Background: Flow diverter (FD) intervention is an emerging endovascular technique\nfor treating intracranial aneurysms. High flow-diversion efficiency is desired to accelerate\nthrombotic occlusion inside the aneurysm; however, the risk of post-stenting\nstenosis in the parent artery is posed when flow-diversion efficiency is pursued by\nsimply decreasing device porosity. For improving the prognosis of FD intervention,\nwe develop an optimization method for the design of patient-specific FD devices that\nmaintain high levels of porosity.\nMethods: An automated structure optimization method for FDs with helix-like wires\nwas developed by applying a combination of lattice Boltzmann fluid simulation and\nsimulated annealing procedure. Employing intra-aneurysmal average velocity as the\nobjective function, the proposed method tailored the wire structure of an FD to a\ngiven vascular geometry by rearranging the starting phase of the helix wires.\nResults: FD optimization was applied to two idealized (S and C) vascular models\nand one realistic (R) model. Without altering the original device porosity of 80%, the\nflow-reduction rates of optimized FDs were improved by 5, 2, and 28% for the S, C, and\nR models, respectively. Furthermore, the aneurysmal flow patterns after optimization\nexhibited marked alterations. We confirmed that the disruption of bundle of inflow is of\ngreat help in blocking aneurysmal inflow. Axial displacement tests suggested that the\noptimal FD implanted in the R model possesses good robustness to tolerate uncertain\naxial positioning errors.\nConclusions: The optimization method developed in this study can be used to\nidentify the FD wire structure with the optimal flow-diversion efficiency. For a given\nvascular geometry, custom-designed FD structure can maximally reduce the aneurysmal\ninflow with its porosity maintained at a high level, thereby lowering the risk of\npost-stenting stenosis. This method facilitates the study of patient-specific designs for\nFD devices.
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