From the *Department of Radiology, Philadelphia VA Medical Center; and †Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA.
Received for publication January 31, 2012; revision accepted March 6, 2012.
Conflicts of interest and sources of funding: none declared.
Reprints: Scott R. Akers, MD, PhD, Department of Radiology, Philadelphia VA Medical Center, 3900 Woodland Ave, Philadelphia, PA 19104. E-mail: Scott.Akers@va.gov.