[1] Vanderbilt Univ, Sch Med, Dept Radiol, Nashville, TN 37203 USA
[2] Amer Heart Assoc, Dallas, TX USA
[3] Univ Minnesota, Sch Publ Hlth, Minneapolis, MN USA
[4] Univ Minnesota, Dept Med, Box 736 UMHC, Minneapolis, MN 55455 USA
[5] Dept Internal Med, Bethesda, MD USA
[6] NIH, Bldg 10, Bethesda, MD 20892 USA
[7] Alfred I DuPont Hosp Children, Wilmington, DE USA