Intracoronary ultrasound is a rapidly evolving imaging modality and the increasing number of published studies indicates that the technique is safe and provides incremental and more detailed diagnostic information than coronary angiography.The technique has the potential to study the pathobiology of atherosclerosis, to clarify the significance of angiographically equivocal lesions and has helped us to understand the mechanisms, effects and complications of catheter-based revascularization procedures. Combinations of imaging and therapeutic devices are being developed for both guidance and assessment of the revascularization procedure. Three-dimensional reconstruction of coronary segments is now possible in real time and provides the opertor with more detailed information on coronary pathology. In this monograph, leading experts in the field present the state of the art of all these new developments.