[1] ARMED FORCES INST PATHOL, DEPT RADIOL PATHOL, WASHINGTON, DC 20306 USA
[2] CHILDRENS NATL MED CTR, DEPT DIAGNOST IMAGING & RADIOL, WASHINGTON, DC 20010 USA
[3] GEORGE WASHINGTON UNIV, SCH MED & HLTH SCI, WASHINGTON, DC 20052 USA
[4] JOHNS HOPKINS UNIV, DEPT RADIOL & RADIOL SCI, BALTIMORE, MD 21218 USA
[5] NORTHWESTERN UNIV, CHILDRENS MEM HOSP, SCH MED, DEPT RADIOL, CHICAGO, IL 60614 USA