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Published November 2013 | Published
Journal Article Open

Ultrasound-heated photoacoustic flowmetry


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.

Additional Information

© 2013 SPIE. Paper 130131RR received Mar. 8, 2013; revised manuscript received Oct. 6, 2013; accepted for publication Oct. 10, 2013; published online Nov. 5, 2013. The authors appreciate Professor Sandra Matteucci's help with editing the manuscript. This work was sponsored by National Institute of Health (NIH) grants R01 EB000712, R01 EB008085, R01 CA134539, U54 CA136398, R01 CA157277, R01 CA159959, and DP1 EB016986 (NIH Director's Pioneer Award). Lihong Wang has a financial interest in Endra Inc., and Microphotoacoustics Inc., which did not support this work. Konstantin Maslov has a financial interest in Microphotoacoustics Inc., which did not support this work.

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