1. From the Department of Radiology (R.P.M., J.G.F., A.F., S.L., T.J.V., M.L.W., C.H.M.) and Department of Biomedical Statistics and Informatics (F.T.E.), Mayo Clinic, 200 1st St SW, Rochester, MN 55905; Siemens Healthcare–Imaging and Therapy Systems, Malvern, Pa (A.F.H.); Siemens Healthcare, Forchheim, Germany (R.G.); and CAMP, Technical University of Munich, Garching (Munich), Germany (R.G.).