1. From the CRICO/Risk Management Foundation of the Harvard Medical Institutions, Boston, Mass (A.C.S., T.Z., J.S.E., L.S.); and Department of Medicine (A.C.S., J.S.E., L.S.) and Department of Radiology, Division of Emergency Radiology (A.D.S.), Brigham and Women’s Hospital, Harvard Medical School, 75 Francis St, PBB-B-422, Boston, MA 02215.