Anomalous hemodynamic effects of a self-expanding intracranial stent: comparing in-vitro and ex-vivo models using ultra-high resolution microCT based CFD.

Previous research on the effects of intracranial stents on arterial hemodynamics has involved computational hemodynamics (CHD) simulations applied to artificially generated stent models. In this study, accurate geometric reconstructions of in-vitro (PTFE tube) and ex-vivo (canine artery) deployed stents based on ultra-high resolution MicroCT imaging were used. The primary goal was to compare the hemodynamic effects of deployment in these two different models and to identify flow perturbations due to deployment anomalies such as stent malapposition and strut prolapse, important adverse mechanics occurring in clinical practice, but not considered in studies using idealized stent models. Ultra-high resolution MicroCT data provided detailed visualization of deployment characteristics allowing for accurate in-stent flow simulation. For stent cells that are regularly and symmetrically deployed, the near wall flow velocities and wall shear stresses were similar to previously published results derived from idealized models. In-stent hemodynamics were significantly altered by misaligned or malapposed stent cells, important effects not realistically captured in previous models. This research shows the feasibility and value of an ex-vivo stent model for MicroCT based CHD studies. It validates previous in-vitro studies and further contributes to the understanding of in-stent hemodynamics associated with adverse mechanics of self-expanding intracranial stents.