Direct spatiotemporal localization of microbubble trajectories for highly resolved hemodynamics in ultrasound localization microscopy

Abstract

Using high concentrations of microbubbles in ultrasound localization microscopy can reduce acquisition time but is also associated with reduced localization precision and accuracy of blood flow measurements. To address these limitations, we introduce Ultrasound Spatio-Temporal Localization (USTL), a novel approach that localizes microbubble trajectories using a spatiotemporal physiological constraint, in contrast to standard approaches that detect, pair, and track microbubbles over time without a priori. We tested USTL in vivo in the brains of rats and mice using a 15 MHz linear array probe and a Vantage system at different concentrations of microbubbles. Overall, USTL increased the number of detected microbubbles while reducing processing time and susceptibility to signal attenuation at depth. USTL provided coherent velocity profiles in vessels regardless of microbubble concentration, making it a valuable tool for studying brain hemodynamics in various conditions. Overall, USTL offers a new approach for the non-invasive measurement of dynamic brain function with high spatial and temporal resolution.