Figure 3.

Three-dimensional quantification of stationary contrast agents using the sensitive particle acoustic quantification technology (SPAQ ⁶). Drawings illustrate the principle of SPAQ. If an ultrasound transducer moves over an object (here: Agar-phantom containing microbubbles), the ultrasound beam destroys the microbubbles within the acoustic field. (A) Low frame-to-frame displacement between the single ultrasound pulses results in a high SPAQ resolution providing good discrimination of single signals. (B and C) Higher displacements (= larger SPAQ-slices) produce lower SPAQ resolutions finally resulting in an overlay of single SAE signals. “Proof-of-principle” in an agar phantom filled with microbubbles. Adapted from reference 16 with permission.