3D Stress Computations in Atherosclerotic Arteries: The Influence of Axial Image Resolution

Abstract

Sudden rupture of vulnerable atherosclerotic plaques is a major contributing cause of acute myocardial infarctions and ischemic strokes [1]. A vulnerable plaque is defined as a plaque with a large necrotic core and a thin fibrous cap. In order to characterize, and further comprehend, plaque vulnerability from a mechanical point of view, the rupture process can be seen as a mechanical process which occurs when the tensile stress in the fibrous cap exceeds its material strength. Biomechanical stress modeling of plaques using the Finite Element Method (FEM) has been used as a tool to provide insight in the stress distribution in plaques and shows potential to facilitate identification of vulnerable plaques using novel biomechanics-based risk-stratification criteria [1, 2, 3]. Accurate stress prediction using computational modeling depends on a number of factors including material models, computational methods, initial conditions and accurate reconstruction of the plaque geometry from ex vivo or in vivo imaging. The latter received limited attention and lacks a critical evaluation. In case of 3D modeling, the arterial geometry is typically reconstructed by stacking MRI or histology slices in the axial direction and interpolating the geometry without consensus on minimal requirements of inter slice distance (axial sampling distance) [4]. Due to time constraints during the imaging procedure, especially MRI suffers from a limited axial resolution (typically an inter slice distance of 1–3 mm), which might compromise accurate geometry reconstruction which could in turn influence resulting stress computations.