scholarly journals Statistical techniques for predicting rupture risk in abdominal aortic aneurysms: A contribution based on bootstrap

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110037
Author(s):  
Félix Nieto-Palomo ◽  
María-Ángeles Pérez-Rueda ◽  
Laurentiu-Mihai Lipsa ◽  
Carlos Vaquero-Puerta ◽  
José-Alberto Vilalta-Alonso ◽  
...  
Keyword(s):  
Abdominal Aortic Aneurysms ◽  
Statistical Technique ◽  
Aneurysm Rupture ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Rupture Risk ◽  
Bootstrap Technique ◽  
Abdominal Aortic ◽  
Pearson Coefficient ◽  
Hemodynamic Stresses

The morphometry of abdominal aortic aneurysms (AAA) has been recognized as one of the main factors that may predispose them to rupture. The need to quantify the morphometry of AAA on a patient-specific basis constitutes a valuable tool for assisting in rupture risk prediction. Previous results of this research group have determined the correlations between hemodynamic stresses and aneurysm morphometry by means of the Pearson coefficient. The present work aims to find how the AAA morphology correlates with the hemodynamic stresses acting on the arterial wall. To do so, the potential of the bootstrap technique has been explored. Bootstrap works appropriately in applications where few data are available (13 patient-specific AAA models were simulated). The methodology developed can be considered a contribution to predicting the hemodynamic stresses from the size and shape indices. The present work explores the use of a specific statistical technique (the bootstrap technique) to predict, based on morphological correlations, the patient-specific aneurysm rupture risk, provide greater understanding of this complex phenomenon that can bring about improvements in the clinical management of aneurysmatic patients. The results obtained using the bootstrap technique have greater reliability and robustness than those obtained by regression analysis using the Pearson coefficient, thus allowing to obtain more reliable results from the characteristics of the samples used, such as their small size and high variability. Additionally, it could be an indicator that other indices, such as AAA length, deformation rate, saccular index, and asymmetry, are important.

STATISTICAL ANALYSIS FOR RUPTURE RISK PREDICTION OF ABDOMINAL AORTIC ANEURYSMS (AAA) BASED ON ITS MORPHOMETRY

2017 ◽  
Vol 17 (04) ◽  
pp. 1750065 ◽  
Author(s):  
VILALTA-ALONSO GUILLERMO ◽  
VILALTA-ALONSO JOSÉ ALBERTO ◽  
SOUDAH EDUARDO ◽  
NIETO-PALOMO FÉLIX ◽  
LIPSA LAUTENTIU ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Temporal Distribution ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Statistical Techniques ◽  
Rupture Risk ◽  
Linear Predictor ◽  
Abdominal Aortic ◽  
Hemodynamic Stresses

The morphometry of the abdominal aortic aneurysms (AAA) has been recognized as one of the main factors that may predispose its rupture. The variation of the AAA morphometry, over time, induces modifications in hemodynamic behavior which, in turn, alters the spatial and temporal distribution of hemodynamic stress on the aneurismatic wall, establishing a bidirectional process that can influence the rupture phenomenon. In order to evaluate potential correlations between the main geometric parameters characterizing the AAA and hemodynamic stresses, 13 unrupture AAA patient-specific models were created. To AAA geometric characterization, 12 indices based on lumen center line were defined and determined. The computing of temporal and spatial distributions of hemodynamic stresses was conducted through Computational Fluid Dynamics. Statistical techniques were used to assess the relationships between the hemodynamic parameters and the different geometrical indices of the AAA. Regression analyses were conducted to obtain linear predictor models for hemodynamic stresses using the different indices defined in this paper as predictor variables. The statistical analysis confirmed that the length L, the asymmetry and the saccular index significantly influenced the hemodynamic stresses. The results obtained show the potential of the use of statistical techniques in predicting the rupture risk of patient-specific AAA.

