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Cerebral aneurysm clips are biomedical implants applied by neurosurgeons to re-approximate arterial vessel walls and prevent catastrophic aneurysmal hemorrhages in patients. Current methods of aneurysm clip production are labor intensive and time-consuming, leading to high costs per implant and limited variability in clip morphology. Metal additive manufacturing is investigated as an alternative to traditional manufacturing methods that may enable production of patient-specific aneurysm clips to account for variations in individual vascular anatomy and possibly reduce surgical complication risks. Relevant challenges to metal additive manufacturing are investigated for biomedical implants, including material choice, design limitations, postprocessing, printed material properties, and combined production methods. Initial experiments with additive manufacturing of 316 L stainless steel aneurysm clips are carried out on a selective laser melting (SLM) system. The dimensions of the printed clips were found to be within 0.5% of the dimensions of the designed clips. Hardness and density of the printed clips (213 ± 7 HV1 and 7.9 g/cc, respectively) were very close to reported values for 316 L stainless steel, as expected. No ferrite and minimal porosity is observed in a cross section of a printed clip, with some anisotropy in the grain orientation. A clamping force of approximately 1 N is measured with a clip separation of 1.5 mm. Metal additive manufacturing shows promise for use in the creation of custom aneurysm clips, but some of the challenges discussed will need to be addressed before clinical use is possible.
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CFD-Driven Topology Optimization for Personalized Intracranial Aneurysm Implant Design
Abstract Intracranial aneurysm rupture causes life-threatening sub-arachnoid hemorrhage. Current endovascular devices like coils, flow diverters, and intravascular implants aim to thrombose the aneurysm but have limitations and varying success rates depending on aneurysm characteristics. We propose a new computational framework integrating CFD and topology optimization to design personalized aneurysm implants. The optimization problem aims to reduce blood flow velocity within the aneurysm while ensuring adequate structural integrity of the implant. The fluid dynamics are governed by the Navier-Stokes equations, while the solid mechanics are described by the linear elasticity equations. A Darcy-Brinkman model is employed to simulate flow through the porous implant in the fluid domain, while the Solid Isotropic Material with Penalization (SIMP) method is used to interpolate between solid and void regions in the structural domain during topology optimization. The objective combines fluid energy dissipation ratio and solid strain energy with spatially varying weights. Global and local volume constraints generate personalized implants with porosity and flow-diverting architectures. The approach is demonstrated on patient-specific aneurysm geometries from rotational angiography. This CFD-driven topology optimization method enables personalized aneurysm implant design to potentially improve occlusion rates and reduce complications compared to current devices. Further studies will validate the optimized designs and investigate their efficacy in vitro and in vivo.
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- PAR ID:
- 10634610
- Publisher / Repository:
- American Society of Mechanical Engineers
- Date Published:
- ISBN:
- 978-0-7918-8837-7
- Format(s):
- Medium: X
- Location:
- Washington, DC, USA
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1115/DETC2024-143347
