title: 1995 AUR Memorial Award. Gamma knife irradiation-induced changes in the normal rat brain studied with 1H magnetic resonance spectroscopy and imaging.
abstract: OBJECTIVE
  The pathogenesis of brain injury following radiosurgery is poorly understood. To better elucidate the relationship between blood-brain barrier disruption and metabolic derangements, we used magnetic resonance (MR) imaging and 1H MR spectroscopy to detect early changes from focused single-fraction, high-dose irradiation injury in rat brains.
  
  
  METHODS
  Using the Leksell gamma knife, we irradiated the frontoparietal cortex of 11 male Wistar rats with a single dose of 120 Gy. Four weeks later, we sequentially performed water-suppressed 1H MR spectroscopy and gadopentetate dimeglumine-enhanced T1-weighted MR imaging. Metabolic maps were created of n-acetylaspartate (NAA), creatine and choline (Cr/Cho), and lactate from the MR spectroscopy data set. Detection of irradiation injury among the tested modalities was assessed by receiver operating characteristic analysis and by quantitative signal intensity changes. Pathologic confirmation of irradiation damage was obtained in all rats.
  
  
  RESULTS
  Gadopentetate dimeglumine-enhanced T1-weighted MR imaging was the only imaging modality that detected statistically significant signal intensity changes (p < .05). No reproducible changes in the metabolites of interest could be detected by 1H MR spectroscopy.
  
  
  CONCLUSIONS
  In our animal model, blood-brain barrier disruption was a reproducible, integral finding of single-fraction, high-dose irradiation injury. No reproducible metabolic derangements of ischemia or necrosis were detected by 1H MR spectroscopy, possibly because of dose-latency effects or sensitivity issues.
authors.affiliation: Department of Radiology, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Omary
authors.forename: S S
authors.initials: SS
authors.lastname: Berr
authors.forename: T
authors.initials: T
authors.lastname: Kamiryo
authors.forename: G
authors.initials: G
authors.lastname: Lanzino
authors.forename: N F
authors.initials: NF
authors.lastname: Kassell
authors.forename: K S
authors.initials: KS
authors.lastname: Lee
authors.forename: M B
authors.initials: MB
authors.lastname: Lopes
authors.forename: B J
authors.initials: BJ
authors.lastname: Hillman
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000528:radiation effects; D001921:Brain / Q000473:pathology* / Q000528:radiation effects* / Q000601:surgery; D003287:Contrast Media; D019786:Gadolinium DTPA; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D016634:Radiosurgery / Q000379:methods; D051381:Rats; D017208:Rats, Wistar
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA