title: New method for retrospective study of hemodynamic changes before and after aneurysm formation in patients with ruptured or unruptured aneurysms.
abstract: BACKGROUND
  Prospective observation of hemodynamic changes before and after formation of brain aneurysms is often difficult. We used a vessel surface repair method to carry out a retrospective hemodynamic study before and after aneurysm formation in a ruptured aneurysm of the posterior communicating artery (RPcomAA) and an unruptured aneurysm of the posterior communicating artery (URPcomAA).
  
  
  METHODS
  Arterial geometries obtained from three-dimensional digital subtraction angiography of cerebral angiograms were used for flow simulation by employing finite-volume modeling. Hemodynamic parameters such as wall shear stress (WSS), blood-flow velocity, streamlines, pressure, and wall shear stress gradient (WSSG) in the aneurysm sac and at the site of aneurysm formation were analyzed in each model.
  
  
  RESULTS
  At "aneurysm" status, hemodynamic analyses at the neck, body, and dome of the aneurysm revealed the distal aneurysm neck to be subjected to the highest WSS and blood-flow velocity, whereas the aneurysm dome presented the lowest WSS and blood-flow velocity in both model types. More apparent changes in WSSG at the aneurysm dome with an inflow jet and narrowed impaction zone were revealed only in the RPcomAA. At "pre-aneurysm" status, hemodynamic analyses in both models showed that the region of aneurysm formation was subjected to extremely elevated WSS, WSSG, and blood-flow velocity.
  
  
  CONCLUSIONS
  These data suggest that hemodynamic analyses in patients with ruptured or unruptured aneurysms using the vessel surface repair method are feasible, economical, and simple. Our preliminary results indicated that the arterial wall was subjected to elevated WSS, WSSG and blood-flow velocity before aneurysm generation. However, more complicated flow patterns (often with an inflow jet or narrowed impaction zone) were more likely to be observed in ruptured aneurysm.
authors.forename: Wei-Jie
authors.initials: WJ
authors.lastname: Le
authors.affiliation: Department of Radiology, The Sixth Affiliated People's Hospital, Medical School of Shanghai Jiao Tong University, No, 600, Yi Shan Road, Shanghai 200233, China. zhuyueqi@hotmail.com.
authors.forename: Yue-Qi
authors.initials: YQ
authors.lastname: Zhu
authors.forename: Ming-Hua
authors.initials: MH
authors.lastname: Li
authors.forename: Lei
authors.initials: L
authors.lastname: Yan
authors.forename: Hua-Qiao
authors.initials: HQ
authors.lastname: Tan
authors.forename: Shi-Min
authors.initials: SM
authors.lastname: Xiao
authors.forename: Ying-Sheng
authors.initials: YS
authors.lastname: Cheng
mesh_terms: D017542:Aneurysm, Ruptured / Q000175:diagnosis* / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D057446:Hydrodynamics; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies