Abstract

The assessment of morphologic changes in sclerotic arteries during interventional procedures such as balloon angioplasty is an issue of highest clinical importance. A MR -based methodology is presented to allow 3D morphomechanical modeling of the artery, the plaque and the lumen at different stages of angioplasty by using multi-spectral images. Using generalized gradient vector flow active contours a segmentation process is used to generate NURBS -based geometric models of an individual artery at different balloon pressures. In the studied arteries an increase in lumen cross-sectional areas after angioplasty was observed. Dissection between the inner and middle arterial layers and reduction of the lipid pool are the primary mechanisms of dilatation.

Physical and finite element models which are able to trace the dissection during angioplasty are presented. The arterial wall is described as an anisotropic, heterogeneous, highly deformable, nearly incompressible solid, whereas tissue failure is captured by strong discontinuity kinematics and cohesive zone models. Numerical implementation is based on the partition of unity FEM and the interface element method. The later is used to link meshes of the different tissue components. The predicted numerical results indicate that dissections develop between the inner and middle arterial layers at the fibrous cap location with the smallest thickness, and that dissections cause localized mechanical trauma, which prevents the main portion of sclerotic arteries from high stress, and hence from continuous tissue damage.