1. From the Departments of Radiology (M.D., M.D.F.M., N.S., A.Z.K., R.V., C.W., W.P.) and General Surgery (J.M.), Clinical Epidemiology Program, University of Ottawa Ottawa Hospital Research Institute, Room c159, Ottawa Hospital Civic Campus, 1053 Carling Ave, Ottawa, ON, Canada K1Y 4E9; and Department of Surgery, Pasqua South Medical Clinic, Regina, Sask, Canada (A.V.).