1. From the Departments of Pediatrics (P.A., O.J.B., M.D.N.), Radiology (S.J.W.), Pathology (M.R.M.), and Medicine (M.R.M.), Massachusetts General Hospital, and the Departments of Pediatrics (P.A., O.J.B., M.D.N.), Radiology (S.J.W.), and Medicine (M.R.M.), Harvard Medical School — both in Boston.