title: Effect of vascular anatomy on the formation of basilar tip aneurysms.
abstract: BACKGROUND
  The pathogenesis of intracranial aneurysms is multifactorial and includes genetic, environmental, and anatomic influences. Hemodynamic stress plays a particular role in the formation of intracranial aneurysms, which is conditioned by the geometry and morphology of the vessel trees.
  
  
  OBJECTIVE
  To identify image-based morphological parameters that correlated with the formation of basilar artery tip aneurysms (BTAs) in a location-specific manner.
  
  
  METHODS
  Morphological parameters obtained from computed tomographic angiographies of 33 patients with BTAs and 33 patients with aneurysms at other locations were evaluated with Slicer, an open-source image analysis software, to generate 3-dimensional models of the aneurysms and surrounding vascular architecture. We examined the diameters and vessel-to-vessel angles of the main vessels at the basilar bifurcation in patients with and without BTAs. To control for genetic and other risk factors, only patients with at least 1 aneurysm were included. Univariate and multivariate analyses were performed to determine statistical significance.
  
  
  RESULTS
  Sixty-six patients (33 with BTAs, 33 with other aneurysms) who were evaluated from 2008 to 2013 were analyzed. Multivariate logistic regression revealed that a larger angle between the posterior cerebral arteries (odds ratio, 1.04; P = 1.42 × 10(-3)) and a smaller basilar artery diameter (odds ratio, 0.23; P = .02) were most strongly associated with BTA formation after adjustment for other morphological and clinical variables.
  
  
  CONCLUSIONS
  Larger posterior cerebral artery angles and smaller basilar artery diameters are associated with the formation of basilar tip aneurysms. These parameters are easily measurable by the clinician and will aid in screening strategies in high-risk patients.
authors.affiliation: ‡Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Anil
authors.initials: A
authors.lastname: Can
authors.forename: Amr
authors.initials: A
authors.lastname: Mouminah
authors.forename: Allen L
authors.initials: AL
authors.lastname: Ho
authors.forename: Rose
authors.initials: R
authors.lastname: Du
mesh_terms: D000328:Adult; D000368:Aged; D001488:Basilar Artery / Q000000981:diagnostic imaging / Q000473:pathology*; D016022:Case-Control Studies; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D002532:Intracranial Aneurysm / Q000209:etiology / Q000473:pathology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020769:Posterior Cerebral Artery / Q000000981:diagnostic imaging / Q000473:pathology; D012307:Risk Factors; D014057:Tomography, X-Ray Computed