title: Biomechanical rupture risk assessment of abdominal aortic aneurysms based on a novel probabilistic rupture risk index.
abstract: A rupture risk assessment is critical to the clinical treatment of abdominal aortic aneurysm (AAA) patients. The biomechanical AAA rupture risk assessment quantitatively integrates many known AAA rupture risk factors but the variability of risk predictions due to model input uncertainties remains a challenging limitation. This study derives a probabilistic rupture risk index (PRRI). Specifically, the uncertainties in AAA wall thickness and wall strength were considered, and wall stress was predicted with a state-of-the-art deterministic biomechanical model. The discriminative power of PRRI was tested in a diameter-matched cohort of ruptured (n = 7) and intact (n = 7) AAAs and compared to alternative risk assessment methods. Computed PRRI at 1.5 mean arterial pressure was significantly (p = 0.041) higher in ruptured AAAs (20.21(s.d. 14.15%)) than in intact AAAs (3.71(s.d. 5.77)%). PRRI showed a high sensitivity and specificity (discriminative power of 0.837) to discriminate between ruptured and intact AAA cases. The underlying statistical representation of stochastic data of wall thickness, wall strength and peak wall stress had only negligible effects on PRRI computations. Uncertainties in AAA wall stress predictions, the wide range of reported wall strength and the stochastic nature of failure motivate a probabilistic rupture risk assessment. Advanced AAA biomechanical modelling paired with a probabilistic rupture index definition as known from engineering risk assessment seems to be superior to a purely deterministic approach.
authors.affiliation: Institute of Solid Mechanics, Mechatronics and Biomechanics, Brno University of Technology, Brno, Czech Republic polzer@seznam.cz.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Polzer
authors.affiliation: KTH Solid Mechanics, School of Engineering Sciences, KTH Royal Institute of Technology, Stockholm, Sweden.
authors.forename: T Christian
authors.initials: TC
authors.lastname: Gasser
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000473:pathology / Q000503:physiopathology; D001019:Aortic Rupture / Q000473:pathology / Q000503:physiopathology; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008297:Male; D008955:Models, Cardiovascular; D018570:Risk Assessment
keywords: abdominal aortic aneurysm; failure; model finite element; uncertainty; wall stress