1. From the Department of Medicine, Brigham and Women’s Hospital (E.R.E.), the Departments of Medicine (N.M.B., A.L.L.), Radiology (L.L.A.), and Pathology (A.S.D.), Massachusetts General Hospital, and the Departments of Medicine (E.R.E., N.M.B., A.L.L.), Radiology (L.L.A.), and Pathology (A.S.D.), Harvard Medical School — all in Boston, and the Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge (E.R.E.).