Dynamic ultrasound localization microscopy

Abstract

Ultrasound localization microscopy (ULM) can map the vasculature at large depth with unprecedented resolution by localizing millions of injected microbubbles in hundreds of thousands of images acquired over a few minutes. The current state of the art in ULM is to use low concentrations to achieve the best possible spatial resolution without providing temporal information, which limits the development of functional biomarkers such as pulsality or the imaging of moving organs like the heart. In this work, we will present dynamic ultrasound localization microscopy (DULM), which enables the generation of dynamic images of the vasculature of periodic phenomena by using a combination of enhanced image formation and processing techniques to drastically increase the number of microbubbles that can be detected in each image. Specifically, we will describe how the detection of microbubbles directly in space time along with novel aberration correction algorithms and a motion-invariant Lagrangian beamforming approach can be used to increase the concentration of microbubbles 5-fold with a limited degradation in resolution. Examples of application for the mapping of pulsatility in the brain and the dynamics of the intramyocardial blood flow in 2D + t and 3D + t will be shown.