title: Brain tumors: full- and half-dose contrast-enhanced MR imaging at 3.0 T compared with 1.5 T--Initial Experience.
abstract: OBJECTIVE
  To prospectively and intraindividually compare the effect of magnetic resonance (MR) imaging at a higher magnetic field strength (3.0 T) on contrast-to-noise ratio (CNR) at different doses of a T1-shortening contrast agent in patients with contrast-enhancing brain lesions, with 1.5-T MR imaging as a reference standard.
  
  
  METHODS
  Institutional review board approval and informed consent were obtained for all patient and volunteer studies. Twelve patients (six women, six men; mean age, 58 years; range, 29-76 years) with 12 enhancing brain lesions (11 patients with primary brain tumors and one with a solitary cerebral metastasis) underwent contrast material-enhanced MR imaging three times, on three separate days: once at 1.5 T with a full dose of 0.10 mmol/kg gadopentetate dimeglumine, once at 3.0 T with a full dose, and once at 3.0 T with half that dose, 0.05 mmol/kg. The same contrast-enhanced T1-weighted spin-echo images (repetition time msec/echo time msec, 500/12; section thickness, 5 mm; matrix, 256 x 205) were obtained at both 3.0 T and 1.5 T after prior optimization of parameters at 3.0 T. The number and conspicuity of enhancing brain lesions were assessed with blinded clinical image reading. Signal-to-noise ratio and CNR were determined with region of interest analysis of enhancing lesions and normal contralateral white matter. For 3.0 T with half the standard dose and with the full dose, CNR of lesions was intraindividually compared with CNR at 1.5 T with the full dose by using the Wilcoxon matched-pairs signed rank test.
  
  
  RESULTS
  At 3.0 T and full dose, CNR was 2.8-fold higher than that at 1.5 T and full dose (P < .001). At the same time, higher lesion conspicuity at clinical image reading was observed. With only half the standard dose, MR imaging at 3.0 T still yielded higher CNR (1.3-fold higher) than that with full dose at 1.5 T (P < .01).
  
  
  CONCLUSIONS
  With the same amount of contrast agent, MR imaging at 3.0 T offered a significantly higher CNR of enhancing cerebral lesions, compared with that at 1.5 T; even with the dose reduced by half, CNR was still higher at 3.0 T.
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn, Germany. Carsten.Krautmacher@ukb.uni-bonn.de
authors.forename: Carsten
authors.initials: C
authors.lastname: Krautmacher
authors.forename: Winfried A
authors.initials: WA
authors.lastname: Willinek
authors.forename: Henriette J
authors.initials: HJ
authors.lastname: Tschampa
authors.forename: Mark
authors.initials: M
authors.lastname: Born
authors.forename: Frank
authors.initials: F
authors.lastname: Träber
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gieseke
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Textor
authors.forename: Hans H
authors.initials: HH
authors.lastname: Schild
authors.forename: Christiane K
authors.initials: CK
authors.lastname: Kuhl
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000175:diagnosis*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA