Deep vein thrombosis (DVT) is a condition characterized by the formation a blood clot in the deep veins of the legs and affects nearly two million Americans per year. Clinical treatments for DVT include thrombolytic drugs and catheter-based surgical procedures, both of which have significant drawbacks, such as invasiveness and risks of bleeding and infection. Guided by ultrasound imaging, histotripsy is a cavitation-based ultrasound therapy that fractionates tissue. Using our laboratory prototype, histotripsy fractionated in vitro clots into debris smaller than red blood cells at a speed fifty-fold faster tan current clinical thrombolysis methods. Using an in vivo porcine DVT model, histotripsy non-invasively eradicated the thrombus in 10 of 12 cases. By eliminating thrombolytic drugs and catheters, shortening the treatment time, and maintaining or possibly increasing the efficacy for clot removal, histotripsy has the potential to truly change the landscape of thrombosis therapy. The goal of this proposal is to advance the clinical translation of histotripsy thrombolysis. To achieve this goal, we propose the following three specific aims. 1) Design and build an integrated image-guided histotripsy thrombolysis system for DVT patients. 2) Develop two technical innovations (microtripsy and bubble-induced color Doppler feedback) to further improve the safety and efficacy of histotripsy thrombolysis. 3) Determine the in vivo safety and efficacy of the clinically designed histotripsy thrombolysis system through a comprehensive pre-clinical study in the porcine DVT model. These aims are designed to obtain results that are crucial towards achieving approval from the United States Food and Drug Administration (FDA) to inaugurate the first clinical trial of histotripsy thrombolysis. In addition, our proposed comprehensive preclinical in vivo safety study will quantitatively measure all the possible adverse effects of cavitation, which will be essential for clinical translation of all cavitation-bsed thrombolysis techniques including histotripsy. While we are currently studying DVT, there are many other diseases which could benefit from this revolutionary new thrombolysis technique, including stroke, myocardial infarction, superficial vein thrombosis, and peripheral arterial and graft thrombosis. Each poses a significant clinical problem where histotripsy thrombolysis may improve upon current treatment methods.