Geometric surrogates of abdominal aortic aneurysm wall mechanics. (September 2018)

• Record Type: Journal Article
• Authors: Urrutia, Jesús; Roy, Anuradha; Raut, Samarth S.; Antón, Raúl; Muluk, Satish C.; Finol, Ender A.
• Is Part Of: Medical engineering & physics. Volume 59(2018)
• Page Start: 43
• Page End: 49
• Publication Date: 2018-09
• Subjects: Aneurysms -- Geometry quantification -- Stress -- Biomechanics -- Medical image analysis; Biomedical engineering -- Periodicals; Biomedical Engineering -- Periodicals; Physics -- Periodicals; Génie biomédical -- Périodiques; Biomedical engineering; Electronic journals; Periodicals; 610.28
• DOI: 10.1016/j.medengphy.2018.06.007
• Languages: English
• ISSNs: 1350-4533

Abstract

Highlights: A combined biomechanics and geometry quantification approach is proposed to find the surrogates of aortic aneurysm mechanics. There are 7 geometric variables that are highly correlated with peak wall stress and differentiate the aneurysm population groups with zero error. The proposed 7 discriminants can be used as surrogates of peak wall stress in lieu of complex finite element modeling for aneurysm rupture risk assessment. Abstract: The maximum diameter criterion is the most important factor in the clinical management of abdominal aortic aneurysms (AAA). Consequently, interventional repair is recommended when an aneurysm reaches a critical diameter, typically 5.0 cm in the United States. Nevertheless, biomechanical measures of the aneurysmal abdominal aorta have long been implicated in AAA risk of rupture. The purpose of this study is to assess whether other geometric characteristics, in addition to maximum diameter, may be highly correlated with the AAA peak wall stress (PWS). Using in-house segmentation and meshing algorithms, 30 patient-specific AAA models were generated for finite element analysis using an isotropic constitutive material for the AAA wall. PWS, evaluated as the spatial maximum of the first principal stress, was calculated at a systolic pressure of 120 mmHg. The models were also used to calculate 47 geometric indices characteristic of the aneurysm geometry. Statistical analyses were conducted using a feature reduction algorithm in which the 47 indices were reduced to 11 based on their statistical significance in differentiating the models in the population ( p < 0.05). A subsequent discriminant analysis was performed and 7 of these indices were identified as having no error in discriminating the AAA models with a significant nonlinear regression correlation with PWS. These indices were: Dmax (maximum diameter), T (tortuosity), DDr (maximum diameter to neck diameter ratio), S (wall surface area), Kmedian (median of the Gaussian surface curvature), Cmax (maximum lumen compactness), and Mmode (mode of the Mean surface curvature). Therefore, these characteristics of an individual AAA geometry are the highest correlated with the most clinically relevant biomechanical parameter for rupture risk assessment. We conclude that the indices can serve as surrogates of PWS in lieu of a finite element modeling approach for AAA biomechanical evaluation.