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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

Simulation results for hemodynamic factors under different combinations of inlet/outlet boundary conditions at the systolic time. Streamlines, velocity contours, wall shear stress (WSS), and oscillatory shear index (OSI) distributions are shown for all the six cases.
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Figure 3: Simulation results for hemodynamic factors under different combinations of inlet/outlet boundary conditions at the systolic time. Streamlines, velocity contours, wall shear stress (WSS), and oscillatory shear index (OSI) distributions are shown for all the six cases.

Mentions: The simulation results for the patient-specific aneurysm model (Fig. 1A) with six combinations of inlet and outlet BCs (Table 1) are shown in Fig. 3. Hemodynamic factors such as streamlines, velocity contours in the neck cross-section, and WSS and OSI distributions in the aneurysm sac at the second systolic time were compared. The first three cases under the same inlet BC of plug velocity profile and three different outlet BCs showed quite similar results, whereas the last three cases changed the inlet BC to the Womersley velocity profile. However, these two groups were different in all these hemodynamic factors. The last three cases under the Womersley flow inlet BC presented larger areas of contours corresponding to higher hemodynamic factors than those under the plug flow inlet BC. Fig. 4 summarizes the mean and maximum values of hemodynamic factors for different combinations of inlet and outlet BCs. As expected from Fig. 3, each hemodynamic factor was almost the same for each group. The differences in the maximum velocity, WSS, and OSI between these two groups were 6.5%, 4.1%, and 66.9%, respectively.


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

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

Simulation results for hemodynamic factors under different combinations of inlet/outlet boundary conditions at the systolic time. Streamlines, velocity contours, wall shear stress (WSS), and oscillatory shear index (OSI) distributions are shown for all the six cases.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Simulation results for hemodynamic factors under different combinations of inlet/outlet boundary conditions at the systolic time. Streamlines, velocity contours, wall shear stress (WSS), and oscillatory shear index (OSI) distributions are shown for all the six cases.
Mentions: The simulation results for the patient-specific aneurysm model (Fig. 1A) with six combinations of inlet and outlet BCs (Table 1) are shown in Fig. 3. Hemodynamic factors such as streamlines, velocity contours in the neck cross-section, and WSS and OSI distributions in the aneurysm sac at the second systolic time were compared. The first three cases under the same inlet BC of plug velocity profile and three different outlet BCs showed quite similar results, whereas the last three cases changed the inlet BC to the Womersley velocity profile. However, these two groups were different in all these hemodynamic factors. The last three cases under the Womersley flow inlet BC presented larger areas of contours corresponding to higher hemodynamic factors than those under the plug flow inlet BC. Fig. 4 summarizes the mean and maximum values of hemodynamic factors for different combinations of inlet and outlet BCs. As expected from Fig. 3, each hemodynamic factor was almost the same for each group. The differences in the maximum velocity, WSS, and OSI between these two groups were 6.5%, 4.1%, and 66.9%, respectively.

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