1. Department of Radiology, Division of Neuroradiology, Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104.
2. Department of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA.
3. School of Osteopathic Medicine, Rowan University, Stratford, NJ.
4. Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
5. Department of Neurology, Vanderbilt University Medical Center, Nashville, TN.