Fig. 7.

Speckle analysis techniques applied to experimental phantoms. Nagakami fits to the PA signal envelope for the phantoms imaged at (a) 5 MHz, (b) 40 MHz, (c) 200 MHz and (d) 400 MHz. The calculated SNR and Generalized Gamma $m$ parameter are provided on top of each figure. For the VevoLAZR 40 MHz probe, the three analysis techniques presented in this paper, namely (e) Envelope statistics, (f) Radiofrequency spectroscopy and (g) Cepstral analysis were applied to phantoms consisting of 3 and 15 μm polystyrene beads. The arrow denotes a peak forming for the 15 μm absorber phantom.