Stress analysis of carotid plaque rupture based on in vivo high resolution MRI

Atherosclerosis Initiation Modeled as an Inflammatory Process

“…Indeed the fibrous cap changes the geometry of the vasculature and modifies the blood flow. The interaction between the flow and the cap may lead to a thrombus, or to the degradation and rupture of the plaque liberating dangerous solid parts in the flow [4,5]. In this study we do not address the fluid-structure interaction between the blood flow and the plaque, and only consider the set up of the chronic inflammatory reaction with its biochemical and mechanical inhibitions.…”

Carotid Plaque Stresses

“…Previous studies have used principal stress levels in excess of 300 kPa to be predictive of plaques at high risk of rupture (Cheng et al, 1993;Li et al, 2006b;Li et al, 2007). However, the choice of material model and parameters may substantially affect simulated stress levels (Li et al, 2006a). Care should thus be taken comparing absolute stress levels across different simulations employing different material models, and the choice of an absolute level at which the plaques are considered to be at risk of rupture may be problematic.…”

“…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 .…”

“…However, the computational demands for performing 3D fluid structure interaction simulations are great requiring substantial solution times. Thus, simulations in 2D cross-sections corresponding to either histological data (Cheng et al, 1993) or MRI scans (Li et al, 2006a) have been suggested. Though the use of cross-sectional data matches the orientation of the available morphologic data, this approach precludes fluid structure interaction analysis and necessitate assumptions regarding the longitudinal blood pressure distribution used to load the blood/vessel wall interface.…”

“…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.…”