Image-Based Modeling for Atherosclerotic Coronary Plaque Progression and Vulnerability Research

Abstract

Medical imaging and image-based computational modeling have been used by many researchers in recent years to quantify atherosclerotic plaque morphological and biomechanical characteristics and predict the coronary plaque growth and rupture processes. However, it has been hard to validate model predictions due to imaging resolution limitation, lack of clinical events and plaque rupture data. This article reviews recent advances in coronary plaque research over the past decade, including medical imaging techniques represented by intravascular ultrasound (IVUS) and optical coherence tomography (OCT), computational modeling and their applications in plaque progression and vulnerability analyses and predictions. The clinical application and future development direction are also briefly described. Cardiovascular disease is a dangerous killer with high mortality rate in human society. China Cardiovascular Disease Report 2017 (Summary) [2] pointed out that at present, cardiovascular diseases (CVD) account for the highest number of deaths among urban and rural residents, with 45.01 percent in rural areas and 42.61 percent in urban areas. Coronary heart disease is closely related to coronary atherosclerosis. In the later stages of atherosclerosis, the lesions (also called plaques) become increasingly unstable with high chance to rupture. The sudden rupture of plaque, followed by complete or incomplete occlusive thrombus clinical syndrome is called acute coronary syndrome (ACS). ACS is one of the main forms of acute death from coronary heart diseases. Vulnerable plaques are atherosclerotic plaques which are more likely to rupture causing severe cardiovascular events. Analyzing the vulnerability of plaques effectively could lead to better patient screening strategies and enable physicians to adopt timely and necessary intervention or conservative treatment, and better guide patient's treatment. Earlier investigations of vulnerable plaques were mostly based on histopathological data. With the accumulation of experience in pathology and the gradual enrichment of autopsy materials, the criteria for the diagnosis of vulnerable plaques appeared in 2001, mainly manifested as the necrotic lipid nuclei, fibrous caps that are infiltrated by a large number of macrophages, and fibrous cap thickness less than 65µm [1,7]. Pathological characteristics such as inflammation, plaque internal bleeding, cholesterol crystals, calcified nodules, and thrombosis are also important aspects of vulnerable plaque investigations [4,[9][10][11]. During the initiation and development of a plaque, macrophages have a high degree of participation. On the one hand, they may increase the area of plaque and the appearance and development of necrotic lipid nuclei. On the other hand, they stimulate inflammatory reactions and promote the formation and lesions of thin fibrous caps. Gene expression, biological and biochemical marker studies, and animal models are some entry points for studying coronary atherosclerosis [3,6,8,14]. Because of the obvious importance o...