title: Ultrasound-heated photoacoustic flowmetry.
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.
authors.forename: Lidai
authors.initials: L
authors.lastname: Wang
authors.forename: Junjie
authors.initials: J
authors.lastname: Yao
authors.forename: Konstantin I
authors.initials: KI
authors.lastname: Maslov
authors.forename: Wenxin
authors.initials: W
authors.lastname: Xing
authors.forename: Lihong V
authors.initials: LV
authors.lastname: Wang
mesh_terms: D057086:High-Intensity Focused Ultrasound Ablation / Q000295:instrumentation; D008853:Microscopy; D008955:Models, Cardiovascular; D019047:Phantoms, Imaging; D061088:Photoacoustic Techniques / Q000295:instrumentation / Q000379:methods*; D012212:Rheology / Q000295:instrumentation / Q000379:methods*; D013016:Sound; D013816:Thermodynamics; D014159:Transducers