1. From the Departments of Medicine (L.T.F.) and Radiology (L.L.T.), Massachusetts General Hospital, and the Departments of Medicine (L.T.F.) and Radiology (L.L.T.), Harvard Medical School — both in Boston; the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institutes of Health — both in Bethesda, MD (R.J.B.); and the Department of Clinical Biochemistry, University of Cambridge, Cambridge, United Kingdom (S.O.).