Improving spatial resolution of cavitation dose mapping for high intensity focused ultrasound (HIFU) therapy by combining ultrafast interframe cavitation image and passive acoustic mapping

Non-thermal ablation introduced by high intensity focused ultrasound (HIFU) has been demonstrated for noninvasive ablation of tumors deep within the body that can be challenging to treat surgically. In order to efficiently ablate the tumor and minimize damage to surrounding tissues, a feedback control strategy, including spatiotemporal monitoring of cavitation intensity and location, is required to guide non-thermal ablation. Active cavitation mapping can spatially localize cavitation bubbles, while alternatively, passive cavitation mapping can quantify the intensity of cavitation events, however, there is no technique for simultaneously monitoring both location and intensity with high resolution. To address this challenge, we propose a new cavitation mapping strategy in which localization of cavitation is achieved by filtering ultrafast ultrasound images, and then these images are weighted with cavitation intensity measurements acquired simultaneously by passive cavitation mapping. Results of cavitation imaging experiments in tissue-mimicking phantoms indicate that the proposed approach can be used to spatiotemporally locate the cavitation introduced by HIFU in a phantom channel filled with microbubbles while simultaneously monitoring the cavitation intensity.