title: Biomechanical Indices for Rupture Risk Estimation in Abdominal Aortic Aneurysms.
abstract: To review the use of biomechanical indices for the estimation of abdominal aortic aneurysm (AAA) rupture risk, emphasizing their potential use in a clinical setting.
  
  
  
  A search of the PubMed, Embase, Scopus, and Compendex databases was made up to June 2015 to identify articles involving biomechanical analysis of AAA rupture risk. Outcome variables [aneurysm diameter, peak wall stress (PWS), peak wall shear stress (PWSS), wall strain, peak wall rupture index (PWRI), and wall stiffness] were compared for asymptomatic intact AAAs vs symptomatic or ruptured AAAs. For quantitative analysis of the pooled data, a random effects model was used to calculate the standard mean differences (SMDs) with the 95% confidence interval (CI) for the biomechanical indices.
  
  
  
  The initial database searches yielded 1894 independent articles of which 19 were included in the analysis. The PWS was significantly higher in the symptomatic/ruptured group, with a SMD of 1.11 (95% CI 0.93 to 1.26, p<0.001). Likewise, the PWRI was significantly higher in the ruptured or symptomatic group, with a SMD of 1.15 (95% CI 0.30 to 2.01, p=0.008). After adjustment for the aneurysm diameter, the PWS remained higher in the ruptured or symptomatic group, with a SMD of 0.85 (95% CI 0.46 to 1.23, p<0.001). Less is known of the wall shear stress and wall strain indices, as too few studies were available for analysis.
  
  
  
  Biomechanical indices are a promising tool in the assessment of AAA rupture risk as they incorporate several factors, including geometry, tissue properties, and patient-specific risk factors. However, clinical implementation of biomechanical AAA assessment remains a challenge owing to a lack of standardization.
authors.affiliation: 1 Department of Surgery, Division of Vascular Surgery, University Medical Center Groningen, University of Groningen, the Netherlands.|2 Department of Biomechanical Engineering and Physics, Academic Medical Centre, Amsterdam, the Netherlands.|3 Department of Radiology, Academic Medical Centre, Amsterdam, the Netherlands.|4 MIRA Institute for Biomedical Engineering and Technical Medicine, University of Twente, Enschede, the Netherlands.
authors.forename: Eva L
authors.initials: EL
authors.lastname: Leemans
authors.affiliation: 5 Department of Radiology, University Medical Center Groningen, University of Groningen, the Netherlands.
authors.forename: Tineke P
authors.initials: TP
authors.lastname: Willems
authors.affiliation: 1 Department of Surgery, Division of Vascular Surgery, University Medical Center Groningen, University of Groningen, the Netherlands.
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: van der Laan
authors.affiliation: 4 MIRA Institute for Biomedical Engineering and Technical Medicine, University of Twente, Enschede, the Netherlands.
authors.forename: Cornelis H
authors.initials: CH
authors.lastname: Slump
authors.affiliation: 1 Department of Surgery, Division of Vascular Surgery, University Medical Center Groningen, University of Groningen, the Netherlands.
authors.forename: Clark J
authors.initials: CJ
authors.lastname: Zeebregts
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000503:physiopathology*; 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; D001696:Biomechanical Phenomena; D016009:Chi-Square Distribution; D000072226:Computed Tomography Angiography; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011857:Radiographic Image Interpretation, Computer-Assisted; D012039:Regional Blood Flow; D018570:Risk Assessment; D012307:Risk Factors; D013314:Stress, Mechanical
keywords: abdominal aortic aneurysm; biomechanical analysis; risk assessment; rupture; rupture risk index; symptomatic aneurysm; wall strain; wall stress