Discrimination of Vessel Wall Components of Abdominal Aortic Aneurysms by Multi-Contrast MRI

2008 ◽  
Author(s):  
Evelyne van Dam ◽  
Marcel Rutten ◽  
Frans van de Vosse
Keyword(s):  
Vessel Wall ◽  
Computational Models ◽  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Western World ◽  
Atherosclerotic Plaques ◽  
Abdominal Aortic ◽  
Wall Components

Rupture of an abdominal aortic aneurysm (AAA) is a major cause of death in the Western world. When the AAA is diagnosed timely, rupture can be prevented by conventional surgical or by endovascular repair. To date, the decision to operate is based on geometry alone, but it has already been suggested that wall stress would be a better predictor [2]. Patient specific computational models have been developed to calculate wall stress [2; 5; 9; 8; 10]. In these models, the AAA wall is assumed to be homogeneous. Patient-specific inhomogeneities such as atherosclerotic plaques and calcifications have large effects on the maximum wall stress and wall stress distribution [6; 7]. Histological examination is not feasible for determining wall composition of patients.

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.

Use of the Photoelastic Method to Determine the Wall Stress in Realistic Abdominal Aortic Aneurysm Models

2011 ◽  
Author(s):  
Barry J. Doyle ◽  
Anthony Callanan ◽  
John Killion ◽  
Timothy M. McGloughlin
Keyword(s):  
Wall Stress ◽  
Aortic Aneurysms ◽  
Maximum Diameter ◽  
Patient Specific ◽  
Western World ◽  
Photoelastic Method ◽  
Element Analysis ◽  
Abdominal Aortic ◽  
The Us ◽  
Numerical Tools

Abdominal aortic aneurysms (AAAs) remain a significant cause of death in the Western world with over 15,000 deaths per year in the US linked to AAA rupture. Recent research [1] has questioned the use of maximum diameter as a definitive risk parameter as it is now believed that alternative factors may be important in rupture-prediction. Wall stress was shown to be a better predictor than diameter of rupture [1], with biomechanics-based rupture indices [2,3] and asymmetry also reported to have potential clinical applicability [4]. However, the majority of numerical methods used to form these alternative rupture parameters are without rigorous experimental validation, and therefore may not be as accurate as believed. Validated experiments are required in order to convince the clinical community of the worth of numerical tools such as finite element analysis (FEA) in AAA risk-prediction. Strain gauges have been used in the past to determine the strain on an AAA [5], however, the photoelastic method has also proved to be a useful tool in AAA biomechanics [6]. This paper examines the approach using three medium-sized patient-specific AAA cases at realistic pressure loadings.

Patient-specific initial wall stress in abdominal aortic aneurysms with a backward incremental method

2007 ◽  
Vol 40 (5) ◽  
pp. 1081-1090 ◽  
Author(s):  
S. de Putter ◽  
B.J.B.M. Wolters ◽  
M.C.M. Rutten ◽  
M. Breeuwer ◽  
F.A. Gerritsen ◽  
...  
Keyword(s):  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Incremental Method ◽  
Abdominal Aortic

scholarly journals Biochemomechanics of Intraluminal Thrombus in Abdominal Aortic Aneurysms

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
J. S. Wilson ◽  
L. Virag ◽  
P. Di Achille ◽  
I. Karšaj ◽  
J. D. Humphrey
Keyword(s):  
Computational Models ◽  
Large Body ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Biologically Active ◽  
Patient Specific ◽  
Inert Material ◽  
Intraluminal Thrombus ◽  
Abdominal Aortic ◽  
Threatening Condition

Most computational models of abdominal aortic aneurysms address either the hemodynamics within the lesion or the mechanics of the wall. More recently, however, some models have appropriately begun to account for the evolving mechanics of the wall in response to the changing hemodynamic loads. Collectively, this large body of work has provided tremendous insight into this life-threatening condition and has provided important guidance for current research. Nevertheless, there has yet to be a comprehensive model that addresses the mechanobiology, biochemistry, and biomechanics of thrombus-laden abdominal aortic aneurysms. That is, there is a pressing need to include effects of the hemodynamics on both the development of the nearly ubiquitous intraluminal thrombus and the evolving mechanics of the wall, which depends in part on biochemical effects of the adjacent thrombus. Indeed, there is increasing evidence that intraluminal thrombus in abdominal aortic aneurysms is biologically active and should not be treated as homogeneous inert material. In this review paper, we bring together diverse findings from the literature to encourage next generation models that account for the biochemomechanics of growth and remodeling in patient-specific, thrombus-laden abdominal aortic aneurysms.

