Abstract
Focused ultrasound (FUS) combined with microbubbles (MBs) has been shown to locally and temporarily open the blood-brain barrier (BBB). However, concurrent opening BBB (long pulse) and mapping the location of BBB opening (short pulse) by pulsed-wave excitation always conflicts. Previously proposed passive cavitation imaging in brain suffered from degraded axial resolution because of long driving pulse and attenuation of skull in general. In this study, a coded excitation technique is combined with the dual-frequency chirp excitation (DFC excitation) method to improve these problems. The DFC excitation can generate a low-frequency chirp envelope component as the driving force of MBs cavitation by using a high-frequency pulse. The MBs cavitation was passively imaged by using chirp component with pulse compression to maintain sufficient insonation energy without any loss in the axial resolution of imaging.