1. Department of Radiology, Section of Neuroradiology, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226.
2. Department of Statistics, Colorado State University, Fort Collins, CO.
3. Department of Radiology, Section of Neuroradiology, Beth Israel Deaconess Medical Center, Boston, MA.
4. Department of Radiology, Section of Neuroradiology, University of California, Davis Medical Center, Sacramento, CA.
5. Department of Public Health Sciences, School of Medicine, University of California, Davis, Davis, CA.