1. Department of Radiology, 200 First St SW, Mayo Clinic, Rochester, MN 55905.
2. Aurora West Allis Medical Center, West Allis, WI.
3. Department of General Internal Medicine, Mayo Clinic, Rochester, MN.
4. Department of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN.
5. Department of Health Sciences Research, Mayo Clinic, Jacksonville, FL.