title: Hemodynamic differences between unruptured and ruptured intracranial aneurysms during observation.
abstract: OBJECTIVE
  We evaluated several hemodynamic parameters for the prediction of rupture in a data set of initially unruptured aneurysms, including aneurysms that ruptured during follow-up observation.
  
  
  METHODS
  Aneurysm geometry was extracted from CT angiographic images and analyzed using a mathematical formula for fluid flow under pulsatile blood flow conditions. Fifty side-wall internal carotid posterior communicating artery aneurysms and 50 middle cerebral artery bifurcation aneurysms of medium size were investigated for energy loss, pressure loss coefficient, wall shear stress, and oscillatory shear index. During follow-up observation, 6 internal carotid posterior communicating artery and 7 middle cerebral artery aneurysms ruptured (44 and 43 remained unruptured, respectively, with the same location and a similar size as the ruptured cases).
  
  
  RESULTS
  A significant difference in the minimum wall shear stress between aneurysms that ruptured and those that remained unruptured was noted only in internal carotid artery aneurysms (P<0.001). Energy loss showed a higher tendency in ruptured aneurysms but statistically not significant. For pressure loss coefficient, a significant difference was noted in both internal carotid artery (P=0.0046) and middle cerebral artery (P<0.001) aneurysms.
  
  
  CONCLUSIONS
  Pressure loss coefficient may be a potential parameter to predict future rupture of unruptured aneurysms.
authors.affiliation: The Jikei University School of Medicine, Department of Neurosurgery, Tokyo, Japan. takao@jikei.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takao
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Murayama
authors.forename: Shinobu
authors.initials: S
authors.lastname: Otsuka
authors.forename: Yi
authors.initials: Y
authors.lastname: Qian
authors.forename: Ashraf
authors.initials: A
authors.lastname: Mohamed
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Masuda
authors.forename: Makoto
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Abe
mesh_terms: D017542:Aneurysm, Ruptured / Q000503:physiopathology*; D002343:Carotid Artery, Internal / Q000503:physiopathology*; D002533:Cerebral Angiography; D004734:Energy Metabolism / Q000502:physiology; D005500:Follow-Up Studies; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D002532:Intracranial Aneurysm / Q000503:physiopathology*; D020768:Middle Cerebral Artery / Q000503:physiopathology*; D008962:Models, Theoretical; D011312:Pressure; D012039:Regional Blood Flow / Q000502:physiology; D033081:Shear Strength / Q000502:physiology