title: Radiation injury to the normal brain measured by 3D-echo-planar spectroscopic imaging and diffusion tensor imaging: initial experience.
abstract: OBJECTIVE
  Whole brain radiation therapy (WBRT) may cause cognitive and neuropsychological impairment and hence objective assessment of adverse effects of radiation may be valuable to plan therapy. The purpose of our study was to determine the potential of echo planar spectroscopic imaging (EPSI) and diffusion tensor imaging (DTI) in detecting subacute radiation induced injury to the normal brain.
  
  
  METHODS
  Four patients with brain metastases and three patients with lung cancer underwent cranial irradiation. These patients were subjected to 3D-EPSI and DTI at two time points (pre-radiation, and 1 month post-irradiation). Parametric maps of N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), mean diffusivity (MD), and fractional anisotropy (FA) were generated and co-registered to post-contrast T1-weighted images. Normal appearing gray-matter and white-matter regions were compared between the two time points to assess sub-acute effects of radiation using independent sample t-tests.
  
  
  RESULTS
  Significantly increased MD (P = .02), Cho/Cr (P = .02) and a trend towards a decrease in NAA/Cr (P = .06) was observed from the hippocampus. Significant decrease in FA (P = .02) from the centrum-semiovale and a significant increase in MD (P = .04) and Cho/Cr (P = .02) from genu of corpus-callosum was also observed.
  
  
  CONCLUSIONS
  Our preliminary findings suggest that 3D-EPSI and DTI may provide quantitative measures of radiation induced injury to the normal brain.
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Chawla
authors.forename: Sumei
authors.initials: S
authors.lastname: Wang
authors.forename: Sungheon
authors.initials: S
authors.lastname: Kim
authors.forename: Sulaiman
authors.initials: S
authors.lastname: Sheriff
authors.forename: Peter
authors.initials: P
authors.lastname: Lee
authors.forename: Ramesh
authors.initials: R
authors.lastname: Rengan
authors.forename: Alexander
authors.initials: A
authors.lastname: Lin
authors.forename: Elias
authors.initials: E
authors.lastname: Melhem
authors.forename: Andrew
authors.initials: A
authors.lastname: Maudsley
authors.forename: Harish
authors.initials: H
authors.lastname: Poptani
mesh_terms: D000368:Aged; D001930:Brain Injuries / Q000175:diagnosis* / Q000209:etiology; D016371:Cranial Irradiation / Q000009:adverse effects*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011832:Radiation Injuries / Q000175:diagnosis* / Q000209:etiology; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
keywords: Radiation injury; diffusion tensor imaging; echo-planar spectroscopic imaging; prophylactic cranial irradiation; whole brain radiation therapy