Destabilization of coronary plaque is one of the key features in the process of acute coronary syndrome. However, a quantitative way of assessing plaque vulnerability has not yet been established. Previous pathologic studies have revealed that plaque vulnerable to rupture is usually eccentric and non-calcified with positive remodeling, a thin fibrous cap, a large lipid core, and accumulated infiltrations of inflammatory cells. Recent plaque imaging modalities, including intravascular ultrasound (IVUS), have been developed for the purpose of detection of plaque with such specific features. Furthermore, structural mechanics imaging modalities, such as in-plaque or shear stress imaging, have also been proposed in this field. Future perspectives in the development of new IVUS imaging technologies involve three-dimensional plaque imaging, more sophisticated tissue characterizing imaging, as well as hybrid ultrasound-infrared-light imaging catheter systems.