1 Department of Radiology and Biomedical Imaging, Yale University, Box 208042, Tompkins East 2, 333 Cedar Street, New Haven, CT 06520-8042, USA. Electronic address: ajay.malhotra@yale.edu.
2 Department of Diagnostic Radiology and Nuclear Medicine, Neurosurgery, and Neurology, University of Maryland, College Park, MD 20742, USA. Electronic address: dgandhi@umm.edu.