RecruitingDevice studyAugmentation of Limb Perfusion With Contrast UltrasoundOur laboratory has discovered that ultrasound (US) imaging together with clinically approved microbubble ultrasound contrast agents can augment limb tissue perfusion. These observations have been made in mice with and without peripheral artery disease (PAD), and also in humans where high power contrast enhanced ultrasound (CEU) was used to measure perfusion but was found also to augment perfusion by almost 2-fold. The latter human studies were performed with ultrasound protocols designed for perfusion imaging and not for flow augmentation. In this study, we will measure the degree to which limb perfusion is augmented with specific therapeutic CEU settings that are still within the FDA-approved limits with regards to US power and contrast dosing.