS distributions and WSS magnitudes, similar OSI distributions but drastically different OSI magnitudes. The OSI magnitude is correlated with the pulsatility index of the waveform. Furthermore, there is a linear relationship between aneurysm-averaged OSI values calculated from one waveform and those calculated from another waveform. In addition, different waveforms produced similar MWSS, EL and PLc in each aneurysm. In conclusion, inlet waveform has minimal effects on WSS, OSI distribution, MWSS, EL and PLc and a strong effect on OSI magnitude, but aneurysm-averaged OSI from different waveforms has a strong linear correlation with each other across different aneurysms, indicating that for the same aneurysm cohort, different waveforms can consistently stratify (rank) OSI of aneurysms.
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