[1] GEORGE WASHINGTON UNIV, CHILDRENS NATL MED CTR, SCH MED & HLTH SCI, DEPT CHILD HLTH & DEV, WASHINGTON, DC 20052 USA
[2] UNIV CINCINNATI, DEPT NEONATOL, CINCINNATI, OH 45221 USA
[3] BOWMAN GRAY UNIV, WINSTON SALEM, NC USA
[4] JOHNS HOPKINS MED INST, DEPT RADIOL, BALTIMORE, MD 21205 USA
[5] JOHNS HOPKINS MED INST, DEPT PEDIAT, BALTIMORE, MD 21205 USA