A Low-Cost Software-Defined Ultrasound System Capable of High-Speed Ultrasound Bubble Tracking

摘要

Localizing and tracking of individual bubbles is an operation required for several new imaging modalities: In ultrafast ultrasound localization microscopy (uULM) individual bubbles injected into the blood flow are localized to map the vascular network below the diffraction limit. Additionally, by tracking the bubble movement over time the streaming velocity of the fluid can be measured. For reliable localization and tracking of bubbles, an ultrafast imaging system providing a frame rate above 100 Hz over multiple seconds is required. Due to the huge amount of data (> 1 GB), data-rates (> 10 Gbit/s) and the required processing performance, ultrafast imaging is currently supported only in large research systems or expensive high-end commercial systems. In this work, we demonstrate for the first time that high-speed bubble tracking can be implemented on a low-cost ultrasound system based on a digital ultrasound probe connected to a standard PC over a high-speed digital link. Prior to implementation, we simulated the imaging system and computed a median bubble localization accuracy of 5.1 μm and 11.7 μm in lateral and axial direction respectively, with a correct bubble detection and step tracking rate of 95.8% and 99.1 %. In the experimental setup we were able to track 376 gas bubbles over 3-237 frames over a length of 0.03-29.4 mm with velocities up to 49.6 mm/s.