1. University of Minnesota Medical School, University of Minnesota, Minneapolis, Minnesota, U.S.A.;
2. Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, Minnesota, U.S.A.;
3. Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, U.S.A;
4. Department of Neurology, University of Minnesota, Minneapolis, Minnesota, U.S.A.; and