title: Ultrasound Tomography Evaluation of Breast Density: A Comparison With Noncontrast Magnetic Resonance Imaging.
abstract: Ultrasound tomography (UST) is an emerging whole-breast 3-dimensional imaging technique that obtains quantitative tomograms of speed of sound of the entire breast. The imaged parameter is the speed of sound which is used as a surrogate measure of density at each voxel and holds promise as a method to evaluate breast density without ionizing radiation. This study evaluated the technique of UST and compared whole-breast volume averaged speed of sound (VASS) with MR percent water content from noncontrast magnetic resonance imaging (MRI).
  
  
  
  Forty-three healthy female volunteers (median age, 40 years; range, 29-59 years) underwent bilateral breast UST and MRI using a 2-point Dixon technique. Reproducibility of VASS was evaluated using Bland-Altman analysis. Volume averaged speed of sound and MR percent water were evaluated and compared using Pearson correlation coefficient.
  
  
  
  The mean ± standard deviation VASS measurement was 1463 ± 29 m s (range, 1434-1542 m s). There was high similarity between right (1464 ± 30 m s) and left (1462 ± 28 m s) breasts (P = 0.113) (intraclass correlation coefficient, 0.98). Mean MR percent water content was 35.7% ± 14.7% (range, 13.2%-75.3%), with small but significant differences between right and left breasts (36.3% ± 14.9% and 35.1% ± 14.7%, respectively; P = 0.004). There was a very strong correlation between VASS and MR percent water density (r = 0.96, P < 0.0001).
  
  
  
  Ultrasound tomography holds promise as a reliable and reproducible 3-dimensional technique to provide a surrogate measure of breast density and correlates strongly with MR percent water content.
authors.affiliation: From the *Cancer Research UK Cancer Imaging Centre; †Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust; ‡Royal Marsden NHS Foundation Trust; §Division of Genetics and Epidemiology, Institute of Cancer Research, London, United Kingdom; ∥Delphinus Medical Technologies, Karmanos Cancer Institute, Wayne State University, Detroit, MI; and ¶Division of Genetics and Epidemiology, and Division of Breast Cancer Research Institute of Cancer Research, London, United Kingdom.
authors.forename: Elizabeth A M
authors.initials: EAM
authors.lastname: OʼFlynn
authors.forename: Jeremie
authors.initials: J
authors.lastname: Fromageau
authors.forename: Araminta E
authors.initials: AE
authors.lastname: Ledger
authors.forename: Alessandro
authors.initials: A
authors.lastname: Messa
authors.forename: Ashley
authors.initials: A
authors.lastname: DʼAquino
authors.forename: Minouk J
authors.initials: MJ
authors.lastname: Schoemaker
authors.forename: Maria
authors.initials: M
authors.lastname: Schmidt
authors.forename: Neb
authors.initials: N
authors.lastname: Duric
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Swerdlow
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Bamber
mesh_terms: D000328:Adult; D001940:Breast / Q000000981:diagnostic imaging*; D000071060:Breast Density / Q000502:physiology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008327:Mammography / Q000379:methods; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D014054:Tomography / Q000379:methods; D016217:Ultrasonography, Mammary / Q000379:methods*