Surface Curvature as a Classifier of Abdominal Aortic Aneurysms: A Comparative Analysis

Lee, Kibaek; Zhu, Junjun; Shum, Judy; Zhang, Yongjie; Muluk, Satish C.; Chandra, Ankur; Eskandari, Mark K.; Finol, Ender A.

doi:10.1007/s10439-012-0691-4

Cited by 41 publications

(42 citation statements)

References 25 publications

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“…The protocol for image segmentation of contrast-enhanced abdominal CT images has been applied previously by our research group for generating patient-specific AAA models. 10,22,23 The masks are used to generate surface and volume meshes using the in-house meshing code AAAMesh. 17 …”

Section: Methodsmentioning

confidence: 99%

“…The point clouds generated from the image segmentation process were used to calculate the 1D and 2D indices, while the 3D indices are quantified from the surface and volume meshes. The biquintic Hermite finite element method (BQFE) was used to evaluate the curvature-based indices, as described by Lee et al 10 This method utilizes a high order interpolation scheme to estimate the global curvature indices derived from local curvature distributions. BQFE discretizes the aneurysm outer wall into 12 elements as opposed to the traditional method of biquadratic surface patching (BSP).…”

Section: Methodsmentioning

confidence: 99%

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The Association Between Geometry and Wall Stress in Emergently Repaired Abdominal Aortic Aneurysms

et al. 2017

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Abdominal aortic aneurysm (AAA) is a prevalent cardiovascular disease characterized by the focal dilation of the aorta, which supplies blood to all the organs and tissues in the systemic circulation. With the AAA increasing in diameter over time, the risk of aneurysm rupture is generally associated with the size of the aneurysm. If diagnosed on time, intervention is recommended to prevent AAA rupture. The criterion to decide on surgical intervention is determined by measuring the maximum diameter of the aneurysm relative to the critical value of 5.5 cm. However, a more reliable approach could be based on understanding the biomechanical behavior of the aneurysmal wall. In addition, geometric features that are proven to be significant predictors of the AAA wall mechanics could be used as surrogates of the AAA biomechanical behavior and, subsequently, of the aneurysm’s risk of rupture. The aim of this work is to identify those geometric indices that have a high correlation with AAA wall stress in the population of patients who received an emergent repair of their aneurysm. In-house segmentation and meshing algorithms were used to model 75 AAAs followed by estimation of the spatially distributed wall stress by performing finite element analysis. Fifty-two shape and size geometric indices were calculated for the same models using MATLAB scripting. Hypotheses testing were carried out to identify the indices significantly correlated with wall stress by constructing a Pearson’s correlation coefficient matrix. The analyses revealed that 12 indices displayed high correlation with the wall stress, amongst which wall thickness and curvature-based indices exhibited the highest correlations. Stepwise regression analysis of these correlated indices indicated that wall stress can be predicted by the following 4 indices with an accuracy of 76%: maximum aneurysm diameter, aneurysm sac length, average wall thickness at the maximum diameter cross-section, and the median of the wall thickness variance. The primary outcome of this work emphasizes the use of global measures of size and wall thickness as geometric surrogates of wall stress for emergently repaired AAAs.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The Association Between Geometry and Wall Stress in Emergently Repaired Abdominal Aortic Aneurysms

et al. 2017

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“…Possibly more insidious, even at 6 cm only 31% of patients have experienced complications suggesting that many large aneurysms are resected that might have remained stable Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jbiomech www.JBiomech.com for the patient's lifetime (Chau and Elefteriades, 2013;Polzer et al, 2013;Sundt, 2013). To move towards the ideal case of patient specific risk assessments, several biomechanical criteria have been explored for aortic aneurysms including wall stress (Fillinger et al, 2003;Gasser et al, 2010;Raut et al, 2013a;Vande Geest et al, 2006a), over-pressure (Martin et al, 2013), and non-diameter shape based criteria (Lee et al, 2013;Raut et al, 2013a;Shum et al, 2011). In fact, for abdominal aortic aneurysms, the peak wall stress was shown to estimate patient risk with a higher accuracy, sensitivity, and specificity than the diameter criterion alone (Fillinger et al, 2003).…”

Section: Introductionmentioning

confidence: 97%

Patient specific stress and rupture analysis of ascending thoracic aneurysms

Trabelsi

Davis

Rodríguez-Matas

et al. 2015

Journal of Biomechanics

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An ascending thoracic aortic aneurysm (ATAA) is a serious medical condition which, more often than not, requires surgery. Aneurysm diameter is the primary clinical criterion for determining when surgical intervention is necessary but, biomechanical studies have suggested that the diameter criterion is insufficient. This manuscript presents a method for obtaining the patient specific wall stress distribution of the ATAA and the retrospective rupture risk for each patient. Five human ATAAs and the preoperative dynamic CT scans were obtained during elective surgeries to replace each patient's aneurysm with a synthetic graft. The material properties and rupture stress for each tissue sample were identified using bulge inflation tests. The dynamic CT scans were used to generate patient specific geometries for a finite element (FE) model of each patient's aneurysm. The material properties from the bulge inflation tests were implemented in the FE model and the wall stress distribution at four different pressures was estimated. Three different rupture risk assessments were compared: the maximum diameter, the rupture risk index, and the overpressure index. The peak wall stress values for the patients ranged from 28% to 94% of the ATAA's failure stress. The rupture risk and overpressure indices were both only weakly correlated with diameter (ρ=-0.29, both cases). In the future, we plan to conduct a large experimental and computational study that includes asymptomatic patients under surveillance, patients undergoing elective surgery, and patients who have experienced rupture or dissection to determine if the rupture risk index or maximum diameter can meaningfully differentiate between the groups.

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“…Without constraining an entire edge, point loading of mesh is more likely to create out-of-plane deformations, resulting in a bending or wrinkling phenomenon along the lines through which force is transmitted, due to the constraint effects of pore deformation. Describing surface deformations, such as bending, has been well characterized in several fields of research, including neurological development (Filas et al, 2008; Batchelor et al, 2002) and cardiology (Lee et al, 2013; Sacks et al, 2002; Smith et al, 2000). Following from these studies, out-of-plane surface deformations for a thin body can be characterized via surface curvature, as the geometric transformation of a flat surface to a curved one implies some local surface deformation.…”

Section: Introductionmentioning

confidence: 99%

The impact of boundary conditions on surface curvature of polypropylene mesh in response to uniaxial loading

Barone

Amini

Maiti

et al. 2015

Journal of Biomechanics

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Exposure following pelvic organ prolapse repair has been observationally associated with wrinkling of the implanted mesh. The purpose of this study was to quantify the impact of variable boundary conditions on the out-of-plane deformations of mesh subjected to tensile loading. Using photogrammetry and surface curvature analyses, deformed geometries were accessed for two commercially available products. Relative to standard clamping methods, the amount of out-of-plane deformation significantly increased when point loads were introduced to simulate suture fixation in-vivo. These data support the hypothesis that regional increases in the concentration of mesh potentially enhance the host’s foreign body response, leading to exposure.

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Surface Curvature as a Classifier of Abdominal Aortic Aneurysms: A Comparative Analysis

Cited by 41 publications

References 25 publications

The Association Between Geometry and Wall Stress in Emergently Repaired Abdominal Aortic Aneurysms

The Association Between Geometry and Wall Stress in Emergently Repaired Abdominal Aortic Aneurysms

Patient specific stress and rupture analysis of ascending thoracic aneurysms

The impact of boundary conditions on surface curvature of polypropylene mesh in response to uniaxial loading

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