title: Morphology parameters for intracranial aneurysm rupture risk assessment.
abstract: OBJECTIVE
  The aim of this study is to identify image-based morphological parameters that correlate with human intracranial aneurysm (IA) rupture.
  
  
  METHODS
  For 45 patients with terminal or sidewall saccular IAs (25 unruptured, 20 ruptured), three-dimensional geometries were evaluated for a range of morphological parameters. In addition to five previously studied parameters (aspect ratio, aneurysm size, ellipticity index, nonsphericity index, and undulation index), we defined three novel parameters incorporating the parent vessel geometry (vessel angle, aneurysm [inclination] angle, and [aneurysm-to-vessel] size ratio) and explored their correlation with aneurysm rupture. Parameters were analyzed with a two-tailed independent Student's t test for significance; significant parameters (P < 0.05) were further examined by multivariate logistic regression analysis. Additionally, receiver operating characteristic analyses were performed on each parameter.
  
  
  RESULTS
  Statistically significant differences were found between mean values in ruptured and unruptured groups for size ratio, undulation index, nonsphericity index, ellipticity index, aneurysm angle, and aspect ratio. Logistic regression analysis further revealed that size ratio (odds ratio, 1.41; 95% confidence interval, 1.03-1.92) and undulation index (odds ratio, 1.51; 95% confidence interval, 1.08-2.11) had the strongest independent correlation with ruptured IA. From the receiver operating characteristic analysis, size ratio and aneurysm angle had the highest area under the curve values of 0.83 and 0.85, respectively.
  
  
  CONCLUSIONS
  Size ratio and aneurysm angle are promising new morphological metrics for IA rupture risk assessment. Because these parameters account for vessel geometry, they may bridge the gap between morphological studies and more qualitative location-based studies.
authors.affiliation: Department of Mechanical and Aerospace Engineering, State University of New York, University at Buffalo, Buffalo, New York 14214, USA.
authors.forename: Sujan
authors.initials: S
authors.lastname: Dhar
authors.forename: Markus
authors.initials: M
authors.lastname: Tremmel
authors.forename: J
authors.initials: J
authors.lastname: Mocco
authors.forename: Minsuok
authors.initials: M
authors.lastname: Kim
authors.forename: Junichi
authors.initials: J
authors.lastname: Yamamoto
authors.forename: Adnan H
authors.initials: AH
authors.lastname: Siddiqui
authors.forename: L Nelson
authors.initials: LN
authors.lastname: Hopkins
authors.forename: Hui
authors.initials: H
authors.lastname: Meng
mesh_terms: D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging* / Q000473:pathology; D002533:Cerebral Angiography / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods* / Q000592:standards; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D018570:Risk Assessment
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