title: Porosity dependency of an optimized stent design for an intracranial aneurysm.
abstract: BACKGROUND
  Optimal design of stents for a cerebral aneurysm is desired for efficient flow reduction in the aneurysm.
  
  
  OBJECTIVE
  In this study, we aimed to optimize stent design at several porosities, estimate the influence of stent design on aneurysm flow, and evaluate the ability of stents to reduce flow.
  
  
  METHODS
  Stent models were constructed as sets of squares or rectangles in the necks of a two-dimensional (2D) and realistic aneurysm. Then, automated optimization was performed using a combination of simulated annealing and lattice Boltzmann flow simulation.
  
  
  RESULTS
  By simulated annealing, stents were gradually modified to reduce the average velocity in an aneurysm. As a result of optimization, stents of all porosities demonstrated an inhomogeneous distribution with dense struts in the inflow area. Flow reduction was increased compared with the initial stent. Under the condition of high porosity, flow reduction by the stent drastically increased as porosity decreased. Under low porosity, the increase of velocity reduction was moderate even as porosity decreased.
  
  
  CONCLUSIONS
  Optimization can enhance flow reduction by stents. However, the increase in reduction associated with decreasing porosity is moderate under lower-porosity conditions. This threshold may help in the choice of stent porosity for each specific aneurysm.
authors.affiliation: Frontier Research Institute of Interdisciplinary Sciences, Tohoku University, Sendai, Japan.|Institute of Fluid Science, Tohoku University, Sendai, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Anzai
authors.affiliation: Graduate School of Engineering, Tohoku University, Sendai, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshida
authors.affiliation: Department of Neurosurgery, Kohnan Hospital, Sendai, Japan.|Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Sugiyama
authors.affiliation: Department of Neurosurgery, Kohnan Hospital, Sendai, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Endo
authors.affiliation: Department of Neuroendovascular Therapy, Kohnan Hospital, Sendai, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Institute of Fluid Science, Tohoku University, Sendai, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ohta
mesh_terms: D002560:Cerebrovascular Circulation / Q000502:physiology; D006801:Humans; D057446:Hydrodynamics; D002532:Intracranial Aneurysm / Q000601:surgery*; D016062:Porosity; D011474:Prosthesis Design / Q000379:methods*; D015607:Stents
keywords: Computational fluid dynamics; cerebral aneurysm; design optimization; flow diverter stent; lattice boltzmann method