[1] JOHNS HOPKINS MED INST,RUSSELL H MORGAN DEPT RADIOL & RADIOL SCI,BALTIMORE,MD 21205
[2] HARVARD UNIV,SCH MED,DEPT HLTH CARE POLICY,BOSTON,MA 02115
[3] THOMAS JEFFERSON UNIV HOSP,DEPT RADIOL,PHILADELPHIA,PA
[4] UNIV MICHIGAN,DEPT RADIOL,ANN ARBOR,MI 48109