RT Journal Article SR Electronic T1 Inter- and Intraobserver Agreement in CT Characterization of Nonaneurysmal Perimesencephalic Subarachnoid Hemorrhage JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology DO 10.3174/ajnr.A1988 A1 W. Brinjikji A1 D.F. Kallmes A1 J.B. White A1 G. Lanzino A1 J.M. Morris A1 H.J Cloft YR 2010 UL http://www.ajnr.org/content/early/2010/01/14/ajnr.A1988.abstract AB