1. From the Departments of Radiology (A. Makoyeva, A. Medellin, S.R.W.) and Medicine (S.R.W.), University of Calgary, Foothills Medical Centre, 1403 29th St NW, Calgary, AB, Canada T2N 2T9; and Department of Medical Imaging, University of Toronto, Toronto, Canada (T.K.K., H.J.J.).