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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

(A) Three dimensional truncated patient-specific model with an inlet length L=6D and an outlet length K=3.5d. The sac of patient-specific aneurysm model, zooming in, is marked by neck section and hemodynamic factors will be shown on sac and the neck section area. (B) An ideal model of side wall type aneurysm with an inlet length L=6D and an outlet length K=3.5d. D, diameter of inlet section; d, diameter of outlet section.
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Figure 1: (A) Three dimensional truncated patient-specific model with an inlet length L=6D and an outlet length K=3.5d. The sac of patient-specific aneurysm model, zooming in, is marked by neck section and hemodynamic factors will be shown on sac and the neck section area. (B) An ideal model of side wall type aneurysm with an inlet length L=6D and an outlet length K=3.5d. D, diameter of inlet section; d, diameter of outlet section.

Mentions: This study protocol was approved by our Institutional Review Board, and informed consent was waived. In order to analyze the combination of different BCs and boundary positions, digital subtraction angiography images of a middle cerebral artery bifurcation aneurysm were gathered from a 72-year-old female patient using a Philips Integris system (Philips Medical Systems, Best, the Netherlands). These images were reconstructed to three-dimensional surface models, and then the aneurysm artery model was selected and truncated. Fig. 1A shows one of these truncating models with an inlet length (L) of 6D (D: inlet diameter) and an outlet length (K) of 3.5d (d: outlet diameter). L and K mean the distances between the inlet and outlet positions and the center of the aneurysm, respectively. Different combinations of BCs were applied to this truncated model to examine the influence of BCs on hemodynamic factors (Table 1). In addition, the inlet and outlet lengths from the aneurysm were also changed, considering the inlet velocity magnitude variation at different inlet positions caused by the change in artery diameter under the same flow rate waveform. Eight truncating models with L varying from 3D to 30D and a fixed K=3.5d were used to analyze the influence of inlet lengths and inlet BCs. Also, four truncating models with a fixed L=26D and K varying from 1d to 4d were selected to analyze the influence of outlet lengths.


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

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

(A) Three dimensional truncated patient-specific model with an inlet length L=6D and an outlet length K=3.5d. The sac of patient-specific aneurysm model, zooming in, is marked by neck section and hemodynamic factors will be shown on sac and the neck section area. (B) An ideal model of side wall type aneurysm with an inlet length L=6D and an outlet length K=3.5d. D, diameter of inlet section; d, diameter of outlet section.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: (A) Three dimensional truncated patient-specific model with an inlet length L=6D and an outlet length K=3.5d. The sac of patient-specific aneurysm model, zooming in, is marked by neck section and hemodynamic factors will be shown on sac and the neck section area. (B) An ideal model of side wall type aneurysm with an inlet length L=6D and an outlet length K=3.5d. D, diameter of inlet section; d, diameter of outlet section.
Mentions: This study protocol was approved by our Institutional Review Board, and informed consent was waived. In order to analyze the combination of different BCs and boundary positions, digital subtraction angiography images of a middle cerebral artery bifurcation aneurysm were gathered from a 72-year-old female patient using a Philips Integris system (Philips Medical Systems, Best, the Netherlands). These images were reconstructed to three-dimensional surface models, and then the aneurysm artery model was selected and truncated. Fig. 1A shows one of these truncating models with an inlet length (L) of 6D (D: inlet diameter) and an outlet length (K) of 3.5d (d: outlet diameter). L and K mean the distances between the inlet and outlet positions and the center of the aneurysm, respectively. Different combinations of BCs were applied to this truncated model to examine the influence of BCs on hemodynamic factors (Table 1). In addition, the inlet and outlet lengths from the aneurysm were also changed, considering the inlet velocity magnitude variation at different inlet positions caused by the change in artery diameter under the same flow rate waveform. Eight truncating models with L varying from 3D to 30D and a fixed K=3.5d were used to analyze the influence of inlet lengths and inlet BCs. Also, four truncating models with a fixed L=26D and K varying from 1d to 4d were selected to analyze the influence of outlet lengths.

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