title: Predicting outcome of patients with high-grade gliomas after radiotherapy using quantitative analysis of T1-weighted magnetic resonance imaging.
abstract: OBJECTIVE
  The aim of this study was to test the hypothesis that measuring quantitative changes in signal intensity early after radiotherapy (RT) in the contrast-enhancing tumor rim and nonenhancing core may be a noninvasive marker of early treatment response in patients with high-grade gliomas.
  
  
  METHODS
  Twenty patients with high-grade gliomas had magnetic resonance imaging (MRI) performed 1 week before RT, during Weeks 1 and 3 of RT, and every 1 to 3 months after RT as part of a clinical prospective study. Regions of interest (ROI) including contrast-enhancing rim, and the nonenhancing core were defined automatically based on a calculated image of post- to precontrast T1-weighted MRI. Pretreatment T1-weighted MRI signal intensity changes were compared with Weeks 1 and 3 RT and 1 and 3 months post-RT MRI. Clinical and MRI parameters were then tested for prediction of overall survival.
  
  
  RESULTS
  Regional T1-weighted signal intensity changes in both the contrast-enhancing rim and the nonenhancing core were observed in all patients during Week 1 and Week 3 of RT. Imaging parameters including signal intensity change within the nonenhancing core after Weeks 1 to 2 RT (p = 0.004), Weeks 3 to 4 RT (p = 0.002) and 1 month after completion of RT (p = 0.002) were predictive of overall survival. Using multivariate analysis including RTOG recursive partitioning analysis (RPA) and signal intensity change, only the signal intensity change in the nonenhancing core at 1 month after RT (p = 0.01) retained significance.
  
  
  CONCLUSIONS
  Quantitative measurements of T1-weighted MRI signal intensity changes in the nonenhancing tumor core (using ratios of pre-post values) may provide valuable information regarding early response during treatment and improve our ability to predict posttreatment outcome.
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA. ctsien@umich.edu
authors.forename: Christina
authors.initials: C
authors.lastname: Tsien
authors.forename: Diana
authors.initials: D
authors.lastname: Gomez-Hassan
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Chenevert
authors.forename: Julia
authors.initials: J
authors.lastname: Lee
authors.forename: Theodore
authors.initials: T
authors.lastname: Lawrence
authors.forename: Randall K
authors.initials: RK
authors.lastname: Ten Haken
authors.forename: Larry R
authors.initials: LR
authors.lastname: Junck
authors.forename: Brian
authors.initials: B
authors.lastname: Ross
authors.forename: Yue
authors.initials: Y
authors.lastname: Cao
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D005910:Glioma / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D020266:Radiotherapy, Conformal; D016896:Treatment Outcome