title: Inflow hemodynamics evaluated by using four-dimensional flow magnetic resonance imaging and the size ratio of unruptured cerebral aneurysms.
abstract: OBJECTIVE
  Prediction of the rupture risk is critical for the identification of unruptured cerebral aneurysms (UCAs) eligible for invasive treatments. The size ratio (SR) is a strong morphological predictor for rupture. We investigated the relationship between the inflow hemodynamics evaluated on four-dimensional (4D) flow magnetic resonance (MR) imaging and the SR to identify specific characteristics related to UCA rupture.
  
  
  METHODS
  We evaluated the inflow jet patterns and inflow hemodynamic parameters of 70 UCAs on 4D flow MR imaging and compared them among 23 aneurysms with an SR ≧2.1 and 47 aneurysms with an SR ≦2.0. Based on the shape of inflow streamline bundles with a velocity ≧75% of the maximum flow velocity in the parent artery, the inflow jet patterns were classified as concentrated (C), diffuse (D), neck-limited (N), and unvisualized (U).
  
  
  RESULTS
  The incidence of patterns C and N was significantly higher in aneurysms with an SR ≧2.1. The rate of pattern U was significantly higher in aneurysms with an SR ≦2.0. The maximum inflow rate and the inflow rate ratio were significantly higher in aneurysms with an SR ≧2.1.
  
  
  CONCLUSIONS
  The SR affected the inflow jet pattern, the maximum inflow rate, and the inflow rate ratio of UCAs. In conjunction with the SR, inflow hemodynamic analysis using 4D flow MR imaging may contribute to the risk stratification for aneurysmal rupture.
authors.affiliation: Department of Neurosurgery, Matto-Ishikawa Central Hospital, 3-8 Kuramitsu, Hakusan, Ishikawa, 920-8588, Japan. kfutami@mattohp.com.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Futami
authors.affiliation: Department of Neurosurgery, Kanazawa University School of Medicine, Kanazawa, Ishikawa, Japan.
authors.forename: Iku
authors.initials: I
authors.lastname: Nambu
authors.affiliation: Department of Neurosurgery, Kanazawa University School of Medicine, Kanazawa, Ishikawa, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kitabayashi
authors.affiliation: Department of Neurosurgery, Kanazawa University School of Medicine, Kanazawa, Ishikawa, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sano
authors.affiliation: Department of Neurosurgery, Kanazawa University School of Medicine, Kanazawa, Ishikawa, Japan.
authors.forename: Kouichi
authors.initials: K
authors.lastname: Misaki
authors.affiliation: Department of Neurosurgery, Kanazawa University School of Medicine, Kanazawa, Ishikawa, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Uchiyama
authors.affiliation: Department of Neurosurgery, Kanazawa University School of Medicine, Kanazawa, Ishikawa, Japan.
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Nakada
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity / Q000502:physiology; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D002532:Intracranial Aneurysm / Q000473:pathology* / Q000503:physiopathology*; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged
keywords: 4D flow MR imaging; Cerebral aneurysm; Inflow hemodynamics; Inflow jet; Size ratio