Abstract
The role of calcification inside fibroatheroma during carotid artery stenting operation is controversial. Cardiologists face a major problem in placing stents: “plaque protrusion” i.e. elastic fibrous caps containing early calcifications that penetrate inside the stent. The aim of this work is to assess the contribution of calcification to plaque vulnerability by using image-based models of carotid artery stenting. Technically, Finite Element Analysis was used to simulate the balloon and stent expansion as a preoperative virtual framework. A nonlinear static structural analysis was performed on 20 image-based models of patients reconstructed from Multidetector Computer Tomography (CT) angiography acquisitions. Subject-specific local Elastic Modulus (EM) of calcified plaques was estimated using the Agatston Calcium (Ca) score, as obtained from CT images. The main findings from the personalized simulations are that maximum values of von Mises stress of 102kPa and 329kPa are obtained on calcified plaques when patient-specific balloon pressure expansion and stent self-expansion, respectively, are modeled. In modeling stent expansion procedure, it is observed a statistically significant positive correlation for EM of calcification with maximum stress (R=0.55; p=0.013) and Plaque Wall Stress (PWS) (R=0.47; p=0.038), while no significant correlation is observed for Ca score with maximum stress (R=0.28; p=0.23) and PWS (R=0.27; p=0.26), this last result suggesting a moderate impact of Ca score in plaque rupture. The approach proposed here could enrich the arsenal of tools available for pre-operative prediction of carotid artery stenting procedure in the presence of calcified plaques.
Keywords: Atherosclerotic calcification, calcified plaques, carotid artery stenting, finite element analysis, plaque mechanics, subject-specific model.
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