Optical coherence tomography (OCT), compared with IVUS, is more sensitive for early detection of CAV. OCT is a new generation catheter-based modality that acquires images at a spatial resolution of 10-20 μm which is 10-fold greater than that of IVUS. OCT could obviously identify the layer of media as a lower-echoic line, which could not be identified by IVUS. When assessing the quality of an intracoronary structure accurately, OCT seems to have more potential than IVUS.