1 Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, 410008, China.
2 Department of Neurosurgery, Yale School of Medicine, New Haven, CT, 06520, USA.
3 Department of Radiology and Biomedical Imaging, MRRC, Yale School of Medicine, The Anlyan Center N137, PO Box 208043, New Haven, CT, 06520-8043, USA. robert.fulbright@yale.edu.