Mechanical characterization of arterial walls based on IVUS studies

Abstract

The understanding of the genesis, development and progression of cardiovascular diseases is key for effective diagnosis, treatment and surgical risk assessment. Notorious advances have been performed in the histological characterization of culprit plaque. In contrast, the development of strategies for the mechanical characterization of plaque and healthy tissue constituents is an active area of research yet in its early stages. This work proposes a methodology to construct patient-specific mechanical models of the arterial wall using in-vivo data from an IVUS study. Firstly, an image processing stage of the IVUS study delivers a set of images that describes the deformation of a vessel cross-section along the cardiac cycle. Optical flow techniques are then employed to estimate the displacement vector field of the vessel wall between the predefined set of images. Also, a geometric patient-specific model for the arterial wall is constructed by manual segmentation of a diastolic image within the set of images. The geometric model is then discretized with a finite element method to obtain a patient-specific mechanical model. Using the optical flow displacements as observations, a reduced-order unscented Kalman filter is employed to calibrate the constitutive parameters of the patient-specific mechanical model. The obtained model allows several clinically relevant applications such as: tissue characterization, computational vessel-wall simulations, stress analysis of the arterial wall, among others. The integrative use of such applications in longitudinal studies is expected to reveal new insights of the plaque characteristics and behavior (genesis, remodeling and destabilization processes).