Surgeons have used localizers in minimally invasive procedures by combining 3D tool tracking with anatomical images obtained before or during the procedure. We previously reported on an ultrasound based 3D real-time localizer system. The system determines location by measuring time of flight between a surgical tool-mounted ultrasound transducer and an array of external single-element transducers. Here we interfaced the localizer with 3D Slicer software for image guided surgery with preoperative CT images. We report on initial in vivo results and experience deploying an abdominal aorta stent in a porcine model using the ultrasound localizer. The system demonstrated real-time tracking in the aorta. CT images and direct inspection of the abdominal cavity showed bowel gas that likely caused poor signal propagation and thus erratic tracking. Despite this, we were able to use the 3D Slicer display to position the delivery catheter in the abdominal aorta. Abdominal aorta explant showed stent deployment within 3 mm of the target location. Future work will consider approaches to avoid bowel gas and improve registration.