title: A theoretical investigation of photoacoustic contrast agents.
abstract: Photoacoustic imaging offers significant potential as a biomedical imaging modality. For some applications, however, there is a need for contrast enhancement. In this paper, a theoretical comparison is presented of the efficacy of three different designs for photoacoustic contrast agents (PACAs), specifically, a droplet of dye, a bubble filled with gas coated by a dye loaded shell, and a droplet of volatile dye. For each case, the governing equations describing the dynamics of a single PACA in a homogenous incompressible fluid are derived. The coupled sets of equations describing the bubble oscillation and resulting radiated pressure, the photo-acoustic energy equation, and the equation of state are then solved numerically. The numerical results predict a stronger radiated acoustic signal for the same optical source energy density in the case of the volatile dye droplet by a factor of up to two orders of magnitude compared with the other two types of agent.
authors.affiliation: Department of Mechanical Engineering, University College London, London, WC1E 7JE, United Kingdom. kamyar.firouzi.09@ucl.ac.uk
authors.forename: K
authors.initials: K
authors.lastname: Firouzi
authors.forename: E
authors.initials: E
authors.lastname: Stride
authors.forename: N
authors.initials: N
authors.lastname: Saffari
mesh_terms: D004396:Coloring Agents; D003287:Contrast Media; D003952:Diagnostic Imaging / Q000379:methods*; D006801:Humans; D057446:Hydrodynamics; D007089:Image Enhancement / Q000379:methods*; D045423:Microbubbles; D008962:Models, Theoretical; D009369:Neoplasms / Q000175:diagnosis*; D061088:Photoacoustic Techniques / Q000379:methods*
chemical_list: D004396:Coloring Agents; D003287:Contrast Media