1. From the Departments of Surgery and Radiology and the School of Public Health, University of Michigan, and the C.S. Mott Children's Hospital, Ann Arbor, Michigan; Brown University, Providence, Rhode Island; St. Vincent's Mercy Children's Hospital, Toledo, Ohio; Strong Memorial Hospital, University of Rochester, Rochester, New York; Baylor College of Medicine, Houston, Texas; The Johns Hopkins University School of Medicine, Baltimore, Maryland; and Columbus Children's Hospital, Columbus, Ohio