1. From the Departments of Radiology (A.C., S.W., G.S.K., A.O.) and Pathology (A.J.G., T.A.), University of Chicago, 5841 S Maryland Ave, Chicago, IL 60637; Faculty of Health Sciences, University of Sydney, Sydney, Australia (R.M.B.); and Philips Research North America, Cambridge, Mass (A.D.).