On the Uptake of Ultrasmall Superparamagnetic Particles of Iron Oxide and Biomechanical Wall Stress in Abdominal Aortic Aneurysms

2012 ◽  
Author(s):  
Barry Doyle ◽  
Jennifer Richards ◽  
Scott Semple ◽  
Tom MacGillivray ◽  
Calum Gray ◽  
...  
Keyword(s):  
Wall Stress ◽  
Inflammatory Cells ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Western World ◽  
Important Work ◽  
General Belief ◽  
Abdominal Aortic ◽  
The Us ◽  
Improved Methods

Abdominal aortic aneurysms (AAAs) remain a significant cause of death in the Western world with over 15,000 deaths per year in the US linked to AAA rupture. There is a general belief among the clinical and engineering community that improved methods of risk prediction are needed. The growth and expansion of AAAs over time is thought to be associated with the mechanobiological interactions within the diseased AAA wall. The stresses and strains induced in the wall by the internal blood pressure trigger increased protease activity and turnover of the extracellular matrix (ECM), thus enabling degradation and expansion of the wall. Inflammatory cells also control collagen synthesis and inflammation can reduce the tensile strength of the wall, thus contributing to the likelihood of rupture. Recently, important work by Richards et al. [1] showed that AAAs with specific sites of focal inflammation have threefold higher growth rates than AAAs with non-specific inflammation.

scholarly journals Patient Specific Wall Stress Analysis and Mechanical Characterization of Abdominal Aortic Aneurysms Using 4D Ultrasound

2016 ◽  
Vol 52 (5) ◽  
pp. 635-642 ◽  
Author(s):  
E.M.J. van Disseldorp ◽  
N.J. Petterson ◽  
M.C.M. Rutten ◽  
F.N. van de Vosse ◽  
M.R.H.M. van Sambeek ◽  
...  
Keyword(s):  
Stress Analysis ◽  
Mechanical Characterization ◽  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
4D Ultrasound ◽  
Abdominal Aortic

scholarly journals Importance of initial aortic properties on the evolving regional anisotropy, stiffness and wall thickness of human abdominal aortic aneurysms

2012 ◽  
Vol 9 (74) ◽  
pp. 2047-2058 ◽  
Author(s):  
J. S. Wilson ◽  
S. Baek ◽  
J. D. Humphrey
Keyword(s):  
Wall Thickness ◽  
Computational Modelling ◽  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Clinical Decision ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Initial State ◽  
Non Invasive ◽  
Abdominal Aortic

Complementary advances in medical imaging, vascular biology and biomechanics promise to enable computational modelling of abdominal aortic aneurysms to play increasingly important roles in clinical decision processes. Using a finite-element-based growth and remodelling model of evolving aneurysm geometry and material properties, we show that regional variations in material anisotropy, stiffness and wall thickness should be expected to arise naturally and thus should be included in analyses of aneurysmal enlargement or wall stress. In addition, by initiating the model from best-fit material parameters estimated for non-aneurysmal aortas from different subjects, we show that the initial state of the aorta may influence strongly the subsequent rate of enlargement, wall thickness, mechanical behaviour and thus stress in the lesion. We submit, therefore, that clinically reliable modelling of the enlargement and overall rupture-potential of aneurysms may require both a better understanding of the mechanobiological processes that govern the evolution of these lesions and new methods of determining the patient-specific state of the pre-aneurysmal aorta (or correlation to currently unaffected portions thereof) through knowledge of demographics, comorbidities, lifestyle, genetics and future non-invasive or minimally invasive tests.

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