1. Department of Medicine, Division of Rheumatology, McMaster University , Hamilton, ON, Canada
2. Department of Medicine, Division of Neurology, McMaster University, Hamilton Health Sciences , Hamilton, ON, Canada
3. Department of Rheumatic and Immunologic Disease, Center for Vasculitis Care and Research, Cleveland Clinic , Cleveland, OH, USA
4. Department of Neuroradiology, Imaging Institute, Cleveland Clinic , Cleveland, OH, USA