1. Mechanical Engineering, Vanderbilt University, Nashville, TN 37235, USA
2. Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37235, USA
3. Division of Cardiothoracic Surgery, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
4. Department of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA