1. Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.
2. Present affiliation: Department of Radiology, Shiga University of Medical Science, Shiga, Japan.
3. Present affiliation: Department of Radiology, Medical College of Wisconsin, Milwaukee, WI.
4. Present affiliation: Department of Radiology, Kanazawa University Graduate School of Medicine, Kanazawa, Japan.
5. Department of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN.
6. Siemens Healthcare GmbH, Erlangen, Germany.
7. Siemens Medical Solutions USA, Malvern, PA.
8. Department of Quantitative Health Sciences, Mayo Clinic, Jacksonville, FL.