Detection of focused ultrasound (FUS)-stimulated microbubble activity (i.e. acoustic cavitation) is a key methodology for monitoring and guidance of FUS therapies that harness the bioeffects of acoustic cavitation. The intensity and location of secondary acoustic emissions emitted by microbubbles can be passively detected and imaged using diagnostic imaging arrays. In turn, ultrasound-guided FUS (USgFUS) systems can be used for planning and evaluating the outcome of microbubble-based FUS therapies. State-of-the-art passive imaging methodologies were developed for monitoring high-intensity focused ultrasound (HIFU) ablation but suffer from poor axial image resolution due to the use of long pulses and asynchronous transmit and receive sequences. The objective of this study was thus to implement passive microbubble imaging (PMI) with short pulses of FUS and synchronous acquisition for improved image resolution by implementing reconstruction techniques similar to B-mode ultrasound imaging. The efficacy of PMI was assessed during blood-brain barrier (BBB) opening with FUS and microbubbles in mice in vivo.