Intravascular ultrasound imaging of human coronary atherosclerotic plaque: Novel morpho-elastic biomarkers of instability

Atherosclerotic plaque rupture is a recognized major cause of acute coronary syndrome. The challenge for new intravascular imaging tools is that to diagnose the risk of plague rupture, interventional cardiologists need to quantify not only the fibrous cap thickness and necrotic core size, but also the mechanical properties of all plaque constituents at any given stage of the plaque growth process and remodeling. Such knowledge can allow a precise estimation of the thin-cap fibro-atheroma peak cap stress amplitude, which has been demonstrated to be a good biomechanical predictor of plaque rupture. Therefore, the development of novel morpho-elastic imaging tools is essential, will help in predicting the risk of acute occlusive syndromes and may allow better and more appropriated therapies. During these last two decades, significant improvements have been performed and two powerful intravascular ultrasound (IVUS) biomarkers of coronary plaque instability (namely iPALP and iMOD for imaging palpography and modulography (or morpho-elasticity), respectively) were developed in our joint laboratories. A thorough review and classification of IVUS imaging models is beyond the scope of this work. In this chapter, we present these two original IVUS imaging techniques developed for the in vivo detection and mechanical characterization of human vulnerable coronary atherosclerotic plaques.