1. Section of Neuroradiology, Santa Casa de Misericórdia de São Paulo, São Paulo SP, Brazil.
2. Section of Radiology, Federal University of Espírito Santo, Vitória ES, Brazil.
3. Division of Neurosurgery, Santa Casa de Misericórdia de São Paulo, São Paulo SP, Brazil.
4. Division of Neuroradiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.