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. 2024 Sep 27;14(10):977.
doi: 10.3390/brainsci14100977.

Fluid-Structure Interaction Simulations of the Initiation Process of Cerebral Aneurysms

Jozsef Nagy  1 , Wolfgang Fenz  2 , Veronika M Miron  3 , Stefan Thumfart  2 , Julia Maier  3 , Zoltan Major  3 , Harald Stefanits  4   5 , Johannes Oberndorfer  4 , Nico Stroh  4   5 , Vanessa Mazanec  4   5 , Philip-Rudolf Rauch  4   5 , Andreas Gruber  4   5   6 , Matthias Gmeiner  4   5
Affiliations

Fluid-Structure Interaction Simulations of the Initiation Process of Cerebral Aneurysms

Jozsef Nagy et al. Brain Sci. .

Abstract

Background: Hemodynamics during the growth process of cerebral aneurysms are incompletely understood. We developed a novel fluid-structure interaction analysis method for the identification of relevant scenarios of aneurysm onset. Method: This method integrates both fluid dynamics and structural mechanics, as well as their mutual interaction, for a comprehensive analysis. Patients with a single unruptured cerebral aneurysm were included. Results: Overall, three scenarios were identified. In scenario A, wall shear stress (WSS) was low, and the oscillatory shear index (OSI) was high in large areas within the region of aneurysm onset (RAO). In scenario B, the quantities indicated a reversed behavior, where WSS was high and OSI was low. In the last scenario C, a behavior in-between was found, with scenarios A and B coexisting simultaneously in the RAO. Structural mechanics demonstrated a similar but independent trend. Further, we analyzed the change in hemodynamics between the onset and a fully developed aneurysm. While scenarios A and C remained unchanged during aneurysm growth, 47% of aneurysms in scenario B changed into scenario A and 20% into scenario C. Conclusions: In conclusion, these findings suggest that WSS and the OSI are reciprocally regulated, and both low and high WSS/OSI conditions can lead to aneurysm onset.

Keywords: cerebral aneurysm; fluid–structure interaction simulation; hemodynamics; initiation; structural mechanics.

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Conflict of interest statement

Author Jozsef Nagy was employed by the company eulerian-solutions e.U., Authors Wolfgang Fenz, Stefan Thumfart were employed by the company RISC Software GmbH. All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements) or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript. Generative AI was not used in the process of scientific writing.

Figures

Figure 2
Figure 2
Hemodynamic scenarios. First two columns show the wall shear stress, the first column without the aneurysm sac and the second with the aneurysm sac; third and fourth columns show the oscillatory shear index OSI, the third column without the aneurysm sac and the fourth column with the aneurysm sac.
Figure 3
Figure 3
Change in hemodynamic features for scenario B. Individual rows show individual aneurysm geometries (row 1—scenario B to scenario A, row 2—scenario B remains scenario B, row 3—scenario B to scenario C); first two columns show the wall shear stress without the aneurysm sac (first column) and with the aneurysm sac (second column); third and fourth columns show the oscillatory shear index OSI without the aneurysm sac (third column) and with the aneurysm sac (fourth column).
Figure 4
Figure 4
Structural dynamic features. The first two columns show the equivalent stress, first column without the aneurysm sac and the second column with the aneurysm sac; the third and fourth columns show the equivalent strain, the third column without the aneurysm sac and the fourth column with the aneurysm sac.
Figure 1
Figure 1
Typical CAD geometry of a cerebral artery, with aneurysm sac (left), aneurysm sac removed (center), and indicator line of the region of aneurysm onset (RAO, right).
See this image and copyright information in PMC

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