Mechanical Analysis of Atherosclerotic Plaques Based on Optical Coherence Tomography

Abstract

Finite element analysis is a powerful tool for investigating the biomechanics of atherosclerosis and has thereby provided an improved understanding of acute myocardial infarction. Structural analysis of arterial walls is traditionally performed using geometry contours derived from histology. In this paper we demonstrate the first use of a new imaging technique, optical coherence tomography (OCT), as a basis for finite element analysis. There are two primary benefits of OCT relative to histology: 1) imaging is performed without excessive tissue handling, providing a more realistic geometry than histology and avoiding structural artifacts common to histologic processing, and 2) OCT imaging can be performed in vivo, making it possible to study disease progression and the effect of therapeutic treatments in animal models and living patients. Patterns of mechanical stress and strain distributions computed from finite element analysis based on OCT were compared with those from modeling based on "gold standard" histology. Our results indicate that vascular structure and composition determined by OCT provides an adequate basis for investigating the biomechanical factors relevant to atherosclerosis and acute myocardial infarction.

Application of Ex Vivo Cryo-imaging Technique for Three-Dimensional Finite Element Analysis of Atherosclerotic Plaque Rupture

“…Investigation of the biomechanics of atherosclerosis has relied upon finite element analysis (FEA) for computing stress and strain distributions in hypothesized vascular cross-sections or more realis-tic morphology derived from histology of autopsy specimens [6]. FEA is a technique that allows re-searchers to go beyond simple image analysis.…”

Carotid Plaque Stresses

“…To estimate stress levels in the fibrous cap, fluid structure interaction analysis has emerged as a tool combining blood flow simulation through computational fluid dynamics combined with finite element analysis of the corresponding stress levels in the surrounding tissues. Thus, a number of studies have been performed investigating intraplaque stresses as a potential risk marker of vulnerable plaques (Li et al, 2006a;Imoto et al, 2005;Kaazempur-Mofrad et al, 2004;Chau et al, 2004;Steinman, 2002;Huang et al, 2001;Li et al, 2006b;Tang et al, 2004;Zhao et al, 2002). Indeed, in vitro studies of coronary arteries have shown markedly elevated fibrous cap stresses in ruptured coronary lesions compared to stable lesions (Cheng et al, 1993) and a recent publication found carotid fibrous cap stress levels in symptomatic patients to be nearly twice those of asymptomatic patients .…”

“…Other researchers have used linear orthotropic models (Imoto et al, 2005), modified Mooney-Rivlin models (Chau et al, 2004;Tang et al, 2004), and Ogden hyperelastic models Versluis et al, 2006;Antheunis et al, 2006). Since different hyperelastic models and material specifications may substantially affect resulting stress levels, comparison of stress levels between different models should be interpreted with caution.…”

“…A variety of imaging modalities have been employed for generating morphology suitable for computational fluid dynamics simulations including magnetic resonance imaging (Li et al, 2006a;Tang et al, 2004), intravascular ultrasound (Wentzel et al, 2003;Ramaswamy et al, 2006), computed tomography (Jin et al, 2004), and optical coherence tomography (Chau et al, 2004). In particular, magnetic resonance imaging has gained widespread usage as the method-of-choice for producing computational fluid dynamic models given the modality's excellent soft tissue contrast and inherent capability of obtaining velocity images alongside the morphological imagery.…”

The Effect of Carotid Plaque Morphology on Longitudinal Fibrous Cap Stress Levels

“…Detailed in vivo morphological characterization of carotid plaques is possible through high resolution imaging techniques such as magnetic resonance imaging (MRI) [5], intravascular ultrasound [14], and optical coherence tomography [15]. The morphological images may be used for constructing geometrical models for the purpose of computational simulations of mechanical stresses and plaque rupture.…”