title: Dedicated 3D photoacoustic breast imaging.
abstract: OBJECTIVE
  To report the design and imaging methodology of a photoacoustic scanner dedicated to imaging hemoglobin distribution throughout a human breast.
  
  
  METHODS
  The authors developed a dedicated breast photoacoustic mammography (PAM) system using a spherical detector aperture based on our previous photoacoustic tomography scanner. The system uses 512 detectors with rectilinear scanning. The scan shape is a spiral pattern whose radius varies from 24 to 96 mm, thereby allowing a field of view that accommodates a wide range of breast sizes. The authors measured the contrast-to-noise ratio (CNR) using a target comprised of 1-mm dots printed on clear plastic. Each dot absorption coefficient was approximately the same as a 1-mm thickness of whole blood at 756 nm, the output wavelength of the Alexandrite laser used by this imaging system. The target was immersed in varying depths of an 8% solution of stock Liposyn II-20%, which mimics the attenuation of breast tissue (1.1 cm(-1)). The spatial resolution was measured using a 6 μm-diameter carbon fiber embedded in agar. The breasts of four healthy female volunteers, spanning a range of breast size from a brassiere C cup to a DD cup, were imaged using a 96-mm spiral protocol.
  
  
  RESULTS
  The CNR target was clearly visualized to a depth of 53 mm. Spatial resolution, which was estimated from the full width at half-maximum of a profile across the PAM image of a carbon fiber, was 0.42 mm. In the four human volunteers, the vasculature was well visualized throughout the breast tissue, including to the chest wall.
  
  
  CONCLUSIONS
  CNR, lateral field-of-view and penetration depth of our dedicated PAM scanning system is sufficient to image breasts as large as 1335 mL, which should accommodate up to 90% of the women in the United States.
authors: OptoSonics, Inc., 108 Straight Road, Oriental, North Carolina 28571.
authors: Robert A
authors: RA
authors: Kruger
authors: Cherie M
authors: CM
authors: Kuzmiak
authors: Richard B
authors: RB
authors: Lam
authors: Daniel R
authors: DR
authors: Reinecke
authors: Stephen P
authors: SP
authors: Del Rio
authors: Doreen
authors: D
authors: Steed
mesh_terms: D000162:Acoustics; D000362:Agar / Q000737:chemistry; D001940:Breast / Q000098:blood supply* / Q000473:pathology*; D001943:Breast Neoplasms / Q000098:blood supply / Q000175:diagnosis; D002244:Carbon / Q000737:chemistry; D004867:Equipment Design; D005260:Female; D064368:Healthy Volunteers; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008327:Mammography / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D015898:Tomography Scanners, X-Ray Computed
chemical_list: D006454:Hemoglobins; D002244:Carbon; D000362:Agar