title: Flow diversion treatment: intra-aneurismal blood flow velocity and WSS reduction are parameters to predict aneurysm thrombosis.
abstract: BACKGROUND
  To evaluate the haemodynamic changes induced by flow diversion treatment in cerebral aneurysms, resulting in thrombosis or persisting aneurysm patency over time.
  
  
  METHODS
  Eight patients with aneurysms at the para-ophthalmic segment of the internal carotid artery were treated by flow diversion only. The clinical follow-up ranged between 6 days and 12 months. Computational fluid dynamics (CFD) analysis of pre- and post-treatment conditions was performed in all cases. True geometric models of the flow diverter were created and placed over the neck of the aneurysms by using a virtual stent-deployment technique, and the device was simulated as a true physical barrier. Pre- and post-treatment haemodynamics were compared, including mean and maximal velocities, wall-shear stress (WSS) and intra-aneurysmal flow patterns. The CFD study results were then correlated to angiographic follow-up studies.
  
  
  RESULTS
  Mean intra-aneurysmal flow velocities and WSS were significantly reduced in all aneurysms. Changes in flow patterns were recorded in only one case. Seven of eight aneurysms showed complete occlusion during the follow-up. One aneurysm remaining patent after 1 year showed no change in flow patterns. One aneurysm rupturing 5 days after treatment showed also no change in flow pattern, and no change in the maximal inflow velocity.
  
  
  CONCLUSIONS
  Relative flow velocity and WSS reduction in and of itself may result in aneurysm thrombosis in the majority of cases. Flow reductions under aneurysm-specific thresholds may, however, be the reason why some aneurysms remain completely or partially patent after flow diversion.
authors.affiliation: Department of Neuroradiology, Swiss Neuro Institute, Hirslanden Clinic, Witellikerstr. 40, 8032, Zurich, Switzerland. kulcsarzsolt22@gmail.com
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Kulcsár
authors.forename: Luca
authors.initials: L
authors.lastname: Augsburger
authors.forename: Philippe
authors.initials: P
authors.lastname: Reymond
authors.forename: Vitor M
authors.initials: VM
authors.lastname: Pereira
authors.forename: Sven
authors.initials: S
authors.lastname: Hirsch
authors.forename: Ajit S
authors.initials: AS
authors.lastname: Mallik
authors.forename: John
authors.initials: J
authors.lastname: Millar
authors.forename: Stephan G
authors.initials: SG
authors.lastname: Wetzel
authors.forename: Isabel
authors.initials: I
authors.lastname: Wanke
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Rüfenacht
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D002343:Carotid Artery, Internal / Q000503:physiopathology; D002533:Cerebral Angiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D013927:Thrombosis / Q000503:physiopathology*