Flow-Induced Wall Pressure Under Average Resting Hemodynamic Conditions for Patient-Specific Abdominal Aortic Aneurysms

2002 ◽  
Author(s):  
Ender A. Finol ◽  
Shoreh Hajiloo ◽  
Keyvan Keyhani ◽  
David A. Vorp ◽  
Cristina H. Amon
Keyword(s):  
Imaging Techniques ◽  
Abdominal Aortic Aneurysms ◽  
Aneurysm Rupture ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Mortality And Morbidity ◽  
Abdominal Aortic ◽  
Lethal Event ◽  
Overall Mortality

Abdominal Aortic Aneurysms (AAAs) are characterized by a continuous dilation of the infrarenal segment of the abdominal aorta. Despite significant improvements in surgical procedures and imaging techniques, the mortality and morbidity rates associated with untreated ruptured AAAs are still outrageously high. AAA disease is a health risk of significant importance since this kind of aneurysm is mostly asymptomatic until its rupture, which is frequently a lethal event with an overall mortality rate in the 80% to 90% range. From a purely biomechanical viewpoint, aneurysm rupture is a phenomenon that occurs when the mechanical stress acting on the dilating inner wall exceeds its failure strength. Since the internal mechanical forces are maintained by the dynamic action of blood flowing in the aorta, the quantification of the hemodynamics of AAAs is essential for the characterization of their biomechanical environment.

scholarly journals On the Relative Impact of Intraluminal Thrombus Heterogeneity on Abdominal Aortic Aneurysm Mechanics

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Joseph R. Leach ◽  
Evan Kao ◽  
Chengcheng Zhu ◽  
David Saloner ◽  
Michael D. Hope
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Aneurysm Rupture ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Rupture Risk ◽  
Intraluminal Thrombus ◽  
Element Analysis ◽  
Aneurysm Wall ◽  
Abdominal Aortic

Intraluminal thrombus (ILT) is present in the majority of abdominal aortic aneurysms (AAA) of a size warranting consideration for surgical or endovascular intervention. The rupture risk of AAAs is thought to be related to the balance of vessel wall strength and the mechanical stress caused by systemic blood pressure. Previous finite element analyses of AAAs have shown that ILT can reduce and homogenize aneurysm wall stress. These works have largely considered ILT to be homogeneous in mechanical character or have idealized a stiffness distribution through the thrombus thickness. In this work, we use magnetic resonance imaging (MRI) to delineate the heterogeneous composition of ILT in 7 AAAs and perform patient–specific finite element analysis under multiple conditions of ILT layer stiffness disparity. We find that explicit incorporation of ILT heterogeneity in the finite element analysis is unlikely to substantially alter major stress analysis predictions regarding aneurysm rupture risk in comparison to models assuming a homogenous thrombus, provided that the maximal ILT stiffness is the same between models. Our results also show that under a homogeneous ILT assumption, the choice of ILT stiffness from values common in the literature can result in significantly larger variations in stress predictions compared to the effects of thrombus heterogeneity.

Local Mechanical Properties of Abdominal Aortic Aneurysms

2008 ◽  
Author(s):  
Evelyne van Dam ◽  
Marcel Rutten ◽  
Frans van de Vosse
Keyword(s):  
Mechanical Properties ◽  
Stress Analysis ◽  
Vessel Wall ◽  
Computational Models ◽  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Rupture Risk ◽  
Abdominal Aortic

Rupture risk of abdominal aortic aneurysms (AAA) based on wall stress analysis may be superior to the currently used diameter-based rupture risk prediction [4; 5; 6; 7]. In patient specific computational models for wall stress analysis, the geometry of the aneurysm is obtained from CT or MR images. The wall thickness and mechanical properties are mostly assumed to be homogeneous. The pathological AAA vessel wall may contain collageneous areas, but also calcifications, cholesterol crystals and large amounts of fat cells. No research has yet focused yet on the differences in mechanical properties of the components present within the degrading AAA vessel wall.

