[1] Univ Calif San Francisco, San Francisco, CA 94143 USA
[2] New Mexico State Univ, Las Cruces, NM 88003 USA
[3] Univ Texas MD Anderson Canc Ctr, Dept Diagnost Radiol, Houston, TX 77030 USA
[4] Mayo Clin, Dept Hlth Sci Res, Div Epidemiol, Rochester, MN USA
[5] Calif Pacific Med Ctr, Res Inst, San Francisco Coordinating Ctr, San Francisco, CA USA