RT Journal Article SR Electronic T1 MR Imaging of Nonmalignant Polyps and Masses of the Nasopharynx and Sphenoid Sinus after Radiotherapy for Nasopharyngeal Carcinoma JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology DO 10.3174/ajnr.A1043 A1 A.D. King A1 A.T. Ahuja A1 S.-F. Leung A1 J. Abrigo A1 J.K.T. Wong A1 W.S. Poon A1 K.S. Woo A1 H.S. Chan A1 G.M.K. Tse YR 2008 UL http://www.ajnr.org/content/early/2008/05/08/ajnr.A1043.abstract AB