第 39 回日本バイオレオロジー学会年会

プログラム・抄録集

脳動脈瘤内の流動不安定性と破裂の相関：流入低調波の影響
EXPLORING ASSOCIATION BETWEEN FLOW INSTABILITY AND RUPTURE IN
MULTIPLE INTRACRANIAL ANEURYSMS: LOW HARMONIC INFLOW EFFECTS
Lijian Xu*, Ryuhei Yamaguchi*, Gaku Tanaka*, Atsushi Saito** and Hao Liu*
*Graduate School of Engineering, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba-shi, Chiba, Japan** Department of Neurosurgery, Aomori Prefectural Central Hospital, 2-1-1 Higashitsukurimichi, Aomori, Japan
1. Introduction
Multiple intracranial aneurysms are observed in 15%and a high-resolution scheme for the stabilization ofthe convective term.

to 35% of patients with aneurysms who present with
SAH [1]. For SAH patients with multiple aneurysms, it
is very crucial for doctors to determine the cause ofSAH [2].

3. Results
Both the ACA and BA models show a stable flow
pattern with a single vortex in the aneurysm. The BA
aneurysm experiences more significant temporal WSS

2. Methods
A patient was confirmed to have two aneurysms withfluctuations than the ACA aneurysm at the feature points
under the same boundary conditions. However, there also

one located in the anterior communicating artery(ACA) and the other in the basilar artery (BA).
Patient-specific geometries of the cerebral aneurysm
and vessels were extracted using a gradient-based levelset segmentation algorithm. The reconstructed surface
model was then smoothened by a Taubin filter. We

exists a combination of high OSI and low WSS at theblebs of the ACA aneurysm and neck of the BA
aneurysm, which is more significant in the ACA
aneurysm. The ACA aneurysm is more likely torupture than the BA aneurysm based on the low-WSS
theory.

included the vessel’s geometric features as much as
possible but added some artificially extended vessels at
inlet and outlet with a length of eight diameters so as
to damp out the numerical reflective waves atboundaries.

4. Conclusion
The present study investigated the flow instabilities
and hemodynamics in multiple intracranial aneurysms.
The ACA aneurysm is more likely to rupture than theBA aneurysm considering that it exhibits an obvious・Mesh
Unstructured grids composed of tetrahedral and prismelements were generated by ANSYS ICEM 15.0with aminimum element size of 0.035 mm and maximum
element size of 0.14 mm. A total number of 0.81 ~1.28 million elements were used in different aneurysm

characteristic of high OSI and low WSS at the bleb.
Acknowledgements
This work has been supported by Research andDevelopment of the Next Generation Integrated
Simulation of Living Matter, JST, Japan.

models. Three prism layers were employed to resolve
the near-wall regions.

References

・Boundary conditions
At inlet a prescribed fully developed Womersley
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0.5 m/s and a period of 0.75s.
・Computational fluid dynamic modeling
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fluid. The governing equations for the fluid are
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