Visualization of atherosclerotic plaque mechanical properties using model based intravascular ultrasound elastography.

Abstract

Cardiovascular disease related deaths occur primarily from fatty plaques inside an artery that rupture and cause clots that disrupt blood flow. The study of arterial plaque mechanics is essential to the monitoring of atherosclerosis and the detection of vulnerable plaques or the likelihood of their rupture. The aim of this work is to measure and image the mechanical behavior of plaques using a clinically available intravascular ultrasound system (IVUS). To test the methods, radial displacements were measured from simulated images and phantom data within two dimensional IVUS rf images using standard elastography techniques. Simulations and phantom experiments were designed to mimic arterial geometries and deformations, which include plaque regions of varying stiffnesses. In addition, an optimization inversion algorithm was used to infer the elastic modulus of the underlying material. This algorithm utilizes a finite element based model and assumes that the deformation is quasi-static, plane strain and that the material is incompressible and linear elastic. The full spatially reconstructed modulus images, with no geometric constraints, are presented and compared to radial strain images. The phantom results are compared to the known modulus contrasts, and the simulated images are compared to contrasts and distributions.