[1] Univ Calif San Francisco, Dept Radiol & Biomed Imaging, 505 Parnassus Ave,Room M-372,Box 0628, San Francisco, CA 94143 USA
[2] Univ Calif San Francisco, Div Mol Imaging & Therapeut, San Francisco, CA 94143 USA
[3] Univ Washington, Dept Radiol, Div Abdominal Imaging, Seattle, WA 98195 USA