1. Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC 27599, USA
2. Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
3. Fox Chase Cancer Center, Philadelphia, PA 19111, USA
4. Triangle Biotechnology, Durham, NC 27709, USA
5. Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
6. Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
7. Department of Medicine, Vanderbilt University, Nashville, TN 37232, USA