title: Introduction of an automated user-independent quantitative volumetric magnetic resonance imaging breast density measurement system using the Dixon sequence: comparison with mammographic breast density assessment.
abstract: OBJECTIVE
  The purposes of this study were to introduce and assess an automated user-independent quantitative volumetric (AUQV) breast density (BD) measurement system on the basis of magnetic resonance imaging (MRI) using the Dixon technique as well as to compare it with qualitative and quantitative mammographic (MG) BD measurements.
  
  
  METHODS
  Forty-three women with normal mammogram results (Breast Imaging Reporting and Data System 1) were included in this institutional review board-approved prospective study. All participants were subjected to BD assessment with MRI using the following sequence with the Dixon technique (echo time/echo time, 6 milliseconds/2.45 milliseconds/2.67 milliseconds; 1-mm isotropic; 3 minutes 38 seconds). To test the reproducibility, a second MRI after patient repositioning was performed. The AUQV magnetic resonance (MR) BD measurement system automatically calculated percentage (%) BD. The qualitative BD assessment was performed using the American College of Radiology Breast Imaging Reporting and Data System BD categories. Quantitative BD was estimated semiautomatically using the thresholding technique Cumulus4. Appropriate statistical tests were used to assess the agreement between the AUQV MR measurements and to compare them with qualitative and quantitative MG BD estimations.
  
  
  RESULTS
  The AUQV MR BD measurements were successfully performed in all 43 women. There was a nearly perfect agreement of AUQV MR BD measurements between the 2 MR examinations for % BD (P < 0.001; intraclass correlation coefficient, 0.998) with no significant differences (P = 0.384). The AUQV MR BD measurements were significantly lower than quantitative and qualitative MG BD assessment (P < 0.001).
  
  
  CONCLUSIONS
  The AUQV MR BD measurement system allows a fully automated, user-independent, robust, reproducible, as well as radiation- and compression-free volumetric quantitative BD assessment through different levels of BD. The AUQV MR BD measurements were significantly lower than the currently used qualitative and quantitative MG-based approaches, implying that the current assessment might overestimate breast density with MG.
authors.affiliation: From the *Division of Molecular and Gender Imaging, †Computational Imaging Research Lab, ‡MR Centre of Excellence, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.
authors.forename: Georg Johannes
authors.initials: GJ
authors.lastname: Wengert
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Helbich
authors.forename: Wolf-Dieter
authors.initials: WD
authors.lastname: Vogl
authors.forename: Pascal
authors.initials: P
authors.lastname: Baltzer
authors.forename: Georg
authors.initials: G
authors.lastname: Langs
authors.forename: Michael
authors.initials: M
authors.lastname: Weber
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bogner
authors.forename: Stephan
authors.initials: S
authors.lastname: Gruber
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
authors.forename: Katja
authors.initials: K
authors.lastname: Pinker
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D001940:Breast / Q000033:anatomy & histology / Q000502:physiology*; D003720:Densitometry / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008327:Mammography / Q000379:methods*; D008875:Middle Aged; D010363:Pattern Recognition, Automated / Q000379:methods; D010865:Pilot Projects; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014584:User-Computer Interface; D055815:Young Adult