1. Faculty of Medicine, University of Ottawa, Ontario, Canada
2. The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
3. Department of Radiology, University of Ottawa, Ontario, Canada
4. School of Epidemiology and Public Health, University of Ottawa, Ontario, Canada
5. Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada