Single Shot Quantification of Gas-Filled Microbubbles with Ultrasound

Abstract

Gas-filled microbubbles (MBs) are well-established echoenhancers that are wildly used as diagnostic tool in various medical fields. Above a certain sound pressure level, MBs burst and emit a strong signal called ”stimulated acoustic emission” (SAE), which can be detected through ultrasound imaging. Since the amplitude of the SAE signal is high enough to distinguish individual MBs within a given tissue, and it has already been shown that MBs can be coated with target-specific tracers, the SAE effect is a promising tool for highly sensitive molecular imaging with ultrasound. For a practical use of SAE for molecular imaging, however, reliable and efficient quantification of MBs within different tissues is necessary. In this work, we present a novel semi-automatic technique for the quantification of MBs, called ”single shot quantification” (SSQ). In contrast to previous approaches [Reinhardt et al. 2005], SSQ does not require a scan of the entire organ, but allows to determine the MB concentration by analyzing a time series of ultrasound frames which are scanned at a single position. The proposed technique has been implemented in a software system (see Fig. 1(a)) based on the Voreen framework [Meyer-Spradow et al. 2009].