[1] George Washington Univ, Med Fac Associates, 900 23rd St Northwest,Suite G 2092, Washington, DC 20037 USA
[2] MD Anderson Canc Ctr, Dept Thorac Imaging, 1515 Holcombe Blvd,Unit 1478, Houston, TX 77030 USA
[3] Walter Reed Natl Mil Med Ctr, Dept Radiol, 4494 North Palmer Rd, Bethesda, MD 20889 USA
[4] Childrens Hosp Philadelphia, Dept Radiol, Philadelphia, PA 19104 USA
[5] Univ Penn, Perelman Sch Med, 3401 Civ Ctr Blvd, Philadelphia, PA 19104 USA