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Session: Vascular - II
Session starts: Friday 27 January, 11:30
Presentation starts: 12:15
Room: Room 559

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Judith Fonken ()
Eline van Engelen ()
Esther Maas ()
Arjet Nievergeld ()
Marc van Sambeek ()
Frans van de Vosse ()
Richard Lopata ()

Abstract:
Insight in abdominal aortic aneurysm (AAA) development, growth and rupture risk requires a large, longitudinal study on mechanical properties of AAAs. For patient-specific risk assessment and analysis of the mechanical state, fluid-structure interaction (FSI) models are considered, which require the AAA geometry and its dynamics. Time-resolved 3-dimensional ultrasound (3D+t US) is the preferred image modality to extract the patient-specific geometry, since it is safe, fast, affordable and provides functional information such as wall motion and blood velocity. A previous study has shown the feasibility of 3D+t US-based FSI simulations [1]. In this study, the FSI framework was improved vastly to better approach the in-vivo situation. Due to the limited field-of-view of 3D+t US, the aorto-iliac bifurcation geometry is often not included in the US acquisition. Due to this limitation, a single outlet AAA geometry was used in our previous study [1]. However, the bifurcation geometry does influence the hemodynamics in the aneurysm region. This study showed the feasibility of adding a parametric bifurcation to the aneurysm geometry, with median differences in hemodynamics below 1% with respect to the patient-specific bifurcation geometry. Furthermore, the framework is further personalized by including patient-specific flow parameters derived from US Doppler acquisitions. These flow parameters include the flow pulse, velocity profile over the vessel cross-section, inlet radius and inlet distance. FSI simulations employing patient-specific flow parameters yielded mean differences of 168% (TAWSS), 40% (OSI) and 7% (wall stress), with respect to simulations using generic flow parameters. Finally, the AAA geometry was embedded in a surrounding soft tissue and spine was included at the posterior side modelled by a stiff rod. This resulted in a decrease (mean: 34%) in displacement, especially at the posterior wall, and a homogenization and decrease (mean: 14%) in wall stress, similar to [2]. In future studies, the obtained FSI framework will be further personalized using 4D US speckle tracking for wall motion [3], and validated with the use of 4D flow MRI. The envisioned framework for realistic and personalized 3D+t US-based FSI simulations paves the way for longitudinal studies on AAA development, growth, and rupture risk. [1] Fonken et al., Front. Physiol., 1255, 2021. [2] Petterson et al., Journal of Biomechanics, 126-133, 2019 [3] Disseldorp et al., Eur. Heart J. Cardiovasc. Imaging., 185-191, 2019.