1. From the Departments of Radiology of Mayo Clinic Arizona, 5777 E Mayo Blvd, Phoenix, AZ 85054 (J.A.F., R.E.S., C.E.J., C.D.T., C.L.H.); Mayo Clinic Rochester, Rochester, Minn (J.A.S., M.N., A.T.F.); and Mayo Clinic Florida, Jacksonville, Fla (A.W.B.).