title: Late radiation injury to the temporal lobes: morphologic evaluation at MR imaging.
abstract: OBJECTIVE
  To study the morphologic characteristics of late radiation injury to the temporal lobes of the brain on magnetic resonance (MR) images.
  
  
  METHODS
  This was a prospective study involving 34 patients (age range, 37-72 years) with known radiation injury to the temporal lobes from radiation therapy administered 2-10 years previously for nasopharyngeal carcinoma MR imaging was performed with T2-weighted gradient- and spin-echo, gradient-recalled echo, T1-weighted spin-echo, fluid-attenuated inversion-recovery, and T1-weighted postcontrast spin-echo sequences.
  
  
  RESULTS
  Radiation injury was present in 57 of the 68 temporal lobes. The white matter lesions in radiation-induced injury were predominantly hyperintense on T2-weighted images, but in 37 (65%) of the 57 lobes, foci with heterogeneous signal intensity consistent with necrosis were detected. In the 57 involved lobes, gray matter lesions were detected in 50 (88%); blood-brain barrier disruption based on parenchymal contrast enhancement, in 51 (89%); and hemosiderin deposits, in 30 (53%). There was a significant correlation between white matter necrosis, gray matter lesions, and blood-brain barrier disruption, all of which were located mainly in the inferior temporal lobes that received the highest radiation dose.
  
  
  CONCLUSIONS
  The lesion components of radiation-induced injury to the temporal lobes at MR imaging were more varied than have been previously described. In addition to the classic white matter lesions, gray matter lesions, blood-brain barrier disruption, and hemosiderin deposition also were frequently seen.
authors.affiliation: Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, People's Republic of China. yl190chan@cuhk.edu.hk
authors.forename: Y L
authors.initials: YL
authors.lastname: Chan
authors.forename: S F
authors.initials: SF
authors.lastname: Leung
authors.forename: A D
authors.initials: AD
authors.lastname: King
authors.forename: P H
authors.initials: PH
authors.lastname: Choi
authors.forename: C
authors.initials: C
authors.lastname: Metreweli
mesh_terms: D000328:Adult; D000368:Aged; D001812:Blood-Brain Barrier / Q000528:radiation effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000175:diagnosis*; D013702:Temporal Lobe / Q000473:pathology / Q000528:radiation effects*