title: A pilot study of compositional analysis of the breast and estimation of breast mammographic density using three-dimensional T1-weighted magnetic resonance imaging.
abstract: OBJECTIVE
  A method and computer tool to estimate percentage magnetic resonance (MR) imaging (MRI) breast density using three-dimensional T(1)-weighted MRI is introduced, and compared with mammographic percentage density [X-ray mammography (XRM)].
  
  
  METHODS
  Ethical approval and informed consent were obtained. A method to assess MRI breast density as percentage volume occupied by water-containing tissue on three-dimensional T(1)-weighted MR images is described and applied in a pilot study to 138 subjects who were imaged by both MRI and XRM during the Magnetic Resonance Imaging in Breast Screening study. For comparison, percentage mammographic density was measured from matching XRMs as a ratio of dense to total projection areas scored visually using a 21-point score and measured by applying a two-dimensional interactive program (CUMULUS). The MRI and XRM percent methods were compared, including assessment of left-right and interreader consistency.
  
  
  RESULTS
  Percent MRI density correlated strongly (r = 0.78; P < 0.0001) with percent mammographic density estimated using Cumulus. Comparison with visual assessment also showed a strong correlation. The mammographic methods overestimate density compared with MRI volumetric assessment by a factor approaching 2.
  
  
  CONCLUSIONS
  MRI provides direct three-dimensional measurement of the proportion of water-based tissue in the breast. It correlates well with visual and computerized percent mammographic density measurements. This method may have direct application in women having breast cancer screening by breast MRI and may aid in determination of risk.
authors.affiliation: Institute of Cancer Research, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Khazen
authors.forename: Ruth M L
authors.initials: RM
authors.lastname: Warren
authors.forename: Caroline R M
authors.initials: CR
authors.lastname: Boggis
authors.forename: Emilie C
authors.initials: EC
authors.lastname: Bryant
authors.forename: Sadie
authors.initials: S
authors.lastname: Reed
authors.forename: Iqbal
authors.initials: I
authors.lastname: Warsi
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Pointon
authors.forename: Gek E
authors.initials: GE
authors.lastname: Kwan-Lim
authors.forename: Deborah
authors.initials: D
authors.lastname: Thompson
authors.forename: Ros
authors.initials: R
authors.lastname: Eeles
authors.forename: Doug
authors.initials: D
authors.lastname: Easton
authors.forename: D Gareth
authors.initials: DG
authors.lastname: Evans
authors.forename: Martin O
authors.initials: MO
authors.lastname: Leach