title: In vitro measurement of fluid-induced wall shear stress in unruptured cerebral aneurysms harboring blebs.
abstract: OBJECTIVE
  Little attention has been focused on the role of fluid-induced wall shear stress in fully developed cerebral aneurysms. The purpose of this study is to evaluate the alternation and distribution of wall shear stress over 1 cardiac cycle in patients' aneurysms.
  
  
  METHODS
  A middle cerebral artery aneurysm and a basilar tip aneurysm with localized outpouching (blebs) in their domes were selected for this study. With the use of a stereo lithography machine, geometrically realistic aneurysm models were created on the basis of 3-dimensional CT angiograms. In vitro shearing velocity measurement was conducted with the use of laser-Doppler velocimetry at multiple points on the aneurysmal wall to calculate the value of wall shear stress. The wall shear stress was documented at multiple points in the aneurysm inflow zone, dome, and outflow zone.
  
  
  RESULTS
  Distribution of wall shear stress was not uniform in the aneurysm walls, and particular regions were exposed to relatively high wall shear stress. The wall shear stress changed dynamically throughout 1 cardiac cycle at the point where a high value of wall shear stress was noted. The blebs of both aneurysms were exposed to high wall shear stress. Unlike previous reports in which an ideal spherical aneurysm model was used, the aneurysm inflow zone was not exposed to high shear stress.
  
  
  CONCLUSIONS
  In vitro aneurysm models based on the patients' angiograms allowed us to conduct a more realistic evaluation of wall shear stress in the aneurysms harboring blebs. These results provide us with further indications of the correlation of wall shear stress with the natural history of cerebral aneurysms.
authors.affiliation: Division of Interventional Neuroradiology, Department of Radiological Sciences, School of Medicine and Medical Center, University of California at Los Angeles, CA 90024, USA. stateshima@mednet.ucla.edu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tateshima
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Murayama
authors.forename: J Pablo
authors.initials: JP
authors.lastname: Villablanca
authors.forename: Taku
authors.initials: T
authors.lastname: Morino
authors.forename: Kiyoe
authors.initials: K
authors.lastname: Nomura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tanishita
authors.forename: Fernando
authors.initials: F
authors.lastname: Viñuela
mesh_terms: D000792:Angiography / Q000379:methods; D002941:Circle of Willis / Q000000981:diagnostic imaging; D006801:Humans; D021621:Imaging, Three-Dimensional; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D008962:Models, Theoretical; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed / Q000379:methods; D014664:Vasodilation