[1] Kaiser Permanente Div Res, 2000 Broadway, Oakland, CA 94612 USA
[2] Kaiser Permanente Santa Clara Med Ctr, Santa Clara, CA USA
[3] Univ Calif Irvine, Dept Radiol Sci, Sch Med, Irvine, CA USA
[4] Korea Res Inst Stand & Sci, Med Measurement Team, Daejeon, South Korea
[5] Univ Calif Irvine, Div Cardiol, Dept Med, Irvine, CA USA
[6] Univ Calif Irvine, Dept Epidemiol, Irvine, CA USA