COMPARISON OF TWO METHODS FOR ESTIMATING THE UNLOADED STATE FOR ABDOMINAL AORTIC ANEURYSM STRESS CALCULATIONS

2019 ◽  
Vol 19 (03) ◽  
pp. 1950015 ◽  
Author(s):  
JOSEPH R. LEACH ◽  
CHENGCHENG ZHU ◽  
DAVID SALONER ◽  
MICHAEL D. HOPE
Keyword(s):  
Finite Element ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Rupture Risk ◽  
Geometric Accuracy ◽  
Abdominal Aortic ◽  
Unloaded State ◽  
Geometric Scaling

Biomechanical analyses can be used to better understand the rupture risk of abdominal aortic aneurysms (AAAs) on a patient-specific basis using vascular geometries obtained from medical imaging. Methodologies of varying complexity are used to estimate the unloaded state of the imaged vessel to provide a reference configuration for finite element simulations. In this work, we compare the implementation and results of two of these methods, one based on geometric scaling and the other using an iterative determination of unloaded vessel geometry. We find that the two methods result in significantly different stress predictions, and that the iterative method offers superior geometric accuracy. Our findings lend context to the variation in finite element results presented in the AAA stress analysis literature.

Aortic Lumen Area Is Increased in Ruptured Abdominal Aortic Aneurysms and Correlates to Biomechanical Rupture Risk

2018 ◽  
Vol 25 (6) ◽  
pp. 750-756 ◽  
Author(s):  
Antti Siika ◽  
Moritz Lindquist Liljeqvist ◽  
Rebecka Hultgren ◽  
T. Christian Gasser ◽  
Joy Roy
Keyword(s):  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Maximum Diameter ◽  
Patient Specific ◽  
Lumen Area ◽  
Rupture Risk ◽  
Cross Sectional ◽  
Vessel Area ◽  
Abdominal Aortic ◽  
Risk Parameters

Purpose: To investigate how 2-dimensional geometric parameters differ between ruptured and asymptomatic abdominal aortic aneurysms (AAAs) and provide a biomechanical explanation for the findings. Methods: The computed tomography angiography (CTA) scans of 30 patients (mean age 77±10 years; 23 men) with ruptured AAAs and 60 patients (mean age 76±8 years; 46 men) with asymptomatic AAAs were used to measure maximum sac diameter along the center lumen line, the cross-sectional lumen area, the total vessel area, the intraluminal thrombus (ILT) area, and corresponding volumes. The CTA data were segmented to create 3-dimensional patient-specific models for finite element analysis to compute peak wall stress (PWS) and the peak wall rupture index (PWRI). To reduce confounding from the maximum diameter, 2 diameter-matched groups were selected from the initial patient cohorts: 28 ruptured AAAs and another with 15 intact AAAs (diameters 74±12 vs 73±11, p=0.67). A multivariate model including the maximum diameter, the lumen area, and the ILT area of the 60 intact aneurysms was employed to predict biomechanical rupture risk parameters. Results: In the diameter-matched subgroup comparison, ruptured AAAs had a significantly larger cross-sectional lumen area (1954±1254 vs 1120±623 mm2, p=0.023) and lower ILT area ratio (55±24 vs 68±24, p=0.037). The ILT area (2836±1462 vs 2385±1364 mm2, p=0.282) and the total vessel area (3956±1170 vs 4338±1388 mm2, p=0.384) did not differ statistically between ruptured and intact aneurysms. The PWRI was increased in ruptured AAAs (0.80 vs 0.48, p<0.001), but the PWS was similar (249 vs 284 kPa, p=0.194). In multivariate regression analysis, lumen area was significantly positively associated with both PWS (p<0.001) and PWRI (p<0.01). The ILT area was also significantly positively associated with PWS (p<0.001) but only weakly with PWRI (p<0.01). The lumen area conferred a higher risk increase in both PWS and PWRI when compared with the ILT area. Conclusion: The lumen area is increased in ruptured AAAs compared to diameter-matched asymptomatic AAAs. Furthermore, this finding may in part be explained by a relationship with biomechanical rupture risk parameters, in which lumen area, irrespective of maximum diameter, increases PWS and PWRI. These observations thus suggest a possible method to improve prediction of rupture risk in AAAs by measuring the lumen area without the use of computational modeling.

