1 Department of Radiology, Faculty of Medicine, University of Ottawa, United States.
2 Department of Radiology, Clinical Epidemiology Program, Ottawa Hospital Research Institute, United States.
3 University of Ottawa Department of Radiology, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Room c159 Ottawa Hospital Civic Campus, 1053 Carling Ave., Ottawa, ON K1Y 4E9, United States. Electronic address: mmcinnes@toh.ca.