Weighting the Passive Acoustic Mapping Technique With the Phase Coherence Factor for Passive Ultrasound Imaging of Ultrasound-Induced Cavitation

Ultrasound (US) cavitationis currently being explored for low-invasive therapy techniques applied to a wide panel of pathologies. Because of the random behavior of cavitation, a real-time spatial monitoring system may be required. For this purpose, the US passive imaging techniques have been recently investigated. In particular, the passive acoustic mapping (PAM) beamformingmethod enables the reconstruction of cavitationactivity maps by beamformingacoustic signals passively recorded by an array transducer. In this paper, an optimized version of PAM, PAM weighted with a phase coherence factor (PAM-PCF), is considered. A general validation process is developed including simulations on a point source and experiments on a wire. Furthermore, using a focused regulated US-induced cavitationgenerator, reproducible cavitationexperiments are conducted in water and in agar gel. The spatial behavior of a bubble cavitationcloud is determined using the PAM-PCF beamformingmethod to localize the focal cavitationpoint in two perpendicular imaging planes.