Processing methods for photoacoustic Doppler flowmetry with a clinical ultrasound scanner

J Biomed Opt. 2018 Feb;23(2):1-8. doi: 10.1117/1.JBO.23.2.026009.


Photoacoustic flowmetry (PAF) based on time-domain cross correlation of photoacoustic signals is a promising technique for deep tissue measurement of blood flow velocity. Signal processing has previously been developed for single element transducers. Here, the processing methods for acoustic resolution PAF using a clinical ultrasound transducer array are developed and validated using a 64-element transducer array with a -6 dB detection band of 11 to 17 MHz. Measurements were performed on a flow phantom consisting of a tube (580 μm inner diameter) perfused with human blood flowing at physiological speeds ranging from 3 to 25 mm / s. The processing pipeline comprised: image reconstruction, filtering, displacement detection, and masking. High-pass filtering and background subtraction were found to be key preprocessing steps to enable accurate flow velocity estimates, which were calculated using a cross-correlation based method. In addition, the regions of interest in the calculated velocity maps were defined using a masking approach based on the amplitude of the cross-correlation functions. These developments enabled blood flow measurements using a transducer array, bringing PAF one step closer to clinical applicability.

Keywords: blood flow; cross correlation; flowmetry; image processing; masking; photoacoustic Doppler effect; transducer array.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Flow Velocity
  • Equipment Design
  • Humans
  • Laser-Doppler Flowmetry / instrumentation
  • Laser-Doppler Flowmetry / methods*
  • Phantoms, Imaging
  • Photoacoustic Techniques / instrumentation
  • Photoacoustic Techniques / methods*
  • Signal Processing, Computer-Assisted*
  • Signal-To-Noise Ratio
  • Transducers
  • Ultrasonography / instrumentation*