Katherine A Zukotynski1, Phillip H Kuo1. 1. From the Departments of Radiology and Medicine, McMaster University, 1200 Main St W, Room 1P11, Hamilton, ON, Canada L8N 3Z5 (K.A.Z.); and Departments of Medical Imaging, Medicine, and Biomedical Engineering, University of Arizona, Tucson, Ariz (P.H.K.).