The study of sub-harmonic cavitation imaging based on pulse inversion technique for the monitoring of high intensity focused ultrasound therapies

For the monitoring of high intensity focused ultrasound (HIFU) therapies, cavitation detection and imaging are essential. In this paper, a sub-harmonic cavitation imaging method based on pulse inversion (PI) technique is proposed for this purpose. Using a sub-harmonic filter, PI sub-harmonic images are obtained after summation of echoes of both positive and negative pulses. Such images could display only the cavitation bubble activities, excluding the information of normal tissue and thermal lesions during HIFU therapy. The experiments with porcine muscle demonstrated that comparing with normal sub-harmonic and PI harmonic images, PI subharmonic images have higher sensitivity and contrast, which is conducive to showing cavitation bubbles.