1. From the Department of Radiology and Biomedical Imaging, University of California–San Francisco, San Francisco, Calif (J.M.); Department of Radiology and Center for Advanced Imaging Innovation and Research, New York University School of Medicine, New York, NY (L.M.); and Department of Radiology, University of Pennsylvania, 3400 Spruce St, 1 Silverstein, Philadelphia, PA 19104 (C.E.K.).