Simultaneous spatial and spectral characterization of flow using Photoacoustic Doppler in a turbid media

Spatial and spectral analysis of flow based on the Photoacoustic Doppler (PAD) effect with tone-burst excitation and time-gated spectral analysis is demonstrated using a model emulating a blood-vessel in a turbid medium. The proposed method mimics pulsed Doppler ultrasound and enables simultaneous measurement of axial position and flow with full characterization of the Doppler spectrum. A wide range of flow velocities in both infusion and withdrawal modes were generated in the phantom. Two-dimensional maps of velocity vs. axial position along with comparison of the estimated velocity to the theoretical prediction demonstrated the feasibility of this method for flow characterization.