**1. Introduction**

Cardiovascular disease (CVD) has remained the leading cause of death in the United States in 2018 [1]. Atherosclerosis is the leading factor in causing cardiovascular death. The main factors that drive atherosclerosis are LDL cholesterol, hypertension, diabetes, and smoking [2]. Currently the United Stated Preventive Services Task Force recommends screening everyone who are at risk for coronary artery disease, all men over age 35 and all women over age 45. For risk stratification a ten year atherosclerotic risk score can be calculated to help decide if treatment should be started [3]. Treatment options can be aided by cardiac imaging. Cardiac imaging is mainly performed via intravascular ultrasound (IVUS), optical coherence tomography (OCT), and coronary computed tomography angiography (CCTA).

This development has made plaque characterization possible. Categories of plaque are placed into 4 broad categories: low-attenuating, fibrofatty, fibrocalcified, and densely calcified plaque [4].
