High-Fidelity Finite Element Mesh Generation for Fluid-Structure Interaction Analysis of Cerebral Aneurysms

2009 ◽  
Author(s):  
Yongjie Zhang ◽  
Wenyan Wang ◽  
Xinghua Liang ◽  
Yuri Bazilevs ◽  
Ming-Chen Hsu ◽  
...  
Keyword(s):  
Mesh Generation ◽  
Interaction Analysis ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Material Strength ◽  
Element Mesh ◽  
Computational Tools ◽  
Unruptured Cerebral Aneurysms ◽  
Ideal Method ◽  
Invasive Measurement

Nowadays approximately 3–6% of the population is estimated to have unruptured cerebral aneurysms. The rupture risk of aneurysms can be predicted by using computational tools and patient-specific models. As an ideal method, we can assess the risk factors by determining the blood tension and the material strength of the wall tissue in the aneurisms. Although it is hard to obtain aneurismal material strength without invasive measurement, it is possible to estimate the wall tension by numerical simulation [1].

scholarly journals Prediction of Thin-Walled Areas of Unruptured Cerebral Aneurysms through Comparison of Normalized Hemodynamic Parameters and Intraoperative Images

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Kwang-Chun Cho ◽  
Ji Hun Choi ◽  
Je Hoon Oh ◽  
Yong Bae Kim
Keyword(s):  
Interaction Analysis ◽  
Cerebral Aneurysms ◽  
Weighted Average ◽  
Weighting Factor ◽  
Hemodynamic Parameters ◽  
Color Analysis ◽  
Risk Of Rupture ◽  
Thin Walled ◽  
Unruptured Cerebral Aneurysms ◽  
Normalization Scheme

Object. Rupture of a cerebral aneurysm occurs mainly in a thin-walled area (TWA). Prediction of TWAs would help to assess the risk of rupture and select appropriate treatment strategy. There are several limitations of current prediction techniques for TWAs. To predict TWAs more accurately, HP should be normalized to minimize the influence of analysis conditions, and the effectiveness of normalized, combined hemodynamic parameters (CHPs) should be investigated with help of the quantitative color analysis of intraoperative images. Methods. A total of 21 unruptured cerebral aneurysms in 19 patients were analyzed. A normalized CHP was newly suggested as a weighted average of normalized wall shear stress (WSS) and normalized oscillatory shear index (OSI). Delta E from International Commission on Illumination was used to more objectively quantify color differences in intraoperative images. Results. CFD analysis results indicated that WSS and OSI were more predictive of TWAs than pressure (P<.001, P=.187, P=.970, respectively); these two parameters were selected to define the normalized CHP. The normalized CHP became more statistically significant (P<.001) as the weighting factor of normalized WSS increased and that of normalized OSI decreased. Locations with high CHP values corresponded well to those with high Delta E values (P<.001). Predicted TWAs based on the normalized CHP showed a relatively good agreement with intraoperative images (17 in 21 cases, 81.0%). Conclusion. 100% weighting on the normalized WSS produced the most statistically significant result. The normalization scheme for WSS and OSI suggested in this work was validated using quantitative color analyses, rather than subjective judgments, of intraoperative images, and it might be clinically useful for predicting TWAs of unruptured cerebral aneurysms. The normalization scheme would also be integrated into further fluid-structure interaction analysis for more reliable estimation of the risk of aneurysm rupture.

scholarly journals Size-Dependent Distribution of Patient-Specific Hemodynamic Factors in Unruptured Cerebral Aneurysms Using Computational Fluid Dynamics

Diagnostics ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 64 ◽  
Author(s):  
Ui Yun Lee ◽  
Gyung Ho Chung ◽  
Jinmu Jung ◽  
Hyo Sung Kwak
Keyword(s):  
Fluid Dynamics ◽  
Shear Rate ◽  
Blood Viscosity ◽  
Cerebral Aneurysms ◽  
Velocity Shear ◽  
Patient Specific ◽  
Complex Flow ◽  
Size Dependent ◽  
Unruptured Cerebral Aneurysms ◽  
Small Aneurysms

Purpose: To analyze size-dependent hemodynamic factors [velocity, shear rate, blood viscosity, wall shear stress (WSS)] in unruptured cerebral aneurysms using computational fluid dynamics (CFD) based on the measured non-Newtonian model of viscosity. Methods: Twenty-one patients with unruptured aneurysms formed the study cohort. Patient-specific geometric models were reconstructed for CFD analyses. Aneurysms were divided into small and large groups based on a cutoff size of 5 mm. For comparison between small and large aneurysms, 5 morphologic variables were measured. Patient-specific non-Newtonian blood viscosity was applied for more detailed CFD simulation. Quantitative and qualitative analyses of velocity, shear rate, blood viscosity, and WSS were conducted to compare small and large aneurysms. Results: Complex flow patterns were found in large aneurysms. Large aneurysms had a significantly lower shear rate (235 ± 341 s−1) than small aneurysms (915 ± 432 s−1) at peak-systole. Two times higher blood viscosity was observed in large aneurysms compared with small aneurysms. Lower WSS was found in large aneurysms (1.38 ± 1.36 Pa) than in small aneurysms (3.53 ± 1.22 Pa). All the differences in hemodynamic factors between small and large aneurysms were statistically significant. Conclusions: Large aneurysms tended to have complex flow patterns, low shear rate, high blood viscosity, and low WSS. The hemodynamic factors that we analyzed might be useful for decision making before surgical treatment of aneurysms.

