title: Effect of contrast dose and field strength in the magnetic resonance detection of brain metastases.
abstract: OBJECTIVE
  To compare the diagnostic efficacy of a standard and cumulative triple dose of magnetic resonance (MR) imaging contrast agent in the evaluation of brain metastases using a high-field 3.0 T MR unit versus a standard field 1.5 T MR unit.
  
  
  METHODS
  Twenty-two patients with suspected brain metastases were examined at both field strengths using identical postcontrast coronal 3D gradient echo with magnetization preparation, which was adjusted separately for each field strength. In both groups initially, iv injection of 0.1 mmol/kg body weight gadolinium chelate (gadodiamide) and thereafter, 0.2 mmol/kg body weight gadodiamide were administered. Subjective assessment of the images was performed independently by 3 neuroradiologists. Objective measurement of signal-to-noise and contrast-to-noise ratios was obtained.
  
  
  RESULTS
  The subjective assessment of cumulative triple-dose 3.0 T images obtained the best results compared with other sequences, detecting 84 metastases, followed by 1.5 T cumulative triple-dose enhanced images with 81 brain metastases. The objective assessment confirmed those results, showing significantly higher signal-to-noise and contrast-to-noise ratios with 3.0 T than with 1.5 T.
  
  
  CONCLUSIONS
  Cumulative triple-dose images of both field strengths were superior to standard field strengths. However, administration of gadodiamide contrast agent produces higher contrast between tumor and normal brain on 3.0 T than on 1.5 T, resulting in better detection of brain metastases and leptomeningeal involvement.
authors.affiliation: Department of Radiology, University of Vienna, A-1090 Vienna, Austria. ahmed.ba-ssalamah@univie.ac.at
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ba-Ssalamah
authors.forename: Iris M
authors.initials: IM
authors.lastname: Nöbauer-Huhmann
authors.forename: Katja
authors.initials: K
authors.lastname: Pinker
authors.forename: Nadja
authors.initials: N
authors.lastname: Schibany
authors.forename: Rupert
authors.initials: R
authors.lastname: Prokesch
authors.forename: Sheida
authors.initials: S
authors.lastname: Mehrain
authors.forename: Vladimir
authors.initials: V
authors.lastname: Mlynárik
authors.forename: Amura
authors.initials: A
authors.lastname: Fog
authors.forename: Karl
authors.initials: K
authors.lastname: Heimberger
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
mesh_terms: D000368:Aged; D001932:Brain Neoplasms / Q000556:secondary*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA