title: On the speckle-free nature of photoacoustic tomography.
abstract: OBJECTIVE
  A long-standing conundrum is why photoacoustic tomography (PAT) possesses the unique ability to produce images devoid of speckle artifacts while all other coherent imaging technologies do not.
  
  
  METHODS
  In this paper, we explain the inherent mechanism that suppresses speckle in PAT, and the analysis was validated by simulations based on an experimental PAT system.
  
  
  RESULTS
  We found that the speckle-free feature of PAT results directly from the optical absorption contrast.
  
  
  CONCLUSIONS
  All optical absorbers expand on laser excitation, and therefore all initial photoacoustic pressure rises are positive, which engenders strong correlations among the photoacoustic waves from the absorbers. As a result, prominent boundaries always build up in photoacoustic images and suppress the interior speckle.
authors.affiliation: Department of Biomedical Engineering, Optical Imaging Laboratory, Washington University, 1 Brookings Drive, Saint Louis, Missouri 63130, USA.
authors.forename: Zijian
authors.initials: Z
authors.lastname: Guo
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Lihong V
authors.initials: LV
authors.lastname: Wang
mesh_terms: D000162:Acoustics; D000465:Algorithms; D016477:Artifacts; D003198:Computer Simulation; D008027:Light; D055095:Optics and Photonics; D019047:Phantoms, Imaging; D014054:Tomography / Q000379:methods*; D014465:Ultrasonics