title: Dynamic T1 estimation of brain tumors using double-echo dynamic MR imaging.
abstract: OBJECTIVE
  To assess the clinical utility of a new method for real-time estimation of T1 during the first pass of contrast agent by using this method to examine brain tumors.
  
  
  METHODS
  The multi-phase spoiled gradient-echo pulse sequence using the double-echo magnetic resonance (MR) technique was modified. In the first half of the pulse sequence, the flip angle was varied systematically. Then, static T1 values were calculated using differences in MR signal intensities between different flip angles. In the latter half of this sequence, changes in absolute T1 were calculated using differences in signal intensities before and after injection of contrast agent. The double-echo MR data were used to minimize the T2* effect. Five cases of neurinoma and seven cases of meningioma were examined. Changes in T1 during the first pass of contrast agent were compared between neurinoma and meningioma.
  
  
  RESULTS
  Changes in absolute T1 were clearly demonstrated on the parametric map. Although the changes in absolute T1 during the first pass of contrast agent did not allow differentiation between the two types of tumors, the mean gradient after the first pass was statistically higher for neurinoma than for meningioma (P < 0.05; meningioma, 0.011 +/- 0.012 second(-1)/second; neurinoma, 0.034 +/- 0.020 second(-1)/second).
  
  
  CONCLUSIONS
  The present method appears to be useful for estimation of dynamic T1 changes in brain tumors in clinical settings.
authors.affiliation: Radiological Center, Fukui Medical University Hospital, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ishimori
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Kimura
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Uematsu
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Matsuda
authors.forename: Harumi
authors.initials: H
authors.lastname: Itoh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000175:diagnosis*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008579:Meningioma / Q000175:diagnosis*; D008875:Middle Aged; D009442:Neurilemmoma / Q000175:diagnosis*
chemical_list: D003287:Contrast Media