title: Preface.
authors.affiliation: Department of Radiology, UPMC Shadyside Hospital, 5230 Centre Avenue, Pittsburgh, PA 15232-1381, USA. Electronic address: blodtm@upmc.edu.
authors.forename: Todd M
authors.initials: TM
authors.lastname: Blodgett
authors.affiliation: Division of Neuroradiology, Department of Diagnostic Radiology, Allegheny General Hospital, 320 East North Avenue, Pittsburgh, PA 15212, USA. Electronic address: mfukui@wpahs.org.
authors.forename: Melanie B
authors.initials: MB
authors.lastname: Fukui