RT Journal Article SR Electronic T1 CT Appearance of the retroisthmic cleft. JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology SP 835 OP 836 VO 5 IS 6 A1 J G Johansen A1 S Hemminghytt A1 V M Haughton YR 1984 UL http://www.ajnr.org/content/5/6/835.abstract AB