title: New contrast media designed for x-ray energy subtraction imaging in digital mammography.
abstract: OBJECTIVE
  In contrast-enhanced dual-energy subtraction imaging 2 images acquired postcontrast media administration at different energies are subtracted to highlight structures hidden in the absence of contrast media. X-ray spectra of the newly developed digital full-field mammography units (GE Senographe 2000 D) are dominated by the emission lines of the Mo or Rh anodes. The K-edge of Zirconium (Zr) is flanked by these 2 emission lines. Thus, the attenuation of Zr should experience a pronounced change of attenuation in parallel with a change of anodes. Under clinically relevant conditions, the contrasting behavior of Zr should be compared with that of other elements having K-edge energies outside the window spanned by the 2 anode emission lines.
  
  
  METHODS
  Solutions containing the contrasting elements Br, Y, Zr, I, and Gd were investigated for dual-energy subtraction in digital mammography with the 2 anode/filter settings (Mo/Mo and Rh/Rh). These solutions were investigated in phantom studies in the energy range conventionally used in mammography. Additionally, the contrasting behavior of Zr and I was compared in an in vivo study in rats.
  
  
  RESULTS
  The sweeping over the K-edge by alternating between the Mo and Rh anodes increases the detection of Zr in energy subtraction imaging at constant high voltage. This procedure does not lead to sufficient contrast enhancement for iodine-based contrast media which become detectable by increasing the high voltage to 40-49 kV.
  
  
  CONCLUSIONS
  The instrumental and physical data outlined predestine Zr as contrasting element with a high potential for energy subtraction imaging in digital mammography in the energy range conventionally applied.
authors.affiliation: Schering AG, Research Laboratories Berlin, Müllerstrasse 178, 13342 Berlin, Germany. ruediger.lawaczeck@schering.de
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Lawaczeck
authors.forename: Felix
authors.initials: F
authors.lastname: Diekmann
authors.forename: Susanne
authors.initials: S
authors.lastname: Diekmann
authors.forename: Bernd
authors.initials: B
authors.lastname: Hamm
authors.forename: Ulrich
authors.initials: U
authors.lastname: Bick
authors.forename: Wolf-Rüdiger
authors.initials: WR
authors.lastname: Press
authors.forename: Heiko
authors.initials: H
authors.lastname: Schirmer
authors.forename: Katja
authors.initials: K
authors.lastname: Schön
authors.forename: Hanns-Joachim
authors.initials: HJ
authors.lastname: Weinmann
mesh_terms: D000818:Animals; D003287:Contrast Media; D011856:Radiographic Image Enhancement; D051381:Rats; D013382:Subtraction Technique; D015040:Zirconium
chemical_list: D003287:Contrast Media; D015040:Zirconium