Numerical investigation of atherosclerotic plaque rupture using optical coherence tomography imaging and XFEM

Myocardial infarction contributes to most fatalities in which atherosclerotic plaque disruption is the underlying pathology. From the mechanics view point, the pulsatile blood flow in the arteries resembles a fatigue environment and generates stresses that affect the rupture of the atherosclerotic plaque. In this context, patient-specific optical coherence tomography (OCT) was used to develop the fatigue crack growth behavior. The impact of location specific morphological features and their relative effect on plaque life were discussed. EXtended Finite Element Method (XFEM) and Paris’ Law were employed to investigate the fatigue crack growth. Twelve 2D slices from six patients were reconstructed for studying the fatigue crack growth behavior. Our results indicate that plaque life decreases with an increase in pulse pressure and 53.5% of the total cracks initiated at various locations on the lumen lead to rupture. 73.7% of the rupture locations did not have calcifications. Correlation between the location specific morphology and the rupture indicates that for a 1 mm increase in the fibrous cap thickness there is a large decrease in the odds of rupture [0.163 (0.073; 0.363)], p-value < 0.0001; and for a 1 mm2 increase of the calcification area, there is a decrease in the odds of rupture by 0.719 (0.619; 0.835), p-value < 0.0001. In conclusion, the XFEM technique can be used to study the fatigue behavior of the atherosclerotic plaque that depends on the combined effects of plaque constituents and their morphology. It may help to better assess plaque vulnerability and make more accurate predictions for plaque rupture

Characterization of the Atherosclerotic Plaque Tissue

Cardiovascular diseases (CVD) are the leading causes of morbidity and mortality globally. Atherosclerosis is a chronic inflammatory CVD associated with the accumulation of plaque activated by the complex interactions between systemic, hemodynamic and biological factors. Thus, identification of plaque vulnerability is essential for the prevention of acute events and treatment of the disease. Despite, advanced imaging technologies, patient-specific computational simulations and availability of experimental data, there are still challenges in developing accurate risk stratification techniques. Therefore, this study aims to characterize the carotid plaque components structurally (histological analysis and immunostaining), mechanically (Nanoindentation tests) and chemically (Fourier Transform Infrared (FT-IR) micro-spectroscopy). The preliminary results showed that arterial remodelling is a dynamic interaction between mechanical forces and plaque progression. The biological content and composition of human atherosclerotic plaque tissue have been shown to significantly influence the mechanical response of samples. This data represents a step towards an enhanced understanding of the behaviour of human atherosclerotic plaque. Future large-scale experimental studies with more cross-sections along the length of the plaque could be used to develop a risk stratification technique

Reproducibility of the computational fluid dynamic analysis of a cerebral aneurysm monitored over a decade

Computational fluid dynamics (CFD) simulations are increasingly utilised to evaluate intracranial aneurysm (IA) haemodynamics to aid in the prediction of morphological changes and rupture risk. However, these models vary and differences in published results warrant the investigation of IA-CFD reproducibility. This study aims to explore sources of intra-team variability and determine its impact on the aneurysm morphology and CFD parameters. A team of four operators were given six sets of magnetic resonance angiography data spanning a decade from one patient with a middle cerebral aneurysm. All operators were given the same protocol and software for model reconstruction and numerical analysis. The morphology and haemodynamics of the operator models were then compared. The segmentation, smoothing factor, inlet and outflow branch lengths were found to cause intra-team variability. There was 80% reproducibility in the time-averaged wall shear stress distribution among operators with the major difference attributed to the level of smoothing. Based on these findings, it was concluded that the clinical applicability of CFD simulations may be feasible if a standardised segmentation protocol is developed. Moreover, when analysing the aneurysm shape change over a decade, it was noted that the co-existence of positive and negative values of the wall shear stress divergence (WSSD) contributed to the growth of a daughter sac

Semantic representations for configurable enterprise systems

Proceedings of the ASME Design Engineering Technical Conference2006

A configuration-based flexible reporting method for enterprise information systems

10.1016/j.compind.2006.09.016Computers in Industry585416-427CINU

Assessing the leanness in product design : a model for planned design reuse

Shrinking product lifecycles, tough international competition, swiftly changing technologies, ever increasing customer quality expectation and demanding high variety options are some of the forces that drive next generation of development processes. To overcome these challenges, design cost and development time of product has to be reduced as well as quality to be improved. Design reuse is considered one of the lean strategies to win the race in this competitive environment. design reuse can reduce the product development time, product development cost as well as number of defects which will ultimately influence the product performance in cost, time and quality. However, it has been found that no or little work has been carried out for quantifying the effectiveness of design reuse in product development performance such as design cost, development time and quality. Therefore, in this study we propose a systematic design reuse based product design framework and developed a design leanness index (DLI) as a measure of effectiveness of design reuse. The DLI is a representative measure of reuse effectiveness in cost, development time and quality. Through this index, a clear relationship between reuse measure and product development performance metrics has been established. Finally, a cost based model has been developed to maximise the design leanness index for a product within the given set of constraints achieving leanness in design process

A solution for knowledge resources provider over the internet

Product development is complicated systematic engineering. The development of a successful product is achieved through cooperation between various design teams and utilisation of a number of design resources that exist in various disciplines, organisations and locations. As product complexity increases, product designers are required to collaborate with others to develop high-quality products. In this process, an effective solution is required from a knowledge resources provider for them to be able to acquire and share knowledge resources in various teams, locations, and domains. Based on the Internet, a solution for a knowledge resources provider, called a web-based product development support system (WPDSS), is proposed in this paper. The structure and implementation of the WPDSS system are both discussed in detail. Issues concerning development of the WPDSS system such as system structure, knowledge representation, and knowledge searches are investigated. Based on design of a rotor-bearing system of turbine machinery, a prototype of the WPDSS is developed to validate the feasibility of the proposed solution

Designed triple-helical peptides as tools for collagen biochemistry and matrix engineering

Collagens, characterized by a unique triple-helical structure, are the predominant component of extracellular matrices (ECMs) existing in all multicellular animals. Collagens not only maintain structural integrity of tissues and organs, but also regulate a number of biological events, including cell attachment, migration and differentiation, tissue regeneration and animal development. The specific functions of collagens are generally triggered by specific interactions of collagen-binding molecules (membrane receptors, soluble factors and other ECM components) with certain structures displayed on the collagen triple helices. Thus, synthetic triple-helical peptides that mimic the structure of native collagens have been used to investigate the individual collagen–protein interactions, as well as collagen structure and stability. The first part of this article illustrates the design of various collagen-mimetic peptides and their recent applications in matrix biology. Collagen is also acknowledged as one of the most promising biomaterials in regenerative medicine and tissue engineering. However, the use of animal-derived collagens in human could put the recipients at risks of pathogen transmission or allergic reactions. Hence, the production of safe artificial collagen surrogates is currently of considerable interest. The latter part of this article reviews recent attempts to develop artificial collagens as novel biomaterials