title: Finite element analysis in asymptomatic, symptomatic, and ruptured abdominal aortic aneurysms: in search of new rupture risk predictors.
abstract: OBJECTIVE
  To compare biomechanical rupture risk parameters of asymptomatic, symptomatic and ruptured abdominal aortic aneurysms (AAA) using finite element analysis (FEA).
  
  
  METHODS
  Retrospective biomechanical single center analysis of asymptomatic, symptomatic, and ruptured AAAs. Comparison of biomechanical parameters from FEA.
  
  
  METHODS
  From 2011 to 2013 computed tomography angiography (CTA) data from 30 asymptomatic, 15 symptomatic, and 15 ruptured AAAs were collected consecutively. FEA was performed according to the successive steps of AAA vessel reconstruction, segmentation and finite element computation. Biomechanical parameters Peak Wall Rupture Risk Index (PWRI), Peak Wall Stress (PWS), and Rupture Risk Equivalent Diameter (RRED) were compared among the three subgroups.
  
  
  RESULTS
  PWRI differentiated between asymptomatic and symptomatic AAAs (p < .0004) better than PWS (p < .1453). PWRI-dependent RRED was higher in the symptomatic subgroup compared with the asymptomatic subgroup (p < .0004). Maximum AAA external diameters were comparable between the two groups (p < .1355). Ruptured AAAs showed the highest values for external diameter, total intraluminal thrombus volume, PWS, RRED, and PWRI compared with asymptomatic and symptomatic AAAs. In contrast with symptomatic and ruptured AAAs, none of the asymptomatic patients had a PWRI value >1.0. This threshold value might identify patients at imminent risk of rupture.
  
  
  CONCLUSIONS
  From different FEA derived parameters, PWRI distinguishes most precisely between asymptomatic and symptomatic AAAs. If elevated, this value may represent a negative prognostic factor for asymptomatic AAAs.
authors.affiliation: Department of Vascular and Endovascular Surgery, Ruprecht-Karls University Heidelberg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Erhart
authors.affiliation: Department of Vascular and Endovascular Surgery, Ruprecht-Karls University Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Hyhlik-Dürr
authors.affiliation: Department of Vascular and Endovascular Surgery, Ruprecht-Karls University Heidelberg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Geisbüsch
authors.affiliation: Department of Vascular and Endovascular Surgery, Ruprecht-Karls University Heidelberg, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Kotelis
authors.affiliation: Department of Radiology, Ruprecht-Karls University Heidelberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Müller-Eschner
authors.affiliation: Department of Solid Mechanics, Royal Institute of Technology, Stockholm, Sweden.
authors.forename: T C
authors.initials: TC
authors.lastname: Gasser
authors.affiliation: Department of Radiology, Ruprecht-Karls University Heidelberg, Germany; Institute of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, Inselspital, Bern, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: von Tengg-Kobligk
authors.affiliation: Department of Vascular and Endovascular Surgery, Ruprecht-Karls University Heidelberg, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Böckler
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001019:Aortic Rupture / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D001027:Aortography / Q000379:methods; D058070:Asymptomatic Diseases; D001696:Biomechanical Phenomena; D020342:Finite Element Analysis; D005858:Germany; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011237:Predictive Value of Tests; D011379:Prognosis; D012039:Regional Blood Flow; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed
keywords: Abdominal aortic aneurysm; Aorta; Finite element analysis (FEA); Rupture risk; Wall stress