Basic study on a filtering method for selectively extracting cavitation bubble region in ultrasound imaging by triplet pulse sequence

Abstract

In the high-intensity focused ultrasound treatment enhanced by cavitation bubbles, monitoring cavitation bubbles is important to ensure the safety and efficacy of the treatment. In previous studies, a triplet pulse sequence (3P) was proposed to extract nonlinear echoes from bubbles. However, it was difficult to distinguish between the bubble component and the component from strong scatterers. In this study, in addition to 3P method, a filtering method to effectively extract cavitation bubble regions was proposed, and its effectiveness was experimentally examined. The proposed method extracts cavitation bubbles by setting a threshold value for the ratio of the amplitude from a 3P image to that from a 1P image (3P/1P). Under the conditions in this study (imaging frequency:2.45 MHz), the proposed can filter out the regions without bubbles by performing 3P/1P with the average values in the region of interest (2 × 2 mm2) and setting a threshold of −20 dB.