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Influence of Parent Artery Segmentation and Boundary Conditions on Hemodynamic Characteristics of Intracranial Aneurysms.

Hua Y, Oh JH, Kim YB - Yonsei Med. J. (2015)

Bottom Line: Hemodynamic factors such as velocity pattern, streamline, wall shear stress, and oscillatory shear index at the systolic time were visualized and compared among the different cases.Hemodynamic factors were significantly affected by the inlet BCs while there was little influence of the outlet BCs.The effect of the outlet length on the hemodynamic factors was similar to that of the inlet length.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Hanyang University, Seoul, Korea.

ABSTRACT

Purpose: The purpose of this study is to explore the influence of segmentation of the upstream and downstream parent artery and hemodynamic boundary conditions (BCs) on the evaluated hemodynamic factors for the computational fluid dynamics (CFD) analysis of intracranial aneurysms.

Materials and methods: Three dimensional patient-specific aneurysm models were analyzed by applying various combinations of inlet and outlet BCs. Hemodynamic factors such as velocity pattern, streamline, wall shear stress, and oscillatory shear index at the systolic time were visualized and compared among the different cases.

Results: Hemodynamic factors were significantly affected by the inlet BCs while there was little influence of the outlet BCs. When the inlet length was relatively short, different inlet BCs showed different hemodynamic factors and the calculated hemodynamic factors were also dependent on the inlet length. However, when the inlet length (L) was long enough (L>20D, where D is the diameter of inlet section), the hemodynamic factors became similar regardless of the inlet BCs and lengths. The error due to different inlet BCs was negligible. The effect of the outlet length on the hemodynamic factors was similar to that of the inlet length.

Conclusion: Simulated hemodynamic factors are highly sensitive to inlet BCs and upstream parent artery segmentation. The results of this work can provide an insight into how to build models and to apply BCs for more accurate estimation of hemodynamic factors from CFD simulations of intracranial aneurysms.

No MeSH data available.


Related in: MedlinePlus

Comparison of the hemodynamic factors in side wall type aneurysm of ideal model at the systolic time for various inlet truncation positions. The Womersley flow and zero pressure condition are used as the inlet and outlet boundary conditions, respectively. Arrows indicate the points where the values are considered most different from each contour. WSS, wall shear stress; OSI, oscillatory shear index.
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Figure 9: Comparison of the hemodynamic factors in side wall type aneurysm of ideal model at the systolic time for various inlet truncation positions. The Womersley flow and zero pressure condition are used as the inlet and outlet boundary conditions, respectively. Arrows indicate the points where the values are considered most different from each contour. WSS, wall shear stress; OSI, oscillatory shear index.

Mentions: In applying same simulation protocol to side wall type aneurysm in ideal model (Fig. 1B), almost same result was obtained. Furthermore, when the inlet was truncated near the curved area (L≤3D), the inflow angle tended to become larger than the others. This indicates that blood flows into the aneurysm sac and rotates at a higher velocity, leading to a larger impact area and a higher WSS value. In contrast, for the inlet positions located beyond the curved part (L≥4D), there was little difference in the flow pattern among them, and the hemodynamic behavior for each case became similar (Fig. 9).


Influence of Parent Artery Segmentation and Boundary Conditions on Hemodynamic Characteristics of Intracranial Aneurysms.

Hua Y, Oh JH, Kim YB - Yonsei Med. J. (2015)

Comparison of the hemodynamic factors in side wall type aneurysm of ideal model at the systolic time for various inlet truncation positions. The Womersley flow and zero pressure condition are used as the inlet and outlet boundary conditions, respectively. Arrows indicate the points where the values are considered most different from each contour. WSS, wall shear stress; OSI, oscillatory shear index.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541663&req=5

Figure 9: Comparison of the hemodynamic factors in side wall type aneurysm of ideal model at the systolic time for various inlet truncation positions. The Womersley flow and zero pressure condition are used as the inlet and outlet boundary conditions, respectively. Arrows indicate the points where the values are considered most different from each contour. WSS, wall shear stress; OSI, oscillatory shear index.
Mentions: In applying same simulation protocol to side wall type aneurysm in ideal model (Fig. 1B), almost same result was obtained. Furthermore, when the inlet was truncated near the curved area (L≤3D), the inflow angle tended to become larger than the others. This indicates that blood flows into the aneurysm sac and rotates at a higher velocity, leading to a larger impact area and a higher WSS value. In contrast, for the inlet positions located beyond the curved part (L≥4D), there was little difference in the flow pattern among them, and the hemodynamic behavior for each case became similar (Fig. 9).

Bottom Line: Hemodynamic factors such as velocity pattern, streamline, wall shear stress, and oscillatory shear index at the systolic time were visualized and compared among the different cases.Hemodynamic factors were significantly affected by the inlet BCs while there was little influence of the outlet BCs.The effect of the outlet length on the hemodynamic factors was similar to that of the inlet length.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Hanyang University, Seoul, Korea.

ABSTRACT

Purpose: The purpose of this study is to explore the influence of segmentation of the upstream and downstream parent artery and hemodynamic boundary conditions (BCs) on the evaluated hemodynamic factors for the computational fluid dynamics (CFD) analysis of intracranial aneurysms.

Materials and methods: Three dimensional patient-specific aneurysm models were analyzed by applying various combinations of inlet and outlet BCs. Hemodynamic factors such as velocity pattern, streamline, wall shear stress, and oscillatory shear index at the systolic time were visualized and compared among the different cases.

Results: Hemodynamic factors were significantly affected by the inlet BCs while there was little influence of the outlet BCs. When the inlet length was relatively short, different inlet BCs showed different hemodynamic factors and the calculated hemodynamic factors were also dependent on the inlet length. However, when the inlet length (L) was long enough (L>20D, where D is the diameter of inlet section), the hemodynamic factors became similar regardless of the inlet BCs and lengths. The error due to different inlet BCs was negligible. The effect of the outlet length on the hemodynamic factors was similar to that of the inlet length.

Conclusion: Simulated hemodynamic factors are highly sensitive to inlet BCs and upstream parent artery segmentation. The results of this work can provide an insight into how to build models and to apply BCs for more accurate estimation of hemodynamic factors from CFD simulations of intracranial aneurysms.

No MeSH data available.


Related in: MedlinePlus