The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Shengzhang Wang - One of the best experts on this subject based on the ideXlab platform.
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discrimination of intracranial aneurysm rupture status patient specific inflow boundary may not be a must have condition in hemodynamic simulations
Neuroradiology, 2020Co-Authors: Shengzhang Wang, Zhongbin Tian, Wei Zhu, Yisen Zhang, Ying Zhang, Yang Wang, Kun Wang, Xinjian Yang, Jian LiuAbstract:Computational fluid dynamics (CFD) are important in evaluating the Hemodynamics of intracranial aneurysm rupture, and the setting of inflow boundary conditions is critical. We evaluated intracranial aneurysm Hemodynamics based on generalized versus patient-specific inflow boundary conditions to examine the effect of different hemodynamic results on the discrimination of intracranial aneurysm rupture status. We enrolled 148 patients with 156 intracranial aneurysms. For each included aneurysm, we performed CFD simulation once based on patient-specific and once based on generalized inflow boundary conditions. First, we compared the Hemodynamics of intracranial aneurysms based on different inflow boundary conditions. Then, we divided the included aneurysms into a ruptured and unruptured group and compared the Hemodynamics between the two groups under patient-specific and generalized inflow boundary conditions. For the hemodynamic parameters using specific inflow boundary conditions, more complex flow (p = 0.002), larger minimum WSS (p = 0.024), lower maximum low WSS area (LSA) (p = 0.038), and oscillatory shear index (p = 0.002) were found. Furthermore, we compared the Hemodynamics between ruptured and unruptured groups based on different inflow boundary conditions. We found that the significant hemodynamic parameters associated with rupture status were the same, including the proportion of aneurysms with flow complex and unstable flow and the minimum and maximum of LSA (p = 0.011, p = 0.003, p = 0.001 and p = 0.004, respectively). Patient-specific and generalized inflow boundary conditions of aneurysmal Hemodynamics resulted in significant differences. However, the significant parameters associated with rupture status were the same in both conditions, indicating that patient-specific inflow boundary conditions may not be necessary for predicting rupture risk.
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high shear stress and flow velocity in partially occluded aneurysms prone to recanalization
Stroke, 2011Co-Authors: Bin Luo, Shengzhang Wang, Yisen Zhang, Ying Zhang, Xinjian Yang, Jialiang Chen, Zhicheng Liu, Guanghong DingAbstract:Background and Purpose—Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. However, the hemodynamic features in the residual neck of the partially embolized aneurysms and their influences on recanalization are rarely reported. In this study, we characterized the Hemodynamics of partially occluded aneurysms, which were proven to undergo recanalization during follow-up using computational fluid dynamic analysis. Methods—From May 2007 to June 2009, we identified 11 partial aneurysms during follow-up, including 5 recanalized cases and 6 stable cases with 3-dimensional digital subtraction angiography. We retrospectively characterized the hemodynamic features around the residual aneurismal pouch using the available postprocedural digital subtraction angiography image data. The occluded part of the aneurysm was regarded as completely separated from the circulation. Results—The overall blood flow patterns before embolization were almost the same ...
Jian Liu - One of the best experts on this subject based on the ideXlab platform.
