Atherosclerosis is associated with the formation of microvessels in the arterial wall, referred to as vasa vasorum (VV). VV imaging may constitute a new intravascular ultrasound (IVUS) metric of coronary artery plaque vulnerability. The potential of nonlinear contrast IVUS to detect VV in vivo was demonstrated using a prototype transducer with dual-peak frequency response. In this study, we report the feasibility of pulse-inversion ultraharmonic IVUS contrast imaging and6 chirp reversal contrast IVUS imaging. Their performance is compared for VV detection. Both sequences operate with limited transducer bandwidths (<60%), and are therefore implementable on clinical IVUS catheters.@en