1. From the Department of Neurosurgery (D.F.K., H.J.C.), Department of Radiology, Mayo Clinic, Rochester, MN (W.B., G.L., H.J.C., D.F.K.); Center for Science of Healthcare Delivery, Mayo Clinic, Rochester, MN (M.H.M.); and Department of Neurosurgery, Mayo Clinic, Rochester, MN (G.L.).