title: Grading abdominal aortic aneurysm rupture risk.
abstract: BACKGROUND
  The aim of this paper was to develop a scoring system to grade the risk of rupture of an abdominal aortic aneurysm (AAA) in individual patients.
  
  
  METHODS
  Computed tomography angiography of an AAA were coupled with computational fluid dynamics (CFD) evaluation performed using open source software (ElmerSolver, Institute of Technology, Espoo, Finland). CFD criteria studied were: Oscillatory Shear Index (OSI), time averaged wall shear stress (TAWSS) and residence relative time (RRT) on both two-dimensional (2D) and three-dimensional (3D) models. AAA rupture predictors were analyzed and a scoring system was generated using Arabic numerals for all significant variables in order to grade the individual patient risk of rupture.
  
  
  RESULTS
  There were 143 patients examined. Ninety-one AAAs (18 ruptured AAAs), and 52 had a non-aneurysmal aorta. The 2D OSI was the best CFD criterion following multivariate analysis and ROC curves evaluation. An AAA was deemed respectively at low, moderate, or high risk of rupture, according to whether the risk score was defined as AAA I (total score <2.3), AAA II (2.3-6.5) or AAA III (>6.5). The only protective factor was found in diabetes (OR=0.775; CI: 0.665-0.902).
  
  
  CONCLUSIONS
  The Florence Risk Score for AAA rupture based on this report may be a useful tool to predict AAA rupture. A prospective multicenter registry will need to confirm its validity.
authors.affiliation: Unit of Vascular and Endovascular Surgery, Department of Surgery, &quot;San Giovanni di Dio&quot; Hospital, Florence, Italy - e.chisci@gmail.com.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Chisci
authors.affiliation: Configuratori.it, Florence, Italy.
authors.forename: Neri
authors.initials: N
authors.lastname: Alamanni
authors.affiliation: Osservatorio Epidemiologico, Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana &quot;M. Aleandri&quot;, Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Iacoponi
authors.affiliation: Unit of Vascular and Endovascular Surgery, Department of Surgery, &quot;San Giovanni di Dio&quot; Hospital, Florence, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Michelagnoli
authors.affiliation: Configuratori.it, Florence, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Procacci
authors.affiliation: Department for Mechanical Engineering, Polytechnic of Milan, Milan, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Colombo
authors.affiliation: Unit of Vascular and Endovascular Surgery, University of Siena, Siena, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Setacci
mesh_terms: D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001019:Aortic Rupture / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D000072226:Computed Tomography Angiography; D005260:Female; D006801:Humans; D057446:Hydrodynamics; D008297:Male; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012307:Risk Factors; D012984:Software; D013314:Stress, Mechanical