1. From the Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 13th Street, Building 149, Room 2301, Charlestown, MA 02129 (S.G., S.K., K.C., C.L., P.S., J.K.C.); and Indian Institute of Technology Delhi, New Delhi, India (S.G., S.K.).