From the Department of Radiology (J.H.B., A.N.K.), William J. von Liebig Center for Transplantation and Clinical Regeneration (A.S.R.), and Departments of Radiation Oncology (L.C.T.), Quality Management (M.A.T.), and Ortho/Neuro and Spine (A.R.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905.