1 Department of Neuroradiology, Neurocenter of Southern Switzerland, Lugano, Switzerland; Department of Neuroradiology, Inselspital Bern, University of Bern, Bern, Switzerland.
2 Department of Neurosurgery, Neurocenter of Southern Switzerland, Lugano, Switzerland.
3 Department of Neuroradiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.