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discrimination of intracranial aneurysm rupture status patient specific inflow boundary may not be a must have condition in hemodynamic simulations
Neuroradiology, 2020Co-Authors: Shengzhang Wang, Zhongbin Tian, Wei Zhu, Yisen Zhang, Ying Zhang, Yang Wang, Kun Wang, Xinjian Yang, Jian LiuAbstract:Computational fluid dynamics (CFD) are important in evaluating the Hemodynamics of intracranial aneurysm rupture, and the setting of inflow boundary conditions is critical. We evaluated intracranial aneurysm Hemodynamics based on generalized versus patient-specific inflow boundary conditions to examine the effect of different hemodynamic results on the discrimination of intracranial aneurysm rupture status. We enrolled 148 patients with 156 intracranial aneurysms. For each included aneurysm, we performed CFD simulation once based on patient-specific and once based on generalized inflow boundary conditions. First, we compared the Hemodynamics of intracranial aneurysms based on different inflow boundary conditions. Then, we divided the included aneurysms into a ruptured and unruptured group and compared the Hemodynamics between the two groups under patient-specific and generalized inflow boundary conditions. For the hemodynamic parameters using specific inflow boundary conditions, more complex flow (p = 0.002), larger minimum WSS (p = 0.024), lower maximum low WSS area (LSA) (p = 0.038), and oscillatory shear index (p = 0.002) were found. Furthermore, we compared the Hemodynamics between ruptured and unruptured groups based on different inflow boundary conditions. We found that the significant hemodynamic parameters associated with rupture status were the same, including the proportion of aneurysms with flow complex and unstable flow and the minimum and maximum of LSA (p = 0.011, p = 0.003, p = 0.001 and p = 0.004, respectively). Patient-specific and generalized inflow boundary conditions of aneurysmal Hemodynamics resulted in significant differences. However, the significant parameters associated with rupture status were the same in both conditions, indicating that patient-specific inflow boundary conditions may not be necessary for predicting rupture risk.
Charles B. L. M. Majoie - One of the best experts on this subject based on the ideXlab platform.
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Generalized versus Patient-Specific Inflow Boundary Conditions in Computational Fluid Dynamics Simulations of Cerebral Aneurysmal Hemodynamics
American Journal of Neuroradiology, 2014Co-Authors: Ilaria Jansen, J.j. Schneiders, Wouter V. Potters, P. Van Ooij, R. Van Den Berg, E. Van Bavel, Henk A. Marquering, Charles B. L. M. MajoieAbstract:BACKGROUND AND PURPOSE: Attempts have been made to associate intracranial aneurysmal Hemodynamics with aneurysm growth and rupture status. Hemodynamics in aneurysms is traditionally determined with computational fluid dynamics by using generalized inflow boundary conditions in a parent artery. Recently, patient-specific inflow boundary conditions are being implemented more frequently. Our purpose was to compare intracranial aneurysm Hemodynamics based on generalized versus patient-specific inflow boundary conditions. MATERIALS AND METHODS: For 36 patients, geometric models of aneurysms were determined by using 3D rotational angiography. 2D phase-contrast MR imaging velocity measurements of the parent artery were performed. Computational fluid dynamics simulations were performed twice: once by using patient-specific phase-contrast MR imaging velocity profiles and once by using generalized Womersley profiles as inflow boundary conditions. Resulting mean and maximum wall shear stress and oscillatory shear index values were analyzed, and hemodynamic characteristics were qualitatively compared. RESULTS: Quantitative analysis showed statistically significant differences for mean and maximum wall shear stress values between both inflow boundary conditions (P CONCLUSIONS: Using generalized and patient-specific inflow boundary conditions for computational fluid dynamics results in different wall shear stress magnitudes and hemodynamic characteristics. Generalized inflow boundary conditions result in more vortices and inflow jet instabilities. This study emphasizes the necessity of patient-specific inflow boundary conditions for calculation of Hemodynamics in cerebral aneurysms by using computational fluid dynamics techniques.
Risto J Ilmoniemi - One of the best experts on this subject based on the ideXlab platform.
