Ultrasound-heated photoacoustic flowmetry

ArticleinJournal of Biomedical Optics 18(11):117003 · November 2013with6 Reads
Impact Factor: 2.86 · DOI: 10.1117/1.JBO.18.11.117003 · Source: PubMed

    Abstract

    We report the development of photoacoustic flowmetry assisted by high-intensity focused ultrasound (HIFU). This novel method employs HIFU to generate a heating impulse in the flow medium, followed by photoacoustic monitoring of the thermal decay process. Photoacoustic flowmetry in a continuous medium remains a challenge in the optical diffusive regime. Here, both the HIFU heating and photoacoustic detection can focus at depths beyond the optical diffusion limit (∼1 mm in soft tissue). This method can be applied to a continuous medium, i.e., a medium without discrete scatterers or absorbers resolvable by photoacoustic imaging. Flow speeds up to 41 mm·s-1 have been experimentally measured in a blood phantom covered by 1.5-mm-thick tissue.