[1] GEISINGER MED CLIN, DEPT RADIOL, DANVILLE, PA USA
[2] UNIV VERMONT, DEPT PATHOL, BURLINGTON, VT 05405 USA
[3] WAKE FOREST UNIV, BOWMAN GRAY SCH MED, DEPT PUBL HLTH SCI, WINSTON SALEM, NC 27103 USA
[4] UNIV WASHINGTON, DEPT BIOSTAT, SEATTLE, WA 98195 USA
[5] UNIV WASHINGTON, DEPT MED, SEATTLE, WA 98195 USA
[6] UNIV WASHINGTON, DEPT EPIDEMIOL, SEATTLE, WA 98195 USA
[7] UNIV WASHINGTON, DEPT HLTH SERV, SEATTLE, WA 98195 USA
[8] JOHNS HOPKINS UNIV, SCH HYG & PUBL HLTH, DEPT EPIDEMIOL, BALTIMORE, MD 21218 USA