1 The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.
2 Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas.
3 University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Boulevard, Dallas, TX 75390. Electronic address: steven.rowe@utsouthwestern.edu.