1. Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USA
2. Department of Radiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
3. Department of Veterinary and Biomedical Sciences, University of Minnesota, Room 205 Veterinary Medicine Building, 1971 Commonwealth Avenue, St. Paul, MN 55108, USA