Direct Structured Finite Element Mesh Generation From Three-Dimensional Medical Images

2013 ◽  
Author(s):  
Sharareh Bayat ◽  
Dan Necsulescu ◽  
Michel Labrosse
Keyword(s):  
Finite Element ◽  
Mesh Generation ◽  
Medical Images ◽  
Three Dimensional ◽  
Finite Element Mesh ◽  
Patient Specific ◽  
Human Aorta ◽  
Element Mesh ◽  
Future Directions ◽  
Finite Element Mesh Generation

In this work, a new methodology is proposed to automatically construct a structured finite element (FE) mesh from the information contained in patient-specific three-dimensional (3-D) images. Testing of the methodology is presented toward meshing of the human aorta from 3-D synthetic images as well as CT medical images. Promising results are obtained and future directions are discussed.

Geometry Anticipates Hemodynamic Phenotype of Basilar Tip Aneurysms

2007 ◽  
Author(s):  
Matthew D. Ford ◽  
Sang-Wook Lee ◽  
Stephen P. Lownie ◽  
David W. Holdsworth ◽  
David A. Steinman
Keyword(s):  
Endovascular Therapy ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Clinical Use ◽  
Hemodynamic Forces ◽  
Risk Of Rupture ◽  
Specific Manner ◽  
Computational Fluid Dynamics Cfd ◽  
Unruptured Cerebral Aneurysms ◽  
Hemodynamic Information

The prevalence of unruptured cerebral aneurysms is estimated to be as high as 5% [1]. Basilar tip aneurysms account for 4–5% of these, but have a higher risk of rupture [2]. They are also difficult to treat surgically, and so endovascular therapy is often the only option. Hemodynamic forces have been implicated in the risk of rupture [3] and complications of endovascular therapy [4]; however, hemodynamic information is difficult to acquire clinically. Computational fluid dynamics (CFD), in combination with clinical imaging, can be used to accurately capture the intra-aneurysmal hemodynamics in a patient-specific manner [5]. Still, these techniques have not translated to routine clinical use, largely due to the time and effort required to construct, simulate, and interpret these models.

Paradoxical Trends in the Management of Unruptured Cerebral Aneurysms in the United States

Stroke ◽  
2011 ◽  
Vol 42 (6) ◽  
pp. 1730-1735 ◽  
Author(s):  
Michael C. Huang ◽  
Ali A. Baaj ◽  
Katheryne Downes ◽  
A. Samy Youssef ◽  
Eric Sauvageau ◽  
...  
Keyword(s):  
United States ◽  
Cerebral Aneurysms ◽  
The United States ◽  
Unruptured Cerebral Aneurysms

scholarly journals Morphological and Hemodynamic Changes during Cerebral Aneurysm Growth

2021 ◽  
Vol 11 (4) ◽  
pp. 520
Author(s):  
Emily R. Nordahl ◽  
Susheil Uthamaraj ◽  
Kendall D. Dennis ◽  
Alena Sejkorová ◽  
Aleš Hejčl ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Swirling Flow ◽  
Morphological Changes ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Aneurysm Wall ◽  
Aneurysm Growth ◽  
Computational Fluid Dynamics Cfd

Computational fluid dynamics (CFD) has grown as a tool to help understand the hemodynamic properties related to the rupture of cerebral aneurysms. Few of these studies deal specifically with aneurysm growth and most only use a single time instance within the aneurysm growth history. The present retrospective study investigated four patient-specific aneurysms, once at initial diagnosis and then at follow-up, to analyze hemodynamic and morphological changes. Aneurysm geometries were segmented via the medical image processing software Mimics. The geometries were meshed and a computational fluid dynamics (CFD) analysis was performed using ANSYS. Results showed that major geometry bulk growth occurred in areas of low wall shear stress (WSS). Wall shape remodeling near neck impingement regions occurred in areas with large gradients of WSS and oscillatory shear index. This study found that growth occurred in areas where low WSS was accompanied by high velocity gradients between the aneurysm wall and large swirling flow structures. A new finding was that all cases showed an increase in kinetic energy from the first time point to the second, and this change in kinetic energy seems correlated to the change in aneurysm volume.

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