[1] NCI, WARREN G MAGNUSON CLIN CTR, DEPT DIAGNOST RADIOL, NIH, BETHESDA, MD 20892 USA
[2] NCI, CYTOPATHOL SECT, NIH, BETHESDA, MD 20892 USA
[3] GEORGETOWN UNIV, CHILDRENS MED CTR, DEPT PEDIAT, WASHINGTON, DC 20007 USA
[4] MAYO CLIN & MAYO FDN, DEPT LAB MED & PATHOL, EMERITUS STAFF, ROCHESTER, MN 55905 USA