This document discusses intravascular ultrasound elastography (IVUS), a technique that measures the elastic properties and stiffness of vessel walls and atherosclerotic plaque. It can identify soft, lipid-rich plaques that are more vulnerable to rupture compared to hard, calcified plaques. The document summarizes a study that found IVUS elastography could successfully identify fatty plaques in vivo in an atherosclerotic pig model, with 100% sensitivity and 80% specificity. The study also showed this technique had high sensitivity and specificity for identifying lipid and macrophages within plaques. However, questions remain about how it can detect plaque inflammation and what normal and abnormal elasticity values mean clinically.