1. Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
2. Department of Radiology, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
3. Department of Radiology, Vanderbilt University, Nashville, TN 37232, USA
4. Department of Chemistry,Carnegie Mellon University, Pittsburgh, PA 15213, USA
5. Department of Neurosurgery, Geisinger Health System,100 North Academy Avenue,Danville, PA 17821, USA.