[1] NIH, Dept Radiol & Imaging Sci, Bethesda, MD 20892 USA
[2] Virginia Tech, Macromol & Interfaces Inst, Blacksburg, VA USA
[3] Purdue Univ, Dept Comparat Pathobiol, W Lafayette, IN 47907 USA
[4] Virginia Tech, Dept Biomed Sci & Pathobiol, Blacksburg, VA USA
[5] Washington State Univ, Pullman, WA 99164 USA