Registration of ultrasound to CT angiography of kidneys: a porcine phantom study D ultrasound (US) to computed tomography (CT) registration is a topic of significant interest because it can potentially improve many minimally invasive procedures such as laparoscopic partial nephrectomy. Partial nephrectomy patients often receive preoperative CT angiography, which helps define the important structures of the kidney such as the vasculature. Intraoperatively, dynamic realtime imaging information can be captured using ultrasound and compared with the preoperative data. Providing accurate registration between the two modalities would enhance navigation and guidance for the surgeon. However, one of the major problems of developing and evaluating registration techniques is obtaining sufficiently accurate and realistic phantom data especially for soft tissue. We present a detailed procedure for constructing tissue phantoms using porcine kidneys, which incorporates contrast agent into the tissue such that the kidneys appear representative of in vivo human CT angiography. These phantoms are also imaged with US and resemble US images from human patients. We then perform registration on corresponding CT and US datasets using a simulationbased algorithm. The method simulates an US image from the CT, generating an intermediate modality that resembles ultrasound. This simulated US is then registered to the original US dataset. Embedded fiducial markers provide a gold standard for registration. Being able to test our registration method on realistic datasets facilitates the development of novel CT to US registration techniques such that we can generate an effective method for human studies.

Robotic Ultrasound for Catheter Navigation in Endovascular Procedures Endovascular procedures require real time visual feedback on the location of inserted catheters. This is currently achieved using Xray fluoroscopy, which causes exposure to radiation. This study describes an alternative method using a robotic ultrasound system for catheter tracking and navigation in endovascular interventions, focusing on endovascular aneurysm repair. This approach relies on the registration of preoperative images to provide both a tracking trajectory and visual feedback of the realtime catheter position. The procedure was validated on healthy volunteers and on a phantom that included a realistic vessel structure, showing an average tracking error of the moving catheter tip of 1.78xc2xb11.02 mm.