title: Daughter Sac Formation Related to Blood Inflow Jet in an Intracranial Aneurysm.
abstract: OBJECTIVE
  We performed a hemodynamic study of an intracranial aneurysm with a newly developed daughter sac during observation to investigate the role of hemodynamics on the formation of a daughter sac.
  
  
  METHODS
  A 75-year-old man underwent magnetic resonance angiography that revealed a large internal carotid artery aneurysm with inflow jet inside the aneurysm. The aneurysm was stable for 18 months, but a new daughter sac developed at the tip of the aneurysm during the next 6 months. The daughter sac seemed to be related to the inflow jet on magnetic resonance angiography. Aneurysm geometries before and after daughter sac formation were reconstructed using the longitudinal data of magnetic resonance angiography. Computational fluid dynamic simulations were conducted under the patient-specific pulsatile inlet conditions measured by magnetic resonance velocimetry.
  
  
  RESULTS
  The hemodynamic simulation revealed that the inflow jet impinged on 2 sites of the aneurysm: the right side of the aneurysmal dome and the tip of the aneurysm. The flow impingement caused elevation of pressure at both sites. However, the daughter sac formed at the latter site surrounded by the basal cistern but did not form at the former site that was in contact with the right temporal lobe.
  
  
  CONCLUSIONS
  Blood inflow jet caused local elevation of pressure, and the formation of the daughter sac occurred at the site with high pressure but without the surrounding structure, which may cancel the perpendicular wall tension.
authors.affiliation: Department of Neuroanesthesia, Kohnan Hospital, Sendai, Japan. Electronic address: sugiyama@nsg.med.tohoku.ac.jp.
authors.forename: Sin-Ichiro
authors.initials: SI
authors.lastname: Sugiyama
authors.affiliation: Department of Neurosurgery, Kohnan Hospital, Sendai, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Endo
authors.affiliation: Department of Neurosurgery, Kohnan Hospital, Sendai, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Omodaka
authors.affiliation: Department of Neurosurgery, Kohnan Hospital, Sendai, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Endo
authors.affiliation: Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Kuniyasu
authors.initials: K
authors.lastname: Niizuma
authors.affiliation: Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Sherif
authors.initials: S
authors.lastname: Rashad
authors.affiliation: National Institute of Technology, Tsuruoka College, Tsuruoka, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Nakayama
authors.affiliation: Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Funamoto
authors.affiliation: Institute of Fluid Science, Tohoku University, Sendai, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ohta
authors.affiliation: Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Teiji
authors.initials: T
authors.lastname: Tominaga
mesh_terms: D000368:Aged; D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology*; D003198:Computer Simulation; D005500:Follow-Up Studies; D006439:Hemodynamics; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000503:physiopathology*; D018810:Magnetic Resonance Angiography; D008297:Male; D008953:Models, Anatomic
keywords: Bleb; Blood flow; Cerebral aneurysm; Pressure; Wall shear stress