Assessment of the rupture risk of abdominal aortic aneurysms by patient-specific hemodynamic modeling—initial results

2004 ◽  
Vol 1268 ◽  
pp. 1090-1095 ◽  
Author(s):  
M Breeuwer ◽  
U Götte ◽  
R Hoogeveen ◽  
B.J.B.M Wolters ◽  
S de Putter ◽  
...  
Keyword(s):  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Rupture Risk ◽  
Abdominal Aortic ◽  
Initial Results

Advancements in identifying biomechanical determinants for abdominal aortic aneurysm rupture

Vascular ◽  
2014 ◽  
Vol 23 (1) ◽  
pp. 65-77 ◽  
Author(s):  
Nikolaos Kontopodis ◽  
Eleni Metaxa ◽  
Yannis Papaharilaou ◽  
Emmanouil Tavlas ◽  
Dimitrios Tsetis ◽  
...  
Keyword(s):  
Growth Rate ◽  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Abdominal Aortic Aneurysms ◽  
Aneurysm Rupture ◽  
Aortic Aneurysms ◽  
Maximum Diameter ◽  
Rupture Risk ◽  
Abdominal Aortic Aneurysm Rupture ◽  
Abdominal Aortic

Abdominal aortic aneurysms are a common health problem and currently the need for surgical intervention is determined based on maximum diameter and growth rate criteria. Since these universal variables often fail to predict accurately every abdominal aortic aneurysms evolution, there is a considerable effort in the literature for other markers to be identified towards individualized rupture risk estimations and growth rate predictions. To this effort, biomechanical tools have been extensively used since abdominal aortic aneurysm rupture is in fact a material failure of the diseased arterial wall to compensate the stress acting on it. The peak wall stress, the role of the unique geometry of every individual abdominal aortic aneurysm as well as the mechanical properties and the local strength of the degenerated aneurysmal wall, all confer to rupture risk. In this review article, the assessment of these variables through mechanical testing, advanced imaging and computational modeling is reviewed and the clinical perspective is discussed.

scholarly journals Ultrasound-Based Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms Incorporating Pre-stress

2021 ◽  
Vol 12 ◽  
Author(s):  
Judith H. C. Fonken ◽  
Esther J. Maas ◽  
Arjet H. M. Nievergeld ◽  
Marc R. H. M. van Sambeek ◽  
Frans N. van de Vosse ◽  
...  
Keyword(s):  
Fluid Structure Interaction ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Maximum Diameter ◽  
Patient Specific ◽  
Risk Indicator ◽  
Rupture Risk ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Abdominal Aortic

Currently, the prediction of rupture risk in abdominal aortic aneurysms (AAAs) solely relies on maximum diameter. However, wall mechanics and hemodynamics have shown to provide better risk indicators. Patient-specific fluid-structure interaction (FSI) simulations based on a non-invasive image modality are required to establish a patient-specific risk indicator. In this study, a robust framework to execute FSI simulations based on time-resolved three-dimensional ultrasound (3D+t US) data was obtained and employed on a data set of 30 AAA patients. Furthermore, the effect of including a pre-stress estimation (PSE) to obtain the stresses present in the measured geometry was evaluated. The established workflow uses the patient-specific 3D+t US-based segmentation and brachial blood pressure as input to generate meshes and boundary conditions for the FSI simulations. The 3D+t US-based FSI framework was successfully employed on an extensive set of AAA patient data. Omitting the pre-stress results in increased displacements, decreased wall stresses, and deviating time-averaged wall shear stress and oscillatory shear index patterns. These results underline the importance of incorporating pre-stress in FSI simulations. After validation, the presented framework provides an important tool for personalized modeling and longitudinal studies on AAA growth and rupture risk.

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