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cyclic alternating pattern is associated with cerebral hemodynamic variation a near infrared spectroscopy study of sleep in healthy humans
PLOS ONE, 2012Co-Authors: Tiina Nasi, Jaakko Virtanen, Jussi Toppila, Tapani Salmi, Risto J IlmoniemiAbstract:The cyclic alternating pattern (CAP), that is, cyclic variation of brain activity within non-REM sleep stages, is related to sleep instability and preservation, as well as consolidation of learning. Unlike the well-known electrical activity of CAP, its cerebral hemodynamic counterpart has not been assessed in healthy subjects so far. We recorded scalp and cortical Hemodynamics with near-infrared spectroscopy on the forehead and systemic Hemodynamics (heart rate and amplitude of the photoplethysmograph) with a finger pulse oximeter during 23 nights in 11 subjects. Electrical CAP activity was recorded with a polysomnogram. CAP was related to changes in scalp, cortical, and systemic hemodynamic signals that resembled the ones seen in arousal. Due to their repetitive nature, CAP sequences manifested as low- and very-low-frequency oscillations in the hemodynamic signals. The subtype A3+B showed the strongest hemodynamic changes. A transient hypoxia occurred during CAP cycles, suggesting that an increased CAP rate, especially with the subtype A3+B, which may result from diseases or fragmented sleep, might have an adverse effect on the cerebral vasculature.
Yisen Zhang - One of the best experts on this subject based on the ideXlab platform.
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discrimination of intracranial aneurysm rupture status patient specific inflow boundary may not be a must have condition in hemodynamic simulations
Neuroradiology, 2020Co-Authors: Shengzhang Wang, Zhongbin Tian, Wei Zhu, Yisen Zhang, Ying Zhang, Yang Wang, Kun Wang, Xinjian Yang, Jian LiuAbstract:Computational fluid dynamics (CFD) are important in evaluating the Hemodynamics of intracranial aneurysm rupture, and the setting of inflow boundary conditions is critical. We evaluated intracranial aneurysm Hemodynamics based on generalized versus patient-specific inflow boundary conditions to examine the effect of different hemodynamic results on the discrimination of intracranial aneurysm rupture status. We enrolled 148 patients with 156 intracranial aneurysms. For each included aneurysm, we performed CFD simulation once based on patient-specific and once based on generalized inflow boundary conditions. First, we compared the Hemodynamics of intracranial aneurysms based on different inflow boundary conditions. Then, we divided the included aneurysms into a ruptured and unruptured group and compared the Hemodynamics between the two groups under patient-specific and generalized inflow boundary conditions. For the hemodynamic parameters using specific inflow boundary conditions, more complex flow (p = 0.002), larger minimum WSS (p = 0.024), lower maximum low WSS area (LSA) (p = 0.038), and oscillatory shear index (p = 0.002) were found. Furthermore, we compared the Hemodynamics between ruptured and unruptured groups based on different inflow boundary conditions. We found that the significant hemodynamic parameters associated with rupture status were the same, including the proportion of aneurysms with flow complex and unstable flow and the minimum and maximum of LSA (p = 0.011, p = 0.003, p = 0.001 and p = 0.004, respectively). Patient-specific and generalized inflow boundary conditions of aneurysmal Hemodynamics resulted in significant differences. However, the significant parameters associated with rupture status were the same in both conditions, indicating that patient-specific inflow boundary conditions may not be necessary for predicting rupture risk.
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high shear stress and flow velocity in partially occluded aneurysms prone to recanalization
Stroke, 2011Co-Authors: Bin Luo, Shengzhang Wang, Yisen Zhang, Ying Zhang, Xinjian Yang, Jialiang Chen, Zhicheng Liu, Guanghong DingAbstract:Background and Purpose—Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. However, the hemodynamic features in the residual neck of the partially embolized aneurysms and their influences on recanalization are rarely reported. In this study, we characterized the Hemodynamics of partially occluded aneurysms, which were proven to undergo recanalization during follow-up using computational fluid dynamic analysis. Methods—From May 2007 to June 2009, we identified 11 partial aneurysms during follow-up, including 5 recanalized cases and 6 stable cases with 3-dimensional digital subtraction angiography. We retrospectively characterized the hemodynamic features around the residual aneurismal pouch using the available postprocedural digital subtraction angiography image data. The occluded part of the aneurysm was regarded as completely separated from the circulation. Results—The overall blood flow patterns before embolization were almost the same ...