title: High shear stress and flow velocity in partially occluded aneurysms prone to recanalization.
abstract: OBJECTIVE
  Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. However, the hemodynamic features in the residual neck of the partially embolized aneurysms and their influences on recanalization are rarely reported. In this study, we characterized the hemodynamics of partially occluded aneurysms, which were proven to undergo recanalization during follow-up using computational fluid dynamic analysis.
  
  
  METHODS
  From May 2007 to June 2009, we identified 11 partial aneurysms during follow-up, including 5 recanalized cases and 6 stable cases with 3-dimensional digital subtraction angiography. We retrospectively characterized the hemodynamic features around the residual aneurysmal pouch using the available postprocedural digital subtraction angiography image data. The occluded part of the aneurysm was regarded as completely separated from the circulation.
  
  
  RESULTS
  The overall blood flow patterns before embolization were almost the same in the recanalized and stable groups. After occlusion, the flow pattern changes, wall shear stress (WSS), and velocity at the remnant neck demonstrated different changes between the 2 groups. Specifically, in the recanalized group, high WSS regions were found near the neck in all 5 cases, with 4 of them being even higher than those before occlusion. Interestingly, in all cases, the high WSS area of the remnant neck coincided with the location where the aneurysm recanalization occurred. In the stable group, 5 out of 6 cases demonstrated lower WSS and velocity at the remnant neck after occlusion.
  
  
  CONCLUSIONS
  High WSS and blood flow velocity were consistently observed near the remnant neck of partially embolized aneurysms prone to future recanalization, suggesting that hemodynamic factors may have an important role in aneurysmal recurrence after endovascular treatment. The difference in flow pattern could be caused by the incomplete occlusion of the aneurysms.
authors.affiliation: Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Tiantan Xili 6, Chongwen District, Beijing 100050, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Luo
authors.forename: Xinjian
authors.initials: X
authors.lastname: Yang
authors.forename: Shengzhang
authors.initials: S
authors.lastname: Wang
authors.forename: Haiyun
authors.initials: H
authors.lastname: Li
authors.forename: Jialiang
authors.initials: J
authors.lastname: Chen
authors.forename: Hongyu
authors.initials: H
authors.lastname: Yu
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yisen
authors.initials: Y
authors.lastname: Zhang
authors.forename: Shiqing
authors.initials: S
authors.lastname: Mu
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Liu
authors.forename: Guanghong
authors.initials: G
authors.lastname: Ding
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D033081:Shear Strength / Q000502:physiology*