1. From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh).